bluuebunny/crossref_metadata_2025_split huggingface dataset:
Indirect adaptive robust control of nonlinear systems with time‐varying parameters in a strict feedback form
Authors: Wu Jinbo , Zhao Jiafeng , Wu Donglai 
Published: April 2018

SummaryWithout any prior knowledge of the physical bounds of unknown parameters and uncertain nonlinearities, an indirect adaptive robust controller is constructed for uncertain nonlinear time‐varying systems in a strict‐feedback form. Firstly, an adaptive strong robust controller is derived based on the command filtered adaptive backstepping approach. This controller not only can guarantee the boundedness of the closed‐loop system signals in the presence of time‐varying (TV) parameters and uncertain nonlinearities but also obviate the need to compute analytic derivatives of virtual control functions. Thus, the problem of “explosion of terms” in the standard adaptive backstepping technique is avoided. Through introduction of a simple adaptation law on the upper bound of uncertainties, a smooth robust control term is used to realize the disturbance attenuation. Afterwards, based on the nonlinear X‐swapping techniques, a modular approach in which the controller and the identifier can be designed separately is exploited. A novel algorithm is proposed to estimate the TV parameters accurately. By adopting the variation trend of the covariance matrix as an indicator of the driving signals' persistent excitation level, this online parameter estimation law is switched between a modified least‐squares algorithm and a gradient algorithm based on fixed σ‐modification. Finally, a series of properties on the asymptotic stability and the global uniform ultimate boundedness of the closed‐loop system is established. Simulation results verify the effectiveness of the suggested method.
Design, control, and visual navigation of the DelftaCopter VTOL tail‐sitter UAV
Authors: De Wagter Christophe , Ruijsink Rick , Smeur Ewoud J. J. , van Hecke Kevin G. , van Tienen Freek , van der Horst Erik , Remes Bart D. W. 
Published: April 2018

AbstractTo participate in the Outback Medical Express UAV Challenge 2016, a vehicle was designed and tested that can autonomously hover precisely, takeoff and land vertically, fly fast forward efficiently, and use computer vision to locate a person and a suitable landing location. The vehicle is a novel hybrid tail‐sitter combining a delta‐shaped biplane fixed‐wing and a conventional helicopter rotor. The rotor and wing are mounted perpendicularly to each other,and the entire vehicle pitches down to transition from hover to fast forward flight where the rotor serves as propulsion. To deliver sufficient thrust in hover while still being efficient in fast forward flight, a custom rotor system was designed. The theoretical design was validated with energy measurements, wind tunnel tests, and application in real‐world missions. A rotor‐head and corresponding control algorithm were developed to allow transitioning flight with the nonconventional rotor dynamics that are caused by the fuselage rotor interaction. Dedicated electronics were designed that meet vehicle needs and comply with regulations to allow safe flight beyond visual line of sight. Vision‐based search and guidance algorithms running on a stereo‐vision fish‐eye camera were developed and tested to locate a person in cluttered terrain never seen before. Flight tests and a competition participation illustrate the applicability of the DelftaCopter concept.
The Volga: Management issues in the largest river basin in Europe
Authors: Schletterer M. , Shaporenko S.I. , Kuzovlev V.V. , Minin A.E. , Van Geest G.J. , Middelkoop H. , Górski K. 
Published: April 2018

AbstractThe Volga is the longest river in Europe and 16th longest in the world. The riverine landscape of the Volga is of exceptional scientific and economic importance to Russia; the basin contains approximately 40% of the Russian population and relates to 45% of the country's industrial and agricultural produce. The Volga River drains an area of 1.4 million km2, covering various biomes from taiga to semidesert. Anthropogenic impacts in the 20th century include pollution as well as hydropower production and navigation purposes, incurring a cost for its historically important migratory fish (e.g., sturgeons) and related fisheries. River basin management in Russia, since 2006, is based on the water code that determines federal competencies in water management. Extensive water quality monitoring programmes provide feedback to regional managers. Monitoring of biological parameters is spatially limited and should be extended in order to provide sufficient data for informed management. Some initiatives have been implemented in recent decades in order to restore the ecological health of the river and manage fisheries resources (e.g., restocking programmes and the definition of total allowable catches). As recreational fishing is popular but presently unregulated in Russia, we suggest additional monitoring. Finally, the headwaters and lower river floodplain of the Volga have remained as free‐flowing and relatively undisturbed systems. Because reference conditions with low levels of anthropogenic disturbance cannot be found in Central European lowland rivers, both the headwaters and lower Volga floodplains below Volgograd are of great importance on European level.
Analysis of bandwidth aggregation techniques for combined use of satellite and xDSL broadband links
Authors: Abdelsalam A. , Luglio M. , Roseti C. , Zampognaro F. 
Published: April 2018

SummaryThe availability of multiple technologies to access the Internet is even more common in today's connectivity scenarios. As an example, smartphones make use of 3G/4G data technology but, when a Wi‐Fi access point is available, they switch from 3G/4G (which typically is a paid per volume service) to the wireless local access. The same principle is applicable for fixed access, when terrestrial ADSL or optical fiber and satellite technologies can be typically available in the same place. This paper focuses on the simultaneous availability of different access technologies with the capability to use them in combination, to offer better performance than the traditional single technology access.
The association between smartphone use, stress, and anxiety: A meta‐analytic review
Authors: Vahedi Zahra , Saiphoo Alyssa 
Published: April 2018

AbstractResearch investigating the various mental, physical, and social effects of smartphone use has proliferated in the previous decade. Two variables of interest in this literature are the levels of anxiety and stress associated with smartphone use. The current meta‐analysis aimed to provide the first quantitative review of this literature, as well as determine potential moderators that might influence this relationship. A total of 39 independent samples (N = 21, 736) were used to compute a summary effect size ofr = .22,p < .001, CI [.17–.28] indicating a small‐to‐medium association between smartphone use and stress and anxiety. Significant moderators included the year in which the article was published, as well as whether problematic or nonproblematic phone use was assessed. In addition, studies using validated measures of smartphone use indicated a (nonsignificantly) larger association than studies using nonvalidated measures. Strengths and limitations of the meta‐analysis, as well as future directions of research are discussed.
Ripple: Reflection analysis for Android apps in incomplete information environments
Authors: Zhang Yifei , Li Yue , Tan Tian , Xue Jingling 
Published: April 2018

SummaryReflection poses grave problems for static security analysis, despite its widespread use in Android apps. In general, string inference has been mainly used to handle reflection, resulting in significantly missed security vulnerabilities. In this work, we bring forward the ubiquity of incomplete information environments (IIEs) for Android apps, where some critical dataflows are missing during static analysis and the need for resolving reflective calls under IIEs. We present Ripple, the first IIE‐aware static reflection analysis for Android apps that resolves reflective calls more soundly than string inference. Validation with 17 popular Android apps from Google Play demonstrates the effectiveness of Ripple in discovering reflective targets with a low false positive rate (due to its trade‐off made among soundness, precision, and scalability). As a result, Ripple enables FlowDroid, a taint analysis for Android apps, to find hundreds of sensitive data leakages that would otherwise be missed. As a fundamental analysis, Ripple will be valuable for many security analysis clients, since more program behaviors can now be analyzed under IIEs.
Differential influence of elevated CO2 on gas exchange and water use efficiency of four indigenous shrub species distributed in different sandy environments in central Inner Mongolia
Authors: Li Qiaoyan , Lai Liming , Zhou Jihua , Du Hui , Guan Tianyu , Zhang Xiaolong , Jiang Lianhe , Zheng Yuanrun , Yu Yi , Gao Yong , An Ping , Shimizu Hideyuki 
Published: April 2018

AbstractIn view of the increase in global warming and carbon dioxide (CO2) concentrations, it is essential to investigate the influences of climate change on plant growth and water use in arid and semi‐arid grassland species. Experiments were conducted to understand the ecophysiological response of four indigenous species to elevated CO2 in the semi‐arid sandy grassland of central Inner Mongolia. Seedlings of the four species were grown for 8 weeks at four different consistently elevated CO2 concentrations in the environment‐controlled growth chambers. All four elevated CO2 concentrations (400, 800, 1200, 1600 ppm) were found to result in decreased stomatal conductance (26–86%), decreased transpiration rate (21–80%), increased shoot water potential (1–42%) and increased water use efficiency (WUE) (10–412%) for two Artemisia species and Caragana korshinskii. Under our experimental conditions, the two Artemisia species and C. korshinskii would benefit more than Hedysarum laeve from exposure to elevated CO2 in terms of higher shoot water potential and WUE combined with lower stomatal conductance and transpiration rate. The results indicate that in a warmer, CO2‐enriched future atmospheric environment, WUE in semi‐arid grasslands may be higher than previously expected. Our findings will provide information for screening appropriate species for restoration of the degraded sandy grasslands in semi‐arid areas under future climate change scenarios.
Catherine Zuckert on Politics and Literature
Authors: Zuckert Michael 
Published: April 2018

AbstractCatherine Zuckert's earliest published work was in the area of Politics and Literature. From the start she saw this work as an important supplement to the dominant forms of political science and American political thought. Her work in this area, especially her manifesto-like journal articles and her first book, Natural Right and the American Imagination, made the case that literature provides insight into both the internal and hidden lives of democratic citizens as well as into the elusive broader regime-character of the political community.
Neuropsychological Test Performance in Parkinsonism Without Dopaminergic Deficiency on [123I]-FP-CIT SPECT Imaging
Authors: Wyman-Chick Kathryn A. , Martin Phillip K. , Minár Michal , Menéndez-González Manuel , Erickson Lauren O. , Álvarez-Avellón Tania , Schroeder Ryan W. 
Published: April 2018

AbstractObjectives: To examine neuropsychological test performance among individuals clinically diagnosed with Parkinson’s disease (PD) without evidence of dopaminergic deficiency on [123]I-CIT single photon emission computed tomography imaging. Methods: Data were obtained from the Parkinson’s Progression Marker Initiative. The sample included 59 participants with scans without evidence of dopaminergic deficiency (SWEDD), 412 with PD, and 114 healthy controls (HC). Tests included Judgment of Line Orientation, Letter-Number Sequencing, Symbol Digit Modalities, Hopkins Verbal Learning Test-Revised, and Letter and Category Fluency. Multivariate analysis of variance was used to compare standardized scores between the groups. Results: There was a statistically significant difference in performances between the groups, F(14,1155)=5.04; p<.001; partial η2=.058. Pairwise comparisons revealed significant differences in Category Fluency between SWEDD (M=0.22; SD=1.08) and HC (M=0.86; SD=1.15) and in Symbol Digit Modalities Test performance between SWEDD (M=45.09; SD=11.54) and HC (M=51.75; SD=9.79). No significant differences between SWEDD and PD were found. Using established criteria, approximately one in four participants in the SWEDD and PD groups met criteria for mild cognitive impairment (MCI). Conclusions: Individuals with SWEDD demonstrate significantly worse mental processing speed and semantic fluency than HC. The neuropsychological test performances and rates of MCI were similar between the SWEDD group and PD groups, which may reflect a common pathology outside of the nigrostriatal pathway. (JINS, 2018, 24, 646–651)
Estimates of Surface and Subsurface Boundary Current Transport Around Australia
Authors: Wijeratne Sarath , Pattiaratchi Charitha , Proctor Roger 
Published: April 2018

AbstractA 15 year (2000–2014) simulation of the oceans around Australia, with the shelf‐scale model ozROMS, was used to estimate the mean, seasonal, and interannual variability of the surface and subsurface boundary currents and associated inflows. The simulation clarified some previous points of uncertainty and provided new information previously unknown and this is listed here. In the Indian Ocean, flow through the Timor Passage was linked to southeast Australia through the Holloway (HLC), Leeuwin (LC), South Australian (SAC), and Zeehan (ZC) Currents. The main inflows were from the Indonesian Throughflow and Eastern Gyral Current in the north whilst the central and southern branches of the South Indian Counter Current (SICC) provided major (>60%) inflows to the LC in the west. The HLC at North‐west Cape was at a maximum in April–May and its annual cycle accounted for 70% of the seasonal variance of LC, SAC, and ZC. In the Pacific Ocean, the northern branches of the South Equatorial Current were the main inputs to initiate the Hiri and East Australian (EAC) Currents flowing north and south, respectively, at ∼15°S. Inflow from the South Caledonia Jet to the EAC was ∼35%. The Flinders Current (FC) contributed to the Leeuwin Undercurrent (LU) directly as a northward flow and LU was enhanced from inflow from the subsurface southern SICC in the west (∼32–33°S). The majority of LU flowed westward offshore between 24 and 29°S while ∼25% continued northward to the northwest shelf. All Australian surface boundary currents systems were enhanced during the 2011–2013 La Niña.
Tidally Induced Instability Processes Suppressing River Plume Spread in a Nonrotating and Nonhydrostatic Regime
Authors: Iwanaka Yuichi , Isobe Atsuhiko 
Published: April 2018

AbstractField surveys near a river mouth and numerical model experiments were conducted to investigate how fine structures generated in a tidally influenced river plume (tidal plume) affect plume behavior. The estuarine front, which was accompanied by a meander with a wavelength of several tens of meters, was visualized based on accumulated foam and debris visible in aerial photographs taken by a ship‐towed balloon equipped with a digital camera. The conductivity‐temperature‐depth sensor casts suggested the bottom of the river plume with a thickness of <5 m undulated because of the development of small eddies with horizontal lengths of <100 m. A nonhydrostatic numerical model was able to reproduce the observed fine‐scale disturbances in the tidal plume. The river plume without tidal currents expanded offshoreward like a balloon, while the tidal plume was confined near the river mouth. It was found that the tidal plume was dynamically equilibrated between the pressure gradient term and the advection term. The latter was composed mainly of contributions from the fine‐scale disturbances, which act as friction because of the momentum exchange between the plume and ambient saline water. The horizontal and vertical components of the disturbances were generated by inertial and Kelvin‐Helmholtz instability processes, respectively. It is considered that a combination of the river plume and tidal currents enhances the current shear favorable for such instabilities to occur.
Influence of River‐Induced Fronts on Hydrocarbon Transport: A Multiplatform Observational Study
Authors: Androulidakis Yannis , Kourafalou Vassiliki , Özgökmen Tamay , Garcia‐Pineda Oscar , Lund Björn , Le Hénaff Matthieu , Hu Chuanmin , Haus Brian K. , Novelli Guillaume , Guigand Cedric , Kang HeeSook , Hole Lars , Horstmann Jochen 
Published: April 2018

AbstractThe Taylor Energy Site is located in the vicinity of the Mississippi Delta region over the Northern Gulf of Mexico (NGoM). Surface oil patches have been persistently observed within this site since 2004, when an oil rig was destroyed by Hurricane Ivan. A multiplatform observational experiment was conducted in April 2017 to investigate, for the first time, the main hydrocarbon pathways from the Taylor Energy Site toward the NGoM continental shelves, and the Gulf interior, under the influence of local and regional physical processes. Results indicate that the Mississippi River (MR)‐induced fronts over the Taylor Energy Site, in combination with local circulation, prevailing winds and broader regional dynamics determine the hydrocarbon transport. The drifters deployed during the field experiment, in tandem with satellite data, drone imagery, wind measurements, and radar‐derived data, efficiently described three major hydrocarbon pathways, associated with MR plume dynamics (downstream/upstream coastal currents) and basin‐wide circulation (offshore pathway). Two different types of drifters, drogued and undrogued, showed clearly different pathways, which suggest potential differences in the expected advection of oil, depending on whether it forms a surface slick or whether it is partially mixed below the surface. The existence of multiple river fronts influenced the fate of oiled waters, preventing the hydrocarbons from reaching the Delta, like a natural boom barrier, trapping and directing the oil either westward or eastward. Thermohaline measurements showed that the MR plume near Taylor was 5–10 m deep, while the clearer ocean was characterized by a 40 m upper ocean homogenous layer.
In Situ and Satellite Observations of Phytoplankton Size Classes in the Entire Continental Shelf Sea, China
Authors: Sun Xuerong , Shen Fang , Liu Dongyan , Bellerby Richard G. J. , Liu Yangyang , Tang Rugang 
Published: April 2018

AbstractPhytoplankton size classes (PSCs) is of great significance for exploring marine ecological and biogeochemical processes. Remote sensing of PSCs has been successfully applied to open oceans; however, it is still quite limited for optically complex coastal oceans. In this study, the entire continental shelf sea of China including Bohai Sea (BS), Yellow Sea (YS), and East China Sea (ECS) characterized by distinctive turbid waters and impacted by plumes of large world‐class river (the Changjiang River) was taken as an example of turbid coastal ocean for remotely sensed spatial‐temporal distributions of PSCs. In situ data were collected from cruises during April to June in 2014 and an improved algorithm for PSCs retrieval was proposed. PSCs derived from GOCI (Geostationary Ocean Color Imager) images revealed that microplankton was dominant in the BS, the YS, and the nearshore ECS and nanoplankton distributed widely in the entire study area, while picoplankton mainly distributed in the offshore ECS in April, which was consistent with in situ investigation and related to environmental factors. Validation indicated that the improved algorithm provided a more accurate estimation of PSCs, with the root mean square error (RMSE) between estimated and measured size‐fractionated concentrations been 0.774, 0.257, and 0.142 mg m−3 for micro, nano, and picoplankton, respectively. Diurnal variations of PSCs were mainly affected by tidal currents and light intensity depending on different water types. These illustrated that remote sensed spatial distributions as well as diurnal variations of PSCs are effective in turbid continental shelf seas of China.
Investigating the Effects of Pacific Sea Surface Temperatures on the Wind Drought of 2015 Over the United States
Authors: Lledó Llorenç , Bellprat Omar , Doblas‐Reyes Francisco J. , Soret Albert 
Published: April 2018

AbstractDuring the first quarter of 2015 the United States experienced a widespread and extended episode of low surface wind speeds. This episode had a strong impact on wind power generation. Some wind farms did not generate enough cash for their steady payments, and the value of some assets decreased. Although the wind industry expressed their concerns, the episode has not received much attention from the scientific community and remains weakly understood. In this paper we aim to fill this gap and advance understanding of the underlying processes at seasonal time scales. Using retrospective climate predictions, we find that high sea surface temperatures in the western tropical Pacific ocean associated with a strongly positive phase of the North Pacific Mode played a central role to establish and maintain those wind anomalies. In a more general way it has also been shown that interannual variability of wind speed over North America is not only dominated by El Niño/Southern Oscillation but also by other sea surface temperature variations in the tropical Pacific. This new knowledge can be useful for industry stakeholders to anticipate future periods of low wind speed.
Atmospheric and Surface Climate Associated With 1986–2013 Wildfires in North America
Authors: Hostetler S. W. , Bartlein P. J. , Alder J. R. 
Published: April 2018

AbstractWe analyze climate simulations conducted with the RegCM3 regional climate model on 50‐ and 15‐km model grids to diagnose the dependence of wildfire incidence and area burned variations on monthly climate long‐term means and anomalies over North America for the period 1986–2013. We created a new wildfire database by merging the Fire Program Analysis Fire‐Occurrence Database, the National Interagency Fire Center Fire History Data, and the Canadian National Fire Database. The database includes 2,083,865 daily fire starts that burned a total of 1.25 × 108 ha in North America. We derive long‐term climatologies, standardized gamma indices, and composite climate anomalies of atmospheric circulation (500‐hPa height and wind) and various surface fields (e.g., solar radiation, soil moisture, vapor pressure deficit, and latent and sensible heat fluxes) to illustrate the climatology of burned area. The immediate and lagged monthly atmospheric circulation and surface climate anomalies differentiate high‐ and low‐fire years and the role of El Niño–Southern Oscillation in wildfire occurrence. Our approach demonstrates the association of the seasonal cycles of wildfire and climate and the strong role of climatic variability in modulating the seasonal cycle as a control of wildfire on monthly time scales.