Vertical Cylindrical Structures Research Articles

A new automatic geo-electric self-potential imaging technique for diverse sustainable development scenarios

This study introduces a rapid and efficient inversion algorithm designed for the interpretation of self-potential responses originating from mineralized and ore sources and hydrothermal activity, specifically addressing spherical, vertical, and horizontal cylindrical structures. The algorithm leverages local wavenumber and correlation imaging techniques to enhance accuracy in modeling. The correlation factor (Cf value) is crucial in this approach, calculated as the correlation between the local wavenumber of the measured self-potential field and that of the computed field. The algorithm identifies the maximum correlation Cf value (CF-max) as indicative of the optimal true model parameters. To validate the proposed algorithm, it was applied to three theoretical examples—one with contamination from regional background and another with multiple sources with and without different types of noises (random Gaussian and white Gaussian noises). Additionally, the approach was tested on three distinct real field cases related to mining, ore investigation and hydrothermal activity in India, Germany and USA. Through a comprehensive analysis of results from theoretical and real-world scenarios, including comparisons with different available data and literature information, the study concludes that the method is effective, applicable to multiple sources, accurate, and does not necessitate prior knowledge of the source shape. This algorithm presents a promising advancement in the field of self-potential interpretation for mineral exploration and geothermal exploration.

Scattering Mechanism Analysis of Large Vertical Cylindrical Structure in Polarimetric SAR Images

Scattering Mechanism Analysis of Large Vertical Cylindrical Structure in Polarimetric SAR Images

TURBULENCE MODELLING OF INCIPIENT WAVE BREAKING ON A VERTICAL CYLINDER ON A SLOPED BED

The extensive use of vertical piles as basic components of coastal structures, e.g. monopile wind turbine foundations, has made the study of wave impact on vertical cylindrical structures in the breaking zone of major practical importance. To investigate the breaking wave forces on a vertical cylinder located on a sloped bed, Reynolds-averaged Navier–Stokes equations (RANS) based turbulence models have been used as closure in most recent computational fluid dynamics (CFD) studies. The present study adopts a Reynolds stress model (RSM), namely the Wilcox (2006) stress-ww model, as our primary turbulence closure model to simulate the experiment of Irschik et al. (2004). The Wilcox (2006) stress-ww model has been analysed in the recent work of Li et al. (2022) and proven to be neutrally stable in the potential flow region beneath surface waves, thus it naturally avoids any unphysical turbulence over-production in the pre-breaking zone (unlike two-equation models in their standard forms). It has also shown good accuracy in predicting surf zone breaking waves in Li et al. (2022) and deep-water wave breaking due to modulational perturbations in Li and Fuhrman (2022). For comparison purposes, the present study also conducts simulations with the stabilized LF18 kk- ww model, as well as with no turbulence model.

Numerical investigation of the discharging process in a latent cold storage unit

In this study, a latent cold storage unit using vertical cylindrical structure coupled with a concentric air duct is proposed. The cold discharging process of the unit is simulated by computational fluid dynamics (CFD) based on the enthalpy-porosity method. The temperature distribution and liquid fraction distribution of the latent cold storage unit are analyzed. In addition, thermal performance including the average temperature of phase change material, outlet air temperature, the liquid fraction and the cold discharging power are analyzed in detail.

CFD analysis of spent fuel dry cask storage system for High burnup nuclear fuel

Storage of nuclear spent fuel and cooling of the fuel assembly is one of the vital requirements for nuclear safety. This engineering technology involves a dynamic thermo-fluid phenomenon in the dry storage casks. Therefore, this study investigated HI-STORM 100 dry cask storage container for thermal-fluid with sensitivity analysis using 3D Computational Fluid Dynamics (CFD) simulations. It is a vertical concrete cylindrical structure (6.09 m height and 3.36 m diameter) containing a welded stainless-steel sealed barrel multi-purpose canister (MPC) for storing the fuel components replaced by the reactor. MPC-32 storage barrel (4.85 m height, 1.78 m outer diameter) and Westinghouse 17 × 17 high burnup (45GWd/MTU) Pressurized Water Reactor (PWR) fuel assembly is selected in this research. 2D and 3D models of this assembly were simulated using CFD with porous media assumption. Further, Boussinesq approximation and incompressible ideal gas models are adopted in simulation; and standard k-ε and k-ω Shear Stress Transport (SST) turbulence models were also compared under natural convection. The internal flow and temperature of the MPC by the incompressible ideal gas model were found to be in line with the actual situation. The standard k-ε model can cause abnormal results at the high-temperature position. The sensitive factors are analyzed to predict the temperature distribution and flow field characteristics of the system during 10–55 cooling years. During this period, the decay thermal power of nuclear waste, the maximum temperature of the system and shell; the air outlet temperature and the volumetric flowrate decreased. Under non-uniform thermal conditions, the heat dissipation performance was studied defining the decay heat ratio (X). The heat dissipation performance of the system was found better when X ≥ 1, and the maximum temperature of the fuel assembly rise when X < 1.

Rheo-SAXS characterization of lead-treated oils: Understanding the influence of lead driers on artistic oil paint’s flow properties

From the 15th century onwards, painters began to treat their oils with lead compounds before grinding them with pigments. Such a treatment induces the partial hydrolysis of the oil triglycerides and the formation of lead soaps, which significantly modify the rheological properties of the oil paint. Organization at the supramolecular scale is thus expected to explain these macroscopic changes.Synchrotron Rheo-SAXS (Small Angle X-ray Scattering) measurements were carried out on lead-treated oils, with different lead contents. We can now propose a full picture of the relationship between structure and rheological properties of historical saponified oils.At rest, lead soaps in oil are organized as lamellar phases with a characteristic period of 50 Å. Under shear, the loss of viscoelastic properties can be linked to the modification of this organization. Continuous shear resulted in a preferential and reversible orientation of the lamellar domains which increased with the concentration of lead soaps. The parallel orientation predominates over the entire shear range (0–1000 s−1). Conversely, oscillatory shear coiled the lamellae into cylinders that oriented themselves vertically in the rheometer cell. This is the first report of such a vertical cylindrical structure obtained under shear from lamellae.

Indoor Point Cloud Segmentation Using Iterative Gaussian Mapping and Improved Model Fitting

Indoor scene segmentation based on 3-D laser point cloud is important for rebuilding and classification, especially for permanent building structure. However, the existing segmentation methods mainly focus on the large-scale planar structures but ignore the other sharp structures and details, which would cause accuracy degradation in scene reconstruction. To handle this issue, an iterative Gaussian mapping-based segmentation strategy has been proposed in this article, which goes from rough segmentation to refined one iteratively to decompose the indoor scene into detectable point cloud clusters layer by layer. An improved model fitting algorithm based on the maximum likelihood estimation sampling consensus (MLESAC) algorithm is proposed for refined segmentation, which is called the Prior-MLESAC algorithm, to deal with the extraction of both vertical and nonvertical planar and cylindrical structures. The experimental results demonstrate that planar and cylindrical structures are segmented more completely by the proposed strategy, and more details of the indoor structure are restored than other existing methods.

Forces and moments exerted by incident internal waves on a plate-cylinder structure in a two-layer fluid

Vertical cylindrical structures are widely used in offshore structures, for instance oil platforms, bridge foundations and so on. This paper presents incident internal waves interaction with a vertical circular cylinder under an elastic plate in a two-layer fluid in the framework of the potential flow theory. By means of an inner product and angular eigenfunction expansions, the effects of the characteristic parameters of structures and fluid on the shear pressures, horizontal forces and moments are investigated with numerical and graphical results. The conservation of energy as well as the relative error at the interface between the open water and plate-covered regions are discussed. Three cases of different boundary conditions of the cylinder are considered in order to investigate the the constraint forces and restraining moments of its ends. The results reveals that more energy can exchange between two wave modes owing to the presence of the elastic plate, which strengthens the horizontal forces on the cylinder. Incident waves of internal wave mode for a given frequency can cause complex polar distribution of the pressure around the cylinder. The values of constraint forces at ends of the cylinder are several times than those of the horizontal forces in some frequencies.

Discontinuous Galerkin Method for Simulating an Ice Floe Impact on a Vertical Cylindrical Offshore Structure

An approach to simulate the impact of an ice floe on a vertical cylindrical offshore structure and a detailed review of its related complications are presented. The information on the ice rheology of the continuum mechanics model used, which makes it possible to achieve a balance between the accuracy of the simulation results and the computational resources required, is presented. A numerical method and some features of the simulation and techniques, which allow us to overcome difficulties associated with the resource intensity of calculations, are described. Typical destruction patterns of the ice floes and pressure distributions on offshore structures are discussed. The numerical results obtained in this work demonstrate the applicability of the ice model and the implemented software to problems of the safety of oil and gas platforms on the Arctic shelf.

Numerical wave basin using incompressible smoothed particle hydrodynamics (ISPH) on a single GPU with vertical cylinder test cases

This paper presents the development of a numerical wave basin for violent hydrodynamics of free-surface waves interacting with vertical cylindrical structures using the incompressible smoothed particle hydrodynamics (ISPH) method accelerated with a graphics processing unit (GPU). ISPH has been implemented on a single GPU based on the open-source DualSPHysics software and using the ViennaCL linear algebra library for solving the pressure Poisson equation. Extensions to the code are presented for a numerical wave basin including development of the solid boundary condition, based on a mirror image particle and moving least squares interpolation approach, for improved accuracy at the free and solid surface interfaces during wave-structure impact. This is applied to focused waves, including breaking for which SPH is well suited, interacting with a cylindrical column to compare with experimental data. Convergence is demonstrated within the limit of 5 million particles for a single GPU. Acceptable agreement with experiment is achieved for force measurements, and variation of free-surface elevation around the column is shown to be significant particularly in larger waves with a correspondingly large force contribution from hydrostatic pressure. While breaking does not have a marked effect on total force, associated high particle velocities amplify local pressures considerably on the column near the water surface. The computer runtime is similar to that for volume-of-fluid and particle-in-cell solvers running on 8 and 80 processors respectively.

Numerical simulations of vortex-induced vibrations on vertical cylindrical structure with different aspect ratios

This paper presents a computational fluid dynamics (CFD) study of vortex-induced vibration (VIV) for different aspect ratio (L/D) cylinder. Of particular interest was to measure hydrodynamic forces and numerically investigate the wake behaviour of VIV while varying the aspect ratio. The simulation models represented the actual experimental conditions with idealised free-surface boundary condition to capture the responses from fluid-structure interaction phenomenon. The simulations were performed in the subcritical flow region (7.4×103 < Re < 2×105), corresponding to a range of reduced velocity (Ur) from 2 to 14. The results of the cases studied were discussed and compared with the experimental data to verify the accuracy and validity of the present simulation. The comparisons have shown a similar curved-shape drag coefficient plot, and however underestimated the value of the drag coefficients over the reduced velocity. Additionally, the simulations seemed to capture a higher lift force response compared with the experimental data for a low aspect ratio. The correlation length was observed to be longer for larger aspect ratio and proportionally decreases as the aspect ratio decreases.

Structural stability and reliability of the underground steel tanks with the Stochastic Finite Element Method

The main aim is to present the Stochastic perturbation-based Finite Element Method analysis of the stability and also reliability of the underground steel vertical cylindrical structure of the waste container. This thin walled structure with constant cross-sectional thickness is loaded with subsoil pressure, snow and surface as well as dead loads and we look for the critical pressure value, when stability loss would be observed; it is done to design in the probabilistic context the safety margins. We employ to achieve this goal the Finite Element Method program ROBOT and computer algebra system MAPLE to get the analytical polynomial functions relating the critical pressure and random design parameters – shell thickness and its Young's modulus as well as to provide all probabilistic calculations. We determine up to the fourth order probabilistic characteristics of the structural response assuming that the input random parameters have Gaussian probability functions truncated to the positive values only. Finally, the reliability index is calculated according to the first order method using a difference in-between critical pressure and maximum tensile stress determined in this structure to verify its durability according to the demands of EU engineering codes.

Attractive radii of vertical and horizontal conductors evaluated using a self consistent leader inception and propagation model—SLIM

A self consistent lightning connecting leader inception and propagation model (SLIM) is utilized to study the attachment of lightning flashes to grounded structures and hence to evaluate the lightning attractive radii of vertical cylindrical structures and horizontal conductors as a function of height of the structure and peak current of the first return stroke. The attractive radius is defined as the maximum lateral distance from where the structure would be able to attract a down-coming stepped leader. The results are compared with the ones that one would obtain using Electro-Geometrical Method (EGM). The results show that for structure heights of the order of 30m or less the attractive radii obtain from SLIM do not deviate significantly (i.e. the error is less than about 20%) from the EGM values. However, for taller objects SLIM predicts significantly larger attractive radii than EGM and the error increases with increasing height.

Layer-by-layer Stacking Method for 3-D Nano Structure Fabrication Using Block Copolymer Self Assembly

ABSTRACTIn this paper, we present layer-by-layer stacking method to fabricate self-assembled structures of block copolymers (BCP) toward the out-of-plane direction. Layer-by-layer stacking is realized by transferring a BCP film on one substrate to another. Specifically, a water-soluble polymer film is coated on the former substrate, which is placed and fixed in contact with a target substrate. Consequently, the BCP film is released from the substrate and transferred to the target substrate when immersed in de-ionized water. In our experiment, PS-b-PMMA is used to form and transfer self-assembled structures, and polyvinyl alcohol is used as a water-soluble polymer. We prepared two kinds of target substrates; one has horizontal cylindrical structures by BCP self assembly, and the other has groove structures by EB lithography. In the case of BCP patterned substrate, BCP film with vertical cylindrical structures is transferred onto the line structures of BCP. In the case of EB lithography patterned substrate, BCP film with vertical cylindrical structures is transferred in a doubly suspended condition. Furthermore, vertical and horizontal cylindrical structures are also observed to align along the grooves.

Preparation of Titanium Oxide Pillars on Glass Substrates and Ultrathin Titanium Oxide Layer using PMMA/PS Blend Films

In this paper, a simple and inexpensive method of preparing nanosized titanium oxide (TiO2) pillars on glass substrates and ultrathin TiO2 layers is presented, utilizing a blend of commercially available polystyrene (PS) and poly(methyl methacrylate) (PMMA). The surface morphology of PS/PMMA blend films is investigated in terms of the processing parameters including solution concentration, blending ratio, and spin-coating speed. For the first time, a phase inversion was revealed for the PS/PMMA blend films spun coated on conducting substrates (ITO and TiO2), with increasing solution concentration. Atomic force microscopy studies show that PMMA forms vertical cylindrical structures in the matrix of PS on glass substrates and on ultrathin TiO2 layers deposited on indium tin oxide (ITO) substrates. After the PMMA phase is etched away by ultraviolet irradiation and acetic acid, TiO2 pillar structures are successfully created on both types of substrates by infiltration of the sol−gel mixture into the nanosized...

Two contrasting granite−greenstone terranes in the Pilbara Craton, Australia: evidence for vertical and horizontal tectonic regimes prior to 2900 Ma

Major tectono-metamorphic differences between two pre-2900Ma granite–greenstone terranes of the Pilbara Craton indicate evolution under fundamentally different tectonic regimes.The East Pilbara Granite–Greenstone Terrane (EP) contains a typical dome and basin regional structural pattern, lacking any preferred orientation of domical granitoid complexes, intervening synclinal greenstone belts, or faults. The EP greenstone succession contains no low-angle thrusting, is demonstrably autochthonous throughout the EP, and most of its stratigraphic components are common to all the greenstone belts. The oldest greenstone successions of the EP were deposited between 3515 and 3320Ma by repeated cycles of plume-related mafic–felsic volcanism onto 3725–3600Ma continental crust. Intrusion of syn-volcanic tonalite–trondhjemite–granodiorite (TTG) sheets and subvolcanic laccoliths at ca. 3490–3430Ma caused locally significant syn-volcanic doming, but had only limited penetration into the uppermost greenstone succession. A major deformation event at 3315Ma is consistent with gravity-driven diapiric doming of the TTG complex and sinking of denser, overlying greenstones into adjacent synclines. This diapiric deformation established the main features of the present dome and basin pattern. Subsequent monzogranite intrusion was almost entirely restricted to the cores of the granitoid domes and, together with renewed diapirism at 3240 and 2950Ma, amplified some of these domes into almost vertical cylindrical structures. The crustal evolution of the EP cannot be satisfactorily explained using plate-tectonic models.The West Pilbara Granite–Greenstone Terrane (WP) exhibits a strong northeast-oriented structural grain defined by the elongation of granitoid complexes, the trend of its two main greenstone belts, and by numerous closely spaced east- and northeast-striking faults. Unlike the EP, the WP is a collage of three separate, fault-bounded tectono-stratigraphic domains, each of which contains a unique stratigraphic succession and a separate set of tectonic structures. The oldest greenstones of the WP belong to the ca. 3280–3250Ma Roebourne Group that is restricted to the Karratha domain. The Roebourne Group is an ultramafic–felsic volcanic succession with overlying, subordinate clastic metasedimentary rocks. Isotopic data indicate that the group was deposited on ca. 3480Ma crust, or was derived from a source region of this age, but the basal contact of the group is obscured by intrusive 3270Ma tonalite and granodiorite. The Roebourne Group is interpreted to have formed on EP basement during rifting of the EP, after which the EP and WP evolved in different tectonic environments. At ca. 3160Ma the Karratha domain was tectonically over-ridden by oceanic-type crust of the Regal Formation, indicating collision with an unknown plate to the north. The Regal Formation forms the lower part of the Cleaverville domain, the upper component being the unconformable, post-collision, ca. 3020Ma Cleaverville Formation. The Sholl domain, containing the 3130–3115Ma Whundo Group, is separated from the Karratha and Cleaverville domains by a major, long-lived fault zone, the Sholl Shear Zone (SSZ). The Whundo Group is a juvenile, predominantly basaltic pile showing no evidence of contamination by crust older than 3280Ma, and is interpreted to have been deposited on oceanic-type crust in the post-3240Ma rift. Four granitoid complexes in the WP were mainly formed between 3015 and 2970Ma, and have no age equivalents in the EP. No diapiric domes are present in the WP, where all deformation is interpreted to be the result of successive episodes of horizontal compression, consistent with evolution in “Phanerozoic-style” plate-tectonic environments.

マグネシウムアノード酸化皮膜の構造と不動態性に対する生成電圧と電解質イオン濃度の影響

Structure and passivity of the films formed on magnesium in alkaline solutions containing aluminate ions were evaluated by using various methods including electrochemical measurements and a field emission scanning electron microscope. When concentration of sodium ions was kept constant, increase in aluminate ions effectively depressed the peak current at around 5 V and increased the breakdown voltage. This is caused by the improvement of surface passivity of magnesium and oxide protectively. Aluminum content incorporated in the film lineally increased with log of increasing concentration of aluminate ions added in the solution. However, besides the concentration of aluminate ions in the solution, the corrosion resistance evaluated by salts spray test was highest in the thick films formed at around 5 V with extremely high current density. Further, it is clarified that all films formed at 5 V exhibit vertical cylindrical cellular structure similar to the Keller model of porous anodic alumina.

Structures cylindriques verticales dans un dépôt meuble Quaternaire, en Galice (Espagne)

Cette note signale pour la première fois l'existence de structures cylindriques verticales dans un dépôt quaternaire, en Espagne. Les deux structures observées se trouvent dans un dépôt limonosableux dans une vallée près de la frontière entre la Galice et la Castille-León, au NO de la péninsule ibérique. La structure principale mesure plus de 225 cm de hauteur, 15 cm de largeur à la base, 20-25 cm à la partie centrale et une quarantaine de centimètres au sommet. Le tiers inférieur est essentiellement sableux et caractérisé par des couches circulaires. La section centrale comprend deux cônes superposés et partiellement emboîtés, remplis de petit gravier sableux, alors que le tiers supérieur de la structure verticale, qui pénètre dans un dépôt de rudites, est essentiellement grossier. Les deux structures cylindriques verticales sont attribuées à des sources ascendantes créées par la pression hydrologique dans le dépôt glacio-lacustre lors de la mise en place de la nappe alluviale d'origine fluvio-glaciaire. Les structures sont vraisemblablement contemporaines de la formation de la nappe alluviale.

Response due to moored multiple structure interaction

This paper describes an efficient analytical/ numerical method that determines the responses of multiple floating structures in waves in the vicinity of each other. The analysis considers the interaction of multiple structures including their scattering and radiation in waves. Multiple structure interaction in waves by the well-known direct method of linear diffraction/radiation is in principle possible with moderate modification of the single-structure diffraction/radiation problem. However, the direct method, while quite accurate and efficient in solving hydrodynamic problems, demands a large amount of memory and requires considerable execution time. It is recognized that for a large number of modules in a structure this approach has serious limitation due to limited personal computer storage and prohibitively excessive execution time. Moreover, the accuracy of this solution for a large multi-moduled structure, if possible, may not be acceptable. The efficiency of the present analysis is accomplished by marrying the direct method of linear diffraction/radiation for arbitrary structure geometry with a semi-closed analytical method of multiple scattering developed for an array composed of vertical cylindrical structures. The analysis is applied to structures of arbitrary geometry. Moreover, the dynamic response of the structure is also included in the analysis. The Mobile Offshore Base (MOB) proposed for use by the US Navy is an interconnected multi-moduled floating offshore structure. The present method will provide the responses, e.g., the six degrees of motion of the individual modules of the MOB and the corresponding connector loads, when subjected to regular waves incident at any heading. The capabilities, and accuracy of the method are demonstrated and its speed relative to the conventional direct method is discussed. Several numerical examples of the multiple interaction method are given. Comparisons are made with the conventional diffraction/radiation results wherever feasible as well as with the available experimental data.

Hydrodynamic interaction forces on multi-moduled structures

The size, complexity and critical operations of many offshore structures, including the mobile offshore bases (MOBs) of current interest, require careful determination of wave forces on the neighboring structures, including their interactions. This paper describes an analytical/numerical approach that determines the wave forces on multiple structures in the vicinity of one another. The method involves the consideration of multiple vessel interaction and scattering in waves. The analysis is an extension of the semi-analytical multiple vertical cylinder analysis published by the author. The analysis is similar to the one proposed by Kagemoto and Yue for axisymmetric bodies.The direct method of linear diffraction, while quite accurate and efficient in solving the hydrodynamic problem, demands a large amount of memory and requires considerable execution time. The present analysis is very efficient in these respects. It is accomplished by marrying the direct method with a semi-closed analytical method of multiple scattering developed for an array composed of vertical cylindrical structures. It is recognized that this analytical method has a limitation owing to the geometry of many offshore structures including MOBs. Therefore, the analysis is extended to an arbitrary geometry. In this method, the direct matrix method of diffraction problem is applied to an isolated module and then extended to structures with the multiple scattering technique to account for the interaction of multiple structures.Comparisons are made of the results from the analytical and conventional numerical diffraction theory with those of the semi-analytical tool using the above-mentioned analysis.