scholarly journals Analysis of the Results of Pulsed Processing of Melts

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 205
Author(s):  
Valerii Krymsky ◽  
Nataliya Shaburova ◽  
Ekaterina Litvinova
Keyword(s):  
Leading Edge ◽  
Pulse Amplitude ◽  
External Action ◽  
Pulse Power ◽  
Low Power Consumption ◽  
Electromagnetic Pulses ◽  
Equilibrium Crystallization ◽  
Pulse Processing ◽  
High Pulse ◽  
The Impact

The paper presents the results of a relatively new method of external action on melts developed by the authors. The essence of the technology is the impact on melts before casting with electromagnetic pulses (EMP) of short duration (1 ns) and with high pulse power (2 kW). To create electromagnetic pulses, a generator with the following characteristics was used: pulse amplitude of 10 kV, the leading edge of the pulse was 0.1 ns, pulse duration of 1 ns, pulse repetition rate at 1 kHz, and a calculated pulse power of 2 MW. A distinctive feature of the generator used was its low power consumption of 50 Watts. The results of processing low-melting melts of the Al–50Pb, Bi–38Pb, and Bi–18Sn–32Pb systems presented in the work indicated that EMP treatment led to the occurrence of equilibrium crystallization of the metal, increasing its density. In addition to the experimental results, a theory is provided to explain the mechanism of the influence of pulse processing on the properties of metals of these and other systems previously studied by the authors.

Microstructure and Properties of Cast Metal Treated with Electromagnetic Pulses while in Molten State

2016 ◽  
Vol 843 ◽  
pp. 106-110 ◽  
Author(s):  
V.V. Krymsky ◽  
N.A. Shaburova ◽  
E.V. Litvinova
Keyword(s):  
Leading Edge ◽  
Molten State ◽  
Electromagnetic Pulses ◽  
Cast Metal ◽  
Metal Melts ◽  
Electric Treatment ◽  
Shock Wave Generation ◽  
Structure Density ◽  
Pulse Electric ◽  
The Impact

The results of experiments on the impact of high power electromagnetic pulses (EMP) on the metal alloy melts are discussed. A generator with the following pulse parameters: the amplitude of 10 kV, the duration of 1 ns, the leading edge of 0.1 ns, repetition rate of 1 kHz was used for pulse electric treatment of metal melts. The maximum network input of the generator equals 100 watts. The treatment was carried out in a furnace immediately before casting. The treatment of the melt by electromagnetic pulses is conducted for 10-15 minutes. Comparative analysis of treated and untreated samples showed a change in structure, density, strength, ductility, and toughness of the cast metal. The mechanism of stepping impact on the metal melts was discussed. Analysis of the results of other external physical melt impact methods showed that the overall match is observed with the results of the ultrasonic treatment of metals. Therefore, the hypothesis of the pulse ultrasonic shock wave generation at the front was accepted as the basis-hypothesis for the mechanism of the impact of electromagnetic pulses on the melt. In the theoretical part of the paper a model of electromagnetic pulses conversion in acoustic pulses is proposed.

scholarly journals Ultracompact and low-power-consumption silicon thermo-optic switch for high-speed data

Nanophotonics ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 937-945
Author(s):  
Ruihuan Zhang ◽  
Yu He ◽  
Yong Zhang ◽  
Shaohua An ◽  
Qingming Zhu ◽  
...  
Keyword(s):  
Power Consumption ◽  
Low Power ◽  
High Speed ◽  
High Performance ◽  
Pulse Amplitude ◽  
Telecommunication Networks ◽  
Low Power Consumption ◽  
Power Efficient ◽  
High Speed Data ◽  
On Chip

AbstractUltracompact and low-power-consumption optical switches are desired for high-performance telecommunication networks and data centers. Here, we demonstrate an on-chip power-efficient 2 × 2 thermo-optic switch unit by using a suspended photonic crystal nanobeam structure. A submilliwatt switching power of 0.15 mW is obtained with a tuning efficiency of 7.71 nm/mW in a compact footprint of 60 μm × 16 μm. The bandwidth of the switch is properly designed for a four-level pulse amplitude modulation signal with a 124 Gb/s raw data rate. To the best of our knowledge, the proposed switch is the most power-efficient resonator-based thermo-optic switch unit with the highest tuning efficiency and data ever reported.

scholarly journals Morphodynamic signatures of MDA-MB-231 single cells and cell doublets undergoing invasion in confined microenvironments

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xingjian Zhang ◽  
Trevor Chan ◽  
Michael Mak
Keyword(s):  
Single Cell ◽  
Single Cells ◽  
Leading Edge ◽  
Cell Group ◽  
Collective State ◽  
Long Term Effects ◽  
Cell Metastasis ◽  
Geometric Confinement ◽  
Short And Long Term ◽  
The Impact

AbstractCancer cell metastasis is a major factor in cancer-related mortality. During the process of metastasis, cancer cells exhibit migratory phenotypes and invade through pores in the dense extracellular matrix. However, the characterization of morphological and subcellular features of cells in similar migratory phenotypes and the effects of geometric confinement on cell morphodynamics are not well understood. Here, we investigate the phenotypes of highly aggressive MDA-MB-231 cells in single cell and cell doublet (an initial and simplified collective state) forms in confined microenvironments. We group phenotypically similar single cells and cell doublets and characterize related morphological and subcellular features. We further detect two distinct migratory phenotypes, fluctuating and non-fluctuating, within the fast migrating single cell group. In addition, we demonstrate an increase in the number of protrusions formed at the leading edge of cells after invasion through geometric confinement. Finally, we track the short and long term effects of varied degrees of confinement on protrusion formation. Overall, our findings elucidate the underlying morphological and subcellular features associated with different single cell and cell doublet phenotypes and the impact of invasion through confined geometry on cell behavior.

Experimental study of heat transfer in the boundary layer of a flat plate with the impact of weak shock waves on the leading edge

2020 ◽  
Author(s):  
V. L. Kocharin ◽  
A. A. Yatskikh ◽  
D. S. Prishchepova ◽  
A. V. Panina ◽  
Yu. G. Yermolaev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Shock Waves ◽  
Flat Plate ◽  
Leading Edge ◽  
Weak Shock ◽  
The Impact

Self-Acceleration in the Parameterization of Orographic Gravity Wave Drag

2010 ◽  
Vol 67 (8) ◽  
pp. 2537-2546 ◽  
Author(s):  
John F. Scinocca ◽  
Bruce R. Sutherland
Keyword(s):  
Gravity Wave ◽  
Middle Atmosphere ◽  
Wave Train ◽  
Leading Edge ◽  
Wave Theory ◽  
Wave Drag ◽  
Tuning Parameter ◽  
Mean Flow ◽  
Propagating Waves ◽  
The Impact

Abstract A new effect related to the evaluation of momentum deposition in conventional parameterizations of orographic gravity wave drag (GWD) is considered. The effect takes the form of an adjustment to the basic-state wind about which steady-state wave solutions are constructed. The adjustment is conservative and follows from wave–mean flow theory associated with wave transience at the leading edge of the wave train, which sets up the steady solution assumed in such parameterizations. This has been referred to as “self-acceleration” and it is shown to induce a systematic lowering of the elevation of momentum deposition, which depends quadratically on the amplitude of the wave. An expression for the leading-order impact of self-acceleration is derived in terms of a reduction of the critical inverse Froude number Fc, which determines the onset of wave breaking for upwardly propagating waves in orographic GWD schemes. In such schemes Fc is a central tuning parameter and typical values are generally smaller than anticipated from conventional wave theory. Here it is suggested that self-acceleration may provide some of the explanation for why such small values of Fc are required. The impact of Fc on present-day climate is illustrated by simulations of the Canadian Middle Atmosphere Model.

scholarly journals Beyond analogy: A model of bioinspiration for creative design

2016 ◽  
Vol 30 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Camila Freitas Salgueiredo ◽  
Armand Hatchuel
Keyword(s):  
Design Process ◽  
Design Theory ◽  
Leading Edge ◽  
Knowledge Bases ◽  
Biologically Inspired ◽  
Concept Knowledge ◽  
Bioinspired Design ◽  
Aerodynamic Properties ◽  
Biologically Inspired Design ◽  
The Impact

AbstractIs biologically inspired design only an analogical transfer from biology to engineering? Actually, nature does not always bring “hands-on” solutions that can be analogically applied in classic engineering. Then, what are the different operations that are involved in the bioinspiration process and what are the conditions allowing this process to produce a bioinspired design? In this paper, we model the whole design process in which bioinspiration is only one element. To build this model, we use a general design theory, concept–knowledge theory, because it allows one to capture analogy as well as all other knowledge changes that lead to the design of a bioinspired solution. We ground this model on well-described examples of biologically inspired designs available in the scientific literature. These examples include Flectofin®, a hingeless flapping mechanism conceived for façade shading, and WhalePower technology, the introduction of bumps on the leading edge of airfoils to improve aerodynamic properties. Our modeling disentangles the analogical aspects of the biologically inspired design process, and highlights the expansions occurring in both knowledge bases, scientific (nonbiological) and biological, as well as the impact of these expansions in the generation of new concepts (concept partitioning). This model also shows that bioinspired design requires a special form of collaboration between engineers and biologists. Contrasting with the classic one-way transfer between biology and engineering that is assumed in the literature, the concept–knowledge framework shows that these collaborations must be “mutually inspirational” because both biological and engineering knowledge expansions are needed to reach a novel solution.

Numerical Investigation of the Solidity Effect on Linear Compressor Cascades

2014 ◽  
Author(s):  
J. Sans ◽  
M. Resmini ◽  
J.-F. Brouckaert ◽  
S. Hiernaux
Keyword(s):  
Numerical Investigation ◽  
State Of The Art ◽  
Leading Edge ◽  
Operating Conditions ◽  
Compressor Cascade ◽  
Minimum Loss ◽  
Low Speed ◽  
High Mach ◽  
The Stability ◽  
The Impact

Solidity in compressors is defined as the ratio of the aerodynamic chord over the peripheral distance between two adjacent blades, the pitch. This parameter is simply the inverse of the pitch-to-chord ratio generally used in turbines. Solidity must be selected at the earliest design phase, i.e. at the level of the meridional design and represents a crucial step in the whole design process. Most of the existing studies on this topic rely on low-speed compressor cascade correlations from Carter or Lieblein. The aim of this work is to update those correlations for state-of-the-art controlled diffusion blades, and extend their application to high Mach number flow regimes more typical of modern compressors. Another objective is also to improve the physical understanding of the solidity effect on compressor performance and stability. A numerical investigation has been performed using the commercial software FINE/Turbo. Two different blade profiles were selected and investigated in the compressible flow regime as an extension to the low-speed data on which the correlations are based. The first cascade uses a standard double circular arc profile, extensively referenced in the literature, while the second configuration uses a state-of-the-art CDB, representative of low pressure compressor stator mid-span profile. Both profiles have been designed with the same inlet and outlet metal angles and the same maximum thickness but the camber and thickness distributions, the stagger angle and the leading edge geometry of the CDB have been optimized. The determination of minimum loss, optimum incidence and deviation is addressed and compared with existing correlations for both configurations and various Mach numbers that have been selected in order to match typical booster stall and choke operating conditions. The emphasis is set on the minimum loss performance at mid-span. The impact of the solidity on the operating range and the stability of the cascade are also studied.

Pulsed-DC Electrospray for Biopolymer Particle Production

2009 ◽  
Vol 1239 ◽  
Author(s):  
Cho-Hui Lim ◽  
Kiersten R Schierbeek ◽  
Michael E Mullins
Keyword(s):  
Pulse Width ◽  
Particle Production ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Process Conditions ◽  
High Duty Cycle ◽  
Pulsed Dc ◽  
High Pulse ◽  
Long Pulse ◽  
Frequency Pulse

AbstractPLLA microparticles were successfully fabricated via pulsed-DC electrospray. In this study, we investigated the effect of the pulsed voltage characteristics (e.g. pulse frequency, pulse amplitude and pulse width) on the particle’s size. We found that pulse frequency, pulse amplitude, pulse width, and the combinations of these factors had a statistically significant effect on the particle’s size. The process conditions to obtain smaller particles with uniform shape and size are a low pulse frequency, high pulse amplitude, and long pulse width (or a high duty cycle).

scholarly journals Grid Dependency Study for the NASA Rotor 37 Compressor Blade

1997 ◽  
Author(s):  
Andrea Arnone ◽  
Ennio Carnevale ◽  
Michele Marconcini
Keyword(s):  
Total Pressure ◽  
Turbulence Modeling ◽  
Leading Edge ◽  
Substantial Improvement ◽  
Compressor Blade ◽  
Computational Domain ◽  
Temperature Ratio ◽  
Turbulent Transition ◽  
Total Temperature ◽  
The Impact

The NASA Rotor 37 has been computed by several authors in the last few years with relative success. The aim of this work is to present a systematic grid dependency study in order to quantify the amount of uncertainty that comes from the grid density. The computational domain is divided onto several regions (i.e. leading edge, trailing edge, shear layer …) and for each of them, the impact of the grid density is investigated. By means of this analysis, substantial improvement has been obtained in the prediction of efficiency and exit angle. On the contrary, the improvement achieved in total pressure and total temperature ratio is less remarkable. It is believed that only after a systematic grid dependency study can the contribution of turbulence modeling, laminar-turbulent transition, and boundary conditions be analyzed with success.

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