3,120 research outputs found
DEVS-based doctrine validation of fleet anti-air defense
No full textThe fleet anti-air defense system is growing increasingly complex. This complexity requires a complicated doctrine for its operators, and the doctrine needs to be analyzed under what-if scenarios. The most ideal analysis method is investigating live combat outcomes, yet such events rarely occur. Hence, we develop a discrete event-based model, perform battle experiments of fleet anti-air defense, and analyze the results. This battle experiment resulted in a better fleet formation against air threats and recommendations for weapon loads on warships
An adaptive loss-aware flow control scheme for delay-sensitive applications in OBS networks
No full textOptical Burst Switching (OBS) is one of the most promising switching technologies for next generation optical networks. As delay-sensitive applications such as Voice-over-IP (VoIP) have recently become popular, OBS networks should guarantee stringent Quality of Service (QoS) requirements for such applications. Thus, this paper proposes an Adaptive Loss-aware Flow Control (ALFC) scheme, which adaptively decides on the burst offset time based on loss-rate information delivered from core nodes for assigning a high priority to delay-sensitive application traffic. The proposed ALFC scheme also controls the upper-bounds of the factors inducing delay and jitter for guaranteeing the delay and jitter requirements of delay-sensitive application traffic. Moreover, a piggybacking method used in the proposed scheme accelerates the guarantee of the loss, delay, and jitter requirements because the response time for. flow control can be extremely reduced up to a quarter of the Round Trip Time (RTT) on average while minimizing the signaling overhead. Simulation results show that our mechanism can guarantee a 10(-3) loss-rate under any traffic load while offering satisfactory levels of delay and jitter for delay-sensitive applications.The work was supported in part by the Korea Science and Engineering foundation(KOSEF) grant funded by the Korea government(MEST) (No.R11-2000-074-01001-0) and MIC, Korea under the ITRC program (ITAC1090060300350001000100100) supervised by IITA
Ultra-low power hydrogen sensor by suspended and palladium coated silicon nanowire
No full textThis paper reports silicon nanowire sensor decorated with palladium nanoparticles for the low temperature hydrogen detection with self-heating for fast response and recovery. Hydrogen gas responses of the palladium coated silicon nanowire (Pd-SiNW) were measured with Joule heating of Pd-SiNW. Even though the Pd-SiNW can detect hydrogen gas at room temperature, transient response is slow and even slower in humid conditions. Self-heating of the Pd-SiNW reduces the response and recovery times by consuming low power without any significant change of sensitivity. Power consumption is further reduced to sub-100 mu W by suspending the Pd-SiNW from substrate. Humidity effect on hydrogen sensing was also reduced by Joule heating. Joule heated Pd-SiNW device is a promising hydrogen gas sensor to apply mobile device
Franny Choi, 41st Annual ODU Literary Festival
No full textFranny Choi is a queer, Korean-American poet, playwright, teacher, organizer, pottymouth, GryffinClaw, and general overachiever. She is the author of Floating, Brilliant, Gone (2014), and a chapbook, Death by Sex Machine (2017). She has received awards from the Poetry Foundation and the Helen Zell Writers Program, as well as fellowships from the Vermont Studio Center and the Rhode Island State Council on the Arts. Her poems have appeared in journals including Poetry magazine, American Poetry Review, New England Review, and her work has been featured by the Huffington Post, PBS NewsHour, and Angry Asian Man
Achromatic elastic metalens for high-performance confocal piezoelectric energy harvesting
No full textIn this study, we analytically, numerically, and experimentally investigated a high-performance confocal piezoelectric energy harvesting system. We achieved a significantly enhanced electrical performance through a Mikaelian lens, which achromatically focuses ambient elastic waves, resulting in the formation of a highly amplified strain energy field in the piezoelectric energy harvester. Previous studies on piezoelectric energy harvesting platforms have limitations, such as the focal position changing with operating frequencies and impedance mismatching owing to inclusions or holes. To address these problems, we utilized the self-focusing ability based on the conformal mapping theory and achromatic ability based on the Kirchhoff-Love thin plate theory to design our Mikaelian lens-based piezoelectric energy harvesting platform. The proposed platform demonstrates a remarkable elastic wave focusing ability at an identical focal position for a broad frequency range. The experimentally visualized wave fields matched well with the numerically calculated full-wave harmonic simulation results. We achieved highly amplified output power up to 1.44 mW within a broad range from 40 to 60 kHz out of the same focal point owing to confined elastic wave energy; the output power extracted at this confocal position was up to 3.76 times higher than that extracted at the lens start position. Our highly performance and broadband achromatic piezoelectric energy harvesting platform lays an attractive foundation for designing potential applications, such as wireless sensing, structural health monitoring, and biomedical devices.
Anisotropic drop spreading on superhydrophobic grates during drop impact
No full textWe study the influence of geometric anisotropy of micro-grate structures on the spreading dynamics of water drops after impact. It is found that the maximal spreading diameter along the parallel direction to grates becomes larger than that along the transverse direction beyond a certain Weber number, while the extent of such an asymmetric spreading increases with the structural pitch of grates and Weber number. By employing grates covered with nanostructures, we exclude the possible influences coming from the Cassie-to-Wenzel transition and the circumferential contact angle variation on the spreading diameter. Then, based on a simplified energy balance model incorporating slip length, we propose that slip length selectively enhances the spreading diameter along the parallel direction, being responsible for the asymmetric drop spreading. We believe that our work will help better understand the role of microstructures in controlling the drop dynamics during impact, which has relevance to various engineering applications
High-efficiency power generation in hyper-saline environment using conventional nanoporous membrane
No full textHere we introduce the new approach to high-efficiency power generation from a salinity difference using conventional nanoporous Nafion membrane. When access areas on each side of nanoporous Nafion membrane are set to be asymmetric, the ratio of ionic current upon a voltage bias of the different polarity also becomes asymmetric, resulting in ionic diode phenomena. When this geometrical ionic diode effect is combined with a salinity gradient, it can help significantly improve the energy conversion efficiency from a salinity difference even under a hyper-saline environment with a large salinity difference, e.g. similar to 41% conversion efficiency and similar to 120 nW power generation with 1M KCl and 1000-fold salinity difference, both of which are comparable with the best performances reported in the previous studies. We propose that the decrease in ion concentration polarization at a low salt concentration side is responsible for the enhanced power generation with the membrane having asymmetric access areas. Our approach is simple to implement and can be applicable to any nanoporous membrane to enhance the power generation from a salinity difference. (C) 2019 Elsevier Ltd. All rights reserved.
Self-Powered Real-Time Temperature Sensing Based on Flexible Ionic Elastomer on Triboelectric Nanogenerators
No full textSelf-powered flexible thermal-management systems have garnered interests in wearable electronic devices and AI semiconductors. However, their efficiency and reliability remain limited in practical applications. In this study, an ionic temperature-sensing triboelectric nanogenerator (iTS-TENG) is proposed with an ionic elastomer containing thermoplastic polyurethane (TPU) and ionic liquids (ILs). The TPU matrix undergoes deformation of microphase separation by thermal stimulation near the glass transition temperature. Furthermore, ILs facilitate the formation of electrical double layers as charge carriers and enhance the thermal sensitivity as heat carriers under mechanical and thermal stimuli. Thus, iTS-TENG demonstrates enhanced outputs (734 V) and high thermal sensitivity (3.87 V/degrees C) from room temperature to 70 degrees C, with fast response time and reproducibility (more than 20 cycles). Finally, real-time and self-powered iTS-TENG is demonstrated, showing that the sensed temperature is comparable to a commercial temperature sensor. These results indicate that iTS-TENG is suitable for thermal-management applications in self-powered wearable electronic systems.
Preso, A Novel PSD-95-Interacting FERM and PDZ Domain Protein That Regulates Dendritic Spine Morphogenesis
No full textPSD-95 is an abundant postsynaptic density (PSD) protein involved in the formation and regulation of excitatory synapses and dendritic spines, but the underlying mechanisms are not comprehensively understood. Here we report a novel PSD-95-interacting protein Preso that regulates spine morphogenesis. Preso is mainly expressed in the brain and contains WW( domain with two conserved Trp residues), PDZ (PSD-95/Dlg/ZO-1), FERM (4.1, ezrin, radixin, and moesin), and C-terminal PDZ-binding domains. These domains associate with actin filaments, the Rac1/Cdc42 guanine nucleotide exchange factor beta Pix, phosphatidylinositol-4,5-bisphosphate, and the postsynaptic scaffolding protein PSD-95, respectively. Preso overexpression increases the density of dendritic spines in a manner requiring WW, PDZ, FERM, and PDZ-binding domains. Conversely, knockdown or dominant-negative inhibition of Preso decreases spine density, excitatory synaptic transmission, and the spine level of filamentous actin. These results suggest that Preso positively regulates spine density through its interaction with the synaptic plasma membrane, actin filaments, PSD-95, and the beta Pix-based Rac1 signaling pathway.This work was supported by the National Creative Research Initiative Program of the Korean Ministry of Science and Technology (E.K.) and the 21C Frontier Research and Development Program in Neuroscience of the Korean Ministry of Science and Technology (Grant M103KV010023-07K2201-02510) (H.K.). We thank the Kazusa DNA Research Institute for the KIAA0316 cDNA clone
QJE-STD-18-253.R2-Supplementary_Material – Supplemental material for Development and assessment of the Korean Author Recognition Test
No full textSupplemental material, QJE-STD-18-253.R2-Supplementary_Material for Development and assessment of the Korean Author Recognition Test by Hyosun Lee, Eunjin Seong, Wonil Choi and Matthew W Lowder in Quarterly Journal of Experimental Psychology</p
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