28,645 research outputs found
Dataset for paper "Sound Transmission Loss Properties of Truss Core Extruded Panels"
No full textDataset supports:
Zhang, Y., Thompson, D., Squicciarini, G., Ryue, J., Xiao, X., & Wen, Z. (2017). Sound Transmission Loss Properties of Truss Core Extruded Panels. Applied Acoustics. </span
Guest editorial guided lightwaves for sensors and measurement systems: advanced techniques and applications
No full textThis IEEE/OSA Journal of Lightwave Technology special issue on \u201cGuided Lightwaves for Sensors & Measurement Systems: Advanced Techniques and Applications\u201d is organized by the IEEE Instrumentation and Measurement Society. It aims to highlight the advancement of guided lightwaves in applications to sensors, instrumentation and measurement. The special issue includes both comprehensive review articles and original technical contributions covering the rapid advancement of guided lightwaves in the applications to instrumentation and measurement. 18 invited papers and 22 contributed papers will be published in this issue. The authors are from universities, government labs and industries. We hope that this JLT Special Issue will provide an in-depth look at the topic areas and serve as a valuable reference for the current and future scientists, engineers, and technical applicators working in the related fields.Peer reviewed: YesNRC publication: Ye
Guest editorial guided lightwaves for sensors and measurement systems: Advanced techniques and applications
No full textSpecific Surface Areas of Porous Cu Manufactured by Lost Carbonate Sintering: Measurements by Quantitative Stereology and Cyclic Voltammetry
No full textOpen-cell porous metals have many applications due to high surface area to volume ratios. Porous metals manufactured by the space holder methods have distinctively different porous structure from commercial open-cell metal foams, but very little research has been conducted to characterise the surface area of this class of materials. This paper measured the geometric, electroactive and real surface areas of porous Cu samples manufactured by the Lost Carbonate Sintering process by quantitative stereology and cyclic voltammetry. A cyclic voltammetry (peak current) procedure has been developed and successfully applied to the measurement of electroactive surface areas of the porous Cu. For porous Cu samples with pore sizes 75-1500 µm and porosities 0.5-0.8, the volumetric and gravimetric specific geometric, electroactive and real surface areas are in the ranges of 15-90 cm-1 and 5-45 cm2/g, 200-400 cm-1 and 40-130 cm2/g, and 1000-2500 cm-1 and 400-800 cm2/g, respectively, varying with pore size and porosity. The geometric, electroactive and real surface areas are found to result from the contributions from primary porosity, primary and secondary porosities, and surfaces of metal particles, respectively. The measurement methods adopted in this study can provide vital information of surface areas at different length scales, which is important for many applications
A new terrestrial analogue site for Mars research: The Qaidam Basin, Tibetan Plateau (NW China)
No full textRemote sensing observations and rover missions have documented the presence of playas, salts, and wind erosion landforms of lacustrine sediments on Mars. All of these observations suggest Mars was aqueous in its early history. However, abundant questions remain: How wet was the environment, what were the properties of the liquids and the possibility of ancient habitability, and what kinds of geological processes shaped the present landforms? To explore these unknowns, analogue studies can play a key role. In this contribution, we introduce the Qaidam Basin, Tibetan Plateau, northwestern China as a new and unique analogue site for studying the past aqueous and present arid environments of Mars. The Qaidam Basin, the highest and one of the largest and driest deserts on Earth, is located in a dry, cold, and high UV environment, similar to the surface of Mars. We demonstrate a variety of landforms and also their counterparts on Mars, which include aeolian dunes and yardangs, polygons, gullies, valleys, and fluvial fans. In the Qaidam Basin, various environmental regimes for the formation of linear and asymmetric barchans have been described. Saline lakes and playas representing different stages of lake evolution in arid environment are also present in the Qaidam Basin and provide promising cases for studying the habitability in Mars-like environments. Results for microorganism isolation suggest that halophiles are the most important fraction in the hypersaline sediments and this may shed light on studying present Martian habitability. Moreover, the remote but ready accessibility of the Qaidam Basin make it a potential site for engineering testing in regards to future martin exploration missions. We propose that the variety of exogenic and endogenic geomorphic types, lacustrine sediments, evaporite mineral assemblages and Mars-like extreme environments collectively point to the Qaidam Basin as an optimal (C) 2016 Elsevier B.V. All rights reserved
Construction of bosonic symmetry-protected-trivial states and their topological invariants via G x SO(∞) nonlinear σ
No full textIt has been shown that the bosonic symmetry-protected-trivial (SPT) phases with pure gauge anomalous boundary can all be realized via nonlinear σ models (NLσMs) of the symmetry group G with various topological terms. Those SPT phases (called the pure SPT phases) can be classified by group cohomology H[superscript d](G,R/Z). But there are also SPT phases with mixed gauge-gravity anomalous boundary (which will be called the mixed SPT phases). Some of the mixed SPT states were also referred as the beyond-group-cohomology SPT states. In this paper, we show that those beyond-group-cohomology SPT states are actually within another type of group cohomology classification. More precisely, we show that both the pure and the mixed SPT phases can be realized by G × SO(∞) NLσMs with various topological terms. Through the group cohomology H[superscript d][G × SO(∞),R/Z], we find that the set of our constructed SPT phases in d-dimensional space-time are described by E[superscript d](G) ⋊ ⊕[d−1 over k=1]H[superscript k](G,iTO[d−k over L]) ⊕ H[superscript d](G,R/Z) where G may contain time reversal. Here iTO[d over L] is the set of the topologically ordered phases in d-dimensional space-time that have no topological excitations, and one has iTO[1 over L] = iTO[2 over L] = iTO[4 over L] = iTO[6 over L] = 0, iTO[3 over L] = Z, iTO[5 over L] = Z[subscript 2], iTO[7 over L] =2Z. For G=U(1) ⋊ Z[ T over 2] (charge conservation and time-reversal symmetry), we find that the mixed SPT phases beyond H[superscript d][U(1) ⋊ Z[T over 2],R/Z] are described by Z[subscript 2] in 3 + 1D, Z in 4 + 1D, 3Z[subscript 2] in 5 + 1D, and 4Z[subscript 2] in 6 + 1D. Our construction also gives us the topological invariants that fully characterize the corresponding SPT and iTO phases. Through several examples, we show how the universal physical properties of SPT phases can be obtained from those topological invariants.National Science Foundation (U.S.) (Grant DMR-1005541)National Science Foundation (U.S.) (Grant NSFC 11274192)BMO Financial GroupTempleton Foundation (Grant 39901
Recent boulder falls within the Finsen crater on the lunar far side: An assessment of the possible triggering rationale
No full textTo better understand the necessary triggers for the origin of the lunar boulder tracks, we report 650 tracks from the ~73 km in diameter Finsen crater. The tracks
were identified on the crater wall and the central peak region of the Finsen crater, located within the South Pole ̶ Aitken basin on the lunar far side. In this manuscript,
we assessed two main possibilities of triggers, 1) ground shakings by the recent meteorite impact, and 2) ground shaking from recent fault reactivation associated
with the lobate scarps identified inside and in the vicinity of the Finsen crater. Our assessments revealed that the impact-induced seismicity could have generated the
moonquake with the maximum moment magnitude (MW) 4.63. We also estimated that the moonquakes excited by the movements along the lobate scarps had an
estimated cumulative (or maximum possible) moment magnitude (MW) up to 6.86 and 6.90, i.e., for the basaltic and noritic basement respectively. Considering the
location of the Finsen crater positioned over the structural discontinuity along the boundary of the central and mid rings of the South Pole ̶ Aitken basin and higher
moment magnitude generated from the fault movements, we propose that the region is potentially seismotectonically active, and reactivation of pre-existing faults
possibly triggered/triggers the necessary ground motion for the boulders to initiate their movements. However, impact-induced ground shakings and deep-focused
moonquakes also remain possibilities for triggers
Dodecatwistarene Imides with Zigzag-Twisted Conformation for Organic Electronics
No full text1D nonplanar graphene nanoribbons generally have three possible conformers: helical, zigzag, and mixed conformations. Now, a kind of 1D nonplanar graphene nanoribbon, namely dodecatwistarene imides featuring twelve linearly fused benzene rings, was obtained by bottom-up synthesis of palladium-catalyzed Stille coupling and C−H activation. Single-crystal X-ray diffraction analyses revealed that it displays a zigzag-twisted conformation caused by steric hindrance between imide groups and neighboring annulated benzene rings with the pendulum angle of 53°. This conformation is very stable and could not convert into other conformations even when heated up to 250 °C for 6 h. Despite of the highly twisted topology, organic field-effect transistor based on it exhibits electron mobility up to 1.5 cm2 V−1 s−1 after annealing
Reduced graphene oxide/iron nanoparticles used for the removal of Pb (II) by one step green synthesis
No full textWhile nanomaterials are increasingly being proposed for contaminant remediation, a major challenge is how to develop high removal functionality while maintaining low cost and environmental friendliness. In this study, a hybrid reduced graphene oxide/iron nanoparticle (rGO/Fe NPs) was prepared via the in situ reduction of GO and FeCl3 by eucalyptus leaf extract in one-pot. The obtained rGO/Fe NPs could rapidly remove 72.7% of Pb(II) from aqueous solution in 10 mins and remove up to the maximum removal efficiency of 82.4%. Electron microscopy, XPS and BET showed that the irregular Fe3O4 nanoparticles, sized between 20 and 40 nm, were disorderly dispersed on rGO sheets, which constituted a mesoporous material. FTIR and XRD indicated that the surface of rGO/Fe NPs was capped by many active organic constituents from the eucalyptus leaf extract. rGO/Fe NPs also showed a high selectivity for Pb(II) with minimal interference from either calcium or magnesium ions in the solution. Finally, GC–MS separated 13 significant active organic constituents from the eucalyptus leaf extract that possibly contributed to the reduction of rGO/Fe NPs. Overall, eucalyptus leaf extracts, acted efficiently as green reducing agents and impacted reactivity of the final material by determining the components and surface properties of rGO/Fe NPs
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