Intermediate Boundaries Research Articles

VARIATIONAL ALGORITHMS OF DEEP KINEMATIC MIGRATION IN TWODIMENSIONAL MEDIA WITH HORIZONTAL VELOCITY GRADIENT

The paper considers three algorithms of kinematic migration (transformation of time fields of normal rays into reflecting boundaries) based on the variational theory of ray tracing developed by Professor of the Department of Seismometry and Geoacoustics of the Geological Faculty of Moscow State University T.I. Oblogina. The results of numerical experiments on theoretical models of layered media of varying complexity have revealed significant drawbacks of the “classical” variational algorithm for solving the inverse kinematic problem. Two mod- ifications of the “classical” variational algorithm are proposed in terms of calculating the starting angle of the rays’ exit from the Earth’s surface, leaving unchanged the principle of taking into account the curvature of seismic rays and refraction at intermediate boundaries: a variational algorithm using “image rays” and a kinematic migration algorithm for layered media with variable reservoir velocities, taking into account the slope of each boundary. The results obtained on theoretical models of complex environments demonstrated high efficiency of solving the inverse kinematic problem by a modified kinematic migration algorithm that takes into account the slope of each boundary.

Passivation of defective states in single crystal MAPbBr3 and their optoelectronic properties study

We fabricated high-quality Methylpropyl lead bromide (MAPbBr3) single crystals (SC) by introducing moderate amount electron-rich amino-terminated polyoxypropylene (PEA) additives via inverse temperature crystallization (ITC) method. The intramolecular vibrations and defective states of prepared MAPbBr3 single crystals were systemically studied by the in situ variable-temperature Fourier Transform Infrared (FTIR), X-ray photoelectron spectroscopy (XPS), the synchrotron-based X-ray absorption near edge structure (XANES) et al. We find the proper amount PEA additives would prevent the formation of intermediate states and crystal boundaries, passivating the density of defective states. The X-ray detection properties of single-crystal MAPbBr3 crystals were investigated, using both high dose and low dose X-ray photons at 40 keV in synchrotron beamlines. The photocurrent of optimized PEA-treated MAPbBr3 single crystals demonstrate better performance compared with the as-prepared single crystals. Meanwhile, the decay time of MAPbBr3 single crystal is decreased from 376 ns to 17.1 ns by Time-resolved photoluminescence (TRPL) decay measurement, owing to the defect passivation by 0.5 wt% PEA additives. The PEA-treated single crystals possess much faster decay time than the commercialized Cerium-doped Yttrium Aluminum Garnet (Ce:YAG) scintillator (∼100ns). These results help elucidate the passivation of defective states and contribute paths to manufacture high-quality single crystal perovskites for next-generation optoelectronic devices.

On the Interaction of Damage Evolution and Thermal Buckling in Stepped Circular Bilaminates

Abstract The behavior and evolution of stepped circular bi-laminates with edge damage are studied for structures subjected to uniform thermal load. The problem is formulated as a moving intermediate boundaries problem in the calculus of variations, where the boundary of an evolving region of damage emanating from the edge of the smaller substructure, as well as the boundary of a progressing/regressing region of sliding contact adjacent to the intact region of the composite structure are each allowed to vary along with the displacements. This yields the associated transversality conditions that define the locations of the propagating boundaries that correspond to equilibrium configurations of the evolving composite structure, as well as the equations of equilibrium and the associated interior and exterior boundary conditions. Various configurations of contact of the detached segments of the composite structure and the associated behavior are considered, and the influence and progression of contact on the overall evolution of the composite structure are assessed. Closed-form analytical solutions to the geometrically nonlinear problem are obtained, and expressions for the critical buckling load are developed. The explicit forms of the total energy release rate along the delamination front, as well as of the conditions for propagation of the contact zone boundary, are obtained from the analytical solutions and the corresponding transversality conditions. Results of numerical simulations based on the analytical solutions are presented and are seen to unveil a rich evolution process involving contact progression/recession and metamorphosis, buckling, and detachment progression during the prebuckling phase, during sling-shot buckling, and during the postbuckling phase, depending on the material properties of the sublaminates, the geometry of the sublaminates, the initial size of the damage, and the strength of the interfacial bond. Characteristic behavior of damage propagation is found to be quite robust and is seen to include stable propagation, stable followed by unstable progression, arrest, and catastrophic propagation.

Seasonal and Spatial Variability of Phytoplankton Primary Production in a Shallow Temperate Coastal Lagoon (Ria Formosa, Portugal).

Coastal lagoons are among the most productive ecosystems in the world, and they provide a wide range of ecosystem services and resources. In the Ria Formosa (southern Portugal), phytoplankton production has rarely been addressed. The main goal of this study is thus to evaluate the variability of phytoplankton production and photosynthetic characteristics over the seasonal cycle and in different locations (landward, urban, intermediate, and seaward boundaries) of the Ria Formosa coastal lagoon, subjected to distinct natural and anthropogenic stressors. Primary production was evaluated using the 14C incorporation technique, and photosynthetic parameters were estimated by fitting photosynthesis-irradiance curves. Primary production showed significant seasonal variations, with higher values in the summer associated with lower euphotic depths, higher water temperatures, and higher nutrient concentrations. No spatial differences were found for primary production or photosynthetic parameters. Primary production values were lower than previous estimates, which reflects an improvement in water quality in the Ria Formosa, but values are higher than primary production estimates for other temperate coastal ecosystems, which reflects the highly productive nature of this coastal lagoon.

Prosody and the interpretation of English relative clauses

This study investigates the prosodic cues involved in the disambiguation of English relative clauses (RCs). For example, in the sentence “The reporter interviewed the daughter of the senator who was controversial,” the underlined RC can modify the higher noun “daughter” or the lower noun ‘senator, thus having a high attachment (HA) or low attachment (LA) interpretation. Prior work shows that prosody influences the interpretation of ambiguous structures (Lehiste, 1973; Nespor & Vogel, 1983) but does not examine specific acoustic cues distinguishing between RC interpretations. An elicited production task was conducted involving 40 target HA and LA RCs. Intermediate boundaries at the higher and lower nouns were examined for prosodic phrasing cues including pauses, syllable lengthening, boundary tones, and final creak. Delaying of prenuclear peaks was also considered. Data from 8 speakers show that 70% of HA utterances contained two intermediate boundaries, compared to 57% of LA utterances. Main results show that the majority of first intermediate boundaries were high (H-) (81% for LA, 70% for HA), while second intermediate boundaries were usually low (L-) (78% for LA, 73% for HA). In addition, LA interpretations had prenuclear delayed peaks on the higher nouns more often (50% vs. 36% of HA cases).

Pitch accents and boundary tones in narrow focus statements in Basque Spanish

This presentation examines the intonation of non-contrastive narrow focus in 15 Spanish-Basque bilinguals from the Basque Country, Spain. A total of 150 semi-spontaneous statements with sentence-final new-information focus were analyzed in Praat following Spanish ToBi conventions (Aguilar et al., 2009). We report the pitch contour of prenuclear and nuclear accents and the prevalence of intermediate phrase boundaries (ip) before the focal element, none of which have been previously investigated in this Spanish variety. Results show that while the first prenuclear accent is generally delayed regardless of bilingualism (93%), the second one is delayed more often in Basque-dominant speakers. Rising-falling nuclear contours (L + H* L%), reported for broad focus in Basque Spanish (Robles Puente, 2012) and for narrow focus in other Spanish dialects (Aguilar et al., 2009), were most common in Spanish-dominant participants, while Basque-dominant participants tended to show falling contours (L* L%). Pre-focal ip boundaries occurred in 69% of sentences, regardless of bilingualism degree. Ip boundaries were typically rising, mostly involving continuation rises, although high plateaus were also attested. We will connect these novel findings to the intonational characteristics of narrow focus in Bizkaian Basque (Elordieta & Hualde, 2014) and other Peninsular Spanish dialects (Face, 2000; 2008).

Examination of high-temperature mechanisms and behavior under compression and processing maps of pure copper

The hot compression behavior of pure copper (commercial grade) was studied in a temperature range between 843 and 993K and in a strain rate range between 10−3 and 10s−1. The activation energy for plastic flow was determined to be 215kJ/mol, which is similar to the activation energy for lattice diffusion in copper (=197kJ/mol). The stress exponent values associated with the plastic flow were 7–9, which are larger than the theoretical values associated with lattice-diffusion controlled dislocation climb creep (4.5–5). A comparison of the current data with the data obtained from the creep tests performed on the pure copper at low strain rates by other investigators in a similar temperature range revealed that the most of the data studied in this study belong to the regime where power-law breakdown occurs. Processing map constructed at a strain where steady-state plastic flow was observed showed that the power dissipation efficiency was low (≤21%) in the entire experimental ranges of strain rate and temperature. Discontinuous dynamic recrystallization (DDRX) associated with a single peak or multiple peaks in the stress-strain curves occurred during the first stage of plastic deformation. Dynamic recovery occurred after the DDRX activity ended, leading to the formation of a subgrains with low-and intermediate angle grain boundaries within the recrystallized grains with high-angle grain boundaries. Due to the formation of extensive substructure within DDRX grains, the fractions of high-angle grain boundaries measured after the compressive deformation were low (≤30%).

The impact of a rapid access clinic on COPD hospital admissions

We reported recently the impact on hospital admissions of different models of community-based chronic obstructive pulmonary disease (COPD) care across Gwent, South Wales. Based on the lessons from this work we changed the Gwent Chronic Respiratory Disease Service (CRDS) to provide COPD care integrated across primary, secondary and intermediate care boundaries. This study explores the impact of the introduction of a consultant-led rapid access outpatient service into the CRDS. When compared to all-Wales data we showed a significant reduction in COPD hospital admissions, readmission and length of hospital stay. The reduction was temporally associated with the date of service change and in Blaenau Gwent where no change took place there was no difference from All-Wales figures. This study data suggests that the introduction of a consultant-led rapid access clinic reduces hospital admissions for patients with COPD.

A phase-field study of domain dynamics in ferroelectric BCT-BZT system

ABSTRACTWe present a thermodynamically consistent phase-field model describing the free energy of perovskite-based BCT-BZT solid solution containing an intermediate morphotropic phase boundaries. The Landau coefficients are derived as functions of composition of zirconium. The electrostrictive and elastic constants are appropriately chosen from experimental findings. The resulting Landau free energy is constructed to describe the stable polarization states as a function of composition. The evolution of the polarization order parameters at a particular composition is described by a set of time-dependent Ginzburg-Landau (TDGL) equations. Additionally, we solve Poisson’s equation and mechanical equilibrium equation to account for the ferroelectric/ferroelastic interactions. We have performed two dimensional and three-dimensional simulations with appropriate electrical boundary conditions to study the effect of external electric field on domain dynamics in BCT-BZT system at the equimolar composition.

Dynamic Response of Axially Moving Beams with Small Non-Idealities at Boundary Supports

The nonlinear response of an axially moving Euler-Bernoulli beam having one intermediate simple support and clamped boundaries with small non-idealities is examined. A small parameter representing real physical clearances at ends is used. The clamped support conditions mean that the beam is passing through two frictionless guides and one intermediate simple support placed between two guides. It is assumed that the beam has immovable boundaries at the outer ends. The assumption introduces nonlinearity because of stretching of neutral fibers. It is considered that the beam is axially moving along its length at a harmonically varying velocity about a constant mean value. In this paper variations at the velocities are assumed to be suitably weak. Differential equations governing the motion of the two sides of the beam are derived using variational formulation. A damping term is added into the equations. The method of multiple scales is applied to obtain approximate analytical solutions in this weakly nonlinear system. Non-ideal conditions at boundary supports of the beam are taken into consideration as small parameters at nonlinear equations. Solvability condition for the case of principal parametric resonance is derived, amplitude-phase curves of steady-state responses and stability conditions are investigated. It is found that the effect of small non-ideality at boundary supports has a role on nonlinear response: the width of unstable regions becomes larger with increase of non-ideality value.

Complementary Periodic Structures for Miniaturization of Planar Antennas

In this paper various layered planar periodic structures which provide miniaturization of planar antennas are proposed and discussed. The proposed designs are based on two concepts, reactive impedance surfaces and complementary periodic structures. In the proposed structures, complementary periodic rings and slots are patterned on the intermediate boundaries of the dielectric layers. A patch antenna is patterned on top of the first layer and the whole structure is grounded. The dielectric layers can be either similar or may have different dielectric constants and thicknesses. The dielectric constants and thicknesses of the layers can be chosen in a wide range of values. Two distinct configurations are studied simultaneously, namely, complementary circular rings and complementary square rings. The proposed designs provide a miniaturization factor in the range of 2.1-4.5 for planar antennas working in the frequency range of 2-22GHz. Parametric studies are provided to demonstrate high flexibility of the structures.

Was macht Radionachrichten verständlich(er)?

This study is part of the investigations concerning the listening comprehensibility of radio news that are carried out at the Seminar for Speech Sciences and Phonetics. The slowly spoken news of Deutsche Welle (a German radio station), which pose a special format of radio news, are the object of investigation. These news are produced to make easier the understanding of radio news for lear-ners of German on the levels B2 to C1. This paper examines, whether slowly spoken is to be equated with comprehensibly spoken. As a pilot study six news readings in original tempo and another six in a slow tempo were analysed. Text-linguistic, stylistic and journalistic features of the text were analysed, along with an auditory-phonetic analysis of the following features: pause duration, speech rate, number and interval of intermediate phrase boundaries and number and interval of accents. The slowly spoken news have specific characteristics: a great number of pauses (some of them stereotypical), decelerated articulation (mainly by high tension in articulating and emphatic lengthening) as well as very frequent, sometimes nonsensical accents. According to the perception of speech scientists, especially the increase in accent density and the nonsensical shortening of prosodic units tend to impair the comprehensibility of a reading. Apart from this, an improvement in comprehensibility is not only achieved by a reasonably slow speech rate but, among other things, by simplifying the text of the news.

A Generalized 3D Multiphysics Model for Li-Ion Intercalation Batteries

We present the computational implementation and results of a unified formulation across the electrode-electrolyte-electrode system. This formulation utilizes a rigorous volume averaging approach typical of multiphase formulation1, 2 and recently extended to supercapacitors3. Unlike previously used methods for Lithium ion batteries based on a segregated formulation4, 5 with intermediate boundaries, by having a unified, single-domain approach, complex geometries are naturally incorporated with the numerical algorithms guaranteeing stability and convergence. The same formulation also applies to 1D, 2D and 3D geometries irrespective of the complexities associated with dimensionality as well as with electrode/electrolyte spatial arrangements. In addition, the formulation accounts for any spatio-temporal variation of the different properties such as electrode/void volume fractions and anisotropic conductivities. This generality will aid in upscaling of local material properties directly into the system-level model. The resulting governing equations are solved using finite element techniques. The modeling results are validated for standard Li-ion cells and compared against the cell level performance (see Fig. 1 for sample results). Furthermore, we conduct an investigation of the effect of spatial variability of the void volume fraction and anisotropy on the performance of multidimensional cell configurations. We analyze the cell level performance and relate it to the detailed spatio-temporal variations of charge and discharge behavior in the electrodes. Finally, we present the coupling of the electrochemical, electrical, thermal, and mechanical processes inherent to cell performance.

Aneurysm Shape Reconstruction from Biplane Angiograms in the ISUIA Collection

The International Study of Unruptured Intracranial Aneurysms (ISUIA) is an epidemiologic international study of the natural history of unruptured intracranial aneurysms that enrolled 4,060 subjects. A conventional biplane cerebral angiogram available for central review was required for enrollment resulting in a large database. Data on aneurysms that ruptured during follow-up of the 1,692 untreated subjects provides an opportunity to investigate the anatomic features that may be predictive of future rupture. The objective of the study is to develop and test a method for three-dimensional (3D) shape reconstruction of aneurysms using biplane angiographic data in the ISUIA for retrospective morphometric assessment. Beginning with the two boundaries of the biplane views, curve morphing techniques were employed to estimate a number of intermediate boundaries around the aneurysm sac resulting in the creation of a 3D sac surface. The method was tested using simulated biplane "angiograms" of pre-reconstructed 3D models of patient-specific aneurysms. An algorithm to perform the image analysis was developed, and the morphometric indices of 150 intracranial aneurysms in the ISUIA database were estimated. Simultaneously, experienced neuroradiologists made manual measurements of key dimensions in the sac from the biplane angiograms for all cases. 3D reconstructions using our proposed method matched well with the original pre-reconstructed 3D geometries and were consistent with manual measurements of the neuroradiologists for the ISUIA aneurysms. A method for reconstructing the 3D geometry of the intracranial aneurysm sac from biplane angiograms in the ISUIA database with reasonable fidelity has been developed.

Empirical observations of capacity drop in freeway merges with ramp control and integration in a first-order model

An accurate density monitoring along a stretch of a freeway, especially under congested time-variant conditions is necessary to evaluate congestion levels, understand complex traffic phenomena and develop efficient control strategies. In the first part of the paper (i) we show empirical evidence from freeway-ramp merges in Twin Cities freeway system, in favor of the capacity drop phenomenon, (ii) we provide a methodology based on phase diagrams to quantitatively estimate the level of the drop, (iii) we show that the level of the drop depends on the ratio of mainline vs. ramp flow and (iv) we investigate whether implementation of control strategies has an effect on the value of capacity drop. In the second part of the paper, we develop a methodology to estimate densities with space and time based on data from loop detectors, by integrating the capacity drop. The methodology is based on solving a flow conservation differential equation (using LWR theory) with intermediate (internal) freeway mainline boundaries, which is faster and more accurate from approaches using only external boundaries. To capture the capacity drop phenomenon into the first-order model we utilize a fundamental diagram with two values of capacity and we provide a memory-based methodology to choose the appropriate value in the numerical solution of the problem with a Godunov scheme. Results compared with real data and micro-simulation of a long freeway stretch show that this model produces more reliable and accurate results than previous theories.

Do contrastive accents modulate the effect of intonational phrase boundaries in parsing?

Two experiments examined the effect of intonational phrase boundaries (Experiment 1) and interactions between intonational phrase boundaries and contrastive accents (Experiment 2) in parsing, using a sentence continuation judgment task. Across experiments, we found that intonational phrase boundaries were consistently interpreted as signaling syntactic structure as long as there were no alternative reasons for them to be present. Experiment 2 showed that different prosodic cues interact in syntactic processing. The effect of intonational phrase boundaries was modulated by contrastive accents through weaker intermediate phrase boundaries that followed contrastive accents, suggesting that the effects of pitch accents are indirect in syntactic processing.

Boundaries and scales in shrublands of the Doñana Biological Reserve, southwest Spain

To verify that the stabilized sand dunes of Donana, southwest Spain, are hierarchically nested, vegetation was sampled along topographic gradients at three spatial scales and Split Moving Window Boundary Analysis was applied to identify vegetation boundaries and ecotones. At small scale, only one window width was used, while for boundaries detection at upper scales the information from five windows was pooled. Environmental factors controlling plant composition were studied along topographic gradients, and diversity was estimated within the boundaries. According to several theoretical frameworks, I discuss the types of boundaries produced at different scales. Lower level boundaries are characterized by transitory gradients linked to local exchanges; intermediate boundaries are symmetric and very stable over the time; the large scale boundary is asymmetric with strong inherent abiotic constraints reinforced by strong biotic feedbacks. In spite of a similar plant composition, a plant community, the mixed shrub, works as an ecocline or an ecotone depending on the spatial scale considered. A certain parallelism exists between shrub composition along dune slopes and dune generations; however, processes at upper scale constraint plant composition at lower scale resulting in different mature formations.

Melting at dislocations and grain boundaries: A phase field crystal study

Dislocation and grain-boundary melting are studied in three dimensions using the phase field crystal method. Isolated dislocations are found to melt radially outward from their core, as the localized excess elastic energy drives a power-law divergence in the melt radius. Dislocations within low angle to intermediate angle grain boundaries melt similarly until an angle-dependent first-order wetting transition occurs when neighboring melted regions coalesce. High angle boundaries are treated within a screening approximation, and issues related to ensembles, metastability, and grain size are discussed.

Comparison of seismic moment release rates along different types of plate boundaries

This is a global survey of seismic moment release rates (scalar moment/length/time) along five categories of plate boundaries; for shallow earthquakes we evaluate divergent, transcurrent and convergent boundaries; for deep earthquakes we consider separately boundaries where the deepest seismicity is intermediate (<300 km) or deep-focus (500–600 km). The objective is to evaluate the typical range of rates observed and present the results in a form where it is straightforward to compare factors that affect rates in the different environments. For earthquakes occurring 1977–2005, the data are scalar moments from the global centroid moment tensor catalogue; for earthquakes 1900–1976, we use a standard formula to obtain moment from magnitudes in the Engdahl—Villaseñor Centennial catalogue. Moment release rates correlate with relative velocity between plates along divergent and transcurrent boundaries; focal depth influences moment release rates along intermediate and deep-focus boundaries. After accounting for these effects and adjusting rates for the influence of the short (29–106 yr) data record, within each category the typical observed variation is about an order of magnitude. We estimate seismic coupling coefficients, that is, the proportions of plate tectonic slip accommodated as earthquake rupture and reflected in the moment rates. Coupling may be 0.7 or greater along shallow convergent boundaries where at least one plate is continental. For all other boundary categories coupling is generally less than 0.4; it is 0.2 or less along most divergent boundaries and for intermediate and deep boundaries at depths exceeding 100 km. These results confirm that there are fundamental mechanical differences in the failure processes acting along different categories of plate boundaries. One implication is that only along a few highly coupled boundaries is it plausible that analysis of seismicity alone might lead to successful algorithms to predict large earthquakes.

Fractional Operators Approach in Electromagnetic Wave Reflection Problems

Applications of fractional operators approach to electromagnetic waves reflection problems are considered. Reflection properties of fractional or intermediate solutions are analyzed. It is shown that this approach is a useful technique for the description of solutions to the reflection problems for some known media in terms of the fractional order and also obtaining boundaries with new features. In this paper intermediate boundaries are modeled with BI slab with a PEC backing and also using anisotropic impedance boundary conditions. The twist-polarizer effect (crosspolarizing reflector) is described in terms of the specific value of the fractional order.