Scalable and Isotropic Expansion of Tissues with Simply Tunable Expansion Ratio

The recent stringent regulations on vehicle safety and reducing CO2 emissions have led to a continuous increase in the application of press-hardened steel (PHS) in automobiles. Similar to other high-strength steels, assembling PHS components using the common welding techniques employed in automotive production lines is significantly difficult because of the surface coating layers and the additives within. This difficulty in post-processing, attributed to its high strength, also limits the mechanical fastening of PHS components. Therefore, this study aims to develop a process for forming a structure enabling mechanical fastening by sequentially applying piercing and hole-flanging operations during the hot stamping process. Our experimental apparatus was designed to perform the hole-flanging operation after the piercing operation within a single stroke at a specific temperature during the quenching process of PHS. At high temperatures of 440 °C or higher, the hole-flanging process was conducted in a direction opposite to that of the piercing operation for creating the pilot hole. An extruded collar with a height of 8.0 mm and a diameter of 17.5 mm was achieved, which is hole expansion ratio(HER) of 82.5%.

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A Theoretical Study on the Thermodynamic Cycle of Concept Engine with Miller Cycle

Processes ◽

10.3390/pr9061051 ◽

2021 ◽

Vol 9 (6) ◽

pp. 1051

Author(s):

Jungmo Oh ◽

Kichol Noh ◽

Changhee Lee

Keyword(s):

Compression Ratio ◽

Thermal Efficiency ◽

Engine Performance ◽

Thermodynamic Cycle ◽

Expansion Ratio ◽

Boost Pressure ◽

Miller Cycle ◽

Compression Pressure ◽

Air Mass ◽

Atkinson Cycle

The Atkinson cycle, where expansion ratio is higher than the compression ratio, is one of the methods used to improve thermal efficiency of engines. Miller improved the Atkinson cycle by controlling the intake- or exhaust-valve closing timing, a technique which is called the Miller cycle. The Otto–Miller cycle can improve thermal efficiency and reduce NOx emission by reducing compression work; however, it must compensate for the compression pressure and maintain the intake air mass through an effective compression ratio or turbocharge. Hence, we performed thermodynamic cycle analysis with changes in the intake-valve closing timing for the Otto–Miller cycle and evaluated the engine performance and Miller timing through the resulting problems and solutions. When only the compression ratio was compensated, the theoretical thermal efficiency of the Otto–Miller cycle improved by approximately 18.8% compared to that of the Otto cycle. In terms of thermal efficiency, it is more advantageous to compensate only the compression ratio; however, when considering the output of the engine, it is advantageous to also compensate the boost pressure to maintain the intake air mass flow rate.

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Kinked Bisamides as Efficient Supramolecular Foam Cell Nucleating Agents for Low-Density Polystyrene Foams with Homogeneous Microcellular Morphology

Polymers ◽

10.3390/polym13071094 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1094

Author(s):

Bastian Klose ◽

Daniel Kremer ◽

Merve Aksit ◽

Kasper P. van der Zwan ◽

Klaus Kreger ◽

...

Keyword(s):

Cell Size ◽

Self Assembly ◽

Large Scale ◽

Elevated Temperatures ◽

Foam Cell ◽

Cell Structure ◽

Expansion Ratio ◽

Low Density ◽

Nucleating Agents ◽

Foam Density

Polystyrene foams have become more and more important owing to their lightweight potential and their insulation properties. Progress in this field is expected to be realized by foams featuring a microcellular morphology. However, large-scale processing of low-density foams with a closed-cell structure and volume expansion ratio of larger than 10, exhibiting a homogenous morphology with a mean cell size of approximately 10 µm, remains challenging. Here, we report on a series of 4,4′-diphenylmethane substituted bisamides, which we refer to as kinked bisamides, acting as efficient supramolecular foam cell nucleating agents for polystyrene. Self-assembly experiments from solution showed that these bisamides form supramolecular fibrillary or ribbon-like nanoobjects. These kinked bisamides can be dissolved at elevated temperatures in a large concentration range, forming dispersed nano-objects upon cooling. Batch foaming experiments using 1.0 wt.% of a selected kinked bisamide revealed that the mean cell size can be as low as 3.5 µm. To demonstrate the applicability of kinked bisamides in a high-throughput continuous foam process, we performed foam extrusion. Using 0.5 wt.% of a kinked bisamide yielded polymer foams with a foam density of 71 kg/m3 and a homogeneous microcellular morphology with cell sizes of ≈10 µm, which is two orders of magnitude lower compared to the neat polystyrene reference foam with a comparable foam density.

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Microstructural Influence on Stretch Flangeability of Ferrite–Martensite Dual-Phase Steels

Crystals ◽

10.3390/cryst10111022 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1022

Author(s):

Jae Hyung Kim ◽

Taekyung Lee ◽

Chong Soo Lee

Keyword(s):

Mechanical Strength ◽

Uniform Distribution ◽

Transverse Direction ◽

Rolling Direction ◽

Expansion Ratio ◽

Dual Phase ◽

Normal Anisotropy ◽

Hole Expansion Ratio ◽

Dp Steels ◽

Microstructural Effect

This work investigated the microstructural effect on stretch flangeability of ferrite–martensite dual-phase (DP) steels. Three types of DP steels with various martensitic structures were prepared for the research: fibrous martensite in water-quenched (WQ) sample, chained martensite in air-quenched (AQ) sample, and coarse martensite in step-quenched (SQ) sample. The WQ specimen exhibited the highest mechanical strength and hole expansion ratio compared to the AQ and SQ samples despite their similar fraction of martensite. Such a result was explained in view of uniform distribution of fine martensite and high density of geometrically necessary dislocations in the WQ specimen. Meanwhile, most cracks initiated at either rolling or transverse direction during the stretch flangeability test regardless of the martensitic morphology. It was attributed to the highest average normal anisotropy in the direction of 45° to rolling direction.

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Effects of Field Processing of Sorghum Grain on Popping Traits

Agronomy ◽

10.3390/agronomy11050839 ◽

2021 ◽

Vol 11 (5) ◽

pp. 839

Author(s):

Mitchell Kent ◽

William Rooney

Keyword(s):

Impact Force ◽

Grain Sorghum ◽

Expansion Ratio ◽

Direct Impact ◽

Order Of Magnitude ◽

Rubber Belt ◽

Sorghum Grain ◽

Harvest Moisture ◽

Quality Measurements

Interest in the use of popped sorghum in food products has resulted in a niche market for sorghum hybrids with high popping quality but little work has been done to assess the relative effects of field processing methods of grain on popping quality. This study evaluated the relative effects of harvest moisture and threshing methods on the popping quality of sorghum grain. A grain sorghum hybrid with good popping quality was produced during two different years in Texas wherein it was harvested at two moisture levels (low and high) and grain was removed from panicles using five different threshing methods (hand, rubber belt, metal brushes and two metal concave bar systems). Years, harvest moisture content and threshing method influenced all three popping quality measurements (popping efficacy, expansion ratio and flake size), but threshing method had an order of magnitude larger effect than either moisture level or year. While many of the interactions were significant, they did not influence the general trends observed. As such, the threshing methods with less direct impact force on the grain (hand and rubber belt) had higher popping quality than those samples threshed with greater impact force on the grain (metal-based systems). The popping quality differences between threshing system are likely due to a reduction in kernel integrity caused by the impacts to the kernel that occurred while threshing the grain. The results herein indicate that field processing of the grain, notably threshing method has significant impacts on the popping quality and should be taken into consideration when grain sorghum is harvested for popping purposes.

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Feasibility of utilizing sweet potato solids in extrusion cooking / Extrusión de pulpa de batata

Food Science and Technology International ◽

10.1177/108201329700300303 ◽

1997 ◽

Vol 3 (3) ◽

pp. 171-174 ◽

Cited By ~ 1

Author(s):

H.M. Khalil ◽

B.R. Henry

Keyword(s):

Moisture Content ◽

Sweet Potato ◽

Sugar Content ◽

Expansion Ratio ◽

Fractional Factorial ◽

Snack Food ◽

Screw Speed ◽

High Sugar Content ◽

Feed Moisture ◽

Best Parameter

A fractional factorial design of four variables at two levels each was employed to assess the feasi bility and best parameter for extruding sweet potato solids (SPS) using a single screw extruder. It was determined that a high expansion ratio is a desired quality factor for this type of snack food, due to its contribution to textural perception. Preliminary trials on extrusion of sweet potato solids as the sole component in the feed resulted in brittle, dense, and burnt extrudate. The high sugar content (65% total sugar) of the sweet potato solids was cited as the cause of these attrib utes, consequently it was necessary to incorporate wheat flour into the feed to provide a starch matrix for expansion and to reduce sugar concentration. The controlled parameters were screw speed, barrel temperature, feed moisture content, and SPS level in the feed. Among all possible combinations of controlled parameters, the highest expansion ratio was obtained at a screw speed of 220 rpm, temperature profile of 110, 105, 115 and 105 °C, 13% feed moisture content, 50% sweet potato solids, and 0.5% leavening agent.

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Performance prediction of solid-propellant rocket motors and application to high expansion-ratio nozzles

10.2514/6.1979-1295 ◽

1979 ◽

Author(s):

L. JACQUES

Keyword(s):

Performance Prediction ◽

Solid Propellant ◽

Expansion Ratio ◽

Rocket Motors ◽

Solid Propellant Rocket ◽

Propellant Rocket

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Bifurcation Characteristics of Flows in Rectangular Sudden Expansion Channels

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2005-77098 ◽

2005 ◽

Cited By ~ 2

Author(s):

Francine Battaglia ◽

George Papadopoulos

Keyword(s):

Reynolds Number ◽

Laminar Flow ◽

Critical Reynolds Number ◽

Three Dimensional ◽

Reynolds Numbers ◽

Expansion Ratio ◽

Sudden Expansion ◽

Two Dimensional ◽

Effective Expansion ◽

Three Dimensional Simulations

The effect of three-dimensionality on low Reynolds number flows past a symmetric sudden expansion in a channel was investigated. The geometric expansion ratio of in the current study was 2:1 and the aspect ratio was 6:1. Both experimental velocity measurements and two- and three-dimensional simulations for the flow along the centerplane of the rectangular duct are presented for Reynolds numbers in the range of 150 to 600. Comparison of the two-dimensional simulations with the experiments revealed that the simulations fail to capture completely the total expansion effect on the flow, which couples both geometric and hydrodynamic effects. To properly do so requires the definition of an effective expansion ratio, which is the ratio of the downstream and upstream hydraulic diameters and is therefore a function of both the expansion and aspect ratios. When the two-dimensional geometry was consistent with the effective expansion ratio, the new results agreed well with the three-dimensional simulations and the experiments. Furthermore, in the range of Reynolds numbers investigated, the laminar flow through the expansion underwent a symmetry-breaking bifurcation. The critical Reynolds number evaluated from the experiments and the simulations was compared to other values reported in the literature. Overall, side-wall proximity was found to enhance flow stability, helping to sustain laminar flow symmetry to higher Reynolds numbers in comparison to nominally two-dimensional double-expansion geometries. Lastly, and most importantly, when the logarithm of the critical Reynolds number from all these studies was plotted against the reciprocal of the effective expansion ratio, a linear trend emerged that uniquely captured the bifurcation dynamics of all symmetric double-sided planar expansions.

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