Flow Texture Research Articles

Characteristics of subvolcanic intrusion: a case study at Tempel Hill, Kalisonggo, Girimulyo, Kulonprogo, Yogyakarta

The genesis of Mount Tempel which is part of Mount Mujil is still being debated by some geologists discussing the Kulon Progo Mountains. The surface and subsurface measurements must be done to know a geological aspect that building the area around Mt. Mujil, precisely in Tempel Hill on the northeast side of Mt. Mujil, Girimulyo, Kulonprogo, Yogyakarta. The geology of this location is still a mystery and has always been a hot topic regarding origins, geotourism, and disasters. The general problem in this study is related to the occurrence of the northeast side of Mt. Mujil which is still not final and much debated, so it is necessary to approach the concept of volcanic geology to help answer these problems. The purpose of this study was to identify the physical characteristics of igneous rocks in Tempel Hill based on surface and subsurface data. The approach method is carried out through geological mapping, geophysical resistivity measurements, and petrological, petrographic and geochemical analysis. The results of the petrological analysis show that the igneous rock has a porphyroafanite – microcrystalline texture without a flow texture, some scoria – massive structures, geochemically it shows that calc – alkali refers to subduction products. On the other hand, resistivity analysis shows the presence of volcanic rocks with density values and resistivity values of intrusive rocks and volcanic breccia in the vicinity. Indications of the presence of volcanic rocks with an area the size of Tempel Hill are defined as magma fossils or subvolcanic intrusion rock bodies. Tempel Hill has potentially for tourist attractions that can improve the welfare of local residents.

External Wetting Efficiency in a Three-Phase Fixed Bed Loaded with Porous and Non-Porous Packings

Films and rivulets are the two basic forms of dynamic liquid in a three-phase fixed bed (trickle bed), which determines the wetting efficiency of the catalyst. This paper is devoted to the conflicting wetting performance observed between non-porous glass beads and less wettable porous alumina, and a parallel zone model is applied to resolve the complex liquid flow texture. It shows in both cases of glass beads and aluminium pellets, the pressure drop, film flow and rivulet flow fractions all display pronounced multiplicities along with the liquid flow rates in increasing and decreasing branches, although the rivulet flow fraction is reduced to 0 in the liquid decreasing branch started from pulsing flow in both cases. Different from the glass beads, there is almost no wetting efficiency difference for the alumina pellets with respect to liquid flow rate increasing or decreasing, which is in agreement with the dynamic liquid holdup measurements. The liquid is significantly more uniformly distributed over the crosssection in the Al2O3 bed since rivulet flow is much reduced than in the case of glass beads.

The effect of heat pretreatment of heavy oil on the pyrolysis performance and structural evolution of needle coke

Needle coke has been widely studied due to its highly oriented carbonaceous structure and low thermal expansion for preparing high power electrode. In order to further investigate the effect of compositions and molecular structure of heavy oil (HO) on the pyrolysis performance and structural evolution of needle coke, the heat pretreatment at 360−400℃ for 2−10 h was used to modify the feedstock and the thermal polymerization method was adopted to prepare needle coke. It was concluded that the heat pretreatment process removed part of small molecular volatiles and increased the polycyclic aromatic content. The decrease of the small molecular volatiles content reduced the disordered disturbance of gas flow and transformed the structure from disordered texture to fine flow texture. The pre-treatment of light components avoided the out-plane crosslinking short carbonaceous sheets within the lamellae to eliminate the steric hindrance and relax the structural strains with few defects. Moreover, the heat pretreatment provided good thermal stability during the accumulation of carbonaceous structure.

IDENTIFICATION OF GEOMORPHOLOGY AND LITOLOGY BASED ON ANALYSIS OF LANDSAT-8 SATELLITE IMAGES IN PADANG CITY

The application of remote sensing to obtain better quality and up to date maps is needs to be done through the utilization of lithology and geomorphology in mapping of Padang city. This study aims to obtain a lithological and geomorphological picture of the appearance of Landsat-8 OLI Composite 567 satellite imagery. The research method was carried out by image interpretation data preparation. The results showed the city of Padang has 2 units of landforms from visual interpretation, namely fluvial and denudational landforms. Lithology identification in Padang using geological imagery and maps as a reference succeeds to acquire geological and lithological units, namely: Alluvial Fan which is smooth texture, lowland topography, hue and color is bright, parallel river flow patterns, sparse vegetation, river area associations. Non-decomposed flow texture is rather rough, hilly topography, hue and color is dark, radial river flow patterns, dense vegetation, associated with forests. Andesite has a rather rough texture, highland topography, hue and color is dark, radial river flow patterns, dense vegetation, associated with mountainous terrain. Alluvial is found in coastal areas, lakes and sandy areas, fine texture, lowland topography, alongside large rivers with valley, has a bright color and hue, its flow patterns are parallel, sparse vegetation, river area associations. Hardened Crystal Tuff with a rather rough texture, topography in mountainous areas, hues and color is dark, radial river flow patterns, dense vegetation, hill area associations. Volcanic Rock has a rough texture, high terrain topography, has dark colors and hues, radial river flow patterns, has dense vegetation, and is associated with mountains.

Investigation on the development and orientation of mesophase microstructure during the two-stage pyrolysis of FCC decant oil

The two-stage pyrolysis was proposed to effectively form uniaxially fibrous mesophase during pyrolysis of FCC decant oil. Detailed investigation focuses on main factors of regulating mesophase orientation and corresponding changes of mesogen stacks. The first-stage treatment under low temperature of 440 °C and high pressure of 2 MPa for 8 h ensures formation of bulk mesophase with well-coalesced texture and good molten fluidity; subsequently, fracture of residual alkyl side-chains together with devolatilization of trapped light molecules under high temperature (450–480 °C) and low pressure (0.2–1.0 MPa), mainly contributes to volatile evolution at solidification of two-stage pyrolysis. Thereby, the overlap between sufficient volatile evolution that provides enough shear force on mesophase and appropriate viscosity of bulk mesophase, high enough for maintenance of mesophase deformation but not too high to prevent penetration of gas bubbles, is readily achieved and then significantly promotes the transition from mesophase domain into acicular flow texture. Moreover, mesophase orientation at solidification is followed by transformation of mesogen stacks from columnar short-range order into nematic order, leading to decrease of stacked height and number of layer per stack. And further cracking and dehydroaromatization reactions at solidification of two-stage pyrolysis facilitate elimination of steric hindrance, relaxation of structural strains and heal of defects within the planar aromatic sheets, thus resulting into a more homogenous distribution of stacked mesogens and a smaller degree of disorder within the 2D mesogen lattice.

Petrogenesis study of quaternary volcanic rocks based on petrography analysis in Lubuk Nipis Village, Muara Enim District, South Sumatra

This study aims to identify the characteristics of quartz volcanic rocks as well as their existing source and process of formation in the Lubuk Nipis area of Muara Enim Regency, South Sumatera Province. In conducting this study, field observation is required to obtain primary data directly and then petrography analyze is needed to analyze volcanic rock samples obtained during field observation. There are 3 types of rock units generated by volcanic activity during the quaternary period in the study area. The three units of rock are, among others, units of andesite intrusion (Qpva), units of andesite lava (Qhv), and units of tuff lapilli & tuff breksi (Qhv). In units of andesite intrusion visible porphyritic crystal texture with Plagioclase minerals become the most dominating minerals with the emergence of other primary minerals such as Quartz, Feldspar, Biotite, Hornblende and Pyroxene. Andesite lava comes with 2 different types of characteristics, porphyritic and microporfiritic texture. There are also seen the flow texture that shows the lava flow process during the formation of rocks in andesit lava units. While other units of rock that is unit of tuff lapilli & tuff brecchia is a product of pyroclastic fall. This unit has a composition of tuff material that dominates, also present are crystalline materials such as plagioclase, quartz, feldspar, and biotite. Further assisted by the analysis of DEM (Digital Elevation Model) to see the geometry of the spread of volcanic facies, can be interpreted the order of formation of rock units in the study area.

Mobilization and agglomeration of uraninite nanoparticles: A nano-mineralogical study of samples from the Matoush Uranium ore deposit

The occurrence of uraninite nanoparticles in the alteration zones of uranium ore deposits suggests potential mobilization of U(IV) under reducing conditions, which is important for understanding the mobility of uranium in contaminated sites and potential repositories for nuclear waste. This study investigates the occurrence of uraninite nanoparticles in the outer alteration zone of the Matoush uranium ore deposit, Quebec, Canada. Selected samples with finely disseminated uraninite from the outer alteration zone of the deposit are examined by X-ray fluorescence spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy on specimens prepared using the focused ion beam milling technique. Uraninite nanoparticles occur as single particles, in clusters, and in larger aggregates in close association with the Cr-rich phases chromceladonite (Cr-rich mica), ideally KMgCr3+(Si4O10)(OH)2, eskolaite, ideally Cr23+O3, bracewellite, Cr3+OOH, and an amorphous Cr-rich oxide matrix as well as with fluorapatite and galena. Nanoparticles on the surface and in the outer rim of single uraninite crystals indicate the growth of larger uraninite crystals via crystallization through particle attachment and Oswald ripening. The flow texture of the uraninite nanoparticles in the amorphous Cr-rich oxide matrix, their aggregation on the surface of nanocrystals of bracewellite, the absence of products of a redox reaction involving U(VI) and Fe(II), and the occurrence of amorphous Fe-depleted alteration layers between uraninite and eskolaite, and uraninite and Cr-rich mica indicate that the uraninite nanoparticles have been mobilized under reducing conditions (leaching of Fe2+ from the alteration layer) at low T (amorphous character of the alteration layer) after the main mineralization event from the center of the mineralization to the outer parts of the Matoush dike complex. These results indicate that fluids can mobilize U(IV) under reducing conditions in the form of uraninite nanoparticles albeit over limited distances. The potential mobilization of these nanoparticles may also explain the occurrence of proximal mineralized zones in U-ore deposits that lack common products resulting from the reduction of U(VI) by Fe2+ (e.g., hematite and other Fe3+-phases).

Effect of Surface Modification on Cumulative Tensile Ductility of AZ31 Magnesium Sheet

Wire brushing and annealing (WBA) process was developed, optimized and utilized to modify the surface layer microstructure of AZ31 automotive magnesium sheet material. The process was carried out using softer brass wire brushes to mitigate the effect of wire brushing on surface quality and damage. The influence of modified surface grain structure and crystallographic texture was studied by continuous uniaxial tension test as well as by a newly proposed multi-step uniaxial stretching and annealing (MUSA) process to assess cumulative uniaxial tensile ductility of AZ31 sheet. A rotational speed of 2800 revolutions per minute for the wire brush with a near-zero depth of cut followed by annealing at 473 K (200 °C) for 60 minutes resulted in acceptable surface quality with a refined grain layer of depth 30 μm, and a modified crystallographic texture on the surface. Material flow behavior, grain microstructure, and texture evolution of WBA-processed material during subsequent MUSA process were analyzed to assess the role of wire brushing in enhancing the MUSA response of AZ31 sheet. Original fully annealed AZ31 sheet (in the non-WBA condition) was also subjected to identical MUSA process for comparison purposes. The results showed improvement in terminal uniaxial tensile ductility of WBA-MUSA-processed material compared to Standard-MUSA material. The ductility improvement is attributed to non-basal texture development and re-distribution of the texture, as well as to grain refinement within the highly deformed surface layer from the combination of WBA and MUSA processes.

Mineralogy and sulfur isotope compositions of the uraniferous black slates in the Ogcheon Metamorphic Belt, South Korea

Uraniferous black slates, extending for over 100km in the Ogcheon Metamorphic Belt, South Korea, have been explored for their uranium mineralization. Coaly slates interbedded in the black slates, forming a layer about 20–40m thick showing brecciated and flow texture with random-oriented minerals, are more carbonaceous and uraniferous than the surrounding rocks. Uranium minerals include uraninite, uranothorite, brannerite, ekanite, thorutite, and coffinite. Of these, uraninite is the most abundant phase in the coaly slates, while uranothorite is the most abundant in the black slates. Chlorites in the black slates have Fe/(Fe+Mg) ratios of 0.42–0.66, while those in the coaly slates have lower values, 0.10–0.20. Chlorite geothermometry indicates temperature ranges of 259–309°C, and 200–287°C in the coaly and black slates, respectively. Muscovites in the coaly slates have higher concentrations of 0.85–1.55wt.% BaO and 0.22–0.28wt.% V2O3 than those in the black slates. This can be ascribed to hydrothermal venting of Ba-V-rich fluids into the marine basin. Most uranothorites in the black slates have lower U and higher Th contents than those in the coaly slates due to their solubility differences. In contrast to the comparatively low and wide-ranging δ34S values of pyrite from −5.9 to 6.6‰ in the black slates, the coaly slates have relatively high and uniform values from 11.0 to 12.7‰, implying an influx of isotopically heavy sulfur derived from the inorganic reduction of seawater sulfate under a high temperature hydrothermal system. The differences of rock texture, mineralogy, and sulfur isotope geochemistry in relation to uranium mineralization between the black slates and the coaly slates would reflect the influence of submarine hydrothermal process before they suffered regional metamorphism.

Rheological and textural properties of microemulsion-based polymer gels with indomethacin

In this paper, we present novel microemulsion (ME)-based semisolid polymer gels designed for topical administration of poorly water soluble non-steroidal anti-inflammatory drugs. Indomethacin (IND) was used as a model compound. The ME consisted of castor oil, water, Tween®80 as a surfactant and ethanol as cosurfactant. To obtain the desired consistency of the formulations Carbopol®960 was applied as a thickening agent. The aim of the study was to analyze in detail the mechanical properties of the obtained systems, with special attention paid to the features crucial for topical application. The rheological and textural experiments performed for samples with and without the incorporated drug clearly indicate that flow characteristics, viscoelastic properties and texture profiles were affected by the presence of IND. Novel semisolid formulations with IND described for the first time in this paper can be considered as an alternative for commercially available conventional topical dosage forms.

Image-Space Texture-Based Output-Coherent Surface Flow Visualization

Image-space line integral convolution (LIC) is a popular scheme for visualizing surface vector fields due to its simplicity and high efficiency. To avoid inconsistencies or color blur during the user interactions, existing approaches employ surface parameterization or 3D volume texture schemes. However, they often require expensive computation or memory cost, and cannot achieve consistent results in terms of both the granularity and color distribution on different scales. This paper introduces a novel image-space surface flow visualization approach that preserves the coherence during user interactions. To make the noise texture under different viewpoints coherent, we propose to precompute a sequence of mipmap noise textures in a coarse-to-fine manner for consistent transition, and map the textures onto each triangle with randomly assigned and constant texture coordinates. Further, a standard image-space LIC is performed to generate the flow texture. The proposed approach is simple and GPU-friendly, and can be easily combined with various texture-based flow visualization techniques. By leveraging viewpoint-dependent backward tracing and mipmap noise phase, our method can be incorporated with the image-based flow visualization (IBFV) technique for coherent visualization of unsteady flows. We demonstrate consistent and highly efficient flow visualization on a variety of data sets.

Nanometer-sized platinum-group minerals (PGM) in base metal sulfides: New evidence for an orthomagmatic origin of the Merensky Reef PGE ore deposit, Bushveld Complex, South Africa

We report new results of a combined focused ion beam and high-resolution transmission electron microscopy (FIB/HRTEM) investigation of platinum group element-rich (PGE) samples from the Merensky Reef of the Bushveld Complex in South Africa. Chromitites and pegmatitic melanorite from the Northam and Rustenburg platinum mines contain Ru-Rh-Pt arsenide nanocrystals ( Occasionally the PGM inclusions form clusters, develop a flow texture, or are aligned like pearls on a string. These observations are inconsistent with sub-solidus exsolution and suggest that the nano-scale PGM crystallized before solidification of the sulfide melt and the formation of their BMS hosts. There is evidence from recently performed laboratory experiments on silicate melts with additives of Ru and Pd that discrete Fe-rich Fe-Ru-Pd alloys (nanometer-sized) can indeed crystallize early. These experiments raise the possibility that the PGE-bearing nanocrystal inclusions found in the BMS of the Merensky Reef might represent preserved relicts of an early phase of magmatic PGM that precipitated from the silicate melt and afterwards were collected by the sulfide melt. Combined FIB/HRTEM techniques open up a window through which the nano-scale mineral population can be viewed. PGE previously thought to be present in BMS solid solution might actually be an artefact of inadequate spatial resolution.

Hydrodynamic modeling on the external liquid–solid wetting efficiency in a trickling flow reactor

A three‐region model was proposed, which considers the bed cross section being composed of a stagnant liquid region, a liquid film region, and a rivulet flow region. To estimate the fractions of the three regions, the fraction of film flow was evaluated first, by transforming the complex trickling flow texture into pure liquid film flow. Through the measurements of liquid holdup and pressure drop for the film flow, a relationship between relative permeability and gas saturation was established, and from which the fraction of film flow region was obtained. It shows packing size is most important to the faction of rivulet flow. The external wetting efficiency of the packing was correlated as the sum of two‐third power of the liquid film fraction and the rivulet flow fraction, besides, a correlation based on Reynolds and Galileo numbers of the two phases in the form of was proposed. © 2012 American Institute of Chemical Engineers AIChE J, 59: 283–294, 2013

Mathematical modeling of catalytic wet oxidation in trickle-bed reactors by a diffusion–convection–reaction approach embedded with an interstitial CFD framework

In this work, we propose a diffusion–convection–reaction methodology to gain further insights into the heterogeneous multiphase flow of trickle beds. Our case-study encompasses a multi-fluid model embedded within an interstitial framework on the numerical simulation of continuous catalytic wet oxidation of hazardous compounds. First, with the proviso that phase holdup, pressure drop, and liquid distribution are fundamental criteria for the efficient design of trickle beds, the multiphase flow constitutive equations have been developed and solved by the conservative unstructured finite volume method. Second, several numerical variables were parametrically optimized based on the application of different under-relaxation parameters, mesh densities, and time stepping strategies. The segregated solver has been found to reveal good properties in terms of convergence and stability criteria, which endorsed the further corroboration. Finally, this theoretical probing-sensing scheme enabled the characterization of liquid flow texture accomplished by three-dimensional flow patterns exposing their deviation from ideal plug flow. The diffusion–convection–reaction framework coupled within a CFD model can then be further exploited on the simulation of complex multiphase reactive flows with adjustable parameters.

The Influence of Alkyl Group on Needle Coke Formation

Co-carbonization properties of toluene soluble (TS) of coal tar pitch and waste polystyrene (WPS) were studied in a tube bomb to correlate the content of alkyl groups in the mesophase pitches with coefficient of thermal expansion (CTE) and anisotropic orientation. The alkyl contents, which were increased from 12.0% to 33.3% by adding WPS into TS, improved the properties of resultant needle coke in terms of optical texture and CTE value. The anisotropic indices of average length of vectors parallel to the CTE axis and average length of anisotropic unit vectors increased from 20.8 μm to 28.4 μm and 23.4 μm to 28.8 μm, respectively, and CTE value decreased from 0.8×10-6 /°C to 0.1×10-6 /°C. Due to the increasing alkyl groups, the lower viscosity of the carbonization system favored the development of flow texture and uniaxial orientation. And the sufficient gas evolution of good timing in co-carbonization forced the uniaxial arrangement of bulk mesophase molecules at the solidification stage.

Evidence for Amazonian northern mid-latitude regional glacial landsystems on Mars: Glacial flow models using GCM-driven climate results and comparisons to geological observations

A fretted valley system on Mars located at the northern mid-latitude dichotomy boundary contains lineated valley fill (LVF) with extensive flow-like features interpreted to be glacial in origin. We have modeled this deposit using glacial flow models linked to atmospheric general circulation models (GCM) for conditions consistent with the deposition of snow and ice in amounts sufficient to explain the interpreted glaciation. In the first glacial flow model simulation, sources were modeled in the alcoves only and were found to be consistent with the alpine valley glaciation interpretation for various environments of flow in the system. These results supported the interpretation of the observed LVF deposits as resulting from initial ice accumulation in the alcoves, accompanied by debris cover that led to advancing alpine glacial landsystems to the extent observed today, with preservation of their flow texture and the underlying ice during downwasting in the waning stages of glaciation. In the second glacial flow model simulation, the regional accumulation patterns predicted by a GCM linked to simulation of a glacial period were used. This glacial flow model simulation produced a much wider region of thick ice accumulation, and significant glaciation on the plateaus and in the regional plains surrounding the dichotomy boundary. Deglaciation produced decreasing ice thicknesses, with flow centered on the fretted valleys. As plateaus lost ice, scarps and cliffs of the valley and dichotomy boundary walls were exposed, providing considerable potential for the production of a rock debris cover that could preserve the underlying ice and the surface flow patterns seen today. In this model, the lineated valley fill and lobate debris aprons were the product of final retreat and downwasting of a much larger, regional glacial landsystem, rather than representing the maximum extent of an alpine valley glacial landsystem. These results favor the interpretation that periods of mid-latitude glaciation were characterized by extensive plateau and plains ice cover, rather than being restricted to alcoves and adjacent valleys, and that the observed lineated valley fill and lobate debris aprons represent debris-covered residual remnants of a once more extensive glaciation.

PSEUDOTACHYLITE IN THE SOUTH BOUNDARY FAULT AT THE COOKE SHAFT, WITWATERSRAND BASIN, SOUTH AFRICA

The steeply-dipping South Boundary Fault in the Cooke Section on the West Rand goldfield hosts a series of crosscutting pseudotachylite fault and injection veins, and pseudotachylitic breccias that formed progressively by abrasive wear in a brittle (elastico-plastic) regime. The crosscutting pseudotachylite veins and breccias are hosted by faulted supracrustal rocks of the Witwatersrand Basin that are exposed by underground workings and production-development borehole cores. Evidence of frictional melting is represented by quenched vein margins, corona texture, turbulent flow and glassy texture. Underground mapping and logging of boreholes has confirmed the existence of at least three generations of pseudotachylite, which were tectonically-induced. The relative age of tectonically-induced pseudotachylite formation is constrained to pre-2.58 Ga, or before deposition of the lower Transvaal Basin sequences, because 3D seismic data show that pseudotachylite-bearing faults do not penetrate the base of the Transvaal Basin. The conclusions made in previous research that the Hekpoort Andesite Formation (2224 ± 21 Ma) of the Transvaal Supergroup provides a maximum age for all pseudotachylite in the West Rand goldfield may therefore need revision.

高速流めっき法による短時間Cu貫通電極形成および電極の微細組織

高速流めっき法による短時間Cu貫通電極形成および電極の微細組織

Study on the Orientation of Unidirectional C/C Composites

This present investigation describes the orientation and its influence factors of unidirectional C/C composites prepared by PAN-based carbon fiber and mesophase pitch (AR-MP) through hot pressure molding process. And the orientation of C/C composites was analyzed by POM and XRD. The experimental results indicated that the AR-MP dispersed in carbon fiber had a strong flow texture, showed a matrix preferentially oriented parallel to fiber surface. Under the pressure of 25MPa, the orientation of composites was better than under 50MPa. Moreover, the sample orientation varies in the two directions both perpendicular to the direction of carbon fiber. Better orientation was obtained in the testing direction which was perpendicular to the direction of carbon fiber and molding pressure.

Geologic reconnaissance of Lautaro Volcano, Chilean Patagonia

Lautaro is the volcano closest to the Chile Triple Junction in the Andean Austral Volcanic Zone. The volcanic edifice of 3,607 m a.s.l. stands out on the north-western part of the plateau of the South Patagonian Ice Field. The volcano basement is composed of low-grade meta-pelites that are cut by tabular intrusive bodies of hornblende-biotite granite. The volcano is almost completely covered by ice and the study was performed on volcanic detritus present in terminal moraines of the Lautaro Glacier and the tephra on the surface of the O'Higgins Glacier. The terminal moraines of Lautaro Glacier contain fragments of light grey dacite rich in plagioclase and hornblende phenocrysts. Some dacite blocks show prismatic jointing, suggesting an origin of hot emplacement and subsequent rapid cooling, possibly resulted from collapse of a steep lava front. Some samples have glassy groundmass and rhyolite-like flow texture, with presence of mafic inclusions and bread crust bomb texture. The surface of the O'Higgins Glacier is covered by lapilli-size pumice fallout deposit. There are many dirt cones covered by volcanic ash composed of pumice fragments, volcanic glass, quartz, plagioclase, biotite, hornblende, and orthopyroxene. The ash and pumice are similar in chemical composition, both indicating an adakitic signature. At least three layers of fallout deposits have been recognised in parts of the surface of the glacier, which may correspond to the latest known eruptions.