Добірка наукової літератури з теми "Elongated beam systems"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Elongated beam systems".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Статті в журналах з теми "Elongated beam systems"
1
Kuriakose, Akhil, Monica Bollani, Paolo Di Trapani, and Ottavia Jedrkiewicz. "Study of Through-Hole Micro-Drilling in Sapphire by Means of Pulsed Bessel Beams." Micromachines 13, no. 4 (April 15, 2022): 624. http://dx.doi.org/10.3390/mi13040624.
Повний текст джерелаАнотація:
Ultrashort Bessel beams have been used in this work to study the response of a 430-μm-thick monocrystalline sapphire sample to laser–matter interaction when injecting the beam orthogonally through the whole sample thickness. We show that with a 12° Bessel beam cone angle, we are able to internally modify the material and generate tailorable elongated microstructures while preventing the formation of surface cracks, even in the picosecond regime, contrary to what was previously reported in the literature. On the other hand, by means of Bessel beam machining combined with a trepanning technique where very high energy pulses are needed, we were able to generate 100 μm diameter through-holes, eventually with negligible cracks and very low taper angles thanks to an optimization achieved by using a 60-μm-thick layer of Kapton Polyimide removable tape.
2
Kim, Wook-Bae, and Sol-Yi Han. "Microinjection Molding of Out-of-Plane Bistable Mechanisms." Micromachines 11, no. 2 (January 30, 2020): 155. http://dx.doi.org/10.3390/mi11020155.
Повний текст джерелаАнотація:
We present a novel fabrication technique of a miniaturized out-of-plane compliant bistable mechanism (OBM) by microinjection molding (MM) and assembling. OBMs are mostly in-plane monolithic devices containing delicate elastic elements fabricated in metal, plastic, or by a microelectromechanical system (MEMS) process. The proposed technique is based on stacking two out-of-plane V-beam structures obtained by mold fabrication and MM of thermoplastic polyacetal resin (POM) and joining their centers and outer frames to construct a double V-beam structure. A copper alloy mold insert was machined with the sectional dimensions of the V-beam cavities. Next, the insert was re-machined to reduce dimensional errors caused by part shrinkage. The V-beam structure was injection-molded at a high temperature. Gradually elongated short-shots were obtained by increasing pressure, showing the symmetrical melt filling through the V-beam cavities. The as-molded structure was buckled elastically by an external-force load but showed a monostable behavior because of a higher unconstrained buckling mode. The double V-beam device assembled with two single-molded structures shows clear bistability. The experimental force-displacement curve of the molded structure is presented for examination. This work can potentially contribute to the fabrication of architected materials with periodic assembly of the plastic bistable mechanism for diverse functionalities, such as energy absorption and shape morphing.
3
Carta, G., M. Brun, and A. B. Movchan. "Dynamic response and localization in strongly damaged waveguides." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470, no. 2167 (July 8, 2014): 20140136. http://dx.doi.org/10.1098/rspa.2014.0136.
Повний текст джерелаАнотація:
In this paper, we investigate the formation of band-gaps and localization phenomena in an elastic strip nearly disintegrated by an array of transverse cracks. We analyse the eigenfrequencies of finite, strongly damaged, elongated solids with reference to the propagation bands of an infinite strip with a periodic damage. Subsequently, we determine analytically the band-gaps of the infinite strip by using a lower-dimensional model, represented by a periodically damaged beam in which the small ligaments between cracks are modelled as ‘elastic junctions’. The effective rotational and translational stiffnesses of the elastic junctions are obtained from an ad hoc asymptotic analysis. We show that, for a finite frequency range, the dispersion curves for the reduced beam model agree with the dispersion data determined numerically for the two-dimensional elastic strip. Exponential localization, boundary layers and standing waves in strongly damaged systems are discussed in detail.
4
Fu, Jia, Ian Richardson, and Marcel Hermans. "Microstructure Study of Pulsed Laser Beam Welded Oxide Dispersion-Strengthened (ODS) Eurofer Steel." Micromachines 12, no. 6 (May 28, 2021): 629. http://dx.doi.org/10.3390/mi12060629.
Повний текст джерелаАнотація:
Oxide dispersion-strengthened (ODS) Eurofer steel was laser welded using a short pulse duration and a designed pattern to minimise local heat accumulation. With a laser power of 2500 W and a duration of more than 3 ms, a full penetration can be obtained in a 1 mm thick plate. Material loss was observed in the fusion zone due to metal vaporisation, which can be fully compensated by the use of filler material. The solidified fusion zone consists of an elongated dual phase microstructure with a bimodal grain size distribution. Nano-oxide particles were found to be dispersed in the steel. Electron backscattered diffraction (EBSD) analysis shows that the microstructure of the heat-treated joint is recovered with substantially unaltered grain size and lower misorientations in different regions. The experimental results indicate that joints with fine grains and dispersed nano-oxide particles can be achieved via pulsed laser beam welding using filler material and post heat treatment.
5
Pantillon, Florian, Bianca Adler, Ulrich Corsmeier, Peter Knippertz, Andreas Wieser, and Akio Hansen. "Formation of Wind Gusts in an Extratropical Cyclone in Light of Doppler Lidar Observations and Large-Eddy Simulations." Monthly Weather Review 148, no. 1 (December 19, 2019): 353–75. http://dx.doi.org/10.1175/mwr-d-19-0241.1.
Повний текст джерелаАнотація:
Abstract Damaging gusts in windstorms are represented by crude subgrid-scale parameterizations in today’s weather and climate models. This limitation motivated the Wind and Storms Experiment (WASTEX) in winter 2016–17 in the Upper Rhine Valley over southwestern Germany. Gusts recorded at an instrumented tower during the passage of extratropical cyclone “Thomas” on 23 February 2017 are investigated based on measurements of radial wind with ≈70-m along-beam spacing from a fast-scanning Doppler lidar and realistic large-eddy simulations with grid spacings down to 78 m using the Icosahedral Nonhydrostatic model. Four wind peaks occur due to the storm onset, the cold front, a precipitation line, and isolated showers. The first peak is related to a sudden drop in dewpoint and results from the downward mixing of a low-level jet and a dry layer within the warm sector characterized by extremely high temperatures for the season. While operational convection-permitting forecasts poorly predict the storm onset overall, a successful ensemble member highlights the role of upstream orography. Lidar observations reveal the presence of long-lasting wind structures that result from a combination of convection- and shear-driven instability. Large-eddy simulations contain structures elongated in the wind direction that are qualitatively similar but too coarse compared to the observed ones. Their size is found to exceed the effective model resolution by one order of magnitude due to their elongation. These results emphasize the need for subkilometer-scale measuring and modeling systems to improve the representation of gusts in windstorms.
6
Mitchell, R. L., M. Coleman, P. Davies, L. North, E. C. Pope, C. Pleydell-Pearce, W. Harris, and R. Johnston. "Macro-to-nanoscale investigation of wall-plate joints in the acorn barnacle Semibalanus balanoides : correlative imaging, biological form and function, and bioinspiration." Journal of The Royal Society Interface 16, no. 157 (August 2019): 20190218. http://dx.doi.org/10.1098/rsif.2019.0218.
Повний текст джерелаАнотація:
Correlative imaging combines information from multiple modalities (physical–chemical–mechanical properties) at various length scales (centimetre to nanometre) to understand the complex biological materials across dimensions (2D–3D). Here, we have used numerous coupled systems: X-ray microscopy (XRM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), optical light microscopy (LM) and focused ion beam (FIB-SEM) microscopy to ascertain the microstructural and crystallographic properties of the wall-plate joints in the barnacle Semibalanus balanoides . The exoskeleton is composed of six interlocking wall plates, and the interlocks between neighbouring plates (alae) allow barnacles to expand and grow while remaining sealed and structurally strong. Our results indicate that the ala contain functionally graded orientations and microstructures in their crystallography, which has implications for naturally functioning microstructures, potential natural strengthening and preferred oriented biomineralization. Elongated grains at the outer edge of the ala are oriented perpendicularly to the contact surface, and the c -axis rotates with the radius of the ala. Additionally, we identify for the first time three-dimensional nanoscale ala pore networks revealing that the pores are only visible at the tip of the ala and that pore thickening occurs on the inside (soft bodied) edge of the plates. The pore networks appear to have the same orientation as the oriented crystallography, and we deduce that the pore networks are probably organic channels and pockets, which are involved with the biomineralization process. Understanding these multiscale features contributes towards an understanding of the structural architecture in barnacles, but also their consideration for bioinspiration of human-made materials. The work demonstrates that correlative methods spanning different length scales, dimensions and modes enable the extension of the structure–property relationships in materials to form and function of organisms.
7
Oi, Takao, Sakiko Enomoto, Tomoyo Nakao, Shigeo Arai, Koji Yamane, and Mitsutaka Taniguchi. "Three-dimensional ultrastructural change of chloroplasts in rice mesophyll cells responding to salt stress." Annals of Botany 125, no. 5 (November 27, 2019): 833–40. http://dx.doi.org/10.1093/aob/mcz192.
Повний текст джерелаАнотація:
Abstract Background and Aims Excess salinity inhibits the metabolism of various systems and induces structural changes, especially in chloroplasts. Although the chloroplast body seems to swell under salinity stress as observed by conventional transmission electron microscopy, previous studies are limited to 2-D data and lack quantitative comparisons because specimens need to be sliced into ultrathin sections. This study shows three-dimensionally the structural changes in a whole mesophyll cell responding to salinity stress by serial sectioning with a focused ion beam scanning electron microscope (FIB-SEM) and compares the differences in chloroplast structures based on reconstructed models possessing accurate numerical voxel values. Methods Leaf blades of rice plants treated with 100 mm NaCl or without (control) for 4 d were fixed chemically and embedded in resin. The specimen blocks were sectioned and observed using the FIB-SEM, and then the sliced image stacks were reconstructed into 3-D models by image processing software. Key Results On the transverse sections of rice mesophyll cells, the chloroplasts in the control leaves appeared to be elongated meniscus lens shaped, while those in the salt-treated leaves appear to be expanded oval shaped. The 3-D models based on serial sectioning images showed that the chloroplasts in the control cells spread like sheets fitted to the shape of the cell wall and in close contact with the adjacent chloroplasts. In contrast, those in the salt-stressed cells curled up into a ball and fitted to cell protuberances without being in close contact with adjacent chloroplasts. Although the shapes of chloroplasts were clearly different between the two treatments, their volumes did not differ. Conclusions The 3-D reconstructed models of whole rice mesophyll cells indicated that chloroplasts under salt stress conditions were not swollen but became spherical without increasing their volume. This is in contrast to findings of previous studies based on 2-D images.
8
Chesnokov, Yury, Andrey Shibaev, Roman Kamyshinsky, Vyacheslav Kralin, Olga Philippova, and Anton Orekhov. "Abstract P-3: The Structure of Self-Assembled Surfactant Micellar Networks by in situ Cryo-Electron Tomography." International Journal of Biomedicine 11, Suppl_1 (June 1, 2021): S12. http://dx.doi.org/10.21103/ijbm.11.suppl_1.p3.
Повний текст джерелаАнотація:
Background: Surfactant molecules can form various self-assembled structures in aqueous solutions, including spherical and cylindrical micelles, lamellae, vesicles, etc. Elongated cylindrical (wormlike) micelles can entangle and form a dense network. The study of the un-perturbed native structure of wormlike micelles in such networks presents a great challenge, since the micelles are formed due to weak non-covalent interactions and may easily break when external conditions are changed. In this work in situ cryo-electron tomography (cryo-ET) was applied to reveal the relaxed structure of such entangled systems. Methods: To prepare samples for the cryo-ET study 1 µl of the aqueous surfactant-containing solution was applied to the glow discharged grid, blotted with filter paper for 10 sec, drained for 60 sec to allow for the relaxation of the system and plunge-frozen with Vitrobot Mark IV. The vitrified sample was transferred to Versa 3D cryo-focused ion beam / scanning electron microscope (cryo-FIB/SEM) to prepare thin (100-150 nm) sections of the sample. Cryo-ET study was conducted using Titan Krios. IMOD and Avizo software packages were used for data processing. Results: In this work, wormlike micelles formed by a mixture of an anionic and a cationic surfactant were investigated at the excess of the anionic surfactant. Cryo-ET study of the obtained lamellae demonstrated the formation of two different phases, consisting of straight rods oriented along the grid substrate (phase 1) and isotropic network formed by wormlike micelles (phase 2) above it. The topology of the second phase corresponded to the branched saturated network or entangled network depending on cation/anion ratio of the sample. However, the analysis of the thin samples obtained without cryo-FIB demonstrated only the presence of the metastable phase (phase 1), which could lead to false conclusions regarding the morphology of the micelles. Conclusion: Here we discuss the influence of different sample preparation approaches on the sample structure and demonstrate that the native un-perturbed conformation of charged cylindrical surfactant micelles in the dense network is that of a slightly bent rod or a wormlike chain with high persistence length.
9
Xu, Menghua, Yali Qin, Kailai Ji, and Hongshun Zhang. "Primary aberrations in tightly focused polarized anomalous vortex beams." Laser Physics 32, no. 3 (January 21, 2022): 035401. http://dx.doi.org/10.1088/1555-6611/ac4912.
Повний текст джерелаАнотація:
Abstract Based on the Richards Wolf vector diffraction theory, the intensity profiles of the radially and azimuthally polarized anomalous vortex beams focused by a high numerical aperture (NA) lens in the presence of primary aberration are obtained. The effects of the primary aberration coefficient on the intensity distribution, longitudinal field and the quality of the aberrated focused field through calculating the Strehl ratio under various polarized input beams are analyzed. The results show that spherical aberration destroys the rotational symmetry of the focused intensity about the optical axis. Coma will shift the focal spot which gradually presents an obvious comet shape. Astigmatism will elongate the focal spot. Meanwhile, defocus technology on compensating aberrations is studied. The results have potential applications in the design and assembly of high NA systems or overcoming aberrations in the future.
10
Heisser, Ronald H., Vishal P. Patil, Norbert Stoop, Emmanuel Villermaux, and Jörn Dunkel. "Controlling fracture cascades through twisting and quenching." Proceedings of the National Academy of Sciences 115, no. 35 (August 13, 2018): 8665–70. http://dx.doi.org/10.1073/pnas.1802831115.
Повний текст джерелаАнотація:
Fracture fundamentally limits the structural stability of macroscopic and microscopic matter, from beams and bones to microtubules and nanotubes. Despite substantial recent experimental and theoretical progress, fracture control continues to present profound practical and theoretical challenges. While bending-induced fracture of elongated rod-like objects has been intensely studied, the effects of twist and quench dynamics have yet to be explored systematically. Here, we show how twist and quench protocols may be used to control such fracture processes, by revisiting Feynman’s observation that dry spaghetti typically breaks into three or more pieces when exposed to large pure bending stresses. Combining theory and experiment, we demonstrate controlled binary fracture of brittle elastic rods for two distinct protocols based on twisting and nonadiabatic quenching. Our experimental data for twist-controlled fracture agree quantitatively with a theoretically predicted phase diagram, and we establish asymptotic scaling relations for quenched fracture. Due to their general character, these results are expected to apply to torsional and kinetic fracture processes in a wide range of systems.
Дисертації з теми "Elongated beam systems"
1
Мариношенко, Олександр Петрович. "Динамічне деформування видовжених балкових систем набігаючим повітряним потоком". Doctoral thesis, 2010. https://ela.kpi.ua/handle/123456789/694.
Повний текст джерелаТези доповідей конференцій з теми "Elongated beam systems"
1
Williams, Eric, and Dennis Hong. "Development of a Shape Memory Alloy Composite Actuator for the Whole Skin Locomotion Robot." In ASME 2009 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2009. http://dx.doi.org/10.1115/smasis2009-1359.
Повний текст джерелаАнотація:
In this paper the development of a novel actuator is presented that utilizes a flexible shape memory alloy composite (SMAC) to generate motion for the Whole Skin Locomotion (WSL) robot. The WSL mechanism for mobile robots is inspired by how single celled organisms use cytoplasmic streaming to generate pseudopods for locomotion. This mobility mechanism is directly suited for robots traversing tight spaces where flexibility and shape changes are deemed necessary. The body of the WSL robot is comprised of an elongated fluid filled torus which turns itself inside out in a single continuous motion, effectively generating the overall motion of the cytoplasmic streaming ecto-plasmic tube in amoebae. The eversion of the entire outer skin of the WSL is driven by a pair of the SMAC actuators in the shape of a torus. The actuation of the SMAC is accomplished by the individually controlled shape memory alloy wires embedded in an elastic beam that is then deformed into a torus shape. The design of the first prototype, fabrication efforts as well as a qualitative model of the behavior are presented. Experiments validating aspects of the modeling are also discussed.
2
Choi, Eunsoo, Dong Joo Kim, Young-Soo Chung, and Chungsung Jung. "Crack-Curing of Concrete Beams Using Cold-Drawn SMA Reinforcing Fibers." In ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/smasis2014-7646.
Повний текст джерелаАнотація:
This study used NiTi shape memory alloy (SMA) wires of 1.0 mm diameter to manufacture reinforcing fibers for cement composite. The wires were elongated by a cold drawing method which also reduced the diameter to 0.965 mm. This study prepared two types of SMA fibers such as straight and dog-bone-shaped. For bending tests, three concrete beams with a dimension of 40 mm × 400 mm × 200 mm (B×H×L) were prepared for each type of specimen. Three points bending tests were conducted. After cracking, the beams were heated at the bottom by fire frame and, then, the recovery stress in the SMA fibers developed. This stress closed the cracks, and the widths of cracks were measured. The SMA fibers, in particular don-bone shaped, were effective to close cracks and will be used for crack-curing of concrete beams.