Common 1D Research Articles

Combined Modelling of Coastal Barrier Breaching and Induced Flood Propagation Using XBeach

Breaching of coastal barriers is a three-dimensional process induced by complex interactions between hydrodynamics, sediment transport and soil avalanching processes. Although numerous coastal barriers are breached every year in many coastal countries, causing dramatic inundations of the nearshore areas, the understanding of the processes and interactions associated with both breaching and subsequent flood propagation is still poor. This might explain why their combined modelling and prediction has not yet been sufficiently addressed. Consequently, barrier breaching and subsequent inundation are still often modelled separately, thus ignoring the strong interaction between breaching and flooding. However, the combined modelling of such strongly coupled processes is crucial. Since the open-source model system “XBeach” consists, among others, of a nonlinear shallow water solver coupled with a morphodynamic model, also including a soil avalanching module, it has the potential to simulate both breaching and subsequent flood propagation together. Indeed, the mutual interactions between hydrodynamics and morphodynamics (including soil avalanching) are properly accounted for. This paper, therefore, aims to examine the applicability of XBeach for modelling coastal barrier breaching and inundation modelling in combination, instead of the current approaches, which address the modelling of each of these two processes separately. The performance of XBeach, in terms of inundation modelling, is assessed through comparisons of the results from this model system (i) with the results from common 1D and 2D flood propagation models and (ii) with observations for barrier breaching and subsequent inundation from a real case study. Besides providing an improved understanding of the breaching process, the results of this study demonstrate a new promising application of XBeach and its potential for calculating time-varying inland discharges, as well as for combined modelling of both dune breaching and subsequent flood propagation in coastal zones.

Modeling of Phase Transitions Kinetics in Systems with Two Interacting Order Parameters

We present common 1D model of first order phase transition based on coupled solution of order parameters evolution and heat transfer equations. Such a model may be used for simulation of phase transitions in multiferroics or magnetostructural phase transitions, for example. First order phase transition process has been described by Landau-Khalatnikov-like equation with the thermodynamic potential of 2-3-4 and 2-4-6 types.

Recommended Specimen Dimensions and Boundary Conditions for Measurement of Hydrogen Permeation in Thick Carbon Steel Plates

The present work discusses the influence of specimen dimensions and boundary conditions on the deviation towards 2D diffusion during hydrogen permeation measurements on thick carbon steel plates. It was mathematically found and experimentally confirmed that hydrogen losses through lateral diffusion could significantly affect the validity of laboratory measurements on thick plates, since the common 1D simplification of diffusion equations is no longer valid. Based on a finite element analysis, two options are proposed to minimize the effects of side diffusion on permeation measurements. The first option, which encompasses ISO 17081 criteria, recommends optimum radii for hydrogen charging and extraction surfaces and is valid for a wide range of specimen thicknesses. The second option relies on modification of boundary conditions and consists of applying a hydrogen-diffusion barrier on the specimen side edges. This second option was experimentally tested and validated by means of an oxide layer deposited usi...

Numerical evaluation of lateral diffusion inside diffusive gradients in thin films samplers.

Using numerical simulation of diffusion inside diffusive gradients in thin films (DGT) samplers, we show that the effect of lateral diffusion inside the sampler on the solute flux into the sampler is a nonlinear function of the diffusion layer thickness and the physical sampling window size. In contrast, earlier work concluded that this effect was constant irrespective of parameters of the sampler geometry. The flux increase caused by lateral diffusion inside the sampler was determined to be ∼8.8% for standard samplers, which is considerably lower than the previous estimate of ∼20%. Lateral diffusion is also propagated to the diffusive boundary layer (DBL), where it leads to a slightly stronger decrease in the mass uptake than suggested by the common 1D diffusion model that is applied for evaluating DGT results. We introduce a simple correction procedure for lateral diffusion and demonstrate how the effect of lateral diffusion on diffusion in the DBL can be accounted for. These corrections often result in better estimates of the DBL thickness (δ) and the DGT-measured concentration than earlier approaches and will contribute to more accurate concentration measurements in solute monitoring in waters.

Multivariate regression approaches for surrogate-based diffeomorphic estimation of respiratory motion in radiation therapy

Breathing-induced location uncertainties of internal structures are still a relevant issue in the radiation therapy of thoracic and abdominal tumours. Motion compensation approaches like gating or tumour tracking are usually driven by low-dimensional breathing signals, which are acquired in real-time during the treatment. These signals are only surrogates of the internal motion of target structures and organs at risk, and, consequently, appropriate models are needed to establish correspondence between the acquired signals and the sought internal motion patterns. In this work, we present a diffeomorphic framework for correspondence modelling based on the Log-Euclidean framework and multivariate regression. Within the framework, we systematically compare standard and subspace regression approaches (principal component regression, partial least squares, canonical correlation analysis) for different types of common breathing signals (1D: spirometry, abdominal belt, diaphragm tracking; multi-dimensional: skin surface tracking). Experiments are based on 4D CT and 4D MRI data sets and cover intra- and inter-cycle as well as intra- and inter-session motion variations. Only small differences in internal motion estimation accuracy are observed between the 1D surrogates. Increasing the surrogate dimensionality, however, improved the accuracy significantly; this is shown for both 2D signals, which consist of a common 1D signal and its time derivative, and high-dimensional signals containing the motion of many skin surface points. Eventually, comparing the standard and subspace regression variants when applied to the high-dimensional breathing signals, only small differences in terms of motion estimation accuracy are found.

Appraisal of a new 1D weighted joint inversion of ground based and helicopter‐borne electromagnetic data

ABSTRACTIn order to couple spatial data from frequency‐domain helicopter‐borne electromagnetics with electromagnetic measurements from ground geophysics (transient electromagnetics and radiomagnetotellurics), a common 1D weighted joint inversion algorithm for helicopter‐borne electromagnetics, transient electromagnetics and radiomagnetotellurics data has been developed. The depth of investigation of helicopter‐borne electromagnetics data is rather limited compared to time‐domain electromagnetics sounding methods on the ground. In order to improve the accuracy of model parameters of shallow depth as well as of greater depth, the helicopter‐borne electromagnetics, transient electromagnetics, and radiomagnetotellurics measurements can be combined by using a joint inversion methodology. The 1D joint inversion algorithm is tested for synthetic data of helicopter‐borne electromagnetics, transient electromagnetics and radiomagnetotellurics. The proposed concept of the joint inversion takes advantage of each method, thus providing the capability to resolve near surface (radiomagnetotellurics) and deeper electrical conductivity structures (transient electromagnetics) in combination with valuable spatial information (helicopter‐borne electromagnetics). Furthermore, the joint inversion has been applied on the field data (helicopter‐borne electromagnetics and transient electromagnetics) measured in the Cuxhaven area, Germany.In order to avoid the lessening of the resolution capacities of one data type, and thus balancing the use of inherent and ideally complementary information content, a parameter reweighting scheme that is based on the exploration depth ranges of the specific methods is proposed. A comparison of the conventional joint inversion algorithm, proposed by Jupp and Vozoff (), and of the newly developed algorithm is presented. The new algorithm employs the weighting on different model parameters differently. It is inferred from the synthetic and field data examples that the weighted joint inversion is more successful in explaining the subsurface than the classical joint inversion approach. In addition to this, the data fittings in weighted joint inversion are also improved.

HR-MAS NMR Spectroscopy: A Practical Guide for Natural Samples

High Resolution Magic Angle Spinning (HR-MAS) NMR spectroscopy is a versatile technique that provides high resolution NMR data on samples containing solutions, gels and swellable solids. In addition to providing structural information HR-MAS can also be used to investigate interfaces (for example organic structures at the solid-aqueous soil interface), processes such as swelling/ flocculation, kinetic transfer between gel/liquid phases, as well as conformation and molecular interactions in situ. As such, HRMAS has potential in a diversity of fields including organic, biological, environmental, and medical research. This manuscript focuses on the application of HR-MAS to intact natural samples. A range of 1D and 2D NMR experiments are reviewed and compared in terms of general performance on a range of samples. Therefore, this practical guide and review should be a useful reference and starting point for those wishing to apply HR-MAS NMR. While this article focuses on natural samples, common key 1D and 2D experiments are considered which may be of interest to readers with diverse research interests. Keywords: 1D NMR, 2D NMR, Algae, High resolution magic angle spinning (HR-MAS), Natural samples, NMR, Soils, Worm tissue.

Developments in frequency domain AEM: Tackling drift and noise with a ferrite-core, receiver triplet.

SUMMARY The polar oceans’ sea ice cover is a challenging geophysical target to map. Current state of practice helicopter-electromagnetic (HEM) ice thickness mapping is limited to 1D interpretation due to common procedures and systems that are mainly sensitive to layered structures. We present a new generation Multi-sensor, Airborne Sea Ice Explorer (MAiSIE) to overcome these limitations. As the actual sea ice structure is 3D and in parts heterogeneous, errors up to 50% are observed due to the common 1D approximation. With MAiSIE we present a new EM concept based on one multi frequency transmitter loop and a three component receiver coil triplet without bucking The small weight frees additional payload to include a line scanner (lidar) and high accuracy INS/dGPS. The 3D surface topography from the scanner with the EM data at from 500 Hz to 8 kHz, in x, y, and z direction, will increase the accuracy of HEM derived pressure ridge geometry significantly. Experience from two field campaigns shows the proof-of-concept with acceptable sensor drift and receiver sensitivity. The preliminary 20 ppm noise level @ 4.1 kHz is sufficient to map level ice thickness with 10 cm precision for sensor altitudes below 13 m.

Controlling growth rate anisotropy for formation of continuous ZnO thin films from seeded substrates

Solution-processed zinc oxide (ZnO) thin films are promising candidates for low-temperature-processable active layers in transparent thin film electronics. In this study, control of growth rate anisotropy using ZnO nanoparticle seeds, capping ions, and pH adjustment leads to a low-temperature (90 ° C) hydrothermal process for transparent and high-density ZnO thin films. The common 1D ZnO nanorod array was grown into a 2D continuous polycrystalline film using a short-time pure solution method. Growth rate anisotropy of ZnO crystals and the film morphology were tuned by varying the chloride (Cl−) ion concentration and the initial pH of solutions of zinc nitrate and hexamethylenetetramine (HMTA), and the competitive adsorption effects of Cl− ions and HMTA ligands on the anisotropic growth behavior of ZnO crystals were proposed. The lateral growth of nanorods constituting the film was promoted by lowering the solution pH to accelerate the hydrolysis of HMTA, thereby allowing the adsorption effects from Cl− to dominate. By optimizing the growth conditions, a dense ∼100 nm thickness film was fabricated in 15 min from a solution of [Cl−]/[Zn2+] = 1.5 and pH= 4.8 ± 0.1. This film shows >80% optical transmittance and a field-effect mobility of 2.730 cm2 V−1 s−1 at zero back-gate bias.

A Novel Approach to the Simulation of Electrochemical Mechanisms Involving Acute Reaction Fronts at Disk and Band Microelectrodes

A new simulation algorithm is presented for describing the dynamics of diffusion reactions at the most common microelectrode 1D (planar, cylindrical, spherical) and 2D geometries (band, disk) for electrochemical mechanisms of any complexity and involving fast homogeneous reactions of any kind. A series of typical electrochemical mechanisms that create the most severe simulation difficulties is used to establish the exceptional performance and accuracy of this algorithm, which stem from the combination of (quasi)conformal transformation of space and a new method for auto-adaptive grid compression.

One-dimensional growth of zinc oxide nanostructures from large micro-particles in a highly rapid synthesis

Large and irregularly-shaped zinc oxide (ZnO) micro-particles commonly found in a high-temperature vapor-phase process known as the catalyst-free combust-oxidized mesh (CFCOM) process, play a crucial role as nucleation hosts for ZnO one-dimensional (1D) nanostructures, especially nanometric wires and rods. Nanowires and nanorods tend to grow from the hillocks of the large micro-particles whereby these hillocks serve as nucleation sites for the acicular structures. Nanowires with aspect ratios exceeding 5 are the most common 1D structures that grow from pillar-like hillocks, while triangular hillocks are probable nucleation hosts for nanorods. The ZnO nanostructures possess a polycrystalline nature with photoluminescent emission in the UV band-edge and visible regimes. A novel and non-destructive electrical resistance measurement method is introduced in that the 1D ZnO nanostructures exhibited very high GΩ resistance that is over five times higher than that of commercial ZnO. A growth model is proposed to offer a probable explanation for the fascinating rapid growth of 1D nanostructures originating from large ZnO micro-particles. The ZnO particles in this work were synthesized using 5-ton industrial furnaces via a university-industry joint effort.

Barbiturates with hydrogen-bonded layer and framework structures

Four N–H⋯OC bonded structures for 5,5-substituted derivatives of barbituric acid are reported, which are distinct from the eight fundamental types that have been previously described. The N–H⋯OC-bonded layer structures L-4, L-5 and L-6 are present in crystal polymorphs of 5-(2-bromoallyl)-5-isopropyl barbituric acid (L-4: 1, noctal), 5,5-dichlorobarbituric acid (L-6: 2a, L-5: 2b) and 5,5-dibromobarbituric acid (L-5: 3a). The monoclinic polymorph (3b) of the dibromo compound contains the framework F-2. In each case, the essential building block consists of two molecules which are doubly N–H⋯OC-bonded via a central R22(8) ring. The L-4 structure is closely related to the common 1D ladder topology C-4. It serves also as a building unit for the L-5 sandwich structure. The essential rings of L-4 and L-6 have the same graph-set descriptor R66(28) but are topologically distinct from one another. In the F-2 framework, ten molecules are linked together to give an L-shaped R1010(48) ring. The IR spectra of the crystal forms 1, 2a–b and 3a–b are discussed and a previously established classification scheme correlating the H-bonding of barbiturates with their IR characteristics is extended.

Intriguing relationships and associations in the crystal structures of a family of substituted aspirin molecules

A number of ring-substituted aspirin molecules have been synthesised and their crystal structures determined. All contain the strongly H-bonded carboxylate dimer found in the two forms of aspirin itself. Detailed analysis of the further packing of this dimer reveals that the 5-chloro, 5-bromo and 5-iodo derivatives form an isostructural group, as do the 5-fluoro, 5-methyl and 5-nitro derivatives. The 3-methyl and 4-methyl structures have close 3D similarity and may be classified as pseudoisostructural. The structures of the first two groups have a common 1D stack of dimers which contributes to two different 2D layers. One of the 2D layers is found in the fluoro, nitro and 5-methyl isostructures and also in the 3-methyl and 4-methyl derivatives. The second layer motif is found in the chloro, bromo and iodo groups and is also present in the fluoro, nitro and 5-methyl structures. The 6-methyl structure shares a 1D motif with the chloro, bromo and iodo groups. The packing variations are linked to different types of intermolecular interactions. In the 5-Cl, Br, and I groups, we find short Hal⋯O contacts to the carboxylate carbonyl; in the 5-F, 5-NO2 and 5-Me derivatives we find the acyl⋯acyl dimer interaction, present also in aspirin form I. In addition, the 5-F structure contains F⋯O short contacts to a carboxylate hydroxyl oxygen and in the 5-NO2 we find N–O⋯H–C contacts to an acyl methyl group.

Density waves in atomic necklaces

O (1D) systems have always captured the imagination of physicists. In the ultimate 1D limit, a crystal is nothing but a string of atoms, akin to a necklace of tiny pearls. Most physics graduates undoubtedly associate 1D systems with the simple models used in introductory level quantum mechanics or statistical mechanics courses. Indeed, 1D model systems represent pedagogical and often most useful illustrations of the basic physics principles that govern more realistic condensed matter systems. These principles tell us, for instance, that an ideal atomic chain with a single metallic band should be unstable with respect to a Peierls distortion. A Peierls distortion is a condensed state of the 1D electron gas whose formation is triggered by the strong coupling between electrons and quantized lattice vibrations (phonons). The upshot is that such a wire would not conduct electricity at low temperature. Alternatively, atom wires could display exotic many-body physics. It has been predicted that, due to strong electron-electron interactions in 1D, the concept of single electrons should even break down and that it is only meaningful to discuss their collective behavior (i.e., excitations). Such a state of matter is referred to as the Luttinger-Tomonaga liquid. But even though the theory of ideal 1D systems has advanced much, experimental realization of truly 1D condensed matter systems remains a daunting task; it is impossible to suspend a long string of atoms in free space. Nonetheless, due to the progress in nanoscience, it is now possible to synthesize and tailor novel nanophase materials that mimic the ultimate 1D limit quite closely. As a result, crucial questions regarding the physics of atom wires can be experimentally addressed. For instance: would a string of atoms conduct if it is laid down on a substrate? How can the often detrimental effects of the inevitable structural imperfections or those of thermodynamic fluctuations be alleviated? Or perhaps the most fundamental and practical issue: would atom wires actually be thermodynamically stable? Experimental approaches toward creating 1D systems are often classified as ‘top down’ or ‘bottom up’ fabrication. The top-down procedure refers to artificial (lithographic) creation of 1D nanostructures. A natural way to produce atom wires is a bottom-up method that employs the most common 1D line-defects on surfaces, namely atomic step-edges, as a template for self-assembly. Moreover, artificially created nanostructures are generally unstable, whereas self-assembled (nano-) structures instead can be thermodynamically stable, just because the driving force in their formation is not a kinetically enforced low-dimensional ordering, but purely a drive toward the lowest energy state [1,2]. We use the symmetry breaking properties of surfaces and the reconstructions of their topmost atom layers to realize self-assembled macroscopic arrays of atom wires. To this end, we have used vicinal (stepped) Si surfaces. Besides the thermodynamic stability inherent to self-assembly based fabrication, an extra advantage of this approach is that the spatial access to these atom wire arrays allows for a detailed investigation of electronic instabilities in these wires, even at a local scale. The atom wires can reach macroscopic lengths on vicinal surfaces; their length is only limited by occasional step edges crossing the wires. On the other hand, producing atom wires via this bottom-up method inevitably introduces (intrinsic) defects. This should not necessarily be viewed as a drawback, since it provides a much-needed opportunity to study the dramatic influence of imperfections in atom wires on their (in-)stabilities. Because they are located at surfaces, the wires can be studied conveniently using well-developed techniques such as Scanning Tunneling Microscopy and Spectroscopy (STM and STS), and Angle Resolved Photoemission Spectroscopy (ARPES).

Polymorphism of tricalcium silicate, the major compound of Portland cement clinker: 1. Structural data: review and unified analysis

This paper reviews the literature devoted to structural investigations, with a special concern to the various notations used by different authors. A unified analysis of the known T1, M1, M3 and R polymorphs is proposed. The superstructure relations between the various unit cells are discussed, together with the evidence of common 1D and 2D structural elements in all these polymorphs. These structural elements are related to the observed properties.

Electronic transition of Au-induced atomic chains onSi(5 5 12): A strong similarity with theAu∕Si(5 5 7)system

We investigated in detail the electronic structures of the $\text{Si}(5 5 12)$ surface with Au adsorbates, which features one-dimensional (1D) atomic chains and a 1D metallic band. From angle-resolved UV photoelectron spectroscopy, we resolved that the nearly half-filled 1D band is actually composed of two parallel branches; one is metallic, but the other is insulating with an energy gap of $50\phantom{\rule{0.3em}{0ex}}\text{meV}$ below ${E}_{F}$ at room temperature. An energy gap evolves gradually from $270\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ on the metallic branch, saturating at $75\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ with a size of $40\phantom{\rule{0.3em}{0ex}}\text{meV}$ below ${E}_{F}$, while the insulating branch is intact. These behaviors are essentially identical with those recently reported on the $\text{Au}∕\text{Si}(5 5 7)$ system [Phys. Rev. Lett. 91, 196403 (2003)]. The scanning tunneling microscopy imaging indicates that these surfaces possess common 1D atomic chain structures, while the interchain distance is different. This explains the very similar electronic structure and transition of the two systems.