29,342 research outputs found

    Evolution of ore-bearing fluids in the Bunardžik ore body, the Bučim porphyry copper deposit, Republic of North Macedonia

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    Porfirno bakreno ležište Bučim (41.7° N, 22.3° E) nalazi se u državi Sjevernoj Makedoniji, 120 km jugoistočno od glavnog grada Skoplja te 15 km zapadno od grada Radoviš. Samo ležište sadrži četiri rudna tijela: Vršnik, Čukar, Centralno rudno tijelo te Bunardžik. Glavni rudni mineral je halkopirit koji je u asocijaciji s piritom, magnetitom, hematitom i rutilom dok je glavni jalovinski mineral kvarc. U ovom radu utvrđeno je sedam tipova fluidnih inkluzija na temelju njihovog petrološkog izgleda te prisutnosti faza: parne, tekuće, soli i rudnog minerala. Za visoko-temperaturne (418 - 643 °C) i visoko-slane inkluzije (30.72 - 59.95 tež. % NaCl ekviv.) smatra se da su rudonosne. Fluidne inkluzije rudnog tijela Bunardžik tipične su za porfirna bakrena ležišta izuzev 10-ak mjerenja inkluzija koje homogeniziraju pri temperaturama od 1200°C - 1300°C. Analizom fluidnih inkluzija u rudnom tijelu Bunardžik otkrivena su tri tipa fluida: fluid 1 čine visoko temperaturne i visoko slane grupacije fluidnih inkluzija (FIA). FIA dvofaznih i višefaznih inkluzija ovog fluida dokaz je ključanja, a raspon Th jest 513-1292°C. Određene faze soli su halit i silvit. Fluid 2 predstavlja FIA koje osim parne i tekuće faze mogu sadržavati jedan ili više kristala soli (L+V i L+V+S). Kristal soli predstavlja halit, te ovaj fluid ne sadrži rudonosni mineral. Raspon Th jest 288 - 643°C dok je raspon saliniteta 15.70 - 59.95 tež. % NaCl ekviv. Fluid 3 čine inkluzije samo s tekućom i parnom fazom (L+V), i umjerenog su saliniteta (15.70 - 47.77 tež. % NaCl ekviv.). Raspon Th jest 288 - 525°C.The Bučim porphyry copper deposit (41.7° N, 22.3° E) is located country of North Macedonia, about 120 km southeast of the capital Skopje and 15 km west of the town of Radoviš. The deposit itself contains four ore bodies: Vršnik, Čukar, Central ore body and Bunardžik. The main ore mineral is chalcopyrite, which is associated with pyrite, magnetite, hematite and rutile, while the main tailings mineral is quartz. Seven types of fluid inclusions were determined based on their petrological appearance and the presence of phases: vapour, liquid, salt phase and ore mineral. High-temperature (418 - 643 °C) and high-salinity inclusions (30.72 - 59.95 wt. % NaCl equiv.) are believed to be ore-bearing. Fluid inclusions of the Bunardžik ore body are typical for porphyry copper deposits, with the exception of about 10 measurements of inclusions that homogenize at temperatures between 1200°C - 1300°C. The analysis of fluid inclusions in the Bunardžik ore body revealed three types of fluids: Fluid 1 is characterized by high temperature and high saility. The FIAs composed of coexisting two-phase and multiphase inclusions reflect a fluid immiscibility. Determined salt phases are halite and sylvite. Th ranges between 513 and 1292°C. Fluid 2 is represented by multiphase inclusions which, in addition to vapor and liquid phases, may also contain one or more salt crystals (L+V and L+V+S). The salt crystal represents halite, this fluid does not contain an ore-bearing mineral. Th range is 288 - 643°C while salinity range is 15.70 - 59.95 wt. % NaCl equiv.). Fluid 3 is represented by two-phase inclusions (L+V) of moderate salinity. Th ranges between 288 and 525°C while salinity ranges between 15.70 and 47.77 wt. % NaCl equiv

    Process intensification of oxidative coupling of methane

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    Thread-safe lattice Boltzmann for high-performance computing on GPUs

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    We present thread-safe, highly-optimized lattice Boltzmann implementations, specifically aimed at exploiting the high memory bandwidth of GPU-based architectures. At variance with standard approaches to LB coding, the proposed strategy, based on the reconstruction of the post-collision distribution via Hermite projection, enforces data locality and avoids the onset of memory dependencies, which may arise during the propagation step, with no need to resort to more complex streaming strategies. The thread-safe lattice Boltzmann achieves peak performances, both in two and three dimensions and it allows to sensibly reduce the allocated memory ( tens of GigaBytes for order billions lattice nodes simulations) by retaining the algorithmic simplicity of standard LB computing. Our findings open attractive prospects for high-performance simulations of complex flows on GPU-based architectures

    Soliton Gas: Theory, Numerics and Experiments

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    The concept of soliton gas was introduced in 1971 by V. Zakharov as an infinite collection of weakly interacting solitons in the framework of Korteweg-de Vries (KdV) equation. In this theoretical construction of a diluted soliton gas, solitons with random parameters are almost non-overlapping. More recently, the concept has been extended to dense gases in which solitons strongly and continuously interact. The notion of soliton gas is inherently associated with integrable wave systems described by nonlinear partial differential equations like the KdV equation or the one-dimensional nonlinear Schr\"odinger equation that can be solved using the inverse scattering transform. Over the last few years, the field of soliton gases has received a rapidly growing interest from both the theoretical and experimental points of view. In particular, it has been realized that the soliton gas dynamics underlies some fundamental nonlinear wave phenomena such as spontaneous modulation instability and the formation of rogue waves. The recently discovered deep connections of soliton gas theory with generalized hydrodynamics have broadened the field and opened new fundamental questions related to the soliton gas statistics and thermodynamics. We review the main recent theoretical and experimental results in the field of soliton gas. The key conceptual tools of the field, such as the inverse scattering transform, the thermodynamic limit of finite-gap potentials and the Generalized Gibbs Ensembles are introduced and various open questions and future challenges are discussed.Comment: 35 pages, 8 figure

    Database for validation of thermo-hydro-chemo-mechanical behaviour in bentonites

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    This paper presents a database of thermo-hydro-chemo-mechanical tests on bentonites, which has been named “Bento_DB4THCM”. After a comprehensive literature review, a set of experimental tests have been compiled. The experimental data are used to perform validation exercises for numerical codes to simulate the coupled thermo-hydro-mechanical and geochemical behaviour of bentonites. The database contains the information required for the simulation of each experimental test solving a boundary value problem. The validation exercises cover a wide range of clays, including the best-known bentonites (MX-80, FEBEX, GMZ) as well as others. The results collected in this database are from free swelling, swelling under load, swelling pressure and squeezing tests. The database is attached as Supplementary material.En este artículo se presenta una base de datos de ensayos termo-hidro-quimio-mecánicos sobre bentonitas, a la que se ha denominado “Bento_DB4THCM”. Después de una revisión exhaustiva de la literatura, se ha compilado un conjunto de pruebas experimentales. Los datos experimentales se utilizan para realizar ejercicios de validación de códigos numéricos para simular el comportamiento termohidromecánico y geoquímico acoplado de las bentonitas. La base de datos contiene la información requerida para la simulación de cada prueba experimental que resuelve un problema de valor límite. Los ejercicios de validación cubren una amplia gama de arcillas, incluidas las bentonitas más conocidas (MX-80, FEBEX, GMZ) entre otras. Los resultados recopilados en esta base de datos provienen de pruebas de hinchamiento libre, hinchamiento bajo carga, presión de hinchamiento y compresión. La base de datos se adjunta como material complementario

    Effect of Pulse Shapes on the Weldability of High Conductivity Copper ‎C101 by Nd-YAG Laser

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    يتضمن هذا البحث دراسة تجريبية  لتأثير درجة الحرارة لجريان مائعين (الهواء والماء)  على الضغط خلال انبوب  ( ذو أنحناء   ͦ90) على جانبي المنحنى   و في المنحنى نفسه. أن هذه  الدراسة  ذات أهمية لفهم وتحسين العمليات الصناعية التي تنطوي على جريان مائعين. أن التجربة الحالية تتألف  من  ثلاث  اجزاء:  أفقي, عمودى, والمسار  المنحنى  للجريان خلال  انبوب  مصنوع  من مادة (البولي فينيل كلورايد ) ويبلغ قطره الداخلي 68 مم ؛ وأما القسم المنحني من الأنبوب يحتوي على نسبة انحناء نصف القطر الى القطر بمقدار  ( R/D) 8.  وقد تم  أستخدام مجموعة متنوعة من معدلات تدفق المياه التي تراوحت من 18 إلى 42 متر مكعب في الساعة وأما معدلات جريان الهواء فقد تراوحت  بين 4 إلى 18 متر مكعب في درجات الحرارة  مختلفة ، وقد تم استخدام  ستة مجسات ضغط لمراقبة الضغط خلال مدة  التجربة . وقد تمت مقارنة النتائج التجريبية  لهبوط الضغط  التي تم الحصول عليها  من التجربة ومقارنتها مع النماذج المنشورة مسبقًا لتقييم نتائج أدائها في التنبؤ بانخفاض الضغط في ظروف انتقال الحرارة ولكن بدون الغليان .بناءً على النتيجة التجريبية ، يزداد الضغط عبر أجزاء  التجربة  مع زيادة درجة حرارة في الحالة التي لا تهيمن فيها لزوجة السائل على لزوجة الخليط نظرًا لارتفاع معدل تدفق السائل أيضًا ، يكون انخفاض الضغط  عبر المنحنى عالياً  عندما يكون  معدل تدفق الهواء قليلاً مقارنة بمعدل تدفق هواء ألعالي  عند ثبوت معدل تدفق الماء و عند درجة حرارة الغرفة ، و تنعكس الحالة بزيادة درجة حرارة الخليط  حيث أن أنخفاض الضغط  عند معدل تدفق الهواء العالي . تكون أعلى  بالمقارنة مع معدل   تدفق الهواء المنخفض .وكشفت الدراسة بان الحرارة تزيد الضغط و هبوط  الضغط عند المنحنى لجريان مائعين عند معدلات تدفق الهواء العالية بثبوت معدل جريان الماء .The current work presents an experimental demonstration of the impact of two-phase flow mixture (water and air) temperature on the pressure across the bend's upstream and downstream sides as well as the bend itself, as it is crucial for understanding and optimizing industrial processes. The test section in this study comprises a horizontal section, a vertical section, and a bend section, all made of PVC-U material with an inner diameter of 68 mm. The bend section has a curvature radius to diameter ratio (R/D) of 8. Pressure was monitored using six sensors over the test length for a range of water flow rates 18 to 42 and air flow rates 4 to 18  at various mixture temperatures. The obtained experimental pressure drop results were also compared to already previously published models to evaluate their performance in predicting pressure drop in conditions with heat transfer but no boiling. Based on the experimental result, the pressure across the test section increases with increasing temperature in a situation in which mixture viscosity is not dominated by liquid viscosity due to its high volume flow rate. Also, the pressure drop across the bend is higher at a lower air flow rate compared to a higher air flow rate at the same water flow rate and mixture temperature at room temperature, but as the mixture temperature increases, the pressure drop at a high air flow rate will be higher compared to a low air flow rate

    Multiscale structural optimisation with concurrent coupling between scales

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    A robust three-dimensional multiscale topology optimisation framework with concurrent coupling between scales is presented. Concurrent coupling ensures that only the microscale data required to evaluate the macroscale model during each iteration of optimisation is collected and results in considerable computational savings. This represents the principal novelty of the framework and permits a previously intractable number of design variables to be used in the parametrisation of the microscale geometry, which in turn enables accessibility to a greater range of mechanical point properties during optimisation. Additionally, the microscale data collected during optimisation is stored in a re-usable database, further reducing the computational expense of subsequent iterations or entirely new optimisation problems. Application of this methodology enables structures with precise functionally-graded mechanical properties over two-scales to be derived, which satisfy one or multiple functional objectives. For all applications of the framework presented within this thesis, only a small fraction of the microstructure database is required to derive the optimised multiscale solutions, which demonstrates a significant reduction in the computational expense of optimisation in comparison to contemporary sequential frameworks. The derivation and integration of novel additive manufacturing constraints for open-walled microstructures within the concurrently coupled multiscale topology optimisation framework is also presented. Problematic fabrication features are discouraged through the application of an augmented projection filter and two relaxed binary integral constraints, which prohibit the formation of unsupported members, isolated assemblies of overhanging members and slender members during optimisation. Through the application of these constraints, it is possible to derive self-supporting, hierarchical structures with varying topology, suitable for fabrication through additive manufacturing processes.Open Acces

    Using coarse-grained molecular dynamics to understand the effect of ionic liquids on the aggregation of Pluronic copolymer solutions

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    This study is aimed to enhance the understanding of the interaction between ionic liquids (ILs) and non-ionic Pluronic triblock copolymers in aqueous two-phase micellar systems (ATPMS) used for the selective separation/purification of hydrophobic biomolecules. The ILs allow a precise control of the cloud point phase separation temperature (CPT), particularly important when the stability of the molecule is highly dependent on temperature. The effect of choline-based ILs, with two different counter-anions, chloride and hexanoate, was evaluated using molecular dynamics simulations (MD) for F-68 and L-35 Pluronic aqueous solutions. The simulations revealed the role played by the anions during the Pluronic self-assembly, with choline chloride hindering Pluronic aggregation and the choline hexanoate favouring micelle formation and coalescence, in agreement with the experimental data. A detailed study of the accessible surface area of Pluronic showed a progressive dehydration of the Pluronic hydrophilic micelle corona in choline hexanoate mixtures promoting inter-micelle interactions and, consequently, micelle coalescence. With the addition of choline hexanoate, it was observed that the hydrophilic segments, which form the micelle corona, twisted towards the Pluronic micelle core. The electrostatic interaction is also shown to play a key role in this IL–Pluronic aqueous solution, as the hexanoate anions are accommodated in the Pluronic micelle core, while the choline cations are hosted by the Pluronic micelle corona, with the ions interacting with each other during the self-assembly process. In addition, a comparison study of F-68 and L-35 aqueous solutions shows that the IL impact depends on the length of the Pluronic hydrophilic segment. This work provides a realistic microscopic scenario of the complex interactions between Pluronic copolymers and ILs.This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. The authors acknowledge the research contract under the project CENTRO-01-0145- FEDER-000005: SusPhotoSolutions: Soluções Fotovoltaicas Sustentáveis. G. Pérez-Sánchez and N. Schaeffer acknowledge the national funds (OE), through FCT – Fundação para a Ciência e a Tecnologia, I. P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29th, changed by Law 57/2017, of July 19th. A. M. Lopes acknowledges the support from the State of São Paulo Research Foundation (FAPESP/Brazil, processes #2017/10789-1 and #2018/10799-0). J. F. B. Pereira also acknowledges FAPESP through the project 2014/16424-7.publishe
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