Structures Of Different Scales Research Articles

Sugarcane production in the subtropics: Seasonal changes in soil properties and crop yield in no-tillage, inverting and minimum tillage

Sugarcane is one of the important energy crops grown globally. Despite the increased sugarcane productivity, the mechanization of sugarcane production has caused the modification of soil structure in different scales. A field study was therefore conducted for three growing seasons (2010 - 2013) to evaluate seasonal changes of soil physico-chemical and mechanical properties and crop yield under different soil management practices for sugarcane (Saccharum Oficinarum) production in southern Brazil. In 2010/2011, the experiment was laid out in a randomized complete block design in three replications, consisting of no-tillage (NT), no-tillage + compaction (NTC), inverting conventional tillage (CT), and minimum tillage of chiseling (Chi) treatments. Disturbed and undisturbed soil samples were collected from soil layers 0–10, 10–20, 20–40 and 40–60 cm for the determination of soil properties, and sugarcane yield was evaluated. Shortly after land preparation, soil tillage significantly reduced the BD and AWmax but increased the macropore volume. Three years after land preparation and continuous no-tillage, there was a significant reduction in soil BD, Ma, FC, PWP, AWmax, TN, Ks, and Ic while SOM and σp increased in the 0–10 cm surface layer. For the 10–20 and 20–40 cm layers, BD and σp increased while Ma, FC, PWP, AWmax, and Ks decreased. Tillage had no significant (p < 0.05) on the soil properties beyond the 40 cm depth. Although sugarcane yield was not influenced by the different land preparation methods, however, NT, Chi or CT treatment could be preferred when considering soil management options for sugarcane production in this region.

Stratigraphy of the Koekoepkop thrust sheet in the Grünau Terrane, Mesoproterozoic Namaqua Province

Abstract The Koekoepkop Formation (KKP), near Kakamas, represents a thrust sheet (~25km2) of supracrustal rocks between granite-gneiss sheets on the southern boundary of the Riemvasmaak-Kenhardt Mega Sheath Fold within the eastern Namaqua Metamorphic Province. The formation with an outcrop strike-length of 106 km, is stratigraphically divided into four main units of which the Upper and Middle Units are laterally continuous. The KKP underwent deformation and metamorphism during the Namaqua Orogeny (1200 to 1100 Ma) resulting in thrust related imbricate structures and wedging-out of lithologies along strike. The four units represent an interbanded sequence of mafic, felsic and quartzo-feldspathic gneisses, with an unduplicated maximum thickness of 57 m. The younging direction in the four units on the south-dipping limb is northwards, as deduced from interpreted primary sedimentary structures of different scales (i.e. grading, load structures and upwards fining bedding cycles). The precursors of the four units are deduced to represent volcano-clastic sediments, a sequence of mafic and felsic pyroclastic tuffs of rhyolitic to dacitic composition. The interpreted primary structures suggest low energy subaqueous depositional environments that are distal from an unidentified source. The upper-most pyroclastic flow unit probably represents a change in depositional environment from low to high energy during syn-eruptive periods. The KKP cannot be directly correlated with other supracrustal sequences in the Grünau Terrane such as the Goede Hoop and Biesje Poort/Puntsit Formations owing to its probably allochthonous nature.

Whistler envelope solitons. I. Dynamics in inhomogeneous plasmas

A self-consistent Hamiltonian model based on equations describing the coupled dynamics of whistler and lower frequency waves in inhomogeneous plasmas is built. On this basis, different aspects of whistler turbulence are studied, concerning mainly the development of modulational instabilities and the dynamics of envelope solitons in irregular plasmas. Numerical simulations based on the model show that modulational instabilities can lead to the generation of a beating of stable nonlinear whistlers propagating with a speed near the group velocity. The whistler envelope soliton is determined analytically, and its propagation in plasmas presenting random density fluctuations and weakly irregular density structures of different scales and amplitudes is studied, showing that the envelope is very weakly affected by these inhomogeneities, whereas the wavelengths and the amplitudes of the phase oscillations strongly vary. Moreover, simulations show for the first time that two whistler solitons moving with different but close velocities and colliding one with the other remain unchanged after this collision, independently of their initial amplitudes and velocities. Finally, we study the dynamics of sonic whistler envelope solitons and show that the propagation of their lower frequency perturbation is governed by a KdV-type equation.

Relation between the Nonuniformity of the Properties and the Structure of Large Forgings

Heterogeneous different-scale structures in large forgings made of a heat-hardenable Cr–Ni–Mo steel are compared. The effect of heterogeneity on the properties of the metal is evaluated.

Multiscale hierarchical analysis of rock mass and prediction of its mechanical and hydraulic properties

Engineering geological and hydro-geological characteristics of foundation rock and surrounding rock mass are the main factors that affect the stability of underground engineering. This paper presents the concept of multiscale hierarchical digital rock mass models to describe the rock mass, including its structures in different scales and corresponding scale dependence. Four scales including regional scale, engineering scale, laboratory scale and microscale are determined, and the corresponding scale-dependent geological structures and their characterization methods are provided. Image analysis and processing method, geostatistics and Monte Carlo simulation technique are used to establish the multiscale hierarchical digital rock mass models, in which the main micro- and macro-structures of rock mass in different geological units and scales are reflected and connected. A computer code is developed for numerically analyzing the strength, fracture behavior and hydraulic conductivity of rock mass using the multiscale hierarchical digital models. Using the models and methods provided in this paper, the geological information of rock mass in different geological units and scales can be considered sufficiently, and the influence of downscale characteristics (such as meso-scale) on the upscale characteristics (such as engineering scale) can be calculated by considering the discrete geological structures in the downscale model as equivalent continuous media in the upscale model. Thus the mechanical and hydraulic properties of rock mass may be evaluated rationally and precisely. The multiscale hierarchical digital rock mass models and the corresponding methods proposed in this paper provide a unified and simple solution for determining the mechanical and hydraulic properties of rock mass in different scales.

Joint Contour Filtering

Edge/structure-preserving operations for images aim to smooth images without blurring the edges/structures. Many exemplary edge-preserving filtering methods have recently been proposed to reduce the computational complexity and/or separate structures of different scales. They normally adopt a user-selected scale measurement to control the detail smoothing. However, natural photos contain objects of different sizes, which cannot be described by a single scale measurement. On the other hand, contour analysis is closely related to edge-preserving filtering, and significant progress has recently been achieved. Nevertheless, the majority of state-of-the-art filtering techniques have ignored the successes in this area. Inspired by the fact that learning-based edge detectors significantly outperform traditional manually-designed detectors, this paper proposes a learning-based edge-preserving filtering technique. It synergistically combines the differential operations in edge-preserving filters with the effectiveness of the recent edge detectors for scale-aware filtering. Unlike previous filtering methods, the proposed filters can efficiently extract subjectively meaningful structures from natural scenes containing multiple-scale objects.

Reconstruction of 3D porous media using multiple-point statistics based on a 3D training image

To date many methods of constructing porous media have been proposed. Among them, the multiple-point statistics (MPS) method has a unique advantage in reconstructing 3D pore space because it can reproduce pore space of long-range connectivity. The Single Normal Equation Simulation (SNESIM) is one of most commonly used algorithms of MPS. In the SNESIM algorithm, the selection of training image is vital because it contains the basic pore structure patterns. In the previous reconstructions of 3D porous media using SNESIM, a 2D slice was usually employed as the training image. However, it is difficult for a 2D slice to contain complex 3D pore space geometry and topology patterns. In this paper, a 3D training image is used in order to provide more realistic 3D pore structure features. Besides, a multi-grid search template is applied for the purpose of capturing the pore structures of different scales and speeding up the reconstruction process. Two sandstone cores are taken as test examples and the 3D porous media are reconstructed. The two-point correlation function, pore network structure parameters and absolute permeability are applied as the evaluation indexes to validate the accuracy of the reconstructed models. The comparison result shows that the reconstructed models are in good agreement with the real model obtained by X-ray computed tomography scanning in the pore throat geometry and topology and transport property, which justifies the reliability of the proposed method.

One-step fabrication of superhydrophobic surfaces with different adhesion via laser processing

In this study, we developed a simple, low-cost and convenient method to fabricate grid structures of different scales on the surface of 6061 aluminum alloy via laser processing. By changing the line spacing (50, 150, 250, 300 μm) during laser beam irradiation, different sizes of the square-shaped unprocessed surface areas and cross groove structures could be achieved. By adjusting the area ratio between the accumulative microstructure and the unprocessed surface, the adhesion of a water droplet to the surface could be varied from a state of low adhesion (line spacing of 50 or 150 μm) to a state of high adhesion (line spacing of 250 or 300 μm). The results indicated that different surface wettabilities could be obtained on aluminum alloy surfaces through the combination of a crisscross groove structure and unprocessed surface, which together formed a square groove structure. Corrugated protuberances, granular bumps and pit texture were formed on the groove structure. The surface showed excellent superhydrophobic properties. The contact angle was as high as 154.6° and the sliding angle was 6° for a line spacing of 150 μm. In this case, the low adhesion led to a rolling and self-cleaning behavior. For the larger line spacings, the wetting state of the water droplet indicated a high adhesion to the surface and a transition of the Cassie-Baxter state to the Wenzel state. Surfaces with high adhesion are of great significance for water collection and preservation. The approach presented in this study provides a facile, low-cost and efficient method to fabricate superhydrophobic surfaces on all types of metallic materials for commercial applications.

Relationship between multi-scale structures and properties of photophobic films based on hydroxypropyl methylcellulose and monosodium phosphate

Photophobic (white) films were prepared with hydroxypropyl methylcellulose (HPMC) and monosodium phosphate (NaH2PO4) to overcome the redox reaction induced by titanium dioxide photocatalysis of HPMC/TiO2 white film. What’s more, HPMC/NaH2PO4 white film could overcome the drying temperature dependent property of white films based on HPMC and calcium salts. Attenuated total reflection Fourier transform infrared spectroscopy, wide angel X-ray diffraction, small angle X-ray scattering, scanning electron microscope and texture analyzer were used to investigate the effect of NaH2PO4 on the short-range, supra-molecular structures and properties of HPMC film. The formation mechanism of the white film was speculated by analyzing the structures of different scales. The results showed that the interaction might happen between H2PO4−1 group of NaH2PO4 and CH, CH2 and CH3 group of HPMC. These interactions influenced the polymer chain movement and combination and further affected the aggregation structures. Specifically, the compactness, smoothness and scale range of the surface fractal scatters in films increased and elongated particles of two scales appeared. These changes of ordered structure in the micro-region might contribute to increasing the reflected light and decreasing the transmission light of films, resulting in white films with photophobic property. The addition of NaH2PO4 decreased the crystallinity and smoothness of the cross-section of HPMC film, which resulted in a little lower tensile strength, elongation and elastic modulus of HPMC/NaH2PO4 films. Films of less than 10% of NaH2PO4 showed similar mechanical properties with pure HPMC film, which offered proper parameters for the production of HPMC/NaH2PO4 photophobic films in the application.

Influence of textural parameters on detrital-zircon age spectra with application to provenance and paleogeography during the Ediacaran−Terreneuvian of southwestern Laurentia

Multiple sedimentary structures of different scales and representative of various flow conditions were sampled from single, sand-dominated, fluvial channels in the Neoproterozoic (Ediacaran) upper member of the Stirling Quartzite and the Cambrian (Terreneuvian) middle member of the Wood Canyon Formation. Sampling was designed to determine if sorting of detrital-zircon populations by their textural properties affects detrital-zircon age spectra in fluvial sandstones. Grain sizes of the sampled host sandstones range from fine to coarse sand, and sorting ranges from moderately well to poorly sorted. Four Wood Canyon Formation samples contain detrital-zircon grains of similar size, whereas detrital zircons in samples of the Stirling Quartzite differ greatly in size between two samples. Paired Kolmogorov-Smirnov, overlap, and likeness statistical tests demonstrate that all samples from each channel are similar. Comparing size, sphericity, and roundness of detrital-zircon grains to their ages yielded no linear correlation. Sorting of sediments by their textural properties did not affect detrital-zircon age spectra in either unit. In this study, different sedimentary structures within a single fluvial channel do not control the age distribution of detrital zircons. Furthermore, the two braidplain systems (Wood Canyon Formation, Stirling Quartzite) have substantially different detrital-zircon age spectra, indicating that the fluvial environment in general is not responsible for selecting specific age populations. The dominant ca. 1.1 Ga Grenvillian peak in the middle member Wood Canyon Formation results from provenance, not sampling bias. Uplift and erosion of Grenvillian rocks along the Ouachita rift flank during the earliest Cambrian may have generated a pulse of sediment that entered a northwestward-flowing braidplain.

Features of forecasting the development of enterprise structures of the regions in the conditions of global economic change

The article substantiates the role of theory in predicting the development of the economies of all levels, in the development of enterprise structures of different scales. The basis for economic and social analysis is the system parameters, which may vary depending on the conditions of economic development, the goals and objectives of the planning period. Prediction of enterprise structures of regional trends should contribute to solving the problem of increasing the productivity and efficiency of the leading sectors of the economy of the region in a globalized economy. Monitoring and forecasting of structural change of business development in a particular region involves the development and formation of appropriate administrative, institutional and financial structures for the creation of investment attractiveness and optimize resource utilization. Keywords – business structures, region, methods of forecasting, economic globalization, management of economic social development and the cluster approach.

Scale space multiresolution correlation analysis for time series data

We propose a new scale space method for the discovery of structure in the correlation between two time series. The method considers the possibility that correlation may not be constant in time and that it might have different features when viewed at different time scales. The time series are first decomposed into additive components corresponding to their features in different time scales. Temporal changes in correlation between pairs of such components are then explored by using weighted correlation within a sliding time window of varying length. Bayesian, sampling-based inference is used to establish the credibility of the correlation structures thus found and the results of analyses are summarized in scale space feature maps. The performance of the method is demonstrated using one artificial and two real data sets. The results underline the usefulness of the scale space approach when the correlation between the time series exhibit time-varying structure in different scales.

A theoretical unsteady‐state model for kL of bubbles based on the framework of wide energy spectrum

An unsteady‐state model for predicting mass‐transfer coefficient kL of bubbles with mobile surface was developed for turbulent gas‐liquid dispersions. This model was derived from an unsteady‐state convection and diffusion equation through a characteristics method. Unlike the previous work, this model considered the contributions of the amount of fluid structures of different scales (i.e., eddies) existing in the turbulent flows, the frequency of eddies arriving at the surface, the deformation and oscillation of bubbles to mass transfer. This model was based on the framework of wide energy spectrum and can account for the role of eddies of different sizes in mass transfer. Thus the assumption adopted by the previous models that mass transfer was controlled by eddies of certain sizes is no more needed. The overall kL predicted by the proposed model showed a better agreement with the reported experimental data. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1007–1022, 2016

Combining wavelet transform and POD to analyze wake flow

To reveal the possibly existed flow phenomena that buried in a two-dimensional symmetric triangle wake, one-dimensional orthogonal wavelet transform and POD are combined to decompose the fluctuating velocity field into different wavelet components and modes. The features of reconstructed flow fields are analyzed in terms of fluctuating energy, time frequency distribution, space correlation and Reynolds shear stress. It is found that the first two wavelet components and POD modes can give representations to the most energetic large-scale structures, contributing about 77 and 73 % to the total fluctuating energy, respectively. Comparing with the first two wavelet components, the first two POD modes are more appropriate to represent the Karman-like vortical structures. The time–frequency and length scale characteristics of wavelet components suggest that frequency behavior can reflect the spatial-related length scale and the wavelet transform can be used to extract turbulent structures of different scales. Similar to the energy distribution, the most significant contributions to the Reynolds shear stresses comes from the large-scale structures that composed of first two wavelet components and POD modes, accounting for 88 and 80 % of the measured maximum Reynolds shear stress, respectively. Due to different classification criterion of wavelet and POD analyses, the combining use of these two methods tends to be more effective for analyzing multi-scale turbulent structures.

The contemporary state of stress and strain at the western pericline of the Greater Caucasus

We collected materials on geological indicators of paleostresses at the western pericline of the Greater Caucasus mega-anticlinorium and within the large transverse flexure-fault zone (Anapa and Dzhiginka zones) limiting this mega-anticlinorium. Based on the data, we reconstructed local stress states in different tectonic zones. The reconstructed local stresses showed a considerable variation of the orientations axes of principal stress near the two zones. In a site adjacent to the flexure-fault zone and located near the western pericline of the Greater Caucasus mega-anticlinorium, the detachment systems of northeastern (NE–SW) strike are determined. Additionally, field structural studies proved elongation in the northwestern (NW–SE) direction. This was also verified by the reconstruction of orientations of minimum compression stress axes (maximum deviatory tension) implemented by cataclastic analysis of structural–kinematic information on the movements of the fault planes (tectonic cracks and minor ruptures). We found a well-expressed multistage regime of the northwestern (NW–SE) tension within the limits of the Semisam anticline. Tension deformations (along the axis of the main folded structure) are manifested in structures of different scales; the values of relative elongation are defined for some of them. At the western pericline of the Greater Caucasus mega-anticlinorium, in the Miocene deposits, a north–south (NNW) compression regime with steep inclinations of axes of maximum compression stresses was identified. In the boundary zone between the Northwestern Caucasus and transverse Kerch–Taman trough, an alteration of the orientations of main axes of normal stresses was found. These changes led to the replacement of horizontal-compression and horizontalshear (with a NE-oriented compression) settings, which are predominant in the Caucasus, with settings of horizontal tension (with steep NNW-oriented compression axes).

A novel dynamics combination model reveals the hidden information of community structure

The analysis of the dynamic details of community structure is an important question for scientists from many fields. In this paper, we propose a novel Markov–Potts framework to uncover the optimal community structures and their stabilities across multiple timescales. Specifically, we model the Potts dynamics to detect community structure by a Markov process, which has a clear mathematical explanation. Then the local uniform behavior of spin values revealed by our model is shown that can naturally reveal the stability of hierarchical community structure across multiple timescales. To prove the validity, phase transition of stochastic dynamic system is used to indicate that the stability of community structure we proposed is able to describe the significance of community structure based on eigengap theory. Finally, we test our framework on some example networks and find it does not have resolute limitation problem at all. Results have shown the model we proposed is able to uncover hierarchical structure in different scales effectively and efficiently.

Multiscale equatorial electrojet turbulence:Baseline 2‐D model

AbstractThe spatial and spectral characteristics of the turbulent plasma density, electric fields, and ion drift in ionospheric E region are studied using a new set of nonlinear plasma fluid equations. The fluid model combines both Farley‐Buneman (Type‐I) and Gradient‐Drift (Type‐II) plasma instabilities in the equatorial electrojet. In our unified model of the plasma instabilities, we include the ion viscosity in the ion momentum equation and electron inertia in the electron momentum equation. These two terms play an important role in stabilizing the growing modes in the linear regime and in driving the Farley‐Buneman instability into the saturation state. The simulation results show good agreements with a number of features of rocket and radar observations, such as (1) saturation of plasma density perturbations depends on the solar condition and reaches 7–15% relative to the background, (2) fluctuation of the horizontal secondary electric field reaches 8–15 mV/m, (3) stabilization of the phase velocity of the perturbed density wave around the value of the ion‐acoustic speed inside the electrojet, (4) “up‐down” asymmetry in the vertical fluxes of the plasma density, (5) “east‐west” asymmetry of the plasma zonal drifts, and (6) generation of small scale of the order of meter scale lengths irregularities embedded in large‐scale structures. Spectral analysis of the density fluctuations reveals the energy cascade due to the nonlinear coupling between structures of different scales. The break‐up of the large‐scale structures into small‐scale structures explains the disappearance of Type‐II echoes in the presence of Type‐I instabilities.

Triangle Cylinder Wake Analysis Based on Wavelet and POD Techniques

The turbulent structure behind a two-dimensional symmetric triangle cylinder is measured by PIV experiment at Reynolds number of 14440. To reveal the possibly existed flow phenomena that buried in the mean flow, one dimensional orthogonal wavelet and POD analyses are employed to decompose the fluctuating velocity field into different wavelet components and modes. The features of reconstructed flow fields are analyzed in terms of fluctuating energy, time frequency distribution and length scale. It is found that the first two wavelet components and POD modes can give representations to the most energetic large scale structures, contributing about 77% and 73% to the total fluctuating energy respectively. Comparing with the first two wavelet components, the first two POD modes are more appropriate to represent the Karman like vortical structures. The time-frequency and length scale characteristics of wavelet components suggest that frequency behavior can reflect the spatial related length scale and the wavelet analysis can be used to extract turbulent structures of different scales.

Scale Invariant Metrics of Volumetric Datasets

Nature reveals itself in similar structures of different scales. A child and an adult share similar organs yet dramatically differ in size. Comparing the two is a challenging task to a computerized approach as scale and shape are coupled. Recently, it was shown that a local measure based on the Gaussian curvature can be used to normalize the local metric of a surface and then to extract global features and distances. In this paper we consider higher dimensions; specifically, we construct a scale invariant metric for volumetric domains which can be used in analysis of medical datasets such as computed tomography (CT) and magnetic resonance imaging (MRI).

Functional Clusters, Hubs, and Communities in the Cortical Microconnectome.

Although relationships between networks of different scales have been observed in macroscopic brain studies, relationships between structures of different scales in networks of neurons are unknown. To address this, we recorded from up to 500 neurons simultaneously from slice cultures of rodent somatosensory cortex. We then measured directed effective networks with transfer entropy, previously validated in simulated cortical networks. These effective networks enabled us to evaluate distinctive nonrandom structures of connectivity at 2 different scales. We have 4 main findings. First, at the scale of 3–6 neurons (clusters), we found that high numbers of connections occurred significantly more often than expected by chance. Second, the distribution of the number of connections per neuron (degree distribution) had a long tail, indicating that the network contained distinctively high-degree neurons, or hubs. Third, at the scale of tens to hundreds of neurons, we typically found 2–3 significantly large communities. Finally, we demonstrated that communities were relatively more robust than clusters against shuffling of connections. We conclude the microconnectome of the cortex has specific organization at different scales, as revealed by differences in robustness. We suggest that this information will help us to understand how the microconnectome is robust against damage.