166 research outputs found
Optical properties and crystallization behavior of 45GeS(2)center dot 30Ga(2)S(3)center dot 25Sb(2)S(3) chalcogenide glass
No full textGlass-ceramics containing Ga2S3 nano-crystals were reproducibly fabricated from the 45GeS(2)center dot 30Ga(2)S(3)center dot 25Sb(2)S(3) chalcogenide glass by heat treatment at 335 degrees C (T-g + 30 degrees C) for different durations. The obtained glass-ceramics are still transparent in the IR region and show improved thermal stability. Crystallization mechanism was investigated using the non-isothermal method. The results show that the crystallization rate constant K at 335 degrees C for the Ga2S3 phase is about 2 orders of magnitude larger than that of the second crystallization peak in the DSC curve. So it is easy to control the crystallization process with only Ga2S3 crystallites precipitated. With the above advantages, it has a great potential for drawing infrared transmitting glass-ceramic fibers with improved mechanical properties and enhanced luminescence for application in optical amplifiers. (C) 2013 Elsevier B.V. All rights reserved
Formation and properties of chalcogenide glasses based on GeS2-Sb2S3-AgI system
No full textInternational audienceNovel glasses in GeS2-Sb2S3-AgI system have been prepd. by melt-quenching method. A large glass-forming region was found in this novel system, in which almost 60 mol% AgI has been incorporated. The basic physiochem. properties of glass samples were investigated. With the addn. of AgI, red shift of short-wavelength absorption edge and distinct drop of the glass transition temp. (Tg) were obsd. In addn., a high Ag+ ion cond. of 6.37×10-4 S/cm at room temp. was obtained in 55(0.6GeS2-0.4Sb2S3)-45AgI sample, indicating that these glasses have potential application as amorphous solid electrolytes
Impact of model resolution on simulating the water vapor transport through the central Himalayas: implication for models’ wet bias over the Tibetan Plateau
No full text© 2018 The Author(s) Current climate models commonly overestimate precipitation over the Tibetan Plateau (TP), which limits our understanding of past and future water balance in the region. Identifying sources of such models’ wet bias is therefore crucial. The Himalayas is considered a major pathway of water vapor transport (WVT) towards the TP. Their steep terrain, together with associated small-scale processes, cannot be resolved by coarse-resolution models, which may result in excessive WVT towards the TP. This paper, therefore, investigated the resolution dependency of simulated WVT through the central Himalayas and its further impact on precipitation bias over the TP. According to a summer monsoon season of simulations conducted using the weather research forecasting (WRF) model with resolutions of 30, 10, and 2 km, the study found that finer resolutions (especially 2 km) diminish the positive precipitation bias over the TP. The higher-resolution simulations produce more precipitation over the southern Himalayan slopes and weaker WVT towards the TP, explaining the reduced wet bias. The decreased WVT is reflected mostly in the weakened wind speed, which is due to the fact that the high resolution can improve resolving orographic drag over a complex terrain and other processes associated with heterogeneous surface forcing. A significant difference was particularly found when the model resolution is changed from 30 to 10 km, suggesting that a resolution of approximately 10 km represents a good compromise between a more spatially detailed simulation of WVT and computational cost for a domain covering the whole TP
On the product of two generic -Gevrey series
No full textIn this paper, we consider a -analog of the Borel-Laplace summation process introduced by Fabienne Marotte and the second author. We specifically examine two power series solutions of linear -difference equations whose Newton polygon admits only positive slopes equal to . These series, known as the generic -Gevrey series, are shown to have the property that the product of two such series is -summable at double level . Furthermore, we prove that the -sum of this product equals the product of the -sums of the original two series
A Crystal-Less Clock Generation Technique for Battery-Free Wireless Systems
No full textThe size of wireless systems is required to be reduced in many applications, such as ultra-low-power sensor nodes and wearable/implantable devices, where battery and crystal are the two main bottlenecks in system miniaturization. In recent years, battery-free radios based on wireless power transfer (WPT) have shown great potential in miniature wireless systems, while a reliable on-chip clock without a crystal remains a design challenge. Conventional methods utilized the RF WPT tone as the reference for clock generation, but the high RF frequency leads to high power consumption. In comparison, using a lower WPT frequency results in an antenna with a larger size. In this work, the 2nd-order inter-modulation (IM2) component of the two RF WPT tones is extracted to lock an on-chip oscillator, providing a low-jitter PVT-robust clock. In this way, the wireless systems can benefit from: 1) The clock recovery circuits operate at a low IM2 frequency, reducing the power consumption. 2) The WPT can be set to a high RF frequency to minimize the antenna. Fabricated in 65 nm CMOS process, the proposed crystal-less clock generator takes a small area of 0.023 mm2 in a wireless system chip. Measured results show -92 dBc/Hz@10 kHz phase noise and 6.8 μ W power.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Instrumentatio
A 2m-Range 711uW Body Channel Communication Transceiver Featuring Dynamically-Sampling Bias-Free Interface Front End
No full textBody Channel Communication (BCC) offers a low-loss signal transmission medium for ultra-low-power wearable devices on human body [1]. However, the effective communication range on human body is limited to less than 1m in the state-of-the-art BCC transceivers [2], where the signal loss at the interface of body surface and BCC receiver remains to be one of the main bottlenecks. The limited communication range has blocked the popularization in many WBAN applications, such as signal transmission from to an intelligent insole to smart watch [3]. Relative to the high impedance of human body [4], the lower input impedance of BCC receiver induces significant signal loss. To reduce the interface loss, conventional interface front end (IFE) of BCC receivers was designed to be with a high input impedance [5], but the DC voltage bias decreased both the input impedance and signal gain of IFE.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Instrumentatio
Phase separation and nanocrystallization in KF–ZnF2–SiO2 glasses: lessons from solid-state NMR
No full text
Au cours de cette étude, le processus de cristallisation ainsi que l évolution des propriétés physico-chimiques de verres infrarouges à base de GeS avec addition de Ga S et de composants MX (Ag S, LiI,et CsCl) a été étudié. Des séries de vitrocéramiques présentant des propriétés thermo-mécaniques améliorées ont été obtenues par cristallisation contrôlée de verres GeS -Ga S . La génération de nanoparticules dans le verre au LiI conduit à des vitrocéramiques présentant un phénomène de génération de seconde harmonique et à une augmentation de conductivité ionique. La connaissance des courbes de nucléation-croissance a permis l obtention de vitrocéramiques hautement transparentes dans le moyen infrarouge à partir de verres du système GeS -Ga S -CsCl totalement transparents dans le domaine du visible. Les changements des propriétés thermo-mécaniques des vitrocéramiques ont été discutés en fonction de l évolution de la structure de la matrice vitreuse résiduelle et des cristaux générés.The crystallization behavior and related physicochemical properties of nontoxic GeS -based chalcogenide glasses were focused on with the addition of Ga S and MX (Ag S, LiI, and CsCl) components. In this study, clear SHG was observed in b-GeS crystallized glasses. Then, series of glass-ceramics with improved physiochemical properties were obtained by controllable crystallization of GeS -Ga S glasses. The well-crystallized samples of 65GeS ·25Ga S ·10LiI glass present clear SHG phenomena and enhanced ionic conductivity. Based on the glass-forming region, phase transformation was determined in GeS -Ga2S -CsCl system. Subsequent to the knowledge of nucleation-rate-like curve, a set of reproducible glass-ceramics with high transparency in the mid-IR region were obtained. Structural dependence on these resultant attractive properties was investigated in detail by employing various techniques, such as DSC, SEM, Raman scattering, and solid state NMR.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF
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