bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Robust Gauss‐Newton Algorithm for the Optimization of Hydrological Models: From Standard Gauss‐Newton to Robust Gauss‐Newton
Authors: Qin Youwei , Kavetski Dmitri , Kuczera George 
Published: August 2018

AbstractModel calibration using optimization algorithms is a perennial challenge in hydrological modeling. This study explores opportunities to improve the efficiency of a Newton‐type method by making it more robust against problematic features in models' objective functions, including local optima and other noise. We introduce the robust Gauss‐Newton (RGN) algorithm for least squares optimization, which employs three heuristic schemes to enhance its exploratory abilities while keeping costs low. The large sampling scale (LSS) scheme is a central difference approximation with perturbation (sampling scale) made as large as possible to capture the overall objective function shape; the best‐sampling point (BSP) scheme exploits known function values to detect better parameter locations; and the null‐space jump (NSJ) scheme attempts to escape near‐flat regions. The RGN heuristics are evaluated using a case study comprising four hydrological models and three catchments. The heuristics make synergistic contributions to overall efficiency: the LSS scheme substantially improves reliability albeit at the expense of increased costs, and scenarios where LSS on its own is ineffective are bolstered by the BSP and NSJ schemes. In 11 of 12 modeling scenarios, RGN is 1.4–18 times more efficient in finding the global optimum than the standard Gauss‐Newton algorithm; similar gains are made in finding tolerable optima. Importantly, RGN offers its largest gains when working with difficult objective functions. The empirical analysis provides insights into tradeoffs between robustness versus cost, exploration versus exploitation, and how to manage these tradeoffs to maximize optimization efficiency. In the companion paper, the RGN algorithm is benchmarked against industry standard optimization algorithms.
A Robust Gauss‐Newton Algorithm for the Optimization of Hydrological Models: Benchmarking Against Industry‐Standard Algorithms
Authors: Qin Youwei , Kavetski Dmitri , Kuczera George 
Published: August 2018

AbstractOptimization of model parameters is a ubiquitous task in hydrological and environmental modeling. Currently, the environmental modeling community tends to favor evolutionary techniques over classical Newton‐type methods, in the light of the geometrically problematic features of objective functions, such as multiple optima and general nonsmoothness. The companion paper (Qin et al., 2018, https://doi.org/10.1029/2017WR022488) introduced the robust Gauss‐Newton (RGN) algorithm, an enhanced version of the standard Gauss‐Newton algorithm that employs several heuristics to enhance its explorative abilities and perform robustly even for problematic objective functions. This paper focuses on benchmarking the RGN algorithm against three optimization algorithms generally accepted as “best practice” in the hydrological community, namely, the Levenberg‐Marquardt algorithm, the shuffled complex evolution (SCE) search (with 2 and 10 complexes), and the dynamically dimensioned search (DDS). The empirical case studies include four conceptual hydrological models and three catchments. Empirical results indicate that, on average, RGN is 2–3 times more efficient than SCE (2 complexes) by achieving comparable robustness at a lower cost, 7–9 times more efficient than SCE (10 complexes) by trading off some speed to more than compensate for a somewhat lower robustness, 5–7 times more efficient than Levenberg‐Marquardt by achieving higher robustness at a moderate additional cost, and 12–26 times more efficient than DDS in terms of robustness‐per‐fixed‐cost. A detailed analysis of performance in terms of reliability and cost is provided. Overall, the RGN algorithm is an attractive option for the calibration of hydrological models, and we recommend further investigation of its benefits for broader types of optimization problems.
Statistical Relations Between Field‐Aligned Currents and Precipitating Electron Energy Flux
Authors: Robinson R. M. , Zhang Y. , Anderson B. J. , Zanetti L. J. , Korth H. , Fitzmaurice A. 
Published: August 2018

AbstractMeasurements of field‐aligned currents from the Active Magnetosphere and Planetary Electrodynamics Response Experiment are combined with measurements of far ultraviolet emissions from the Global Ultraviolet Imager on the Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics satellite to examine the correlation between parallel currents and auroral electron energy flux. The energy flux is derived from the far ultraviolet emissions in the N2 Lyman‐Birge‐Hopfield bands. We find that energy flux correlates with field‐aligned currents in both upward and downward current regions. The correlations vary with magnetic local time with the strongest dependences near magnetic midnight. The data are binned and averaged to construct a model of precipitating particle energy flux as a function of field‐aligned current and magnetic local time. With Active Magnetosphere and Planetary Electrodynamics Response Experiment data as input, the model yields accurate estimates of the hemispheric power input from precipitating particles.
Extensional Polarity Change in Continental Rifts: Inferences From 3‐D Numerical Modeling and Observations
Authors: Balázs A. , Matenco L. , Vogt K. , Cloetingh S. , Gerya T. 
Published: August 2018

AbstractExtensional basins often show along‐strike variability in terms of fault geometries, basement structures, subsidence, and thermal evolution. This is particularly pronounced when extension reactivates preexisting suture zones with opposing dip directions, that is, opposite polarities, which creates wide strike‐slip transfer zones. We have studied this extensional variability by means of thermomechanical lithospheric‐scale 3‐D numerical modeling. We conducted a series of experiments to model the extension of a thick lithosphere simulating a young orogenic area containing segmented suture zones inherited from former opposing subduction polarities, implemented as rheologically weak inclined layers with opposite dips. Numerical experiments demonstrate that the initial subduction sutures are reactivated by two long‐lived lithospheric‐scale detachment faults, which remain active until the onset of oceanic spreading. The opposite polarity of these faults causes their migration toward each other by asymmetric mantle lithosphere extension and thermal accretion. Crustal kinematics shows the formation of extensional detachment faults and high‐offset listric normal faults. These structures undergo gradual tilting during their footwall exhumation, while the rheological weak suture layers are redistributed beneath the crust. The results demonstrate an active interaction along the strike of the system between the two opposite dipping weak zones, where fault segments mechanically interact. During extension, the maximum horizontal fault offset switches the apparent sense of shear in the separating strike‐slip transfer zone. This kinematics explain the rapid change in the sense of shear in major strike‐slip transfer zones or transform faults, such as observed during the extension of the Pannonian back‐arc basin.
Source Apportionment and Secondary Transformation of Atmospheric Nonmethane Hydrocarbons in Chengdu, Southwest China
Authors: Song Mengdi , Tan Qinwen , Feng Miao , Qu Yu , Liu Xingang , An Junling , Zhang Yuanhang 
Published: August 2018

AbstractNonmethane hydrocarbons (NMHCs) have an important influence on the formation of photochemical smog and secondary organic aerosols in the atmosphere. We investigated 55 NMHCs in Chengdu from 27 October 2016 to 30 September 2017 to identify their sources, pollution levels, and secondary transformation potential. The average concentration of NMHCs in Chengdu was 41.8 ± 20.8 ppbv. Meteorological conditions play a vital role in the formation and dispersion of NMHCs, PM2.5, and O3. The photochemical conversion of NMHCs was inhibited by lower solar radiation, leading to low O3 concentrations and high NMHC concentrations. Aromatics and alkenes played a leading role in the secondary transformation, accounting for 60 ± 16% and 29 ± 11% of the total secondary formation potential, respectively. The southwest air mass trajectory was the most significant transportation path affecting the NMHC concentration in Chengdu. The results of the positive matrix factorization model indicated that there were seasonal differences in the sources of NMHCs in Chengdu. Four major emission sources were identified, namely, vehicle exhaust, industrial, paint solvents, and biogenic sources. Vehicle exhaust emissions were the greatest contributor to NMHCs in Chengdu, accounting for approximately 45% of the NMHCs. Overall, toluene, m/p‐xylene and ethylbenzene constitute a large fraction of the calculated ozone and secondary aerosol formation potential. Future studies should consider targeting these compounds when evaluating ozone and aerosol reduction strategies. However, in terms of total control of NMHC pollution, Chengdu should focus on effective control measures for traffic emissions.
Analytical Model to Detect Fault Permeability Alteration Induced by Fault Reactivation in Compartmentalized Reservoirs
Authors: Molina Oscar M. , Zeidouni Mehdi 
Published: August 2018

AbstractUnderground fluid injection induces changes in in situ stress condition of the target formation and local faults that can potentially lead to fault reactivation, which may result in the leakage of injected and/or native fluids into neighboring formations. In this paper, we introduce an analytical method to detect fault reactivation caused by fluid injection into deep faulted aquifers considering across‐fault leakage. The fundamental assumption made in our model is that fault permeability will be altered upon fault slip. Therefore, we model fault reactivation as a sudden change in fault permeability at the onset of fault slip. The fault is modeled as a linear interface between two permeable formations with equal rock and fluid properties. The governing equations are coupled through the fault interface and are solved using the Laplace‐Fourier integral transform technique. Based on the analytical solution, we find the characteristic bottomhole pressure and pressure derivative responses that enable detecting fault reactivation using diagnostic plots. We observe that pressure derivative undergoes a rapid change at the onset of fault slip followed by a late‐time trend to attain a new equilibrium governed by the altered fault permeability. Furthermore, we discuss the evolution of the across‐fault leakage rate upon and after fault slippage. Results from this study are presented in the form diagnostic plots and type curves that may be used for reservoir and fault characterization purposes.
Three-dimensional X-ray thermography using phase-contrast imaging
Authors: Yoneyama Akio , Iizuka Akiko , Fujii Tatsuo , Hyodo Kazuyuki , Hayakawa Jun 
Published: August 2018

AbstractThermal management is a key technology to desterilize unused energy sources for building sustainable societies. However, conventional temperature measurement methods such as infrared thermography can detect only the surface temperature of objects because they use infrared light. We thus present a novel three-dimensional X-ray thermography using a phase-contrast X-ray imaging technique, which enables non-destructive observations of the inner thermal distribution of samples. The sensitivity of phase-contrast X-ray imaging is about 1000 times higher than that of conventional X-ray imaging. Therefore, temperature changes can be detected by using density changes caused by thermal expansion. We applied X-ray interferometric imaging (XI) that detects phase-shift by using a crystal X-ray interferometer. The highest sensitivity of XI was utilized to successfully obtain the first three-dimensional image that visualizes the thermal distribution in heated water nondestructively. Additionally, projection images visualizing the dynamic thermal flow in heated water were also obtained, and their distribution and diffusion velocity agreed well with those of the calculated images obtained by computational fluid dynamics analysis. These results show that the novel thermography enables nondestructive observations of inner temperature and thermal flow and can provide solutions for optimum thermal design of electrical devices, motors, and engines.
Dynamic robustness of endoreversible Carnot refrigerator working in the maximum performance per cycle time
Authors: Lü Ke , Nie Wenjie , He Jizhou 
Published: August 2018

AbstractIn this work, we study the dynamic robustness of an endoreversible Carnot cycle working at the maximum per-unit-time performance regime, based on the linearization technique for dynamical systems and the local stability analysis. Our analysis is focused on the endoreversible Carnot refrigerator model, which works in the maximum per-unit-time coefficient of performance. At the steady-state of the maximum performance, the expressions of the relaxation times describing the stability of the system are derived. It is found that the relaxation times in the cycle condition are the function of thermal conductances σh and σc, the temperatures of the heat reservoirs Th and Tc, and the heat capacity C. The influence of the temperature ratio τ = Tc/Th and the thermal conductance ratio σr = σh/σc on the relaxation times is discussed in detail. The results obtained here are useful and provide a potential guidance for the design of an endoreversible Carnot refrigerator working in the maximum performance per cycle time optimization condition.
Preverbal infants utilize cross-modal semantic congruency in artificial grammar acquisition
Authors: Tseng Chia-huei , Chow Hiu Mei , Ma Yuen Ki , Ding Jie 
Published: August 2018

AbstractLearning in a multisensory world is challenging as the information from different sensory dimensions may be inconsistent and confusing. By adulthood, learners optimally integrate bimodal (e.g. audio-visual, AV) stimulation by both low-level (e.g. temporal synchrony) and high-level (e.g. semantic congruency) properties of the stimuli to boost learning outcomes. However, it is unclear how this capacity emerges and develops. To approach this question, we examined whether preverbal infants were capable of utilizing high-level properties with grammar-like rule acquisition. In three experiments, we habituated pre-linguistic infants with an audio-visual (AV) temporal sequence that resembled a grammar-like rule (A-A-B). We varied the cross-modal semantic congruence of the AV stimuli (Exp 1: congruent syllables/faces; Exp 2: incongruent syllables/shapes; Exp 3: incongruent beeps/faces) while all the other low-level properties (e.g. temporal synchrony, sensory energy) were constant. Eight- to ten-month-old infants only learned the grammar-like rule from AV congruent stimuli pairs (Exp 1), not from incongruent AV pairs (Exp 2, 3). Our results show that similar to adults, preverbal infants’ learning is influenced by a high-level multisensory integration gating system, pointing to a perceptual origin of bimodal learning advantage that was not previously acknowledged.
Gas phase electrochemical analysis of amino acids and their fragments
Authors: Calleja Maria , Elahi Atif , Caruana Daren J. 
Published: August 2018

AbstractAll chemical reactions involve electron rearrangement within or between molecules. The changes are best studied by methods such as electrochemistry, but these have been developed mainly for liquids and solids rather than gases. This exclusion limits our understanding of electron transfer processes that are central in plasma systems, which are of high scientific, industrial, and environmental importance. Here we describe electrochemical measurements in the gas phase of small organic molecules contained in flame plasma, by probing the redox activity of the resulting chemical fragments using cyclic voltammetry. Unique current-voltage spectra are recorded for eight amino acids and their fragments, through specific electron transfer reactions at the solid/gas interface. We identify and assign Faradaic peaks in the current-voltage spectra to the fragments using stable analogues of the fragments and in situ mass spectroscopy. We show that this approach provides unambiguous identification of organic based molecules, with a sensitivity and power of speciation to rival mass spectrometry.
8–10 Gbit/s full synthesised continuous‐half‐rate reference‐less all‐digital CDR with sub‐harmonic frequency extraction
Authors: Yu C. , Lee D. , Park H. , Jin S. , Ahn G.‐C. , Burm J. 
Published: August 2018

Continuous‐rate all‐digital reference‐less clock and data recovery (CDR) circuit that utilises a sub‐harmonic extraction scheme for wide‐range frequency detection is presented. In the proposed CDR, the capture range of the frequency locked loop (FLL) is extended to the tuning range of digital controlled oscillator, thanks to the subharmonic extraction scheme. The frequency errors of FLL in lock state are within the tracking range of CDR loop. The prototype reference‐less all‐digital CDR, fabricated using a 40 nm CMOS technology, successfully detects 8–10 Gbit/s PRBS 231 − 1 data and produces the recovered clock. The CDR consumes 29 mW from a supply voltage of 1 V for 10 Gbit/s input data. The measured RMS jitter of the recovered clock is 2.24 ps.
A hydrodynamic mechanism of meteor ablation
Authors: Girin Oleksandr G. 
Published: August 2018

Aims. We aim to obtain an approximate analytical solution to the equations of meteoroid dynamics within the frames of the suggested mechanism of ablation due to meteoroid melt spraying.
Methods. We have described the droplet breakaway of the melt in terms of hydrodynamic instability theory for the case of a shallow angle of meteoroid entry. The differential equation of meteoroid spraying was derived, together with the equation for the distribution function of sprayed particles by sizes. The latter was obtained considering two different frameworks for meteoroid motion law: empirical and theoretical.
Results. The trinal problem of an ablating meteoroid is solved analytically. The approximate solution is found for the system of equations of motion, ablation and number of sprayed droplets. The latter yields the equation for the distribution function of breakaway droplets by sizes, for which the approximate solution is obtained by providing the intermediate and final number distributions. The meteoroid ablation–deceleration balance remains in the regime of dynamic ablation, when the meteoroid velocity deficit due to aerodynamic drag is negligible until the instant of almost total meteoroid destruction. The responsible “h”-criterion is found, which depends only on the physical properties of the media, so that for melts of materials with lower viscosity such as iron the balance is closer to dynamic ablation than for the stony melt. The differential equation for meteoroid spraying is derived and integrated, showing a near-linear decrease of the meteoroid radius with time.
Conclusions. The proposed spraying model allows us to obtain approximate laws of meteoroid dynamics, which can serve as a base of a comprehensive study of meteor formation and evolution. The model provides intermediate and final number distributions of the breakaway droplets by sizes through direct numerical integration of the governing equations, or, alternatively, in the form of approximate relationships. The theory can be extended to the general case of a molten meteoroid entering atmosphere at an arbitrary angle.
Extra-articular Hip Impingement: Anterior Inferior Iliac Spine/Subspine Impingement, Ischiofemoral, and Anterior and Lateral Greater Trochanteric-Pelvic Impingement
Authors: Zaltz Ira , Larson Christopher 
Published: August 2018

AbstractAlthough femoroacetabular impingement (FAI) is traditionally considered an intra-articular phenomenon, the result of abutment between the femoral head and/or neck and the acetabular rim, there are unique and relatively uncommon patterns of pathologic extra-articular hip impingement that can mimic the clinical presentation and clinical findings of traditional FAI. Anterior inferior iliac spine (AIIS) or “subspine” impingement may occur as a consequence of an abnormally anterior or distal prominence of the AIIS that may be developmental, posttraumatic, or the result of high range of motion (ROM) activities. This type of impingement can crush the capsule, labrum, and rectus femoris between the AIIS and distal femoral neck in straight hip flexion. Greater trochanteric/pelvic impingement is quite complex and can be further divided into three unique anatomic patterns. Anterior greater trochanteric–pelvic impingement is the result of impingement between the anterior hip soft tissue structures or the anterior facet/greater trochanter and anterolateral rim/lateral AIIS and pelvis when the hip is flexed, internally rotated, and abducted. This can occur in association with a prominent greater trochanter, short femoral neck, relative femoral retrotorsion, and high ROM activities. Lateral greater trochanteric–pelvic impingement is the result of impingement between an abnormally prominent or a high riding greater trochanter with a short femoral neck and the lateral pelvis when the hip is abducted. This type of impingement is characteristic of a Perthes-like hip and, in extreme cases, can be associated with severe leg length discrepancy (and abductor muscle dysfunction). Posterior greater trochanteric–pelvic/ischiofemoral impingement is the result of impingement of the quadratus femoris and/or proximal hamstring tendons between the lesser trochanter or posterior proximal femur and intertrochanteric line and the ischial tuberosity when the hip is extended and external rotated (ER). This can occur in association with deformities of the ischial tuberosity caused by prior avulsion fractures, lesser trochanteric overgrowth, extreme coxa valga, femoral antetorsion, complex proximal femoral developmental deformities, and activities requiring high degrees of extension and external rotation. A thorough understanding of these unique patterns of impingement, their clinical presentations, and complex treatment options can help in optimizing outcomes and minimizing complications in this very challenging patient population.
Ist die subkutane Immuntherapie (SCIT) Schnee von gestern?
Authors: Kopp M. V. 
Published: August 2018

ZusammenfassungAuf der Suche nach aktuellen Daten zur Wirksamkeit der spezifischen Immuntherapie bei allergischer Rhinitis oder Asthma bronchiale im Kindes- und Jugendalter stößt man fast ausschließlich auf Studien, welche die sublinguale Applikationsform (SLIT) untersucht haben. Arbeiten zur subkutanen Applikationsform (SCIT) finden sich nur in geringer Zahl. Ist die SCIT aufgrund fehlender Evidenz damit Schnee von gestern? Bei indirekten Vergleichen zur Wirksamkeit beider Therapieformen schneidet die SCIT eher besser ab als die SLIT. Zudem bestehen Unsicherheiten über eine ausreichende Adhärenz und Compliance bei der SLIT im Kindes- und Jugendalter. Das Dilemma zwischen einer rein evidenzgetriebenen Betrachtungsweise und dem über Jahrzehnte bewährten Therapieprinzip der SCIT lässt sich womöglich nur lösen, indem für die spezifische Immuntherapie im Kindes- und Jugendalter separate Leitlinien formuliert werden.