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1
Makhdum, Farrukh, Alastair Conway, and Paul Blackwell. "Experimental Investigation on Shape Evolution in Metal Forming Hybrid Process." Key Engineering Materials 716 (October 2016): 420–27. http://dx.doi.org/10.4028/www.scientific.net/kem.716.420.
Повний текст джерелаАнотація:
The feasibility of combining spinning, shear forming and flow forming processes has been demonstrated through manufacturing of a representative of a hub component using industrial scale hybrid-forming machine available at the Advanced Forming Research Centre (AFRC). The manufacturing cycle consisted of single to multiple passes of shear forming, spinning and flow forming. The research has proven that the spinning, shear forming and flow forming can be combined using a single machine with a single set of tooling and single process cycle. Circumferential and axial cracking was observed in initial set of trials which were eliminated using a series of experiments. The methodology that was used in these series of trials to remove the cracks/defects that may occur during forming of such component is presented here.
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Wang, Zhang Feng, Chi Xiang Ou, Meng Jun Wang, Bai Chen Chen, and Gang Xian Fan. "Mechanical Properties and Microstructure of A356-T6 Aluminum Alloy Wheel Hub Based on Casting-Spinning Process." Materials Science Forum 1036 (June 29, 2021): 3–10. http://dx.doi.org/10.4028/www.scientific.net/msf.1036.3.
Повний текст джерелаАнотація:
The mechanical properties and microstructure of the A356-T6 wheel hub based on low pressure die casting-hot flow forming process were analyzed by means of optical microscopy (OM), scanning electron microscopy (SEM) and tensile tests. Results showed that the size of the eutectic region and the morphology of the Si phase were the main factors affecting the mechanical properties and fracture morphology of the wheel hub. There was a uniform distribution of eutectic area and fine Si phase morphology in the microstructure of the upper rim and lower rim, moreover, the ultimate tensile strength and yield strength of the upper rim reached 282.4MPa and 185.1MPa, respectively. The fractures were mainly composed of fine quasi-cleavage platform and dimple. The microstructure of the rim showed a long strip along the deformation direction and the eutectic structure and Si particles were uniformly distributed. Irregular polygonal eutectic regions and coarse rod-like Si particles were accumulating in the spoke, causing a serious decrease in mechanical properties, especially in the spoke center and spoke R angle.
3
Ūdre, Sandra. "LATGALIAN VOCABULARY AND IDIOMS RELATED TO SPINNING." Via Latgalica, no. 7 (March 22, 2016): 125. http://dx.doi.org/10.17770/latg2015.7.1215.
Повний текст джерелаАнотація:
<em>Spinning (rotation) as a physical phenomenon is an interesting thing. Many archaic notions remain in the language of the dominating perceptions of physical phenomena. Specific studies associated with the Latgalian language have determined that the use of various Latgalian lexemes in contemporary texts creates problems with archaic semantics. These are practical questions for users of Latgalian (primarily writers): which synonym is more appropriate – „doncuot” or „dzyguot” (both meaning ‘to dance’)? Are these terms equivalent? Does the word „maule” (meaning ‘wheel hub’) have only one meaning, even when used in the interjection „ot, maule!”? Why, in Latgalian, does snow spin („snīgs grīž”), but in standard Latvian different words and a different sentence structure must be used for the same expression? This study not only answers these particular questions of lexeme semantics in use, but will also use the linguoculturological approach to discuss the following thematic arcs in Latgalian phraseology and lexicon: 1) signs of natural processes and tools; 2) characteristics of the weather; 3) signs of the process of dancing; 4) lexemes representing the semantics of chaos. An archaic understanding of spinning in language is associated with the concept of the mystic triangle (underworld, world and heaven) model of the world, in which one of the ways to tear down the boundaries between the worlds is to spin in an uncontrollably fast spiral vortex. This notion is reminiscent of Stephen Hawking’s theory of singularity in black holes.</em>
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Sundaram, Maruthachalam, Mouttouvelou Anand, Jaganathan Chelladurai, Paramasivam Varunraj, Sam Joshua Smith, Shubham Sharma, Mamdouh El Haj Assad, and Reza Alayi. "Design and FEM Analysis of High-Torque Power Density Permanent Magnet Synchronous Motor (PMSM) for Two-Wheeler E-Vehicle Applications." International Transactions on Electrical Energy Systems 2022 (July 25, 2022): 1–14. http://dx.doi.org/10.1155/2022/1217250.
Повний текст джерелаАнотація:
Launch of electric vehicles have seen a substantial rise for the past few years in emerging economies like India. In countries like India, the growth and penetration of the electric vehicles in the Indian automotive industry specifically for the two-wheeler segments are driven by the demand surge where cost and motor metrics have a substantial deciding factor. The in-wheel hub-motor, which is the prime mover for the two wheelers, decides the comfort zone of the customer in various metrics such as efficiency, torque, speed range, charging, and hence the distance covered. This paper addresses the design formulation of achieving a high torque Permanent Magnet Synchronous Motor (PMSM) conventionally known as the hub-motor, explicitly for electric two-wheeler application. The hub-motor is aimed for the defined D and L (280 × 30 mm) of volumetric constraints to deliver the rated torque of 50 Nm at the spinning speed of 400 rpm. The hub-motor design is aimed for distance range of 108 km/charge, at the vehicle speed of 54 km/hr for the designed diametric and volumetric constraints. This will lead to a typical cost-effective e-vehicle system since the required distance range of 108 km is achievable at the defined rim size and geometry with an enhanced efficiency greater than 90%. The design is carried out by Finite Element Analysis (FEA) using the electromagnetic software MotorSolve. The results computed are analyzed and validated for the optimal loading conditions for the ambient temperature of 50°C. The results confirm the effectiveness of the proposed design formulation and methodology for achieving the high power density hub-motors for satisfying the customer’s comfort zone in establishing the performance metrics of the electromagnetic system.
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Zhou, Heng, Hui Li, Jing Liu, Xinlei Guo, Weiguo Wang, Xi Lu, and Shengjie Di. "Study on Structure Design of Generator of Flood Discharge Tunnel with Level Swirling Flow." E3S Web of Conferences 276 (2021): 02013. http://dx.doi.org/10.1051/e3sconf/202127602013.
Повний текст джерелаАнотація:
Through the design of the Generator of the spillway tunnel, the safe operation efficiency of flood discharge tunnel with the level swirling flow is further improved. This paper takes the horizontal swirl spillway tunnel of Gongboxia Hydropower Station on the Yellow River as an example. First, the project hub facilities of the Gongboxia Hydropower Station are introduced. Moreover, the design of the gradient section and the spinning chamber section in the Generator is also studied. Based on the calculation scheme of structural mechanics, the internal force of the structure under various load combinations such as external water pressure and internal water pressure is calculated. According to Design Codes For Hydraulic Concrete Structure, the structural reinforcement is computed. These provide the basis for the design of the flood discharge tunnel with level swirling flow of large hydropower engineering facilities in Northwest China.
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Usubamatov, R., and T. Zhumaev. "Inertial Forces Acting on a Propeller of Aircraft." Open Aerospace Engineering Journal 7, no. 1 (August 29, 2018): 1–13. http://dx.doi.org/10.2174/1874146001807010001.
Повний текст джерелаАнотація:
Background:Aerospace vehicles use propellers with the different design that possess gyroscopic properties. Recent investigations in the area of gyroscope theory have demonstrated that the gyroscope properties are based on the action of the centrifugal, common inertial, and Coriolis forces of the distributed mass elements of the spinning rotor, as well as the change in the angular momentum.Objective:The combined action of the interrelated inertial forces on the propellers presents the interests for the design of the blades. The objective of the manuscript is the derivation of mathematical models for the inertial torques acting on the spinning propellers that enable computing the stresses of the blades and increasing their reliability.Method:The inertial torques generated by the masses of the rotating blades acting on the propellers are represented by mathematical models in L. Euler’s form.Results:The inertial torques are generated by the several inertial forces of the propeller’s blades and hub and manifested the fluctuation of the variable resistance and precession torques acting around different axes of the propeller. Derived mathematical models for the inertial torques are new and should be used for the computing forces and stresses acting on the propellers of the aircraft.Conclusion:The mathematical models for the torques acting on the propellers consider the several inertial forces of the rotating masses that manifest their gyroscope properties. Derived mathematical models for inertial torques enable for computing the stresses of the aircraft propellers and clearly demonstrate the physical principles and origin of the acting inertial forces.
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Perederiy, V. G., B. G. Gasanov, and A. A. Aganov. "Structurization and Properties of Magnetoplastics Made of Mechanically Activated Amorphous-Crystalline Powder Alloys Based on the Nd-Fe-B System." Solid State Phenomena 284 (October 2018): 455–59. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.455.
Повний текст джерелаАнотація:
The influence of the method of melt spinning on the basis of the Fe-Nd-B system on the amorphous-crystal structure of ribbons and flakes is shown. It is established that the magnetic properties of magnetoplasts depend on the powders particle size, the parameters of mechanic activation during flake milling, the kinetics of formation and growth of Fe2Nd14B phase nuclei at all stages of their preparation and processing, etc. Isotropic and anisotropic magnetoplasts and sintered magnets with magnetic properties: Br = 0.5-1.25 T, HcB = 180-700 kA/m; (BH)max = 50-280 kJ/m3.
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Truong, Nguyen Xuan, and Nguyen Van Vuong. "Magnetic field assisted melt–spinning Nd-Fe-B ribbons and anisotropic bonded NdFeB magnets prepared thereof." Communications in Physics 26, no. 1 (April 14, 2016): 59. http://dx.doi.org/10.15625/0868-3166/26/1/7686.
Повний текст джерелаАнотація:
The magnetic-field-assisted melt-spinning (FAMS) Nd10.5Fe72Co11B6.5 ribbons were spun in an external magnetic field of 3 kG. The prepared ribbons were ball-milled in xylene solvent for 30 minutes followed by adding in and mixing with the high-temperature binder HTB-1 (3 wt%) for further 10 minutes. The mixed powder was dried and in-mold aligned in a magnetic field of 18 kOe and hot-compacted at 200 oC. The parameters of the FAMS ribbon preparation, ball-milling process, hot-compaction and anisotropic bonded magnets’ fabrication were optimized leading to the magnet’s energy product (BH)max of 10 MGOe. The microstructure and magnetic properties of prepared ribbons and bonded magnets will be discussed in details.
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Nagy, Roland, Réka Kothencz, Máté Hartyányi, and László Bartha. "Relationship between Some Colloidal Properties of Non-Ionic-Anionic Surfactant Mixtures." Processes 10, no. 6 (June 6, 2022): 1136. http://dx.doi.org/10.3390/pr10061136.
Повний текст джерелаАнотація:
Non-ionic surfactants are compatible with different types of materials, therefore they can be applied in various packages. Fatty-acid derivates as non-ionic surfactants and their mixtures were investigated to study their colloidal behavior. The HLB value, the particle size, the emulsification capacity and the interfacial tension of various commercial, non-ionic surfactants, and their mixtures with sodium lauryl-ether-sulfate (SLES), were determined. The surfactant mixtures were prepared in different non-ionic: anionic surfactant ratios to examine their effect on several surfactant characteristics. The interfacial tension between the oil phase and aqueous phase was measured using the spinning drop method and the average hydrodynamic diameter of surfactants in the aqueous solution was determined using the dynamic light scattering method. The relationship between various colloidal properties of surfactants was investigated. It was found that there is a significant relationship between the colloidal characteristics and the structure of surfactants that can contribute to their efficient selection method.
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Chu, Fang-Yi, Shannon C. Haley, and Alexandra Zidovska. "On the origin of shape fluctuations of the cell nucleus." Proceedings of the National Academy of Sciences 114, no. 39 (September 12, 2017): 10338–43. http://dx.doi.org/10.1073/pnas.1702226114.
Повний текст джерелаАнотація:
The nuclear envelope (NE) presents a physical boundary between the cytoplasm and the nucleoplasm, sandwiched in between two highly active systems inside the cell: cytoskeleton and chromatin. NE defines the shape and size of the cell nucleus, which increases during the cell cycle, accommodating for chromosome decondensation followed by genome duplication. In this work, we study nuclear shape fluctuations at short time scales of seconds in human cells. Using spinning disk confocal microscopy, we observe fast fluctuations of the NE, visualized by fluorescently labeled lamin A, and of the chromatin globule surface (CGS) underneath the NE, visualized by fluorescently labeled histone H2B. Our findings reveal that fluctuation amplitudes of both CGS and NE monotonously decrease during the cell cycle, serving as a reliable cell cycle stage indicator. Remarkably, we find that, while CGS and NE typically fluctuate in phase, they do exhibit localized regions of out-of-phase motion, which lead to separation of NE and CGS. To explore the mechanism behind these shape fluctuations, we use biochemical perturbations. We find the shape fluctuations of CGS and NE to be both thermally and actively driven, the latter caused by forces from chromatin and cytoskeleton. Such undulations might affect gene regulation as well as contribute to the anomalously high rates of nuclear transport by, e.g., stirring of molecules next to NE, or increasing flux of molecules through the nuclear pores.
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Carlino, S. "High-resolution solid-state magic-angle spinning nuclear magnetic resonance studies on the thermal decomposition of the layered antimony hydrogen phosphate, HSb(PO4)2·2H2O." Solid State Ionics 106, no. 3-4 (February 1, 1998): 269–77. http://dx.doi.org/10.1016/s0167-2738(97)00501-8.
Повний текст джерела
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Carlino, Simon, and Michael J. Hudson. "High-resolution solid-state magic-angle spinning nuclear magnetic resonance studies on the layered antimony hydrogen phosphate, HSb(PO4)2·2H2O and some organic amine intercalation compounds." Solid State Ionics 99, no. 1-2 (August 1, 1997): 103–14. http://dx.doi.org/10.1016/s0167-2738(97)00264-6.
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Carlino, Simon, Michael J. Hudson, and William J. Locke. "High-resolution solid-state magic angle spinning nuclear magnetic resonance studies on the layered antimony hydrogen phosphate, HSb(PO4)2·2H2O, and its reaction products with tetrakis(pyridyl)iron(II) chloride." Journal of Materials Chemistry 7, no. 5 (1997): 813–19. http://dx.doi.org/10.1039/a700151g.
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Stando, Grzegorz Jan, Pyry-Mikko Hannula, Bogumiła Kumanek, Mari Lundström, Haitao Liu, and Dawid Janas. "(Digital Presentation) Recovery of Copper from Wastewater By Electrodeposition Onto Nanocarbon Composites." ECS Meeting Abstracts MA2022-01, no. 9 (July 7, 2022): 761. http://dx.doi.org/10.1149/ma2022-019761mtgabs.
Повний текст джерелаАнотація:
The connection of carbon nanostructures such as graphene or carbon nanotubes with other materials like metals [1] or polymers [2] is often beneficial. For example, composites consisting of copper and nanocarbon materials have improved electrical [1] and mechanical [3] properties due to the synergy effect. Unfortunately, the integration between copper and nanocarbon is not an easy task because of the “cuprophobic” nature of nanocarbon [4]. Recently, many methods have been developed to accomplish this challenge. Out of all available techniques, physical (casting, spark plasma sintering or metal spinning) and electrochemical [5] gained a considerable share of attention. In particular, electrodeposition is a commonly employed strategy to deposit copper onto nanocarbon electrodes. In this method, nanocarbon surface plays the role of working electrode, onto which copper ions are reduced, thereby creating a Cu coating on the surface. This study demonstrates the recovery of copper from industrial wastewater by thin films based on carbon nanotubes (CNTs). Such a substrate was found as an ideal surface for the electrodeposition of metallic particles. Single/multi-walled CNTs, oxidized CNTs, nitrogen-doped CNTs and graphene were combined to obtain nanocarbon-nanocarbon composite electrodes, which were then used as substrates in Cu electrodeposition [6]. To establish the coating process parameters, synthetic solution of CuSO4 was first used as a source of copper ions. Then, wastewater of complex composition was employed directly for the electrodeposition process. Besides the 40 ppm of Cu, the wastewater contained other elements like salts Fe, Mg, Al, Zn and As in much greater amounts. It was discovered that such nanocomposite materials may be an excellent substrate for electrochemical recovery of Cu also from such a problematic waste, while simultaneously giving a product of high added value. Interestingly, the product was free from other metals, and only copper was detected on the nanocarbon surface. After just 1-hour of electrodeposition at -0.1V vs. SCE, a nanocarbon-based composite evenly coated with Cu was manufactured. Thorough investigation of the microstructure, and chemical composition of the nanocomposites correlated with the properties of the Cu coated materials enabled us to deduce critical parameters needed to make the Cu coating process effective [7]. [1] C. Arnaud, F. Lecouturier, D. Mesguich, N. Ferreira, G. Chevallier, C. Estournès, A. Weibel, C. Laurent, High strength - High conductivity double-walled carbon nanotube - Copper composite wires, Carbon N. Y. 96 (2016) 212–215. doi:10.1016/j.carbon.2015.09.061. [2] S.N. Beesabathuni, J.G. Stockham, J.H. Kim, H.B. Lee, J.H. Chung, A.Q. Shen, Fabrication of conducting polyaniline microspheres using droplet microfluidics, RSC Adv. 3 (2013) 24423–24429. doi:10.1039/c3ra44808h. [3] R. Jiang, X. Zhou, Q. Fang, Z. Liu, Copper-graphene bulk composites with homogeneous graphene dispersion and enhanced mechanical properties, Mater. Sci. Eng. A. 654 (2016) 124–130. doi:10.1016/j.msea.2015.12.039. [4] D. Janas, B. Liszka, Copper matrix nanocomposites based on carbon nanotubes or graphene, Mater. Chem. Front. 2 (2018) 22–35. doi:10.1039/c7qm00316a. [5] A. Singh, T. Ram Prabhu, A.R. Sanjay, V. Koti, An Overview of Processing and Properties of CU/CNT Nano Composites, Mater. Today Proc. 4 (2017) 3872–3881. doi:10.1016/J.MATPR.2017.02.286. [6] D. Janas, M. Rdest, K.K.K. Koziol, Free-standing films from chirality-controlled carbon nanotubes, Mater. Des. 121 (2017) 119–125. doi:10.1016/j.matdes.2017.02.062. [7] G. Stando, P.-M. Hannula, B. Kumanek, M. Lundström, D. Janas, Copper recovery from industrial wastewater - Synergistic electrodeposition onto nanocarbon materials, Water Resour. Ind. 26 (2021) 100156. doi:10.1016/J.WRI.2021.100156. G.S. and P.S. would like to thank the Ministry of Science and Higher Education of Poland for financial support of research (under Diamond Grant, grant agreement 0036/DIA/201948). G.S. also would like to thank European Union for thanks for financing the costs of the conference (European Social Fund, grant nr POWR.03.05.00-00-Z305) and National Agency for Academic Exchange of Poland (under the Iwanowska program, grant agreement PPN/IWA/2019/1/00017/UO/00001) for financial support during the stay at the University of Pittsburgh in the USA. G.S. and H.L. acknowledge NSF (CBET-2028826) for partial support of this work. G. S. and D.J. acknowledge the National Agency for Academic Exchange of Poland (under the Academic International Partnerships program, grant agreement PPI/APM/2018/1/00004) for supporting training in the Aalto University. G.S, B.K. and D.J. would like to thank the National Centre for Research and Development, Poland (under the Leader program, grant agreement LIDER/0001/L-8/16/NCBR/2017).
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Tai, W. C., and I. Y. Shen. "Closed-Form Vibration Response of a Special Class of Spinning, Cyclic Symmetric Rotor-Bearing-Housing Systems." Journal of Vibration and Acoustics 137, no. 6 (September 28, 2015). http://dx.doi.org/10.1115/1.4031314.
Повний текст джерелаАнотація:
Vibration of a spinning, cyclic symmetric rotor supported by flexible bearings and housing is governed by a set of ordinary differential equations with periodic coefficients. As a result, analytical solutions of such systems are generally not available. This paper is to prove that closed-form solutions are available for such systems if the following two conditions are met. First, the rotor has a rigid hub and the rest of the rotor is flexible. Second, elastic mode shapes of the rotor's flexible part only present axial displacement. Under these two conditions, the periodic coefficients will only appear between repeated modes of the spinning rotor and vibration modes of the stationary housing. This unique structure enables a coordinate transformation to convert the governing ordinary differential equations with periodic coefficients into a set of ordinary differential equations with constant coefficients, whose closed-form solution is readily available. Moreover, the coordinate transformation can be derived explicitly. Finally, we demonstrate the closed-form solution through a benchmark numerical model that consists of a spinning rotor, a stationary housing, and two elastic bearings. In particular, the rotor is a circular disk with four evenly spaced radial slots and a central rigid hub. The housing is a square plate with a central rigid shaft and is fixed at four corners. The two elastic bearings connect the rotor and the housing between the hub and shaft. Numerical results confirm that the original equation of motion with periodic coefficients and the closed-form solutions predict the same vibration response.
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Landry, Céderick, Patrick K. Dubois, Jean-Sébastien Plante, François Charron, and Mathieu Picard. "Rotordynamics of a Highly Flexible Hub for Inside-Out Ceramic Turbine Application: Finite Element Modeling and Experimental Validation." Journal of Vibration and Acoustics 140, no. 1 (September 29, 2017). http://dx.doi.org/10.1115/1.4037700.
Повний текст джерелаАнотація:
The inside-out ceramic turbine (ICT) is a promising concept to increase turbine inlet temperatures in microturbines by integrating individual monolithic ceramic. This architecture uses a carbon–polymer composite rim to support the blades mainly in compression. High tangential velocities lead to elevated radial displacement of the rim, and therefore, the rotor hub needs to have sufficient compliance to follow this radial displacement. However, the rotordynamics of a flexible hub is not widely understood. This paper presents the rotordynamic analysis of a highly flexible hub for an ICT architecture. Finite element modeling (FEM) is used to design a simplified turbine prototype that maximizes the hub flexibility to explore the limits of the concept. The rotordynamics behavior of the highly flexible hub is measured by spinning a 171-mm diameter prototype up to 49 krpm. This paper highlights three principal challenges of this particular rotordynamics. First, critical speeds mode shape becomes highly coupled with bearings displacement, shaft bending, and hub deformation. At high-speed, the hub deforms out of phase with the shaft, which can cause high stresses in the hub. Second, the angular position between unbalance masses of the flexible hub and the composite rim changes the unbalance response significantly. Finally, vibration causes high stresses in the hub, due to the relative displacement between the composite rim and the shaft, which could lead to failure of the hub. Nevertheless, the rotordynamics of an ICT configuration is manageable as long as the vibration-induced stress in the hub is kept under its limit.
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Buchwald, Patrick, Damian M. Vogt, Julien Grilliat, Wolfgang Laufer, Michael B. Schmitz, Andreas Lucius, and Marc Schneider. "Aeroacoustic Analysis of Low-Speed Axial Fans With Different Rotational Speeds in the Design Point." Journal of Engineering for Gas Turbines and Power 140, no. 5 (November 14, 2017). http://dx.doi.org/10.1115/1.4038122.
Повний текст джерелаАнотація:
One of the main design decisions in the development of low-speed axial fans is the right choice of the blade loading versus rotational speed, since a target pressure rise could either be achieved with a slow spinning fan and high blade loading or a fast spinning fan with less flow turning in the blade passages. Both the blade loading and the fan speed have an influence on the fan performance and the fan acoustics, and there is a need to find the optimum choice in order to maximize efficiency while minimizing noise emissions. This paper addresses this problem by investigating five different fans with the same pressure rise but different rotational speeds in the design point (DP). In the first part of the numerical study, the fan design is described and steady-state Reynolds-averaged Navier–Stokes (RANS) simulations are conducted in order to identify the performance of the fans in the DP and in off-design conditions. The investigations show the existence of an optimum in rotational speed regarding fan efficiency and identify a flow separation on the hub causing a deflection of the outflow in radial direction as the main loss source for slow spinning fans with high blade loadings. Subsequently, large eddy simulations (LES) along with the acoustic analogy of Ffowcs Williams and Hawkings (FW–H) are performed in the DP to identify the main noise sources and to determine the far-field acoustics. The identification of the noise sources within the fans in the near-field is performed with the help of the power spectral density (PSD) of the pressure. In the far-field, the sound power level (SWL) is computed using different parts of the fan surface as FW–H sources. Both methods show the same trends regarding noise emissions and allow for a localization of the noise sources. The flow separation on the hub is one of the main noise sources along with the tip vortex with an increase in its strength toward lower rotational speeds and higher loading. Furthermore, a horseshoe vortex detaching from the rotor leading edge and impinging on the pressure side as well as the turbulent boundary layer on the suction side represent significant noise sources. In the present investigation, the maximum in efficiency coincides with the minimum in noise emissions.
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Parry, A. B., and M. J. Kingan. "Acoustic theory of the many-bladed contra-rotating propeller: physics of the wake interaction noise critical sources." Journal of Fluid Mechanics 880 (October 7, 2019). http://dx.doi.org/10.1017/jfm.2019.755.
Повний текст джерелаАнотація:
In the theory of interaction noise from contra-rotating propellers with many blades, the usual far-field radiation formulae can be re-cast as a double integral, over a source surface, which can be evaluated asymptotically solely in terms of the contributions from critical points. The paper shows that these critical points have a particularly interesting physical meaning. They relate to locations on an event line, running between hub and tip, that represent the locus of the wake–blade interactions at a fixed point in time. The event line rotates at the speed of the spinning interaction tone but does not coincide with the radial variation in either the wake location or the rear blade leading edge. At the precise critical locations on the event line, it is shown that the Mach number of the event line is unity in the direction of the observer (the sonic condition) and the tangent to the event line – at a fixed time – is normal to a line drawn between it and the observer (the normal-edge condition). The zero-mode case is also considered, for which we show that, even though the event line rotates at infinite speed, there can still exist locations that satisfy the sonic and normal-edge conditions. The paper also discusses the physical meaning of the lower-order boundary solutions from the hub and tip.
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Abd El-Hafiz, M. M., M. A. A. Emam, W. A. H. Oraby, and S. Shaaban. "Modeling and Simulation of Off-Road Vehicle Mobility with Driving Torque Distribution Control on Split Adhesion Conditions." International Journal of Vehicle Structures and Systems 9, no. 2 (April 19, 2017). http://dx.doi.org/10.4273/ijvss.9.2.07.
Повний текст джерелаАнотація:
This paper presents a theoretical model for simulation of driving torque distribution control to improve off-road vehicle mobility on split adhesion conditions. The model is constructed and then validated with experimental test rig results. A MATLAB simulink modeling of an electronically controlled device is used to modulate the applied force over multi-plate clutches located between the automotive driven axle shafts and the stationary hub. On driving over split adhesion roads, the control device brakes the spinning axle wheel running over ground low adhesion side and accordingly biases more torque to the other wheel with good adhesion side. This would improve the vehicle off-road mobility and save the power losses on low adhesion wheels. The proposed control model had been validated with experimental results obtained from an experimental tests conducted on a specially designed and built test rig. Consequently, the proposed control system has been embedded within a full car theoretical model to predict the vehicle performance on split adhesion drive conditions. The results showed that the constructed simulink model is suitable for simulating the proposed controlled device for torque distribution after matching the simulation results with experimental test rig results. Moreover, the proposed control model could be implemented to improve the transmitted traction power to the road from a conventional deferential.
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Grindheim, Ole-Martin, Yihan Xing, and Thomas Impelluso. "Dynamic analysis and validation of a multi-body floating wind turbine using the moving frame method." Frontiers in Mechanical Engineering 9 (August 28, 2023). http://dx.doi.org/10.3389/fmech.2023.1156721.
Повний текст джерелаАнотація:
This research applies the moving frame method (MFM) to the multi-body dynamic analysis of an OC3 phase IV spar buoy with the NREL 5MW turbine. Further, it verifies previous results obtained through numerical comparisons with commercial software. The long-term goal is to lay the foundation for leveraging the MFM to create a self-contained software system for future analyses that can incorporate effects that are more sophisticated, when commercial codes fall short. In this first evidentiary phase, this project treats the floating turbine as a three-bodied system consisting of the platform (platform + tower), nacelle and rotor (hub + blades). Then the paper presents the MFM in a tutorial style—in the context of this problem’s resolution. The paper supplements the multi-body dynamic equations of motion obtained through the MFM with simplified and reduced hydrodynamic, aerodynamic and mooring loads to simulate the translational and rotational response of the floating turbine under various load conditions. The results closely approximate those found in previous work and, in the process, demonstrates MFM’s analytical advantage. Current results capture the coupled responses in all degrees of freedom and gyroscopic effects occurring when the platform pitches with the spinning rotor. The project thus provides an accurate model for the dynamics of the turbine and opens the door to inserting correct advanced hydrodynamics to validate the model further. The work presents simulations for the different load cases through a 3D web page using WebGL and the ThreeJS library. Users may download all software to verify the results. An undergraduate student conducted the work alone, demonstrating the ease of implementation of the MFM.
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Mrgić, Jelena. "Pictures and Words 2 – An Italian Caricature at the End of the Great Vienna War (1683–1699) as “Icono-Text”." Etnoantropološki problemi / Issues in Ethnology and Anthropology 18, no. 1 (April 19, 2023). http://dx.doi.org/10.21301/eap.v18i1.9.
Повний текст джерелаАнотація:
This paper is a branch of my previous research, dealing with allegorical and persuasive cartography, as an exercise in more recent theoretical interpretations of marginalized historical sources – caricatures. The introduction gives the readers an overview of the modern methodology and secondary literature. Furthermore, Giuseppe Maria Mitelli (1634–1718) is unknown to our audience. Therefore, this paper cannot deal with his immenseoeuvre, but only one example of his mastery, the caricature “An International Array of Doctors Counselling the Sultan”. This engraving is dated approximately to 1696, or slightly later, to the last phase of the War of the Holy League (1683–1699). The staging and the characters, as presented in the analysis, show beyond doubt a strong influence from commedia dell’arte in costumes and apparel, recognizing the oldest stock images of Dottore Gracian, originating in Mitelli’s Bologna, and Pantalone, who is precisely attributed to the “medico Venetiano”. This “icono-text” merges visual arts and comedy theatre with text, criticizing the Christian “nations” for their lack of unity in opposing the common foe and nemesis – the Ottoman sultan. The satire is more pronounced in the para-text, adequately written for each one of the actors, including those without the lyrics – headfirst fleeing grand vizier Kara Mustapha, and wool spinning Protestant Prince Imre Thököly, doing the woman’s and not the warrior’s task. Including the sultan, historians have plenty of material for an imagology analysis from the point of view of a witty Bolognese, well-educated and informed, placed in a hub of the baroque network of Europe, bursting with “furor geographicus” and the sound of the printing machines, street vendors, artisans, and carnivals. As any intellectual work, Mitelli’s art piece is placed within its historical-geographical, cultural and socio-political context.
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Smrt, Sean T., Nicole Gonzalez Salguero, Justin K. Thomas, Mohamad Zandian, Michael G. Poirier, and Christopher P. Jaroniec. "Histone H3 core domain in chromatin with different DNA linker lengths studied by 1H-Detected solid-state NMR spectroscopy." Frontiers in Molecular Biosciences 9 (January 4, 2023). http://dx.doi.org/10.3389/fmolb.2022.1106588.
Повний текст джерелаАнотація:
Chromatin, a dynamic protein-DNA complex that regulates eukaryotic genome accessibility and essential functions, is composed of nucleosomes connected by linker DNA with each nucleosome consisting of DNA wrapped around an octamer of histones H2A, H2B, H3 and H4. Magic angle spinning solid-state nuclear magnetic resonance (NMR) spectroscopy can yield unique insights into histone structure and dynamics in condensed nucleosomes and nucleosome arrays representative of chromatin at physiological concentrations. Recently we used J-coupling-based solid-state NMR methods to investigate with residue-specific resolution the conformational dynamics of histone H3 N-terminal tails in 16-mer nucleosome arrays containing 15, 30 or 60 bp DNA linkers. Here, we probe the H3 core domain in the 16-mer arrays as a function of DNA linker length via dipolar coupling-based 1H-detected solid-state NMR techniques. Specifically, we established nearly complete assignments of backbone chemical shifts for H3 core residues in arrays with 15–60 bp DNA linkers reconstituted with 2H,13C,15N-labeled H3. Overall, these chemical shifts were similar irrespective of the DNA linker length indicating no major changes in H3 core conformation. Notably, however, multiple residues at the H3-nucleosomal DNA interface in arrays with 15 bp DNA linkers exhibited relatively pronounced differences in chemical shifts and line broadening compared to arrays with 30 and 60 bp linkers. These findings are consistent with increased heterogeneity in nucleosome packing and structural strain within arrays containing short DNA linkers that likely leads to side-chains of these interfacial residues experiencing alternate conformations or shifts in their rotamer populations relative to arrays with the longer DNA linkers.