2,859 research outputs found
Influence of equal-channel angular pressing on the superplastic properties of commercial aluminum alloys
No full textThe use of acoustics in space exploration
No full textIn recent years increased attention has been paid to the potential uses of acoustics forextraterrestrial exploration. The extent to which acoustics per se is used in these studiesvaries greatly. First, there are the cases in which acoustics is simply the medium throughwhich some other time-varying non-acoustic signal (such as the output of a cosmic raydetector) is communicated to humans. Second, perturbations in a non-acoustic signal (e.g.EM) are interpreted through mechanisms relating to acoustic perturbations in the sourcematerial itself. Third, some probes have made direct measurements of acoustic signalswhich have been generated by the probe itself, as is done for example to infer the localatmospheric sound speed from the time-of-flight of an acoustic pulses over a shortdistance (O(10 cm)). Fourth, some studies have discussed ways of interpreting thenatural acoustic signals generated by the extraterrestrial environment itself. The reportdiscusses these cases and the limitations, implications and opportunities forextraterrestrial exploration using acoustics
The effect of fluid loading on the generation of extraterrestrial sound
No full textIn recent years increased attention has been paid to the potential uses of acoustics for extraterrestrial exploration. Acoustical instrumentation can be deployed in gas, liquid, or solid media for measurement. This report deals specifically with acoustic sensors in gaseous media. Given the variety of atmospheric conditions that could be encountered in other worlds, and the cost and effort associated with sending sensors to them, it is vital that predictive modelling be done to inform the design of the instrumentation and associated acquisition systems, and for mission planning. To this end, it is important to revisit assumptions which have become embedded in our predictions for acoustics in Earth’s atmosphere. This report deals specifically with the issue of fluid loading, and assesses the extent to which the radiation mass associated with immersion of an acoustic source in a gas (an effect which is usually negligible on Earth) affects its resonance frequency
Palpita incesta Ko & Bayarsaikhan & Lee & Cha & Lee & Bae 2021, sp. nov.
No full textPalpita incesta Ko & Bae, sp. nov. (Figs. 1, 3, 5) Type materials. Holotype: 1 m #, Laos, Xieng Khouang Province, Ban Tha (N19˚43′31.40″, E103˚35′25.73″ Alt. 1212 m), 26.VII.2018 (Bae Y.S., Lee D.J., Ko J.H., Lee T.G., Jang C.M., U. Bayarsaikhan), Gen. Slide No. INU–7015L(NIBR). Paratypes (10 m #, 1 fm#): LAOS; 1 m #, Xieng Khouang Province, Ban Tha (N19˚43′0.70″, E103˚35′24.20″ Alt. 1204 m), 30. VI.2017 (Bae Y.S., Na S.M., Lee D.J., Ko J.H., Lee T.G.), Gen. Slide No. INU- 6682L(NIBR); 4 m #, Xieng Khouang Province, Ban Tha (N19˚44′55.46″, E103˚35′5.46″ Alt. 1158 m), 24.VII.2018 (BaeY.S., Lee D.J., Ko J.H., Lee T.G., Jang C.M.,U. Bayarsaikhan), Gen.Slide No. INU-6679L(NIBR), 6680L(NIBR), 6681L(NIBR), 6683L(NIBR); 4 m #, Xieng Khouang Province, Ban Tha (N19˚43′28.92″, E103˚35′26.02″ Alt. 1245 m), 25.VII.2018 (Bae Y.S., Lee D.J., Ko J.H., Lee T.G., Jang C.M., U. Bayarsaikhan), Gen. Slide No. INU- 7011L(INU), 7012L(INU), 7013L(INU), 7014L(INU); 1 m #, Xieng Khouang Province, Ban Tha (N19˚43′31.40″, E103˚35′25.73″ Alt. 1212 m), 26.VII.2018 (Bae Y.S., Lee D.J., Ko J.H., Lee T.G., Jang C.M., U. Bayarsaikhan), Gen. Slide No. INU-7016L(INU); 1 fm#, Xieng Khouang Province, Ban Tha (N19˚43′31.40″, E103˚35′25.73″ Alt. 1212 m), 02.IX.2018 (Bae Y.S., Na S.M., Lee D.J., Ko J.H., Lee T.G., Cha Y.B., Jang C.M.), Gen. Slide No. INU- 7020L(INU). Diagnosis. Palpita incesta sp. nov. is morphologically similar to P. inusitata (Butler), but can be distinguished by the following characters: ground color of wings grayish white (Fig. 1); in male genitalia, sacculus not projected at distal 1/3 (Fig. 3); in female genitalia, ductus bursae entirely sclerotized, except for partly membranous laterally and folded at middle (Fig. 5). In P. inusitata, ground color of wings white (Fig. 2); in male genitalia, sacculus projected at distal 1/3 (Fig. 4); in female genitalia, ductus bursae membranous overall, except for partly sclerotized near antrum and not folded at middle (Fig. 6). Description. Adult (Figs. 1–4). Length of forewing 10–11 mm in both sexes. Vertex covered with grayish white scales; frons flat, covered with grayish white scales; antenna filiform; chaetosema absent; labial palpus upturned, brown, mixed with grayish-white scales; proboscis brown, mixed with grayish-white scales. Patagium and tegula grayish white. Ground color of forewing grayish white; costal margin brownish orange; basicellular dot brownish orange; midcellular mark brownish orange, semicircular, edged with brown line; infracellular mark brownish orange, edged with brown line; discal mark brownish orange, reniform, edged with brown line; subterminal fascia brown, irregularly undulate; terminal area with two brown dots at R 5 and M 1; fringe grayish white. Ground color of hindwing grayish white; basal area with a brown dot; posterior discal dot brownish orange, irregularly ovoid, edged with brown line, with black dot at 1/3 of M 2; subterminal fascia brown, irregularly undulate; terminal area with three brown dots at Rs, M 1, CuP; tornal dot brown; fringe grayish white (Fig. 1). Abdomen slender, grayish white (Fig. 1). Male genitalia (Fig. 3). Uncus rod–shaped, widened at base; valva ovoid, weakly sclerotized from basal to postmedian area, sparsely setose at apex; costa arched, strongly sclerotized; sacculus strongly sclerotized, expanded near apex of valva, tip of sacculus pointed; juxta lobate, strongly sclerotized; saccus small, U-shaped; phallus cylindrical, sclerotized ventrally, almost same length as valva, with one long and two short, thorn-like cornuti (Fig. 3). Female genitalia. Papilla anales simple, setose; posterior apophyses about half length of anterior apophyses; antrum broad, sclerotized; ductus bursae about 3 times length of corpus bursae, sclerotized overall, except partly membranous at laterally, swollen near antrum and strongly curved, folded at middle; corpus bursae ovate, with a pair of spine-shaped signa (Fig. 5). Distribution. Laos (Ban Tha). Etymology. The specific name is derived from the Latin incesta, referring to the cloudy wings of the adults.Published as part of Ko, Jae-Ho, Bayarsaikhan, Ulziijargal, Lee, Tak-Gi, Cha, Yeong-Bin, Lee, Jong Koo & Bae, Yang-Seop, 2021, A new species of Palpita Hübner from Laos (Lepidoptera, Crambidae Spilomelinae), pp. 577-582 in Zootaxa 4990 (3) on pages 578-581, DOI: 10.11646/zootaxa.4990.3.9, http://zenodo.org/record/509873
Effect of moisture on tuffstone weathering
No full textTuffstone elements with a large length/width ratio, as e.g. mullions, often suffer damage in the form of cracks parallel to the surface and spalling of the outer layer. The response of tuff to moisture might be a reason for this behaviour. This research aimed at verifying if a differential dilation between parts with different moisture content (as outer and inner part of partially encased mullion) can lead to damage. The effect of moisture on the degradation of Ettringen and Weibern tuff has been investigated. A purpose-made weathering test was carried out to simulate the wetting-drying process. Despite no cracks developed during the test, existing cracks widened up and the flexural tensile strength of both materials decreased. The moisture transport properties of the stones were determined as well as their porosity and pore size. Ettringen tuff has a considerable amount of very fine porosity, resulting in slow moisture transport and significant hygroscopic adsorption. Both tuffstones have an extreme hydric dilation. Environmental X-ray diffraction analyses showed that Ettringen tuff undergoes (reversible) mineralogical changes when subjected to RH cycles, whereas this does not occur for Weibern. All results support the hypothesis that moisture gradients in tuff elements may enhance decay in this stone
An investigation of cavity development in a superplastic aluminium alloy prepared by equal-channel angular pressing
No full textExperiments were conducted on a commercial aluminum Al-2004 alloy known as Supral 100 and containing 6% Cu and 0.4% Zr. This material was subjected to Equal-Channel Angular Pressing (ECAP) over a range of experimental conditions and the mechanical properties of the as-pressed samples were determined using standard tensile testing. Samples were pulled to failure and the level of internal cavitation was then recorded quantitatively using metallographic techniques. The results show this alloy exhibits good superplastic properties after ECAP with total tensile elongations up to >1000%. As in conventional superplasticity, there is the development of extensive internal cavitation in this alloy in the as-pressed condition. Measurements are reported for the average sizes and shapes of these cavities
Een plaag van alle tijden: zout: Over oude en toekomstige schade, oud en toekomstig onderzoek
No full textIn deze bijdrage wordt nader ingegaan op de achtergronden van zoutschade, de vraag of we er in de toekomst meer last van zullen krijgen, en op oud, nieuw en gewenst onderzoek.Heritage & Technolog
Thermal and Mechanical Characterization of Poly(L-lactic acid) Nanocomposite Scaffold
No full textInorganic nanosized silicate nanoplatelets were incorporated into biodegradable poly(L-lactic acid) (PLLA) for the purpose of tailoring mechanical stiffness of PLLA porous scaffold systems. Increasing the nucleation density around the foreign body surfaces, the montmorillonite (MMT) nanoplatelets modified with dimethyl dihydrogenated tallow ammonium cations decreased the glass transition temperature and the degree of PLLA crystallinity, which seemingly caused the accelerated biodegradation rate of PLLA nanocomposites due to the enhanced segmental mobility of backbone chains and the expanded amorphous region of PLLA matrix. The tensile modulus was increased from 121.2 MPa of pristine polymer scaffold to 170.1 MPa of MMT/PLLA nanocomposite scaffold (ca. 40% increment) by the addition of small amount of MMT platelets (5.79 vol%) acting as a mechanical reinforcement of polymer chains in the nanoscale molecular level. Overall, the nanotechnology used in this study may be applied to various scaffold systems of biodegradable polymers and hard/soft scaffold structures requiring critical control and design characteristics of mechanical stiffness and biodegradation rate. (C) 2003 Elsevier Science Ltd. All rights reserved.the Korea
Research Foundatio
Tomato sequence FastQC
No full textKim, J., Lee, T.G. Genome sequence data of the contemporary fresh-market tomatoes. BMC Genomic Data 25, 65 (2024). https://doi.org/10.1186/s12863-024-01249-3</p
Microstructural evolution and mechanical properties in a Zn-Al eutectoid alloy processed by high-pressure torsion
No full textExperiments were conducted to examine the evolution of microstructure and mechanical properties in a Zn–22% Al eutectoid alloy processed by high-pressure torsion (HPT). Measurements of the Vickers microhardness revealed significant weakening in the alloy after HPT, and microstructural analysis showed that the initial duplex structure, consisting of equiaxed grains and lamellae, was retained at the disk centers after HPT, whereas equiaxed fine grains were observed at the disk edges. Direct evidence is presented for a transformation of the lamellae into equiaxed very fine grains and subsequent dynamic recrystallization in the early stages of HPT. The reduction of the lamellar structure and the loss of Zn precipitates account for the weakening in the alloy in HPT processing. Excellent high strain rate superplasticity was recorded after HPT, with elongations up to ?1800% at 473 K at a strain rate of 10?1 s?1. The experiments show that the maximum elongations are displaced to faster strain rates with increasing numbers of HPT turn
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