Horizontal Cross-section Research Articles

The interaction between wheat roots and soil pores in structured field soil.

Wheat (Triticum aestivum L.) root growth in the subsoil is usually constrained by soil strength, although roots can use macropores to elongate to deeper layers. The quantitative relationship between the elongation of wheat roots and the soil pore system, however, is still to be determined. We studied the depth distribution of roots of six wheat varieties and explored their relationship with soil macroporosity from samples with the field structure preserved. Undisturbed soil cores (to a depth of 100 cm) were collected from the field and then non-destructively imaged using X-ray computed tomography (at a spatial resolution of 90 µm) to quantify soil macropore structure and root number density (the number of roots cm–2 within a horizontal cross-section of a soil core). Soil macroporosity changed significantly with depth but not between the different wheat lines. There was no significant difference in root number density between wheat varieties. In the subsoil, wheat roots used macropores, especially biopores (i.e. former root or earthworm channels) to grow into deeper layers. Soil macroporosity explained 59% of the variance in root number density. Our data suggested that the development of the wheat root system in the field was more affected by the soil macropore system than by genotype. On this basis, management practices which enhance the porosity of the subsoil may therefore be an effective strategy to improve deep rooting of wheat.

Effect of the Direction of Uniform Horizontal Magnetic Field on the Linear Stability of Natural Convection in a Long Vertical Rectangular Enclosure

The effect of the direction of external horizontal magnetic fields on the linear stability of natural convection of liquid metal in an infinitely long vertical rectangular enclosure is numerically studied. A vertical side wall is heated and the opposing vertical wall is cooled both isothermally, whereas the other two vertical walls are adiabatic. A uniform horizontal magnetic field is applied either in the direction parallel or perpendicular to the temperature gradient. In this study, the height of the enclosure is so long as to neglect the top and bottom effects where returning flow takes place, and thus the basic flow is assumed to be a parallel flow and the temperature field is in heat conduction state. The Prandtl number is limited to the value of 0.025 and horizontal cross-section is square. The natural convection is monotonously stabilized as increase in the Hartmann number when the applied magnetic field is parallel to the temperature gradient. However, when the applied magnetic field is perpendicular to the temperature gradient, it is once destabilized at a certain low Hartmann number, but it is stabilized at high Hartmann numbers.

Transition to doubly diffusive chaos

Doubly diffusive convection driven by horizontal gradients of temperature and salinity is studied in a three-dimensional enclosure of square horizontal cross section and large aspect ratio. Previous studies focused on the primary instability and revealed the formation of subcritical branches of spatially localized states. These states lose stability because of their twist instability, thereby precluding the presence of any related stable steady states beyond the primary bifurcation and giving rise to spontaneous temporal complexity for supercritical parameter values. This paper investigates the emergence of this behavior. In particular, chaos is shown to be produced at a crisis bifurcation located close to the primary bifurcation. The critical exponent related to this crisis bifurcation is computed and explains the unusually abrupt transition. The construction of a low-dimensional model highlights that only a few requirements are necessary for this type of transition to occur. As a consequence, it is believed to be observable in many other systems.

The efficacy of five different techniques in identifying C-shaped canals in mandibular molars.

Information regarding the canal anatomy especially in complex cases such as C-shaped canals is essential for a successful treatment. In this study, five different methods for identification of C-shaped canal configuration were compared. 108 extracted mandibular molars with fused roots were studied. Radiographic evaluation was carried out using periapical radiography and CBCT. After access cavity preparation, all specimens were evaluated by direct visual examination and then under dental operating microscope. Finally, the actual anatomy of each sample was determined by preparing horizontal cross sections of the roots (1mm thick) and examining them under stereomicroscope as the gold standard. Among the techniques used, high-resolution CBCT manifested the highest accuracy, whereas periapical radiography had the lowest. All approaches can be useful in reaching a correct diagnosis. CBCT, especially the low-resolution modality, is an effective technique in the diagnosis of C-shaped anatomy.

Impact of reservoir heterogeneity on fluid injection-induced fault slip: insights from numerical simulation

In order to meet the growing energy demand worldwide, the technology of hydraulic fracturing for shale gas extraction has been rapidly developed and applied in recent years. However, man-made fluid injection has also caused several problems of high societal concern such as induced earthquakes. The focus of this paper is on the process of induced fault activation in shale reservoirs caused by hydraulic stimulation activities. We constructed a two-dimensional numerical model representing the horizontal cross-section of a faulted reservoir and simulated important coupled hydro-mechanical processes during fluid injection. We parameterized our model with the site investigation data of an actual shale gas project including in-situ stress, rock properties and injection protocol, etc. We represented the natural fault zone as a geological composite involving a fault core and a damage zone consisting of a set of subsidiary fractures parallel to the fault strike. We coupled the solid deformation and fault displacement with Darcy-type fluid flow based on poroelasticity principles and hydro-mechanical constitutive relationships. The heterogeneous nature of the permeability of the shale formation is mimicked by a random field model governed by a log-normal probability density function and directional correlation lengths, such that we can explore the impact of reservoir heterogeneity on the fault slip behaviour. In addition, we also studied the effects of fault length, dip angle and injection point-to-fault distance on the fault slip. Specifically, we analysed the link between fault slip and fluid flow field, permitting the capture of fluid movement in the heterogeneous faulted reservoir, the temporal and spatial evolution of preferential flow channels and their consequences on induced fault slip. The results of this research have important implications for understanding the triggering processes and mechanisms of fault slip during shale gas exploitation as well as many other injection-related engineering activities.

FILLING LEVEL MEASUREMENTS OF WASTE BINS USING LOW POWER SENSORS OF THE INTERNET OF THINGS AND LORAWAN TECHNOLOGY

The article discusses IoT based solutions to improve waste collection and monitoring in public waste containers. The paper examines whether the monitoring system used in the measurement process can be used to monitor the filling of containers. The system consists of a wireless module connected to an ultrasonic sensor. The data sent makes it possible to calculate the empty space in the waste containers. The values are obtained by measuring the distance from the top of the container to the surface of the waste. Low-power long-distance broadband network (LoRaWAN) transmitters were used for data transmission. The aim of the research: to test an inexpensive monitoring system and to describe a new system of sensors and transmitter modules. The system is characterized by extremely low power consumption and a wide range of sensors used. Measurements were performed in Vilnius. Containers of two types of sizes were analyzed, measurements were performed at five points of horizontal cross section of the containers. The study was performed at two different levels of container filling. The results show that an ultrasonic sensor can representatively measure waste filling depths at different levels of container filling. Based on the results, this sensor can be recommended in the intelligent waste management market. Such a system can provide the necessary data for optimizing waste collection processes in cities and avoid container overcrowding problems.

Evaluating the Performance of a Convection-Permitting Model by Using Dual-Polarimetric Radar Parameters: Case Study of SoWMEX IOP8

In this study, a dual-polarimetric radar observation operator is established and modified for the Taiwan area for the purpose of model verification. A severe squall line case during the Southwest Monsoon Experiment Intensive Observing Period 8 (SoWMEX IOP#8) on 14 June 2008, is selected and examined. Because the operator is adopted from the use of the midlatitude region, sensitivity tests are performed to obtain the optimal setting of the operator in the subtropical region. To accurately capture the dynamic structure of the squall lines, the ensemble-based data assimilation system, which assimilates both radial wind and reflectivity data, is used to obtain the optimal analysis field on the mesoscale for evaluating the performance of model simulation. The characteristics of two microphysics schemes are investigated, and the results obtained using the schemes are compared with the S-band dual-polarimetric radar observations. The horizontal and vertical cross-sections show that the analyses resemble the observations. Both schemes can replicate the polarimetric parameter signature such as ZDR and KDP columns. When comparing model simulation with polarimetric parameters through the drawing of contour frequency by altitude diagrams (CFADs), the results reveal that the single moment microphysics scheme performs better than the double moment scheme in this case. However, the reflectivity field in the stratiform area is more accurately captured when using the double moment scheme. Furthermore, validation with polarimetric variables (ZH, ZDR and KDP) histograms shows underestimation of the KDP field in both schemes. Overall, this study indicates the benefit of assimilating radial wind and reflectivity data for the analyses of severe precipitation systems and the necessity of assimilating polarimetric parameters for the accuracy of microphysical processes, especially complex microphysics schemes in subtropical region.

Decay of Solutions to the Linearized Free Surface Navier–Stokes Equations with Fractional Boundary Operators

In this paper we consider a slab of viscous incompressible fluid bounded above by a free boundary, bounded below by a flat rigid interface, and acted on by gravity. The unique equilibrium is a flat slab of quiescent fluid. It is well-known that equilibria are asymptotically stable but that the rate of decay to equilibrium depends heavily on whether or not surface tension forces are accounted for at the free interface. The aim of the paper is to better understand the decay rate by studying a generalization of the linearized dynamics in which the surface tension operator is replaced by a more general fractional-order differential operator, which allows us to continuously interpolate between the case without surface tension and the case with surface tension. We study the decay of the linearized problem in terms of the choice of the generalized operator and in terms of the horizontal cross-section. In the case of a periodic cross-section we identify a critical order of the differential operator at which the decay rate transitions from almost exponential to exponential.

Insight into the fracturing of silty mudstone in cyclic hydrothermal environments based on computed tomography

The objective of this study was to examine the fracture evolution and related mechanism of silty mudstone in cyclic hydrothermal environments. Fracture evolution tests and computed tomography (CT) scans were carried out on silty mudstone specimens subjected to cyclic wetting-heating. The spatial–temporal variations of fracture parameters including the total length ratio, fracture rate, mean fracture width, fracture direction and fractal dimension were investigated. The mechanism underlying the fracture evolution in silty mudstone was also analyzed. The results show that fractures initiate and propagate from the wetting-heating surface down to the deep layer with increasing cycle number. Most of the fractures are parallel or perpendicular to each other and form a reticulate fracture network on every horizontal cross-section. The total length ratio, fracture rate, mean fracture width and fractal dimension considerably decrease as the depth increases, and the total length ratio and fracture rate significantly increase with increasing cycle number. After a wetting-heating cycle, only the zone within a depth of 14 mm shows slight fracturing; however, after 17 wetting-heating cycles, slight fracturing occurs within a depth of 104 mm. The fracture mechanism mainly involves the hydrothermal stress effect, water-softening effect, and mineral hydrolysis.

Studying the potentiality of using low cost system based on image analysis technique to survey the gravel’s size in asphalt mixes

This study aims to develop the micro-analysis of the bituminous mixtures using 2D scanner and Image Analysis Techniques (IAT). A new methodology and scheme are developed for faster and accurate procedure to compute Gradation of aggregates using (IAT) instead of the conventional methods. 2D scanner is used to analyze the horizontal cross section of HMA slices. This dissertation focuses on introducing a more elaborate method for characterization of the internal structure of aggregates which characterization of internal structure is necessary to understand the behavior of the bituminous mixtures under different conditions. Image Analysis Techniques (IAT) the technological advantages to better understand construction materials and it also provides information that can help to improve the properties of various construction materials. The aggregate internal structure provides the skeleton of the asphalt mixture, which plays an important role in rutting resistance. The Results helped to analyze the internal structure thus improving the ability to understand the behavior of construction materials. Also, the results indicate potential for using this method to evaluate the internal structure of mixtures in field where using this non-destructive, cost effective and a time efficient approach.

The Influence of Cross-Section Thickness on Diameter at Breast Height Estimation from Point Cloud

Circle-fitting methods are commonly used to estimate diameter at breast height (DBH) of trees from horizontal cross-section of point clouds. In this paper, we addressed the problem of cross-section thickness optimization regarding DBH estimation bias and accuracy. DBH of 121 European beeches (Fagus sylvatica L.) and 43 Sessile oaks (Quercus petraea (Matt.) Liebl.) was estimated from cross-sections with thicknesses ranging from 1 to 100 cm. The impact of cross-section thickness on the bias, standard error, and accuracy of DBH estimation was statistically significant. However, the biases, standard errors, and accuracies of DBH estimation were not significantly different among 1–10-cm cross-sections, except for oak DBH estimation accuracy from an 8-cm cross-section. DBH estimations from 10–100-cm cross-sections were considerably different. These results provide insight to the influence of cross-section thickness on DBH estimation by circle-fitting methods, which is beneficial for point cloud data acquisition planning and processing. The optimal setting of cross-section thickness facilitates point cloud processing and DBH estimation by circle-fitting algorithms.

3D reconstruction of internal wood decay using photogrammetry and sonic tomography

AbstractKnowledge of deteriorations within tree trunks is critical for arborists to conduct individual tree health assessments. Sonic tree tomography, a non‐destructive technique using sound waves, has been widely used to estimate the size and shape of internal decay based on sound wave velocity variations. However, it has commonly been applied to 2D horizontal or vertical cross sections and its accuracy is questionable due to the poor approximation of the shape of the cross section. This paper proposes an integration of close‐range photogrammetry and sonic tomography to enable accurate reconstruction of the exterior and interior of the tree trunk in 3D. The internal wood quality is represented by the spatially interpolated sound wave velocities, using the time of flight of the sound waves and the coordinates of the acoustic sensors obtained from the photogrammetric model. Experimental results show that the proposed approach provides a realistic 3D visualisation of the size, shape and location of the internal deteriorations.

Predicting biofilm deformation with a viscoelastic phase-field model: Modeling and experimental studies.

Biofilms commonly develop in flowing aqueous environments, where the flow causes the biofilm to deform. Because biofilm deformation affects the flow regime, and because biofilms behave as complex heterogeneous viscoelastic materials, few models are able to predict biofilm deformation. In this study, a phase-field (PF) continuum model coupled with the Oldroyd-B constitutive equation was developed and used to simulate biofilm deformation. The accuracy of the model was evaluated using two types of biofilms: a synthetic biofilm, made from alginate mixed with bacterial cells, and a Pseudomonas aeruginosa biofilm. Shear rheometry was used to experimentally determine the mechanical parameters for each biofilm, used as inputs for the model. Biofilm deformation under fluid flow was monitored experimentally using optical coherence tomography. The comparison between the experimental and modeling geometries, for selected horizontal cross sections, after fluid-driven deformation was good. The relative errors ranged from 3.2 to 21.1% for the synthetic biofilm and from 9.1 to 11.1% for the P. aeruginosa biofilm. This is the first demonstration of the effectiveness of a viscoelastic PF biofilm model. This model provides an important tool for predicting biofilm viscoelastic deformation. It also can benefit the design and control of biofilms in engineering systems.

BIM-Based Registration and Localization of 3D Point Clouds of Indoor Scenes Using Geometric Features for Augmented Reality

Augmented reality can improve construction and facility management by visualizing an as-planned model on its corresponding surface for fast, easy, and correct information retrieval. This requires the localization registration of an as-built model in an as-planned model. However, the localization and registration of indoor environments fail, owing to self-similarity in an indoor environment, relatively large as-planned models, and the presence of additional unplanned objects. Therefore, this paper proposes a computer vision-based method to (1) homogenize indoor as-planned and as-built models, (2) reduce the search space of model matching, and (3) localize the structure (e.g., room) for registration of the scanned area in its as-planned model. This method extracts a representative horizontal cross section from the as-built and as-planned point clouds to make these models similar, restricts unnecessary transformation to reduce the search space, and corresponds the line features for the estimation of the registration transformation matrix. The performance of this method, in terms of registration accuracy, is evaluated on as-built point clouds of rooms and a hallway on a building floor. A rotational error of 0.005 rad and a translational error of 0.088 m are observed in the experiments. Hence, the geometric feature described on a representative cross section with transformation restrictions can be a computationally cost-effective solution for indoor localization and registration.

Leveraging Polarization of WiFi Signals to Simultaneously Track Multiple People

This paper presents WiPolar, an approach that simultaneously tracks multiple people using commodity WiFi devices. While two recent papers have also demonstrated multi-person tracking using commodity devices, they either require the people to continuously keep moving without stopping, and/or require the number of people to be input manually, and/or keep the WiFi devices from performing their primary function of data communication. Motivated by the increasing availability of polarized antennas on modern WiFi devices, WiPolar leverages signal polarization to perform accurate multi-person tracking using commodity devices while addressing the three limitations of prior work mentioned above. The key insight that WiPolar is based on is that different people expose different instantaneous horizontal and vertical radar cross-sections to WiFi transmitters due to differences in their physiques and orientations with respect to the transmitter. This enables WiPolar to accurately separate the multipaths reflected from different people, which, in turn, allows it to track them simultaneously. To the best of our knowledge, this is the first work that leverages polarization of WiFi signals to localize and track people. We implement WiPolar using commodity WiFi devices and extensively evaluate it for tracking up to five people in three different environments. Our results show that WiPolar achieved a median tracking error of just 56cm across all experiments. It also accurately tracks people even when they were not moving. WiPolar achieved a median tracking error of 74cm for people that were either stationary or just taking a small pause.

Underwater blast loading of partially submerged sandwich composite materials in relation to air blast loading response

The research presented in this paper focusses on the underwater blast resilience of a hybrid composite sandwich panel, consisting of both glass-fibre and carbon-fibre. The hybrid fibres were selected to optimise strength and stiffness during blast loading by promoting fibre interactions. In the blast experiment, the aim was to capture full-field panel deflection during large-scale underwater blast using high-speed 3D Digital Image Correlation (DIC). The composite sandwich panel was partially submerged and subjected to a 1 kg PE7 charge at 1 m stand-off. The charge was aligned with the centre of the panel at a depth of 275 mm and mimicked the effect of a near-field subsurface mine. The DIC deflection data shows that the horizontal cross-section of the panel deforms in a parabolic shape until excessive deflection causes core shear cracking. The panel then forms the commonly observed “bathtub” deformation shape. DIC data highlighted the expected differences in initial conditions compared to air-blast experiments, including the pre-strains caused by the mass of water (hydrostatic pressure). Furthermore, water depth was shown to significantly influence panel deflection, strain and hence damage sustained under these conditions. Panel deformations and damage after blast was progressively more severe in regions deeper underwater, as pressures were higher and decayed slower compared to regions near the free surface.An identical hybrid composite sandwich panel was subjected to air blast; one panel underwent two 8 kg PE7 charges in succession at 8 m stand-off. DIC was also implemented to record the panel deformations during air blast. The air and underwater blast tests represent two different regimes of blast loading: one far-field in air and one near-field underwater. The difference in deflection development, caused by the differing fluid mediums and stand-off distances, is apparent from the full-field results. During underwater blast the panel underwent peak pressure loading of approximately 52.6 MPa whilst during air blast the panel was subjected to 67.7 kPa followed by 68.9 kPa peak pressure loads in succession. The two experiments demonstrate the response of the same hybrid composite sandwich panel under two differing blast regimes.The post-blast damage and strength of the hybrid panels following air and underwater blasts were evaluated. Post-blast testing revealed that the underwater blast causes significantly more damage compared to air blast, particularly debonding between the skins and core. The air blast panel sustains no visible rear skin/core debonding, whereas 13 regions of rear-face debonds are identified on the underwater blast panel. Sustaining no front-skin breakage was advantageous for retaining a high proportion of the compressive modulus for this hybrid layup following underwater blast. Damage mechanisms were interrelated. Determining the most detrimental type is not straightforward in real explosive and non-idealised experiments, however debonding was understandably shown to be significant. A further study to isolate failure modes and improve in situ instrumentation is ongoing.

The Effect of Tax Revenues on Inflation in Selected OECD Countries

If the seniorage leads revenue through state which can cause inflation at the same time, the expected income growth does not occur because of being delays in tax collection. In countries where the price elasticity of the tax system is less than 1, the Olivera-Tanzi effect, which states that the flaw in tax collection creates inflation and reduces real tax revenues, advocated a negative relationship between tax revenues and inflation. However, the main point here is the real value of taxes. In countries that adopt more liberal policies, the share of tax revenues in GDP is low. In this context, the aim of this study is to examine the effects of tax revenues on inflation in 28 OECD countries for the period 1995-2018 through panel data analysis. In the study, the horizontal cross-section dependency was neglected and first generation panel unit root tests were applied. Since the variables are stationary at the level, the cointegration test that gives the long-term relationship has not been passed. As a result of the Hausman test, it has been determined that the model will be estimated based on random effects. As a result of the study, it was determined that the increasing in tax revenues will increase inflation.

MODELLING THE EFFECTS OF RELEASE AND PROPAGATION OF GASES, VAPOURS AND AEROSOLS FROM HAZARDOUS MATERIALS

The effects of release and propagation of gases, vapours and aerosols from hazardous substances are modelled using: ideal models that presuppose that the surface of the horizontal cross section of the container (tank) is constant, that substances are released from the hole in the wall, that the system is not a two-phase system, and that there is no resistance in the discharge; realistic models that take into account the phenomenon of friction; two-phase models that take into account the quality and the specific volume of the mixture of vapour and liquid; and models that take into account the abrupt release of liquids, gases and vapours.

The Impact of the Development of the Bankıng Sector On Economic Growth: The Case of Mena Countries

The purpose of this study is to analyze the impact of banking sector development on economic growth in the period of 1991-2017 for eight MENA countries. Credit to the private sector were used as an indicator of financial depth to represent the development of the banking sector. In this study, in which eight MENA countries are discussed, new generation panel data analysis was applied for the relationship between variables. In order to determine the long-term relationship between the development of the banking sector and growth, a horizontal cross-section dependency test was used first. Panel bootstrap cointegration test developed by Wester Lund and Edgerton (2007), which takes into account this situation by determining the dependency between horizontal sections, was used. According to the result obtained, it is seen that the development of the banking sector and economic growth act together in the long term. As a result of cointegration, the coefficients of the variables were analyzed with the Augmented Mean Group estimator. However, the homogeneity of the slope coefficients for the entire panel was determined using the delta test. A 1% increase in the banking sector in MENA countries has been found to increase economic growth by 0.66%. It is seen that the development and deepening of the banking sector in economic growth policies will play an effective role in achieving the goal. In this context, increasing financial access and efficiency is thought to support economic growth.

Effect of micropillars with varying geometry and density on the efficiency of impaction-based quartz crystal microbalance aerosol sensors

Inertial impaction is frequently used for the collection and subsequent measurement of aerosol particles in resonator-based airborne particulate matter (PM) sensors. However, particle bounce is known to significantly reduce particle collection efficiency (CE) on surfaces exhibiting low roughness, such as those present in quartz crystal microbalance (QCM) PM sensors. This paper shows that the addition of micropillars to impaction surfaces can significantly enhance their particle collection. Similarities in particle capture mechanisms between fibrous filters and pillar-enhanced surfaces are explained, and we show the adaptability of fibrous filter theory to pillared surface collection efficiency. Experiments confirm that the micropillar cross section and spacing have a significant role in particle capture. Pillars with circular, rectangular, and cross-shaped horizontal cross sections with 15 μm height and 12 μm (dense), 20 μm (nominal), and 27 μm (sparse) center-to-center spacings were printed using two-photon micro stereolithography. The efficiency increased by 35%–52% in the dense case, while the effect of the pillar shape was negligible. At nominal spacing, CE depended heavily on the pillar shape. The cross-shaped and circular pillars improved the CE by 26%–29%, although the rectangular pillars were as efficient as the bare surface. No significant difference between the bare and pillar-enhanced surfaces was visible in sparse spacing. We further show that, upon addition of a nominal distribution of micropillars to the surface of a QCM sensor for real-time mass measurements, the sensor response improved significantly (approximately 2.5 times) compared to a QCM with a bare surface.