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1
Yin, Ya Jun, Xue Wen Xie und Yong Mei Qian. „The Research of Horizontal Resistance Coefficient of Pile Lateral Soil in Horizontal Loads“. Applied Mechanics and Materials 501-504 (Januar 2014): 228–33. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.228.
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By finite element method and on the basis of measured data of horizontal static test of pile foundation, the article analyzed horizontal lateral resistance of pile lateral soil under the interaction of piles and soil and horizontal resistance coefficient of foundation soil. The results prove that weighting horizontal resistance coefficient ( m) of foundation soil and the displacement of pile top changed in the reduce of hyperbolic. Meanwhile, it indicates that the constraints of pile top can enhance pile horizontal resistance obviously.
2
Griffiths, Terry, David J. White, Scott Draper, Adam Leighton, Liang Cheng, Hongwei An und Antonino Fogliani. „Lateral resistance of “rigid” pipelines and cables on rocky seabeds“. Canadian Geotechnical Journal 56, Nr. 6 (Juni 2019): 823–39. http://dx.doi.org/10.1139/cgj-2018-0208.
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Accurate assessment of lateral resistance is critical to ensure the on-bottom stability and integrity of subsea pipelines and cables in the oil–gas and marine renewable energy industries. However, on rocky seabeds recommended practices provide limited recommendations on pipe–seabed interaction, suggesting only a single value for the friction coefficient of 0.6. This paper reports on a programme of physical experiments and theoretical modelling investigating the lateral resistance of pipes on rocky seabeds. It is shown that the peak and mean effective friction can significantly exceed the interface (or Coulomb) friction coefficient when the pipe diameter (D) is similar to the median rock diameter (dn50). Only when the pipe diameter becomes large compared to the rock size does the mean effective friction approach the interface friction. The effective friction coefficient was found to vary with variability in rock size and shape, as well as the length of pipe relative to median rock diameter. Each of these findings is reproduced well using the theoretical model. Collectively, the results demonstrate that the effective lateral friction coefficient may be higher than 0.6 for mean friction, and significantly higher for peak friction. This implies that inaccuracy may exist in current design, which may be rectified using the theoretical model.
3
Kong, L. G., und L. M. Zhang. „Experimental study of interaction and coupling effects in pile groups subjected to torsion“. Canadian Geotechnical Journal 45, Nr. 7 (Juli 2008): 1006–17. http://dx.doi.org/10.1139/t08-038.
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Piles in a pile group subjected to torsion simultaneously mobilize lateral and torsional resistances. Hence, complicated pile–soil–pile interaction effects and load deformation coupling effects occur in the pile group. In this study, a series of centrifuge model tests were carried out to investigate these effects in three-diameter spaced 1 × 2, 2 × 2, and 3 × 3 pile groups subjected to torsion in both loose and dense sands. The test results showed that the effect of horizontal movement of a pile on lateral behaviors of its adjacent piles is significant in 3 × 3 pile groups and such effect varies with group configuration and pile position. The p-multiplier concept can be used to quantify the effect and values for the p-multiplier are suggested. The effect of lateral movement of a pile on the torsional resistances of its adjacent piles and the effect of torsional movement of a pile on the lateral resistances of its adjacent piles were found to be minor in these tests. For an individual pile in a pile group subjected to torsion, the mobilized lateral resistance was found to substantially increase the torsional resistance of the pile. Such a coupling effect is quantified by a coupling coefficient, β, which describes the contribution of subgrade reaction to the increase of torsional shear resistance.
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Skvortsov, K. D., und A. I. Osokin. „Optimization of the formulaof the design resistance of soil“. Вестник гражданских инженеров 17, Nr. 5 (2020): 117–22. http://dx.doi.org/10.23968/1999-5571-2020-17-5-117-122.
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The assumptions made in the derivation of the formula for the design soil resistance are considered. It is shown that in the conditions of the plane problem, taking into account the coefficient of lateral soil pressure leads to lower values of the initial critical load and, consequently, to a decrease in the design resistance. The equation of limiting equilibrium is implemented in the MathCad software package, which makes it possible to obtain isolines of deviation angles at any depth from the applied uniformly distributed load. To determine the initial critical load, a formula is given that takes into account the coefficient of lateral soil pressure K0. In the final part of the article, the solution to the problem is given according to the formula of N. P. Puzyrevsky and according to the formula derived by the author, taking into account K0, the difference in the isolines of the deflection angles is presented, and an analysis of a similar problem in the Plaxis 2D software package is carried out.
5
Hosseini, Ahmad, und Morteza Esmaeili. „Effect of different contact surfaces between concrete sleeper and ballast on mobilized lateral resistance against impact loads“. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 231, Nr. 6 (07.03.2016): 678–89. http://dx.doi.org/10.1177/0954409716636924.
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The amount of ballast particles surrounding a railway track significantly influences its resistance in all directions. As time goes by, with the development of high-speed trains, more attention has been paid to this issue owing to the increase in dynamic effects of rolling stock on track loading. The focus of the present study is on the investigation of the interaction between different surfaces (base, crib, and shoulder) of concrete sleeper and their adjacent ballast layer along with the related parameters under lateral impact loading condition. In this regard, by utilizing a pendulum loading test device, a number of lateral impact tests were conducted on an instrumented concrete sleeper in laboratory. On the basis of experimental results, the average contribution of base, crib, and shoulder zones in the total dynamic lateral resistance of sleeper was calculated as 48%, 23%, and 29%, respectively. Furthermore, in the lateral impact force domain of 13–28 kN, the sleeper–ballast dynamic friction coefficient at base and crib zones varied in the ranges 0.8–1.5 and 0.5–0.6. Moreover, a maximum impact factor of 2.5 was obtained for analysis and design purposes. It should be stated that the trend of laboratory results confirmed the common static friction coefficient of 0.8.
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Li, Feng, Shen Li, Guan Nan Wu und Dong Wang. „Experimental Investigation on Four Types of Steel Plate Shear Walls“. Applied Mechanics and Materials 166-169 (Mai 2012): 657–63. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.657.
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The overall seismic performance of steel plate shear walls, including unstiffened SPSW, cross-stiffened SPSW, and SPSW with opening, SPSW with slits and holes, under low cyclic loading were tested. Contrastive analyze their hysteretic curve, loading capacity, lateral stiffness, ductility and energy dissipation coefficient. Results indicate that the unstiffened SPSW seem to be with high resistance lateral stiffness and carrying capacity; however its hysteretic curve show pinch effect obviously. When cross-stiffener was set on unstiffened SPSW, the resistance lateral stiffness and loading capacity can be significantly improved. However, the pinch effect of hysteretic curve does not distinctly change. The resistance lateral stiffness and loading capacity of SPSW with holes and slits is lower, however hysteretic curve is full. In addition, the energy dissipation capacity and the phenomenon which the thin steel plate shear wall shows the zero stiffness even negative stiffness at the point of zero displacement under cyclic loading are dramatically improved.
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Shobolova, Т. А., S. V. Obolensky und Yu А. Kabalnov. „RADIATION RESISTANT BIPOLAR SOI TRANSISTORS“. Electronic engineering Series 2 Semiconductor devices 258, Nr. 3 (2020): 34–42. http://dx.doi.org/10.36845/2073-8250-2020-258-3-34-42.
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In this paper the new design of lateral bipolar transistors is presented, made on the basis of the charge carrier transport modeling. New design provides high level of base current transmission coefficient and enhanced radiation resistance. The manufacturing technology of the lateral bipolar transistors is compatible with a submicron SOI CMOS technology and can be of vital importance when developing RF analogue-to-digital microcircuits for ionizing radiation resistant satellite-navigation equipment.
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Yang, Yi Bo, Zhao Qiong Lai, Li Tao Ai, Wen Ying Guo, Hong Jian Huang und Heng Chang Wang. „Experimental Research on the Evaluation Method of the Resistance to Chloride Ion Penetration of Autoclaved PHC Pile“. Key Engineering Materials 629-630 (Oktober 2014): 587–92. http://dx.doi.org/10.4028/www.scientific.net/kem.629-630.587.
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The usage of autoclaved PHC pile in chloride environment becomes common, so how to evaluate the resistance to chloride ion penetration of autoclaved PHC pile becomes urgent. This article Compare the resistance to chloride ion penetration of pile and pile concrete specimens based the Rapid Chloride Migration Synthesis Method and RCM. The results show that the Rapid Chloride Migration Synthesis Method is not suitable for pile, RCPT and RCM are suitable for pile; the resistance to chloride ion penetration of the pile inner and outer lateral concrete has a rather large different, so the sample must distinguish the direction when testing. Steel bar has little influence on the resistance to chloride ion penetration of autoclaved PHC pile, and the resistance to chloride ion penetration of pile outer lateral concrete is similar with pile concrete specimen, using pile concrete specimen to test the resistance to chloride ion penetration of autoclaved PHC pile is suitable. The chloride diffusion coefficient values have a good relationship with the electricity value, using the electricity value of square pile concrete specimen as commonly quality control way are suggested. The resistance to chloride ion penetration of pile can test the outer lateral concrete of pile or pile head, using the electricity value as daily quality control method and basis for project acceptance, and using RCM method as life assessment and basis for project acceptance.
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Luo, Guanwen, Leming Cheng, Liyao Li, Junfeng Wang, Xiaoguo Jiang und Weiguo Zhang. „Effect of Connection Resistance between Cyclones and Backpass on Furnace Solids Suspension Density Profile and Circulation Rates in CFB“. Energies 14, Nr. 19 (27.09.2021): 6162. http://dx.doi.org/10.3390/en14196162.
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The connection section between cyclones and backpass is an important configuration in multi-cyclone circulating fluidized bed boilers (CFB). In this work, the resistance coefficient of different connection modes, and connection resistance distribution from each cyclone outlet to backpass (connection branch) in one mode are defined and calculated, in order to investigate their effects on furnace solids suspension density distribution and circulation rates. Three connection modes with different overall resistance coefficients were tested experimentally and analyzed by a 1.5-dimensional model in a four-cyclone scaling CFB apparatus. Both experimental and theoretical results show that, with larger overall resistance of a connection, there are more solids suspended in the furnace bottom and fewer in the top section. The investigation of the C-type connection has revealed that when the branch resistance of the connection decreases from branch No. 1–4, the solids suspension density and circulation rate from corresponding solids recycle loops (No. 1–4) increase. Moreover, the non-uniformity of connection branch resistance distribution will lead to uneven lateral solids suspension density distribution and circulation rates allocation. This effect is enhanced by growing superficial velocity.
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Yeo, Na Eun, Doo-In Kim und Myung Yung Jeong. „Compressive and Shear Resistances of Confined Water Droplet in Sliding Motion Against Hydrophobic Counterpart“. Science of Advanced Materials 12, Nr. 4 (01.04.2020): 589–93. http://dx.doi.org/10.1166/sam.2020.3671.
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The compressive and shear resistances of the water droplet confined between the hydrophobic surfaces were investigated to evaluate the effect of the micro-scale surface pattern on the repulsive capillary force and friction of droplet. The hydrophobic surfaces covered with square pillar structures in the hexagonal array were prepared and the repulsive normal load and friction coefficient of the droplet were characterized. The force measurements in the vertical and lateral directions on the droplet confined between the prepared hydrophobic surfaces revealed that the compressive resistance to the vertical motion which is identical with the repulsive capillary force increases with deformation when the deformed droplet is horizontally symmetric. On the other hand, the friction coefficient of the squeezed droplet is inversely proportional to the repulsive capillary force. It was found that the reduced pressure acting on the solid–liquid interface results in the abnormal reduction in friction coefficient. In addition, the critical hydraulic pressure analysis confirmed that the partially wetted Cassie-Baxter (CB) state is maintained during sliding motion.
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Jabonero, Christopher, Jin-Whoy Park, SungWoo Ryu, Wuguang Lin und Yoon-ho Cho. „Development of a multi-modal overlay tester for the evaluation of asphalt overlay cracking behaviors“. Canadian Journal of Civil Engineering 47, Nr. 11 (November 2020): 1258–66. http://dx.doi.org/10.1139/cjce-2019-0227.
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Reflection cracking is a critical issue in asphalt overlay pavement. Temperature variation and traffic loading are the main fracture modes acting on the material. In this paper, a multi-modal overlay tester is proposed for the evaluation of the reflection cracking resistance of an asphalt mixture, an approach that simulates three loading modes on asphalt specimens. A fine dense-grade hot mix asphalt is used as the test specimen and subjected to different loading conditions such as single Mode I, II, and III loading simulations and combined I+II and I+II+III loading simulations. Results show coefficients of variation (CVs) of 2.5%, 10.3%, and 7.4% for the Mode I, II, and III loading simulations, respectively. Furthermore, the β coefficient, with a CV of 7%, is used to represent the crack resistance of the asphalt mixture. Finally, the crack propagation occurs rapidly when subjected to tension and lateral displacement prior to repeated traffic loading simulations.
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Krasnoshchekov, Y. V. „LATERAL FORCE PERCEIVED BY CONCRETE IN THE INCLINED SECTION OF REINFORCED CONCRETE ELEMENTS“. Vestnik SibADI 15, Nr. 3 (11.07.2018): 434–44. http://dx.doi.org/10.26518/2071-7296-2018-3-434-444.
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Introduction. The article presents results of the empirical dependence analysis of transverse force in the inclined section of reinforced concrete elements.Materials and methods. Long-term application of such dependence at the reinforced concrete design demonstrates high parameters’ reliability. Thus, analyzed information could be used in innovated calculation model, which includes joint action of cross forces and bending moments.Results. The analysis of empirical dependence by the design standards seems to obtain information about the limit value of shear stresses in the compressed zone of inclined concrete and their interrelations with normal stresses. The results of the analysis were tested on computer models of the beam using finite elements. It does, however, assume that the shear resistance is specifically related to compression resistance by means of a special coefficient, which could be determined by computer simulation.Discussion and conclusions. The calculated values of the inclined section of reinforced concrete elements in the transverse bending could be specified by experimental or computer modeling.
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Zan, Yingfei, Ruinan Guo, Lihao Yuan und Zhaohui Wu. „Experimental and Numerical Model Investigations of the Underwater Towing of a Subsea Module“. Journal of Marine Science and Engineering 7, Nr. 11 (29.10.2019): 384. http://dx.doi.org/10.3390/jmse7110384.
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In underwater towing operations, the drag force and vertical offset angle of towropes are important considerations when choosing and setting up towing equipment. The aim of this paper is to study the variation in drag force, vertical offset angle, resistance, and attitude for towing operations with a view to optimizing these operations. An underwater experiment was conducted using a 1:8 scale physical model of a subsea module. A comprehensive series of viscous Computational Fluid Dynamics (CFD) simulations were carried out based on Reynolds-averaged Navier–Stokes equations for uniform velocity towing. The results of the simulation were compared with experimental data and showed good agreement. Numerical results of the vorticity field and streamlines at the towing speeds were presented to analyze the distribution of vortexes and flow patterns. The resistance components were analyzed based on the numerical result. It was found that the lateral direction was a better direction for towing operations because of the smaller drag force, resistance, and offset angle. Similar patterns and locations of streamlines and vortexes were present in both the longitudinal and lateral directions, the total resistance coefficient decreases at a Reynolds number greater than that of a cylinder.
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Prachasaree, Woraphot, Sitthichai Piriyakootorn, Athawit Sangsrijun und Suchart Limkatanyu. „Behavior and Performance of GFRP Reinforced Concrete Columns with Various Types of Stirrups“. International Journal of Polymer Science 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/237231.
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Fiber reinforced polymer (FRP) composites are gaining acceptance in concrete structural applications due to their high ratio of strength/stiffness to self-weight and corrosion resistance. This study focused on the structural behavior and the performance of concrete columns internally reinforced with glass fiber reinforced plastic (GFRP) rebars. Twelve series of concrete columns with varied longitudinal reinforcement, cross section, concrete cover, and type of lateral reinforcement were tested under compression loading. The results show that the amount of GFRP longitudinal and lateral reinforcement slightly affects the column strength. The lateral reinforcement affects the confining pressure and inelastic deformation, and its contribution to the confined compressive strength increases with the GFRP reinforcement ratio. In addition, the confining pressure increases both concrete strength and deformability in the inelastic range. The confinement effectiveness coefficient varied from 3.0 to 7.0 with longitudinal reinforcement. The average deformability factors were 4.2 and 2.8 with spirals and ties, respectively. Lateral reinforcement had a more pronounced effect on deformability than on column strength.
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Maślak, Mariusz, Krzysztof Kuchta und Marcin Łukacz. „Bending resistance of steel beams with corrugated web under fully developed fire“. Budownictwo i Architektura 12, Nr. 2 (11.06.2013): 229–36. http://dx.doi.org/10.35784/bud-arch.2136.
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More accurate design algorithm helpful in bending resistance evaluation of steel beams with corrugated web exposed to fully developed fire is presented and discussed in detail. The condition of fire resistance limit state is proposed to be determined by the interactive formula based on the consideration of biaxial bending in which the transverse out-of-plane bending phenomenon is the spatial effect of in-plane shear. Such an influence, usually neglected in formal models dealing with the persistent design situation, can become more significant under fire conditions, when the steel yield point decreases as a consequence of the flanges temperature growth. Dependence between the material temperature and the global instability factors is considered in the methodology proposed by the authors, especially with relation to the assessment of the adequate values of lateral – torsional buckling coefficient as well as of flexural transverse buckling coefficient specified for the compressed flange. The conclusive safety condition should be supplemented by the additional interactive component in which the influence of the axial compression force is expressed, in the case when such internal force is induced in a considered beam as a result of thermal strains constrainment.
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Lee, Allan Y. „Coordinated Control of Steering and Anti-Roll Bars to Alter Vehicle Rollover Tendencies“. Journal of Dynamic Systems, Measurement, and Control 124, Nr. 1 (18.09.1998): 127–32. http://dx.doi.org/10.1115/1.1434982.
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A Variable Dynamic Testbed Vehicle is presently being built for the National Highway Traffic Safety Administration. It will have four-wheel steering, front and rear active antiroll bar systems, four adjustable dampers, and other active controls. Using these active devices, we can alter the vehicle’s understeer coefficient, front/rear load transfer distribution in high-g lateral maneuvers, and roll mode frequency and damping. This study investigates how these active systems could be controlled to alter the vehicle rollover tendencies. In particular, we study how an increased front antiroll bar stiffness, in conjunction with an increased front damper rate and out-of-phase rear steering could improve vehicle rollover resistance and enhance vehicle safety. Similar but “reverse” algorithms could be used to artificially degrade the rollover resistance of a vehicle. Rollover-related accidents could then be studied using such a vehicle. Results obtained could also provide guidelines for the safe operation of the variable dynamic vehicle in limit lateral maneuvers.
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RYNIEWICZ, Wojciech, Mariola HERMAN, Anna M. RYNIEWICZ, Łukasz BOJKO, Paweł PAŁKA, Andrzej RYNIEWICZ und Tomasz MADEJ. „TRIBOLOGICAL TESTS OF THE NANOMATERIALS USED TO RECONSTRUCT MOLARS AND PREMOLARS WITH THE APPLICATION OF THE DIRECT METHOD“. Tribologia 273, Nr. 3 (30.06.2017): 155–64. http://dx.doi.org/10.5604/01.3001.0010.6253.
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Physiological abrasion of teeth is a process of gradual loss of the hard tissue of opposite teeth resulting from age-related natural dental wear. In abrasion, the cusps and their slopes in the jaw and the mandible become flattened due to the mechanical load applied. The aim of this paper is to carry out a tribological and microstructural evaluation of modern composite materials used to reconstruct the teeth in the lateral part of the dental arch. Five light-cured composite materials were selected for tests. The tests involved the coefficient of friction and resistance to wear in a sliding contact in the presence of artificial saliva and the microstructure of the external surface of samples before the wear process and in the wear-related damaged area. The test method applied, which combines a biomechanical analysis of resistance to wear and the analysis of the microstructure before the wear process and in the wear-related damaged area, makes it possible to evaluate the tribological properties of composite materials used to reconstruct teeth in the lateral part of the dental arch.
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Beltaos, S. „Configuration and properties of a breakup jam“. Canadian Journal of Civil Engineering 15, Nr. 4 (01.08.1988): 685–97. http://dx.doi.org/10.1139/l88-089.
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Favourable weather conditions in January, 1986, resulted in a breakup jam on the Thames River that froze in place. This afforded safe access and performance of detailed thickness measurements that are normally not possible to obtain. The thickness of the jam is highly variable in the lateral direction but without consistent trends, which, in a crude sense, justifies the assumption of lateral uniformity made for analytical purposes. In the downstream direction, the thickness increased, except for a short reach downstream of the toe where it rapidly decreased to zero. Approximate assessment of the absolute roughness of the jam indicated fair agreement with earlier deductions based on hydraulic resistance data. Using existing theoretical concepts, it was deduced that the downstream portion of the jam was likely formed by "shoves" or internal collapse ("wide") whereas the upstream portion was likely formed by frontal progression ("narrow") and juxtaposition. For the former reach, the present data enabled approximate evaluation of coefficients utilized in pertinent theories. Agreement with previously published values was good, though in one instance there are no previous field determinations. To study the decline of jam thickness past the toe, the "wide" jam theory was adapted to describe a jam overlain by solid ice cover. This enabled approximate determination of the friction coefficient between the jam and the cover. Key words: breakup, coefficients, hydraulics, ice, internal collapse, jam, river, roughness, theory, thickness.
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Baronins, Janis, Vitali Podgursky, Maksim Antonov, Sergei Bereznev und Irina Hussainova. „Electrochemical Behaviour of TiCN and TiAlN Gradient Coatings Prepared by Lateral Rotating Cathode Arc PVD Technology“. Key Engineering Materials 721 (Dezember 2016): 414–18. http://dx.doi.org/10.4028/www.scientific.net/kem.721.414.
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TiCN and TiAlN gradient coatings were deposited on the AISI 316L stainless steel substrates by lateral rotating cathode arc (LARC) physical vapour deposition (PVD) technology. Corrosion and tribocorrosion behaviour was studied in 3.5 wt. % NaCl solution. The thickness of coatings was about 3 μm. For both coatings the corrosion potential shifted to more positive values as compared to the uncoated substrate. The corrosion current density decreased for TiCN and TiAlN coatings indicating up to 40 folds higher polarization resistance. The coefficient of friction value of TiCN coating is three times lower and durability is six times higher than that of TiAlN coating under the same tribocorrosion conditions.
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Holzheimer, G., und D. Winne. „Influence of distension on absorption and villous structure in rat jejunum“. American Journal of Physiology-Gastrointestinal and Liver Physiology 256, Nr. 1 (01.01.1989): G188—G197. http://dx.doi.org/10.1152/ajpgi.1989.256.1.g188.
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In urethan-anesthetized rats the appearance rates of urea (U), antipyrine (A), and alpha-methyl-D-glucoside (MG) in the venous blood of perfused jejunal segment were measured in the undistended state and after elevation of the intraluminal pressure up to 10 cmH2O. Serosal and inner cylindrical surface area of the jejunal segment were enlarged by maximally 100 and 150%, respectively. The absorption rates, however, increased only by 34 (U), 28 (A), and 26% (MG). The increase of the supravillous diffusion resistance contributed only partially to this effect. The "cylindrical" permeability coefficient (Pcyl, average permeability coefficient related to inner cylindrical area, neglecting villous structure) decreased by 39, 57, and 50%, respectively. Due to circular stretching, broad intervillous spaces were formed that covered finally approximately 40% of the mucosal surface area. The additional intervillous diffusion resistance in these spaces was more effective than the absorption through the lateral surface of the villi. Thus the overall permeability of the mucosa, i.e., Pcyl, was reduced. Calculations based on a simplified model of the mucosa confirmed the experimental results.
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Zachariah, S. G., und J. E. Sanders. „Standing interface stresses as a predictor of walking interface stresses in the trans-tibial prosthesis“. Prosthetics and Orthotics International 25, Nr. 1 (April 2001): 34–40. http://dx.doi.org/10.1080/03093640108726566.
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Interface pressures and shear stresses within the socket, in standing and walking, were measured for two unilateral, male, trans-tibial amputee subjects, during two sessions each. The ratios of equal weight-bearing standing stresses to peak walking stresses showed regional variation, ranging from 0.24:1 for pressure over the anterior region to 1.01:1 for resultant interface shear stress over the lateral region. Interface stresses in standing were only moderate predictors of peak walking stresses. The best correlation coefficient between standing in full weight-bearing and peak walking stress was 0.88 for pressure over the lateral region. As the amputees progressed from minimal to full weight-bearing in standing, and then to walking, the interface stresses increased in a nonlinear fashion, consistent with the assumption that the anterior tibia provides much resistance to the bending moment in the sagittal plane during walking.
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Bagheri, Ahmad, Shahram Azadi und Abbas Soltani. „A combined use of adaptive sliding mode control and unscented Kalman filter estimator to improve vehicle yaw stability“. Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 231, Nr. 2 (07.10.2016): 388–401. http://dx.doi.org/10.1177/1464419316673960.
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In this paper, an adaptive sliding mode controller is proposed to improve the vehicle yaw stability and enhance the lateral motion by direct yaw moment control method using active braking systems. As the longitudinal and lateral velocities of the vehicles as well as many other vehicle dynamics variables cannot be measured in a cost-efficient way, a robust control method combined with a state estimator is required to guarantee the system stability. Furthermore, some parameters such as the tyre–road friction coefficient undergo frequent changes, and the aerodynamics resistance forces are often exerted as a disturbance during the wide driving condition. So, an adaptive sliding mode controller is applied to make vehicle yaw rate to track its reference with robustness against model uncertainties and disturbances and a non-linear estimator based on unscented Kalman filter is used to estimate wheel slip, yaw rate, road friction coefficient, longitudinal and lateral velocities. The estimation algorithm directly uses non-linear equations of the system and does not need the linearization and differentiation. The designed controller, which is insensitive to system uncertainties, offers the adaptive sliding gains to eliminate the precise determination of the bounds of uncertainties. The sliding gain values are determined using a simple adaptation algorithm that does not require extensive computational load. Numerical simulations of various manoeuvres using a non-linear full vehicle model with seven degrees of freedom demonstrate the high effectiveness of the presented controller for improving the vehicle yaw stability and handling performance.
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Makarov, Vladimir, Yuriy Molev, Dimitriy Proshin und Maksim Cherevastov. „Response of Motor Vehicles, Front and Rear Axles of Which Are Fitted with Different Tires. Main Aspects“. MATEC Web of Conferences 329 (2020): 01012. http://dx.doi.org/10.1051/matecconf/202032901012.
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This work shows the modelling of change of such a controllability indicator as the stabilization time, using the design model of a vehicle with tires of different stiffness on the front and rear axles. The influence of the change in the lateral slip resistance coefficient of the front and rear wheels of the vehicle on the safe speed at which the stabilization reaction of the vehicle to the steering wheel turn will be aperiodic monotonic rather than oscillating, is established. The dependences of the magnitude of the stabilization time on the degree of change in the lateral slip resistance coefficient of the front and rear wheels, are obtained. The limiting values of the change in the parameters of the wheels providing the specified parameters of controllability which ensure acceptable road traffic safety level, are established. It is established that the maximum impact on the deterioration of the response of vehicle is exerted by the wheels design. On the other hand, their geometric dimensions have little to no road traffic safety impact. Based on the research carried out, it is necessary to conclude that in order to ensure road traffic safety, it is necessary to stop using the tires with different designs on different axles of the vehicle. Herewith, the pressure in the tires of the vehicle must not be less than the values set by the manufacturer. The results obtained are of interest to employees of institutions monitoring traffic indicators and technical condition of vehicles as well as carrying out road accident reviews.
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Fitriadhy, Ahmad, Sun Yin Lim und Adi Maimun. „Prediction of an Optimum Total Resistance Coefficient on Catamaran using Design of Experiment (DOE) Incorporated with CFD Approach“. EPI International Journal of Engineering 3, Nr. 1 (01.09.2020): 74–83. http://dx.doi.org/10.25042/epi-ije.022020.11.
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In presence of complex hydrodynamic interferences between two demihulls on a catamaran ship has been prone to have a reliable prediction to her optimum total resistance. To achieve this, the author presents a Computational Fluid Dynamic (CFD) modelling incorporated with Design of Experiment (DOE) approach. Several parameters such as effect of Froude number ( ) with respect to various lateral separation ratios (S/L) of the catamaran have been taken into account. Here, the optimum total resistance coefficient (CT) has been mainly set within the range of S/L ratio 0.2 ≤ S/L ≤ 0.4 associated with Froude number 0.56 ≤ ≤ 0.66. The primary objective function of this optimization model has led towards minimizing a drag force and increased a lift force with respect to the above S/L ratios. In general, the simulation results had seemed quantitative similarity values for the optimum of 0.6589, 0.6599 and 0.6596 with S/L ratios of 0.2, 0.3 and 0.4, respectively. In the case of = 0.56, the optimum S/L ratios of 0.2993 and 0.3988 have resulted in insignificant reduction of CT by 0.62% and 0.32% as compared to S/L of 0.3 and 0.4, respectively. Similarly, the optimum S/L ratios of 0.2750 and 0.3750 with = 0.66 have led to reduce by 0.14% and 0.46% as compared to S/L of 0.3 and 0.4, respectively. This CFD simulation results are very useful as preliminary data for the optimised ship resistance, which is mainly required to predict a ship powering in the early design stage.
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Kennedy, J. A., und J. J. Dias. „Effect of triggering and entrapment on tendon gliding properties following digital flexor tendon laceration: in vitro study on turkey tendon“. Journal of Hand Surgery (European Volume) 39, Nr. 7 (03.06.2013): 708–13. http://dx.doi.org/10.1177/1753193413490898.
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The optimal management of partial flexor tendon laceration is controversial and remains a clinical challenge. Abnormal tendon gliding (triggering and entrapment) was assessed at the A2 pulley in 40 turkey tendons in three groups: intact, partially divided (palmar or lateral), and trimmed. Testing was of gliding resistance and friction coefficient at 30° and 70° of flexion, loaded with 2 and 4 N. We observed for triggering and entrapment. The changes in gliding properties were compared and analysed using Wilcoxon matched pair testing. A significant difference was found in the change in gliding properties of intact to lacerated and lacerated to trimmed tendons and between tendons that glided normally compared with those exhibiting triggering or entrapment. This suggests that palmar and lateral lacerations which, through clinical examination and visualization, are found to glide normally should be treated with early mobilization. However, partial lacerations that exhibit triggering or entrapment should be trimmed.
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Sun, Qiang, Qiu Yi Lin und Jing Wei Wu. „Determined Methods of Dynamic Stability Critical Length of the Foundation Pile“. Advanced Materials Research 261-263 (Mai 2011): 1434–38. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.1434.
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Based on the principle of elastic stability, this paper deduces the calculating formulas for dynamic stability critical length of foundation piles when lateral syntony occurs under the axial dynamic loads, and analyzes the effects on dynamic stability critical length of foundation piles from the aspects of parameters such as section dimensions of piles, horizontal resistance forces of foundation soil and excitation frequency etc. Study shows that different soil stratum has the bigger effects on the critical length of piles, while damping coefficient smaller. It also puts forward some related measures for reducing vibration of foundation piles, and can provide reference values to the practical engineering.
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DIZHUR, E. M., A. N. VORONOVSKY, A. V. FEDOROV, I. N. KOTEL'NIKOV und S. E. DIZHUR. „PRESSURE-INDUCED TRANSITION OF 2DEG IN δ-DOPED GaAs TO INSULATING STATE“. International Journal of Nanoscience 06, Nr. 03n04 (Juni 2007): 209–13. http://dx.doi.org/10.1142/s0219581x07004602.
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The tunneling and the lateral conductance of 2DEG formed in the GaAs with the δ-doped layer were measured simultaneously at hydrostatic pressures at helium temperatures. The resistivity of the δ-doped layer sharply increases by > 3 orders of magnitude at about 2 GPa, and its temperature coefficient changes from ~ - 0.04 to ~ - 4 K -1. The tunneling resistance shows only slight change of exponential behavior at about 1.5 GPa, while a drastic change of the Zero Bias Anomaly (ZBA) takes place just at the metal–insulator transition. Such a behavior is interpreted in terms of pressure dependence of the GaAs band structure and the DX-level position.
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Azinović, Boris, David Koren und Vojko Kilar. „Principles of Energy Efficient Construction and their Influence on the Seismic Resistance of Light-weight Buildings“. Open Civil Engineering Journal 8, Nr. 1 (27.06.2014): 105–16. http://dx.doi.org/10.2174/1874149501408010105.
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Recently, an increasing trend of passive and low-energy buildings transferring from non earthquake-prone to earthquake-prone regions has thrown out the question about the seismic safety of such buildings. The paper describes the most commonly used details of energy efficient construction, which could be critical from the point of view of earthquake resistance. The paper focuses on the prevention of ground floor slab thermal bridge and presents a case study on the seismic response of multi-storey wooden buildings founded on the RC foundation slab lying on a thermal insulation (TI) layer made of extruded polystyrene (XPS). The structural response is investigated with reference to the following performance parameters: the building’s lateral top displacement, the ductility demand of the superstructure, the friction coefficient demand, the maximum compressive stress in the TI layer and the percentage of the uplifted foundation. A comparison between the response of models founded on a fixed base and models founded on a layer of TI with the same wooden crosslam structure differing in the number of storeys, strength capacity and subjected to earthquakes with different levels of seismic intensity is done. Regarding the building’s top displacements, the maximum compressive deformation in the TI layer, and the percentage of the uplifted foundation, the results have shown that the potentially negative influences of inserting the TI under the foundation slab could be expected only for high-rise buildings subjected to severe earthquakes. Oppositely, for the superstructure’s ductility demand and for the friction coefficient demand it was demonstrated that the largest demands could be expected in the case of low-rise buildings. The control of friction coefficient demand, which was recognized as critical parameter for analyzed wooden buildings, has shown that the capacity value could be exceeded yet in the case of moderate earthquake occurrence.
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Nagao, T. „An Experimental Study on the Way Bottom Widening of Pier Foundations Affects Seismic Resistance“. Engineering, Technology & Applied Science Research 10, Nr. 3 (07.06.2020): 5713–18. http://dx.doi.org/10.48084/etasr.3590.
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The resistance of a pier to horizontal loads, like seismic loads, is due to the flexural rigidity of its foundations and the horizontal subgrade reaction. In the event of a massive earthquake, the latter becomes very small because of the softening of the ground, while the structure may experience a large inertial force and lateral spreading pressure. Therefore, structures with high seismic resistance are required in areas with high seismicity. When a wide caisson is used as a pier foundation, a rotational resistance moment caused by the vertical subgrade reaction acting on the foundation bottom can be expected. Although this rotational resistance moment increases if the foundation is widened, in design practice the subgrade reaction coefficient is evaluated as being low under such circumstances. Therefore, even if the foundation is widened, the rotational resistance moment does not increase greatly. Rotational resistance commensurate with the increased construction cost due to foundation widening cannot be expected. In the present study, horizontal loading experiments were performed at one pier with a normal foundation and at one with widened at the bottom foundation, and the way that the widening affected the seismic performance was examined. The results show that compared with the normal foundation, the bottom-widened one experienced far less displacement and offered higher earthquake resistance.
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Li, Qiang, und Chang Gao Xia. „Research of Electric Power Steering System Assistance Characteristic Based on the Identification of the Road“. Advanced Materials Research 756-759 (September 2013): 4401–6. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.4401.
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Study of traditional assist characteristic cure does not take into account the difference of steering resistance torque caused by different road adhesion coefficient. Vehicle dynamics analysis model is established based on ADAMS/CAR. Simulation of steering wheel torque is realized under different road conditions. Departure from the ideal boost characteristics requirements and combined with ideal steering wheel torque under different speed and lateral acceleration., the article built assist characteristic curve under a certain road conditions. The system can real-time select the assist characteristic curve through identifying the vehicle traveling road conditions by the way of BP neural network. The theory provided a feasible method for the improvement of the EPS system performance.
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B., De la Cruz-Torres. „Ultrasound-guided percutaneous neuromodulation in chronic lateral elbow pain“. Revista Fisioterapia Invasiva / Journal of Invasive Techniques in Physical Therapy 02, Nr. 02 (Dezember 2019): 103–4. http://dx.doi.org/10.1055/s-0039-3401878.
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Abstract Background Lateral epicondylalgia (LE), also known as tennis elbow, refers to a painful condition around the lateral epicondyle of the humerus and the common extensor tendon, which worsens with dorsiflexion and/or wrist supination against resistance. The aim of this study was to evaluate the effect of ultrasound-guided percutaneous neuromodulation (PNM) applied to the radial nerve in relation to pain, functionality, electrophysiological excitation and the morphology of the nerve in patients with chronic lateral epicondylalgia. Material and Methods A randomized clinical trial was performed. In total, 28 patients (15 women, 13 men) with chronic unilateral LE were randomly divided into two groups: a control group (CG = 12) who did not receive any treatment and an experimental group (PNM = 16) who received a weekly session during three weeks of ultrasound-guided PNM on the affected radial nerve. Concretely, the therapy consisted of the application of an asymmetric biphasic current on the symptomatic side, with a frequency of 10 Hz, a phase duration of 250 microseconds, and sufficient current intensity to observe a contraction in the forearm during 1.5 minutes. The variables analyzed were: pain, measured via the visual analog scale (VAS); functionality, measured using the Patient-Rated Tennis Elbow Evaluation (PRTEE); the morphology of the nerve with the calculation of the cross-sectional area (CSA) and the electrophysiological excitability with the intensity-time curve (accommodation coefficient) of the radial nerve studied Results There were no differences between the two groups in the initial assessment regarding pain, functionality and nerve morphology (all comparisons obtained a p > 0.05). However, at the end of the study, the groups were significantly different. After treatment, there were significant differences in all variables: for the VAS (p < 0.001) with a large effect size (d > 0.8); for all values of the PRTEE (p < 0.001) the effect size was median (d > 0.5) and for the CSA (p = 0.001) the effect size was large (d > 0.8). Only the PNM group displayed significant increases in their values compared to the initial assessment, with a large effect size for all variables (d > 0.8). Regarding the accommodation coefficient, 75% of patients (12/16) displayed hypoexcitability of the nerve in the PNM group and 64% of patients (8/12) in the CG at the beginning of the study. After treatment, only the PNM group showed significant improvements in the pattern of excitability of the radial nerve, reaching normal nerve function in all subjects (p < 0.001). Conclusion Ultrasound-guided PNM leads to a decrease in pain and CSA of the radial nerve; furthermore, it produces an increased functionality of the elbow and normalization of the electrophysiological excitability of the affected radial nerve. Ultrasound-guided PNM appears to be an appropriate tool for the treatment of patients with chronic LE.
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Stawowiak, Michał, Marcel Żołnierz und Zenon Rożenek. „Research on the coefficient of friction of becorit K22 and K25SB linings“. New Trends in Production Engineering 2, Nr. 1 (01.10.2019): 367–75. http://dx.doi.org/10.2478/ntpe-2019-0039.
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Abstract The article presents the method and results of experimental tests of the coefficient of friction between a steel rope and friction lining. The BECORIT K22 and BECORIT K25SB floor coverings were tested. The tests were carried out in accordance with the recommendations of the new German standard: DIN 21258 – Lubricants and impregnating agents for drive discs and transport ropes in mining – safety and testing requirements. The authors in this article emphasize that the Becorit K22 and K25SB linings are used for the wheels of propeller drums of mining machines. Characterized by high coefficients of friction (μ ≥ 0.25), also in cases of extreme weather conditions on the surface. The chemical properties of BECORIT linings ensure their resistance to swelling in the event of different oils and lubricants as well as mine waters. The material of which the claddings are made ensures very good machinability during rolling of rope grooves with the use of turning or milling tools. BECORIT K22 plastic cladding is particularly suitable for use in hoisting machines, where the rope base forms a large overlap angle on the wheel grooves (max 1°31'), which causes its lateral wear faster. BECORIT K22 material in this case provides a higher service life compared to other materials. Due to the way they are mounted on the wheel, they are made as 1-piece (monolith) or bipartite. In this article, moreover, the structure and principle of operation of the measuring station on which the tests were carried out are presented in great detail.
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Anoushehei, Majid, und Farhad Daneshjoo. „Geometric Parameters and Behavior Factor of Knee-Braced Steel Frames Using Nonlinear Static Pushover (NSP) Analyses“. Modern Applied Science 10, Nr. 11 (29.07.2016): 110. http://dx.doi.org/10.5539/mas.v10n11p110.
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During the recent years, the new knee-braced frame (KBF) system has been interested to achieve a proper seismic behavior. Briefly introducing KBF, the present study evaluates the geometric parameters and behavior factor of multi-story knee-braced steel frames. The studied models include three-, five- and eight-story steel CBFs, EBFs and KBFs. Using linear static analyses, the present study evaluates lateral stiffness of knee-braced frames and plots their co-stiffness curves. Using co-stiffness curves, then, the best range is determined for geometric parameters of KBFs to achieve the proper stiffness. In addition, ductility-related seismic force reduction factor (Rμ), incremental resistance coefficient (RS), and behavior factor (R) are calculated for the frames using incremental nonlinear static analyses, and compared with the corresponding concentric and eccentric frames.
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Wijewickreme, Dharma, Hamid Karimian und Douglas Honegger. „Response of buried steel pipelines subjected to relative axial soil movement“. Canadian Geotechnical Journal 46, Nr. 7 (Juli 2009): 735–52. http://dx.doi.org/10.1139/t09-019.
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The performance of buried steel pipelines subjected to relative soil movements in the axial direction was investigated using full-scale pullout testing in a soil chamber. Measured axial soil loads from pullout testing of pipes buried in loose dry sand were comparable to those predicted using guidelines commonly used in practice. The peak values of axial pullout resistance observed on pipes buried in dense dry sand were several-fold (in excess of 2 times) higher than the predictions from guidelines; the observed high axial pullout resistance is primarily due to a significant increase in normal soil stresses on the pipelines, resulting from constrained dilation of dense sand during interface shear deformations. This reasoning was confirmed by direct measurement of soil stresses on pipes during full-scale testing and numerical modeling. The research findings herein suggest that the use of the coefficient of lateral earth pressure at-rest (K0) to compute axial soil loads, employing equations recommended in common guidelines, should be undertaken with caution for pipes buried in soils that are likely to experience significant shear-induced dilation.
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Gao, Rui, und Ling Qiang Yang. „Analysis of Rock Slope Stability Using Anti-Slide Pile“. Advanced Materials Research 446-449 (Januar 2012): 2470–73. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2470.
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Using the measured experimental field data of two faults of a rock slope engineering, based on the large number of measured data analysis results of similar projects and rock style to determine the internal friction angle of the fault.the method of how to choose the good date was given. Back analysis method and number fitting method was used to determine the cohesion of fault; anti-slide pile is the lateral force column, the relation of the four failure modes of anti-slide pile was considered. The statistical parameters of resistance of anti-slide pile was calculated by structure mechnics. The norm recommended coefficient transmission method was used to determine function of random variables of slope sliding. The results show that using back analysis method and structure mechnics method to modify the parameter can decrease the uncertainty and improve the reliability of engineering design .
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Avila, Jorge A., und Jorge Arturo Avila-Haro. „Structural Safety Review of a Building Damaged by Explosion in Mexico City“. Key Engineering Materials 713 (September 2016): 111–14. http://dx.doi.org/10.4028/www.scientific.net/kem.713.111.
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The structural assessment of a building damaged by the effects of an explosion located in Mexico City is presented. The structure consists in 12 complete levels, a thirteenth partially completed level for elevators, and a basement. The building is mainly conformed of steel frames with box columns, I-beams and trusses; peripherally reinforced concrete slabs attached to girders through shear connectors; its reinforced concrete box foundation (basement slab, grade beams and floor slab) is supported on control piles at a depth of 5.9 m. The building did not present any damage in the 1985 Mexico City earthquake; the original structural design is from the 1960’s (RCDF-66) [1], for a reduced seismic coefficient cs= 0.06. A review of the present condition of the structure against the requirements of the current RCDF-04 (transition seismic zone: Ts~1.0 s and cs=0.32; Q=2) was performed in this work [2]. Based on the three-dimensional structural behavior, spectral modal dynamic analyses were performed, including the joint work of the super-structure and the foundation. The structure does not present any lack of lateral stiffness and/or resistance problems, even after the explosion. According to the non-linear static (Push-over) analyses (with and without over-strenghts effects), the lateral capacity curves prove that the building has a slightly higher lateral capacity in the longitudinal direction and, to a lesser extent, in the short direction, than the one required in the current regulation. No corrective structural actions were needed, except for the rehabilitation of the structural elements affected by the explosion.
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Das, Mrinal K., Q. Jon Zhang, Robert Callanan, Craig Capell, Jack Clayton, Matthew Donofrio, Sarah K. Haney et al. „A 13 kV 4H-SiC n-Channel IGBT with Low Rdiff,on and Fast Switching“. Materials Science Forum 600-603 (September 2008): 1183–86. http://dx.doi.org/10.4028/www.scientific.net/msf.600-603.1183.
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For the first time, high power 4H-SiC n-IGBTs have been demonstrated with 13 kV blocking and a low Rdiff,on of 22 mWcm2 which surpasses the 4H-SiC material limit for unipolar devices. Normally-off operation and >10 kV blocking is maintained up to 200oC base plate temperature. The on-state resistance has a slight positive temperature coefficient which makes the n-IGBT attractive for parallel configurations. MOS characterization reveals a low net positive fixed charge density in the oxide and a low interface trap density near the conduction band which produces a 3 V threshold and a peak channel mobility of 18 cm2/Vs in the lateral MOSFET test structure. Finally, encouraging device yields of 64% in the on-state and 27% in the blocking indicate that the 4H-SiC n-IGBT may eventually become a viable power device technology.
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Lukaszkowicz, Krzysztof, Justyna Wiśniewska, Agnieszka Paradecka und Paulina Borylo. „Characteristics of Hybrid Coating Deposited by PVD and PACVD Process“. Advanced Materials Research 1036 (Oktober 2014): 225–29. http://dx.doi.org/10.4028/www.scientific.net/amr.1036.225.
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Deposited on hot work tool steel substrate coating system composed of AlTiCrN film covered by diamond-like carbon (DLC)-based lubricant, was the subject of the studies. The AlTiCrN and DLC layers were deposited by PVD lateral rotating ARC-cathodes (LARC) and PACVD technology on the X40CrMoV5-1 respectively. This paper provides an analysis of the microstructure, mechanical and tribological properties. Several surface sensitive techniques and methods, i.e. High Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM), Raman spectroscopy and ball-on-disk were used to performed study of the coating. TEM investigation shows an amorphous character of DLC layer. It was found that tested AlTiCrN layer has nanostructural character with fine crystallites. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.02-0.04. The investigated coating reveals high wear resistance. The coating demonstrated good adhesion to the substrate.
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Bogdanov, V. L., T. A. Vyshemyrska, A. Ya Grigorenko, N. N. Tormakhov und P. S. Flis. „RELATIONSHIP BETWEEN PARAMETERS OF THE DENTAL APPARATUS AND RESPIRATORY ORGANS IN ORTHODONTIC TREATMENT“. Ukrainian Dental Almanac, Nr. 2 (29.06.2021): 87–94. http://dx.doi.org/10.31718/2409-0255.2.2021.16.
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The dental apparatus and the respiratory organs of the skull are closely related. Respiratory tract defects lead to mouth breathing and abnormalities in the development of the dental apparatus. Elimination of dental anomalies does not guarantee against recurrence of dental diseases and encourages the improvement of methods of comprehensive examination and diagnosis. There are many methods for determining the transverse parameters of the facial skull: by diagnostic models or by frontal teleradiography. These methods do not always reflect the true position of the facial skull. We have proposed a method of measuring the transverse dimensions of the upper jaw and upper respiratory tract using computed tomography, which through the use of appropriate mathematical modeling can improve the diagnosis of respiratory organs and dental apparatus during orthodontic treatment.
In the clinic of the dental medical center of the National Medical University. O.O. Bogomolets underwent orthodontic treatment of children with the first form of gnatal mesial occlusion according to Betelman. Treatment of mesial occlusion was performed using a fixed device for transverse dilation of the upper jaw. From the patients treated, we selected a group of 17 boys and 20 girls. Children aged 7 to 12 years had the first molars, clinically established 3rd or 2nd grade molar defects, congestion of more than 3 millimeters and nasal breathing problems. Before and after treatment with computed tomography, three distances of the upper jaw were measured: between the medial-palatine mounds of the first permanent molars, between the bones of the alveolar arch at the level of the resistance center of the first permanent molar, and between the cortical plates of the basal arch at the resistance center of the first permanent molars. In addition, three distances of the upper respiratory tract were measured: between the lateral points of the nasal walls at the level of the large palatal canals, between the lateral points of the nasal walls at the level of the large palatal canals and between the rudiments of the canines at the level of the pear-shaped opening.
The results of changes in these parameters of the facial skeleton were subjected to statistical processing to determine the maximum and minimum values, mean, confidence interval. Testing the hypothesis of the normal distribution of sample data by the Shapiro-Wilk test showed that the frequency distribution of measurement data in the samples is close to normal.
The closeness of the relationship between the parameters of the facial skeleton was assessed by the correlation coefficient and the adequacy of these coefficients - by Student’s criterion. As a result, there was no statistically significant dependence of the change in the distance between the medial palatine mounds of the first permanent molars on changes in the distances between the bones of the alveolar arch at the resistance center of the first permanent molar, between the cortical plates of the basal arch at the level of the center of resistance of the first permanent molars and the lateral points of the nasal walls at the level of the large palatal canals. It is shown that the change in the distance between the lateral points of the nasal walls at the level of the large palatal canals is statistically weakly related to the change in the distance between the medial palatal mounds of the first permanent molars and is not related to other parameters considered.
Linear regression equations were constructed between the parameters of the change in the transverse dimensions of the facial skeleton. Verification of these models by Fisher's parameter showed their adequacy in general. Additional verification of the adequacy of the constant coefficients included in these models, according to Student's test, showed that the free member in the model changes the distance of the upper respiratory tract between the lateral points of the nasal walls at the level of the large palatal canals from the change in the distance between the cortical plates of the basal arch at the level of the center of resistance of the first permanent molars is not statistically significant. The rejection of the free term in this regression dependence led to an increase in the Fisher and Student criteria, which indicates an increase in the adequacy of this equation. The obtained regression equations allow predicting the change of some transverse dimensions of the facial skeleton depending on the change of others in the treatment of mesial occlusion and thus can improve the diagnosis of patients.
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Ji, Guomin, und Muk Chen Ong. „On-Bottom Stability of Umbilicals and Power Cables for Offshore Wind Applications“. Energies 12, Nr. 19 (24.09.2019): 3635. http://dx.doi.org/10.3390/en12193635.
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With the increase in offshore wind farms, the demands for umbilicals and power cables have increased. The on-bottom stability of umbilicals and power cables under the combined wave and current loading is the most challenging design issue, due to their light weight and the complex fluid–cable–soil interaction. In the present study, the methodology for dynamic lateral stability analysis is first discussed; and the reliable hydrodynamic load model and cable–soil interaction model based on large experimental test data are described in detail. The requirement of the submerged weight of a cable w s to obtain on-bottom stability is investigated for three types of soil (clay, sand and rock), using the finite element program PONDUS, and the results are w s , r o c k > w s , c l a y > w s , s a n d under the same load conditions. Several different aspects related to optimization design of the on-bottom stability are explored and addressed. There is a significant benefit for the on-bottom stability analysis to consider the reduction factors, due to penetration for clay and sand soil. The on-bottom stability is very sensitive to the relative initial embedment z 0 / D for clay and sand soil, due to the small diameter of the cables, and therefore, reliable prediction of initial embedment is required. In the energy-based cable–soil interaction model, the friction coefficient μ and the development of penetration affect each other and the total effect of friction force F f and passive resistance F r is complicated. The effect of the friction coefficient μ on the on-bottom stability is different from engineering judgement based on the Coulomb friction model. The undrained shear strength of clay is an important parameter for the on-bottom stability of umbilicals and cables. The higher the undrained shear strength of the clay, the larger the lateral displacement. Meanwhile, the submerged weight of sand has a minor effect on the lateral displacement of cables. The method used in the present study significantly improves the reliability of the on-bottom stability analysis of umbilicals and power cables for offshore wind application.
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Markogiannaki, Olga, und Ioannis Tegos. „Strengthening of a Multistory R/C Building under Lateral Loading by Utilizing Ties“. Applied Mechanics and Materials 82 (Juli 2011): 559–64. http://dx.doi.org/10.4028/www.scientific.net/amm.82.559.
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The scope of the study is to examine of the possibility of applying steel ties, which can consist of common steel wires, as means to restrain the seismic displacements of buildings structural systems. The method seems to be competitive to the conventional ones, since fewer disturbances are created during the retrofitting works, i.e. the installation of ties as compared to the conventional strengthening methods. The method also proved to be more economic than the conventional method of constructing and infilling concrete walls in the vulnerable structural system. Initially, the efficiency of the ties was studied in multistory building models, such as frame, combined frame-wall and combined frame-wall without beams. Based on the results of the analytical study, the method was applied on a 5 storey existing and seismically deficient building. More specifically, the long side of the building was chosen for the method’s application. The last choice was deemed more preferable due to the fact that it has no openings which allowed the easy application of straight ties. The one end of the ties is anchored in the concrete slab of the upper stories, while the other end on the basement’s upper concrete slab. Although the seismic demand was higher for the implemented solution of the steel wires due to multiple loading, caused by the low value of the seismic performance coefficient equal to 1.5, an adequate level of earthquake resistance was achieved. The results of the case study confirmed the applicability of the proposed method. It should be underlined that the ties method looks promising in the field of structures retrofitting and could be studied analytically in campaigns, either independently or in combination with the conventional in concrete shear wall method.
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Timofeev, Pavel. „FLOW SIMULATION OVER REENTRY CAPSULE AT SUPERSONIC AND HYPERSONIC SPEEDS. THE COMPARE BETWEEN TWO REENTRY CAPSULES. PART 2“. Perm National Research Polytechnic University Aerospace Engineering Bulletin, Nr. 62 (2020): 52–60. http://dx.doi.org/10.15593/2224-9982/2020.62.06.
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This study is a continuation of the first part “Flow simulation over reentry capsule at supersonic and hypersonic speeds. The comparison between two reentry capsules. Part 1”. This study presents a comparison between two reentry capsules, which are made in Russia. Numerical algorithms solve for the CFD method, which is produced using help ANSYS Fluent 19.2. The using GPU core to get a solution faster. The main purpose – flow simulation and numerical analysis two tips reentry capsule understand the behavior of supersonic and hypersonic flow and its effect on the reentry capsule; compare temperature results and compare drag coefficient for the range Mach numbers equals 2–6. This study showed results on velocity counters, on temperature counters and drag coefficient for range Mach numbers equals 2–6. This study demonstrates the importance of understanding the effects of shock waves and illustrates how the shock wave changes as the Mach number increases. For every solves, the mesh had adapted for pressure gradient and velocity gradient to get the exact solution. As a result of the obtained solution, it is found that the “Prototype 2” reentry vehicle has a lower temperature a lateral surface, than the “Prototype 1”, but a higher temperature over the frontal segment at Mach number M = 6. A general trend has been observed, which is that the resistance drag coefficient decreases with increasing Mach number, which is associated with high height and low density and pressure values. The relevance and significance of this problem for the design of new and modernization of old reentry capsules.
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Fang, Shu, Zhen Wei Zhang und Lei Zhang. „Turning Dynamics of Series Hybrid Power All-Terrain Vehicle“. Advanced Materials Research 512-515 (Mai 2012): 2620–24. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.2620.
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The complex and unstructured working environment of all-terrain vehicle cause large resistance when they are turning. The turning power which affects a lot on the mobility of all-terrain vehicle is much larger than the power in running straight. In this paper, a series hybrid power system of an all-terrain fire robot was discussed, the turning model of the robot is simplified to 2D mechanical model, force analysis was made, a power formula in which the power is only related to the drag coefficient and relative turning radius was derived, and a dynamic model based on the driving power of lateral side and the braking power of medial side has been set up, simulation has been made in the condition of paddy field, hard soil road and asphalt road, the simulation reults shows the characteristic curve of driving power and baking power in turning, and the extreme power needed in turnning have been found.
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Alawneh, Ahmed Shlash, Abdallah I. Husein Malkawi und Husein Al-Deeky. „Tension tests on smooth and rough model piles in dry sand“. Canadian Geotechnical Journal 36, Nr. 4 (22.11.1999): 746–53. http://dx.doi.org/10.1139/t98-104.
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In order to delineate the significant variables affecting the ultimate uplift shaft resistance of a pile in dry sand, a testing program comprising 64 pullout tests was conducted on open- and closed-ended rough and smooth model piles of two sizes (41 and 61 mm outside diameter). The model piles were installed in medium dense and dense sand to an embedded depth of 0.8 m using two methods of pile placement, static jacking and driving. A rigid steel box measuring 1.1 × 1.1 × 1.3 m was used as a sand container. The results obtained from this study indicated that pile placement method, initial sand condition, pile surface roughness, and pile end type are all significant variables (given in descending order) affecting the ultimate uplift shaft resistance of a single pile in dry sand. Overall, the closed-ended piles showed a 24% increase in shaft resistance compared with the open-ended piles and the average unit shaft resistance of the driven model pile was 1.33 times that of the jacked model pile in the dense sand condition and 1.52 times that of the jacked model pile in the medium dense sand condition. Depending on the test variables, the rough model piles tested in this study experienced a 12-54% increase in capacity compared with the smooth model piles. Also, the lateral earth pressure coefficient values for the rough model piles were greater than those for the smooth model piles. This suggests that part of the increase in capacity due to pile surface roughness is attributed to an increase in the radial effective stress during tensile loading.Key words: piles, shaft resistance, pile placement method, smooth pile, rough pile.
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Chen, Yen-Shu, Kuo-Hsiang Chien, Chi-Chuan Wang, Tzu-Chen Hung, Yuh-Ming Ferng und Bau-Shei Pei. „Investigations of the Thermal Spreading Effects of Rectangular Conduction Plates and Vapor Chamber“. Journal of Electronic Packaging 129, Nr. 3 (19.12.2006): 348–55. http://dx.doi.org/10.1115/1.2753970.
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This study examines the spreading ability of rectangular plates numerically, analytically, and experimentally. The effect of aspect ratio, defined as an equivalent radius of a heater divided by that of a spreader plate, is investigated. The numerical results show a very good agreement with the analytical solutions. From the calculated results, the spreading resistance of the conduction plates with a small aspect ratio is higher than the one-dimensional conduction resistance. Calculated results also show that the spreading ability of a metal plate would be affected slightly by the external convective heat-transfer coefficient when the ratio of the longitudinal heat convection to the lateral heat spreading is less than 0.1. In addition to the numerical analysis, experimental comparisons between copper∕aluminum plates and a vapor chamber having the same thickness have been conducted. The experimental results show that the thermal resistance of the metal plates is independent of input power whereas that of the vapor chamber shows a noticeable drop with increased power. For the influence of concentrated heat source, the surface temperature distributions for the metal plates become concentrated with a reduced aspect ratio. However, the variations of the aspect ratio and the input power would yield minor effects to the surface temperature distribution of the vapor chamber. As compared with the conduction plates, the vapor chamber would offer a lower temperature rise and a more uniform temperature distribution. Thus, the vapor chamber provides a better choice as a heat spreader for concentrated heat sources.
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Ahmed, A. M., N. A. Duncan und M. Tanzer. „In Vitro Measurement of the Tracking Pattern of the Human Patella“. Journal of Biomechanical Engineering 121, Nr. 2 (01.04.1999): 222–28. http://dx.doi.org/10.1115/1.2835107.
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This study sought to determine whether a general pattern describing the three-dimensional tracking characteristics of the human patella could be established, and if not, then to determine the extent and nature of interspecimen variations in the characteristics in a normal population. Using 32 fresh-frozen knees subjected to extensor moment magnitudes similar to those in “static-lifting” and “leg-raising against resistance” maneuvers, patellar displacements were measured in the knee extension range 120 to 0 deg. For static-lifting, a constant foot-floor reaction of 334 N was applied. For leg-raising, a constant net quadriceps tension of 668 N was used throughout the extension range. Measurements were taken with a calibrated six-degree-of-freedom electromechanical goniometer and a displacement coordinate system referenced to the geometry of individual specinens. The three patellar displacements in the plane of knee extension/flexion (extension rotation, and anterior and proximal translations) consistently demonstrated the same pattern in the entire knee extension range with an average coefficient of variation of 13 percent. For knee angles greater than 45 deg, the three other displacements (medial lateral translation, and rotations about the anterior–posterior and proximal–distal axes) followed a general pattern. However, for knee angles less than 45 deg, these displacements differed considerably between specimens for each loading condition, both in terms of magnitude (average coefficient of variation: 70 percent), and direction.
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Fatemi, Hediyeh, Hongjun Zeng, John Carlisle und Reza Abdolvand. „High-Frequency Thin-Film AlN-on-Diamond Lateral–Extensional Resonators“. Microelectromechanical Systems, Journal of 22, Nr. 3 (Mai 2013): 678–86. http://dx.doi.org/10.1109/jmems.2013.2240259.
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In this paper, low-impedance lateral–extensional microresonators are fabricated on a stack of aluminum nitride (AlN) directly deposited on a polished ultrananocrystalline diamond (UNCD) film. The large acoustic velocity of UNCD is utilized to extend the frequency of such resonators beyond 1 GHz while the frequency-defining features are not reduced excessively. In order to promote the growth of a <jats:formula formulatype="inline"><jats:tex Notation="TeX">$c$</jats:tex> </jats:formula>-plane piezoelectric AlN film, the surface of the UNCD film is polished after deposition. Three different UNCD films with different Young's modulus values were prepared, and frequencies up to two times that of similar devices fabricated on silicon have been achieved. The finite-element analysis is employed to evaluate the effect of various physical parameters on the performance of the thin-film piezoelectric-on-substrate resonators in order to achieve very low motional resistance <jats:formula formulatype="inline"><jats:tex Notation="TeX" >$(R_{m})$</jats:tex></jats:formula>. Several resonators were designed with various lateral dimensions and different numbers of support tethers to evaluate the propositions. The lowest <jats:formula formulatype="inline"><jats:tex Notation="TeX" >$R_{m}$</jats:tex></jats:formula> was measured from a multitethered 29th-order thin-film piezoelectric-on-diamond (TPoD) resonator (22 <jats:formula formulatype="inline"><jats:tex Notation="TeX"> $Omega$</jats:tex></jats:formula>) and <jats:formula formulatype="inline"><jats:tex Notation="TeX">$fcdot Q$</jats:tex></jats:formula> product of <jats:formula formulatype="inline"><jats:tex Notation="TeX">$2.72 ast 10^{12}$</jats:tex></jats:formula> at 888 MHz. The temperature coefficient of frequency of this TPoD resonator is measured to be <jats:formula formulatype="inline"><jats:tex Notation="TeX">$-9.6 hbox{ppm}/^{circ} hbox{C}$</jats:tex></jats:formula>, which is much lower than that of the devices fabricated on silicon. Also, this device can withstand input powers up to <jats:formula formulatype="inline"><jats:tex Notation="TeX">$+$</jats:tex></jats:formula>27 dBm, leading to a delivered power density per unit area of <jats:formula formulatype="inline" ><jats:tex Notation="TeX">$sim!!2.9 muhbox{W}/muhbox{m}^{2}$</jats:tex> </jats:formula>.<jats:formula formulatype="inline"><jats:tex Notation="TeX" >$hfill$</jats:tex></jats:formula>[2012-0099]
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Herms, Martin, Matthias Wagner, Alexander Molchanov, Mathias Rommel, Markus Zschorsch und Sindy Würzner. „Comparative Spatially Resolved Characterization of a Czochralski-Grown Silicon Crystal by Different Laser-Based Imaging Techniques“. Solid State Phenomena 242 (Oktober 2015): 478–83. http://dx.doi.org/10.4028/www.scientific.net/ssp.242.478.
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The axial distribution of electrical and optical properties of a 4 inch Czochralski-grown silicon single crystal were analyzed by different methods that can be applied in the scanning mode. These methods were tested with respect to the suitability to reveal growth striations. The residual stress was visualized by SIRIS (Scanning Infrared Stress Inspection System) and SIREX (Scanning Infrared Stress Explorer), the electrical resistivity by LPS (Lateral Photovoltage Scanning) and SRP (Spreading Resistance Profiling), and the lifetime of the minority charge carriers by MDP (Microwave Detected Photoconductivity) mapping. The concentration of interstitial oxygen (Oi) across the growth striations was determined by FTIR (Fourier Transform Infrared) spectroscopy. We demonstrate for the first time on the micrometer scale that the Oi scan is very well-correlated with the profile of Δσ (difference of the in-plane principal stress components). The stress field is tensile oriented in growth direction, i. e. perpendicularly to the growth striations. The stress-concentration coefficient has been estimated to be in the order of 10-13 Pa cm-3 what does agree well with previous XRD results.
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Wong, J. Y., und C. F. Chiang. „A general theory for skid steering of tracked vehicles on firm ground“. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 215, Nr. 3 (01.03.2001): 343–55. http://dx.doi.org/10.1243/0954407011525683.
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A general theory for skid steering of tracked vehicles under steady state conditions on firm ground, taking into account the shear stress-shear displacement relationship on the track-ground interface, is presented. The steering behaviour predicted using the general theory bears a strong resemblance to that observed in the field. The variations of sprocket torques for the outer and inner tracks with turning radius predicted by the general theory are in reasonably close agreement with available experimental data. On the other hand, predictions based on Steeds’ theory developed earlier differ greatly from measured results. Using the general theory, the lateral coefficient of friction used in the conventional method for predicting the moment of turning resistance of the track can be quantitatively determined as a function of turning radius. It is believed that the new theory presented in this paper provides a unified approach to the study of the mechanics of skid steering of tracked vehicles and that it may be extended to the study of transient handling behaviour of tracked vehicles.
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Zheng, Li, Zhang Wenda, Han Ruihua und Tian Yongsheng. „Design and Performance Analysis of Distributed Equal Angle Spiral Vertical Axis Wind Turbine“. Recent Patents on Engineering 14, Nr. 1 (21.06.2020): 120–32. http://dx.doi.org/10.2174/1872212113666191002150551.
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Background: The wind turbine is divided into a horizontal axis and a vertical axis depending on the relative positions of the rotating shaft and the ground. The advantage of the choke wind turbine is that the starting torque is large and the starting performance is good. The disadvantage is that the rotation resistance is large, the rotation speed is low, the asymmetric flow occurs when the wind wheel rotates, the lateral thrust is generated, and the wind energy utilization rate is lowered. How to improve the wind energy utilization rate of the resistance wind turbine is an important issue to be solved by the wind power technology. Objective: The nautilus isometric spiral wind turbines studied in this paper have been introduced and analyzed in detail, preparing for the further flow analysis and layout of wind turbines, improving the wind energy utilization rate of wind turbines, introducing patents of other structures and output characteristics of its generator set. Methods: Combined with the flow field analysis of ANSYS CFX software, the numerical simulation of the new wind turbine was carried out, and the aerodynamic performance of the new vertical axis wind turbine was analyzed. The mathematical model and control model of the generator were established by the maximum power control method, and the accuracy of the simulation results was verified by the measured data. Results: The basic parameters of the new wind turbine tip speed ratio, torque coefficient and wind energy utilization coefficient are analyzed. Changes in wind speed, pressure and eddy viscosity were investigated. Three-dimensional distribution results of wake parameters such as wind speed and pressure are obtained. By simulating the natural wind speed, the speed and output current of the generator during normal operation are obtained. Conclusion: By analyzing the wind performance and power generation characteristics of the new wind turbine, the feasibility of the new wind turbine is determined, which provides reference and reference for the optimal design and development of the wind turbine structure.