Abstract
Flexible electronics have suggested tremendous potential to shape human lives for more convenience and pleasure. Strenuous efforts have been devoted to developing flexible organic ...field-effect transistor (FOFET) technologies for rollable displays, bendable smart cards, flexible sensors and artificial skins. However, these applications are still in a nascent stage for lack of standard high-performance material stacks as well as mature manufacturing technologies. In this review, the material choice and device design for FOFET devices and circuits, as well as the demonstrated applications are summarized in detail. Moreover, the technical challenges and potential applications of FOFETs in the future are discussed.
Debris flows represent one of the most dangerous types of mass movements, because of their high velocities, large impact forces and long runout distances. This review describes the available ...debris-flow monitoring techniques and proposes recommendations to inform the design of future monitoring and warning/alarm systems. The selection and application of these techniques is highly dependent on site and hazard characterization, which is illustrated through detailed descriptions of nine monitoring sites: five in Europe, three in Asia and one in the USA. Most of these monitored catchments cover less than ∼10km2 and are topographically rugged with Melton Indices greater than 0.5. Hourly rainfall intensities between 5 and 15mm/h are sufficient to trigger debris flows at many of the sites, and observed debris-flow volumes range from a few hundred up to almost one million cubic meters. The sensors found in these monitoring systems can be separated into two classes: a class measuring the initiation mechanisms, and another class measuring the flow dynamics. The first class principally includes rain gauges, but also contains of soil moisture and pore-water pressure sensors. The second class involves a large variety of sensors focusing on flow stage or ground vibrations and commonly includes video cameras to validate and aid in the data interpretation. Given the sporadic nature of debris flows, an essential characteristic of the monitoring systems is the differentiation between a continuous mode that samples at low frequency (“non-event mode”) and another mode that records the measurements at high frequency (“event mode”). The event detection algorithm, used to switch into the “event mode” depends on a threshold that is typically based on rainfall or ground vibration. Identifying the correct definition of these thresholds is a fundamental task not only for monitoring purposes, but also for the implementation of warning and alarm systems.
Polymer-based gate dielectrics have received growing attention due to their important role in field-effect transistors (OFETs). This review article aims to present the recent progress of polymer ...dielectrics for high-performance OFET applications. We first discuss the requirements for polymer dielectrics in tailoring the overall performance of OFETs from the perspective of both bulk material properties and surface characteristics of the polymers. On this basis, we introduce the design strategies and desired processing techniques of polymer dielectrics for optimizing the charge transport and stabilizing the operation of OFETs. Then, we highlight the recent advances in polymer-based dielectrics by classifying and comparing different categories of polymeric materials as well as polymer nanocomposites, and focus is also given to elucidating the critical relationships between polymer structures, gate dielectric properties and OFET performance. Finally, a perspective of future research directions and challenges for polymer dielectrics is provided.
The Ms 8.0 Wenchuan Earthquake has greatly altered the rainfall threshold for debris flows in the affected areas. This study explores the local intensity–duration (I–D) relationship based on 252 ...post-earthquake debris flows. It was found that I=5.25 D-0.76 accounts for more than 98% of the debris flow occurrences with rainfall duration between 1 and 135h; therefore the curve defines the threshold for debris flows in the study area. This gives much lower thresholds than those proposed by the previous studies, suggesting that the earthquake has greatly decreased the thresholds in the past years. Moreover, the rainfall thresholds appear to increase annually in the period of 2008–2013, and present a logarithmic increasing tendency, indicating that the thresholds will recover in the future decades.
Debris flows occur frequently and cause considerable damage in the Wenchuan Earthquake area; however, there has been no systematic real-time monitoring of such events. This study used a monitoring ...system to consider the spatial variation of meteorological and flow processes in a 39.4 km2 watershed. The system comprised three rainfall gauges at different locations, and three hydrological monitoring stations, located on the mainstream and tributaries, with instruments to measure the velocity, height, and density of debris flows. Based on the monitoring data, the debris flow events were categorized and the general runoff velocity, discharge, and density were analysed. We proposed empirical methods for estimating the velocity and the total volume of debris flows based on other easily obtainable parameters, e.g., maximum flow depth and duration. Comparison of the results derived using the monitoring data and empirical formulas with those obtained in other small watersheds worldwide revealed the debris flow characteristics in this relatively large watershed. Rainfall threshold for the debris flows was proposed, which is higher than those proposed for the same region for periods shortly after the Wenchuan Earthquake (2008–2013), and the temporal evolution of the rainfall conditions necessary for debris flows was addressed.
•The debris flow behaviours of small tributaries and the main stream are presented and their differences were addressed.•The empirical methods for estimating the flow velocity and total volume were derived.•The rainfall thresholds for debris flow occurrence were proposed.
Simulation and projection of the characteristics of heat waves over China were investigated using 12 CMIP5 global climate models and the CN05.1 observational gridded dataset. Four heat wave indices ...(heat wave frequency, longest heat wave duration, heat wave days, and high temperature days) were adopted in the analysis. Evaluations of the 12 CMIP5 models and their ensemble indicated that the multi-model ensemble could capture the spatiotemporal characteristics of heat wave variation over China. The inter-decadal variations of heat waves during 1961–2005 can be well simulated by multi-model ensemble. Based on model projections, the features of heat waves over China for eight different global warming targets (1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 °C) were explored. The results showed that the frequency and intensity of heat waves would increase more dramatically as the global mean temperature rise attained higher warming targets. Under the RCP8.5 scenario, the four China-averaged heat wave indices would increase from about 1.0 times/year, 2.5, 5.4, and 13.8 days/year to about 3.2 times/year, 14.0, 32.0, and 31.9 days/year for 1.5 and 5.0 °C warming targets, respectively. Those regions that suffer severe heat waves in the base climate would experience the heat waves with greater frequency and severity following global temperature rise. It is also noteworthy that the areas in which a greater number of severe heat waves occur displayed considerable expansion. Moreover, the model uncertainties exhibit a gradual enhancement with projected time extending from 2006 to 2099.
•The late-Paleoproterozoic granites in Lüliang Complex show a transition from high-K I-type to A-type granites.•The 1.89–1.76 Ga granites were formed under a post-collisional setting.•The occurrence ...of A2-type granites indicate a crustal thinning in the extensional setting after 1.82 Ga.
The late-Paleoproterozoic granitoids from Lüliang Complex can provide pivotal constraints on the amalgamation process between Eastern and Western blocks of North China Craton along the Trans-North China Orogen. LA-ICP-MS zircon dating gives emplacement ages of 1854 ± 20 Ma for the Huijiazhuang granite, 1830 ± 21 Ma for the Xiyupi granite vein and 1760 ± 20 Ma for the Dacaoping porphyritic granite, respectively. The Huijiazhuang granite and Xiyupi granite dyke have variable SiO2 (66.71–74.31 wt%), high K2O (5.09–6.35 wt%), low P2O5 (0.02–0.16 wt%), Al2O3 (13.92–15.31 wt%), right inclined REE patterns with medium negative Eu anomalies, enrichment in LILE, depletion in HFSE, especially Nb, Ta, consisting to high-K I-type granite in a post-collisional setting. The Sr/Y (7.36–59.95), εNd(t) (−5.7 to −4.1) with TDM (2381 Ma to 2570 Ma) from whole rock Sm-Nd isotope and εHf(t) (−9.6 to 2.3) with TCDM (2360 Ma to 3070 Ma) from zircon Lu-Hf isotope suggest that they are produced by partial melting of slightly thickened Neoarchean-Paleoproterozoic basement materials (including both meta-sedimentary and meta-igneous rocks). The Dacaoping porphyritic granites are characterized by high SiO2 (70.83–74.30 wt%), K2O (4.84–5.60 wt%), FeOT/(FeOT + MgO) (0.86–0.92), “seagull-type” REE pattern with strong negative Eu anomaly (δEu=0.16–0.35) and higher 10000∗Ga/Al (2.99–3.36), HFSE (Zr + Nb + Ce + Y = 378–583 ppm), showing an affinity of A2-type granite. They have low Sr/Y (1.17–8.62), εNd(t) (-6.1 to -6.4) with TDM (2690 Ma to 2776 Ma) from whole rock Sm-Nd isotope and εHf(t) (-7.9 to -5.2) with TCDM (2775–2938 Ma) from zircon Lu-Hf isotope, indicating a result from the melting of thinned Neoarchean calc-alkaline intermediate basement. Taking into account the temporal-spatial distributions of late-Paleoproterozoic rocks in the Trans-North China Orogen, it suggests a post-collisional extension occurred during 1.89–1.76 Ga and the crustis thinnedvisibly since 1.82 Ga.
Attributed to its advantages of super mechanical flexibility, very low-temperature processing, and compatibility with low cost and high throughput manufacturing, organic thin-film transistor (OTFT) ...technology is able to bring electrical, mechanical, and industrial benefits to a wide range of new applications by activating nonflat surfaces with flexible displays, sensors, and other electronic functions. Despite both strong application demand and these significant technological advances, there is still a gap to be filled for OTFT technology to be widely commercially adopted. This paper provides a comprehensive review of the current status of OTFT technologies ranging from material, device, process, and integration, to design and system applications, and clarifies the real challenges behind to be addressed.
Time difference of arrival (TDoA) based on a group of sensor nodes with known locations has been widely used to locate targets. Two-step weighted least squares (TSWLS), constrained weighted least ...squares (CWLS), and Newton-Raphson (NR) iteration are commonly used passive location methods, among which the initial position is needed and the complexity is high. This paper proposes a hybrid firefly algorithm (hybrid-FA) method, combining the weighted least squares (WLS) algorithm and FA, which can reduce computation as well as achieve high accuracy. The WLS algorithm is performed first, the result of which is used to restrict the search region for the FA method. Simulations showed that the hybrid-FA method required far fewer iterations than the FA method alone to achieve the same accuracy. Additionally, two experiments were conducted to compare the results of hybrid-FA with other methods. The findings indicated that the root-mean-square error (RMSE) and mean distance error of the hybrid-FA method were lower than that of the NR, TSWLS, and genetic algorithm (GA). On the whole, the hybrid-FA outperformed the NR, TSWLS, and GA for TDoA measurement.
Efficient approach based on the photochemistry of benzophenone has been developed for the cross-linking of the polymer hole-transporting layer (HTL). The cross-linked ...poly(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-butylphenyl) (TFB) thin films showed high solvent stability, smooth surface morphology, and improved charge-carrier mobility. The solution-processed red, green, and blue (RGB) quantum dot light-emitting diodes (QLEDs) based on the cross-linked HTLs showed much better performances than the corresponding devices based on the pristine TFB HTLs. The spin-coated red QLEDs based on the cross-linked HTLs showed the maximum current efficiency (CE), the maximum power efficiency (PE), and the peak external quantum efficiency (EQE) of 32.3 cd A–1, 42.3 lm W–1, and 21.4%, respectively. The inkjet-printed red QLEDs with the cross-linked HTLs exhibited the CE, PE, and EQE of 26.5 cd A–1, 37.8 lm W–1, and 18.1%, respectively. The high-performance HTLs were obtained by significantly reducing the amount of cross-linking agents.
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