Formation Of Zone Research Articles

The Distribution of Surface Heat Flow on the Tibetan Plateau Revealed by Data‐Driven Methods

AbstractSurface heat flow (SHF) serves as a vital parameter for assessing the heat transfer from deep Earth to the surface, which can provide crucial insights into internal geodynamic processes. As the “roof of the world,” the Tibetan Plateau and its tectonic evolution are highly important in terms of global climate change and geodynamic study. However, a comprehensive understanding of the SHF distribution across most regions of the Tibetan Plateau is limited due to sparse measurement data. To surmount this limitation, a spatially intelligent approach has been developed: The geographically neural network weighted regression with enhanced interpretability (EI‐GNNWR). This method integrates spatial heterogeneity and nonlinear interactions between geophysical and geological factors to predict the SHF distribution across the Tibetan Plateau. In this study, the EI‐GNNWR model is used to accurately predict SHF across the entire region. After evaluating the effectiveness and interpretability of the EI‐GNNWR model, our results demonstrate that medium to high SHF values are predominantly concentrated in the southern, northeastern, and southeastern sectors of the Tibetan Plateau. These observations suggest that the formation of zones with high SHF values may be strongly influenced by the Moho depth, ridges, topography, and average curvature of satellite gravity gradients. Especially, higher SHF values may indicate more profound geodynamic activities such as collisional orogeny, shear deformation zones, or lithospheric extension. These findings offer novel insights into the spatial patterns of SHF and deepen our understanding of the geothermal formation mechanisms driven by underlying tectonic activities.

New Analytical Solutions for Constant Rate Pumping in Two‐Zone Double‐Porosity Confined Aquifer: A New Source Term Reflecting Effects of Well Skin and Wellbore Storage

AbstractThis study develops two new analytical models for constant rate pumping at a partially penetrating well in a double‐porosity confined aquifer, considering skin and formation zones. One model, referred to as the two‐zone model, incorporates a flow equation to depict the flow in the skin around the well. The other model, named the source‐term model, introduces a novel source term at the outer rim of the skin to reflect the effects of both the skin and wellbore storage. The analytical solutions for both models are derived by the Laplace transform and finite Fourier cosine transform. Additionally, a finite element solution for the source‐term model is presented. Results suggest the source‐term model is suitable to most wells when the width of the skin is less than 1 m and the radius of influence exceeds the outer rim of the skin. Temporal drawdown distribution for a negative skin exhibits a triple‐humped shape with two flat stages, while that for a positive skin shows monotonous increase. The source‐term model enables orthogonal 5 × 5 nodes for finite element approximation to discretize a well and its adjacent skin. The finite element solution aligns with early drawdown data measured at an observation well under the effects observed in two field constant rate pumping tests. In conclusion, this study introduces a novel approach to modeling two‐zone flow, which may find practical utility in field applications.

Strengthening mechanism of T8-aged Al−Cu−Li alloy with increased pre-deformation

The microstructure evolution and mechanical properties of a T8-aged Al−Cu−Li alloy with increased pre-deformation (0−15%) were investigated, revealing the microstructure−strength relationship and the intrinsic strengthening mechanism. The results show that increasing the pre-deformation levels remarkably improves the strength of the alloy but deteriorates its ductility. Dislocations introduced by pre-deformation effectively suppress the formation of Guinier-Preston (GP) zones and provide more nucleation sites for T1 precipitates. This leads to more intensive and finer T1 precipitates in the samples with higher pre-deformation levels. Simultaneously, the enhanced precipitation of T1 precipitates and inhibited formation of GP zones cause the decreases in number and sizes of θ′ precipitates. The quantitative descriptions of the strength contributions from different strengthening mechanisms reveal that strengthening contributions from T1 and θ′ precipitates decrease with increasing pre-deformation. The reduced diameters of T1 precipitates are primarily responsible for their weakened strengthening effects. Therefore, the improved strength of the T8-aged Al−Cu−Li alloy is mainly attributed to the stronger strain hardening from the increased pre-deformation levels.

Laser additive manufacturing of Ti and Ce co-modified 2195 difficult-to-process aluminum alloy: Grain refinement, cracking suppression and enhanced mechanical properties

High cracking susceptibility of Al-Li alloys with Ti/CeB6 addition is thoroughly suppressed in laser powder bed fusion (LPBF) processing of Ti/Ce co-modified 2195 alloys at relatively high scan speeds, while the cracking suppression mechanism and phase formation in these composites are not clarified. In this work, microstructure evolution and mechanical performance of the LPBF-fabricated Ti/Ce co-modified 2195 are investigated to reveal their cracking suppression and strengthening mechanisms. The results show that apparent grain refinement of the composites is ascribed to high supercooling from rapid formation of constitutional supercooling zone in front of solid–liquid interfaces by high-Q-value Ti solute, and heterogeneous nucleation of in situ formed Al3Ti and Al11Ce3 precipitates. Their synergistic interactions promote formation of fine equiaxed grains and thus inhibit crack initiation. The composites exhibit high microhardness of 100 ± 5 HV0.2, nano-hardness of 1.6 ± 0.1 GPa and elastic modulus of 97 ± 3 GPa, where the elastic modulus increases by ∼27% and ∼31% compared to those of LPBF-processed and conventionally manufactured 2195 alloys, respectively. A tensile strength of ∼336 MPa and an elongation of ∼3% are obtained from in-situ synchrotron X-ray diffraction measurement. The improved properties are derived from grain refinement and Orowan strengthening. Based on the optimal processing parameter and composition, a bracket component filled with lattice structures is designed and manufactured with good manufacturing quality and processing accuracy.

Microstructure-Linked Mechanical Properties of P91-Incoloy 800HT Dissimilar Metal Welds

Dissimilar metal welds (DMWs) between P91 steel and Incoloy 800HT® using shielded metal arc welding (SMAW) with ENiCrCoMo-1 filler electrode were characterized in detail. The impact of multiple weld passes on microstructure in the heat-affected zone (HAZ) and weld fusion zone (WFZ) was thoroughly investigated. Postweld heat treatment (PWHT) impacts on mechanical characteristics and microstructure were also observed. The DMW was observed with heavy C, Cr, and Mo microsegregation in the WFZ, which deteriorated mechanical strength. The microstructural changes directly affected the mechanical behavior of the DMW. The ultimate tensile strength of the weld fusion zone was low at 576 MPa compared to the base metals’ strength. The tensile specimens failed in the IN 800HT base metal and WFZ. The WFZ had significant microsegregation near the solidified grain boundaries (SGBs). The metallurgical heterogeneity in the WFZ caused the formation of localized stress zones, which directly affected the mechanical behavior of the WFZ. The carbide particles influenced the microhardness in the WFZ and P91 HAZ regions. The PWHT successfully homogenized the microhardness in the WFZ and P91 HAZ regions. The impact toughness decreased to 64 J from 82 J after PWHT due to precipitation at SGBs and its coarsening. The SMAW process involves multiple thermal cycles during welding. The deposition of filler metal in multiple welding passes created uncontrolled variations in the solidification behavior of the WFZ. Microsegregation had a detrimental impact on the microstructure and mechanical properties of the P91 and IN 800HT dissimilar metal welds.

Dynamics of single cavitation bubble collapse jet under particle-wall synergy

The interaction between a particle and a cavitation bubble significantly influences the erosive effect on the wall surface of flow passage components in fluid machinery. This paper investigates the dynamics of a single bubble collapse jet under the synergetic effects of a particle and a wall, using Kelvin impulse theory and high-speed photographic experiments. A theoretical model to predict the intensity and direction of the collapse jet at arbitrary locations near the particle and the wall is constructed on the basis of the image method and Weiss's theorem. The accuracy of the model is verified by comparison with a large number of experimental results. The mechanisms underlying the relative contributions of the particle and wall to the behavior of jet intensity and direction are explored. The effects of key parameters on jet intensity and direction are also quantitatively analyzed, including the relative positions of the particle, wall, and the bubble and the dimensionless particle radius. The main conclusions are as follows: (1) the particle will cause a deflection in the direction of the collapse jet near the wall, leading to the formation of a jet attraction zone. The proposed theoretical model effectively predicts the spatial location of this zone. (2) There exists a region in which the jet is weak, and there is a jet equilibrium point with zero impulse between the particle and the wall. The position of this equilibrium point gradually approaches the wall in a nonlinear manner with increasing particle size and in a quasi-linear manner with decreasing particle–wall distance. (3) When the particle and the bubble are the same distance from the wall, the jet direction gradually changes from toward the particle to vertical to the wall in a nonlinear manner as the bubble–particle distance increases. Moreover, the effective range of the particle's influence on the jet direction decreases as the particle–wall distance decreases.

Bio-mediated enhancement of supergene copper mineralization: Evidence from Cu isotope geochemistry

The relationship between microbial activity and the supergene modification of ore systems has been a major subject of debate. Here, we present isotopic evidence of microbial-driven secondary copper mineralization in the active cementation zone of the Las Cruces deposit, a volcanogenic massive sulfide deposit located in Iberian Pyrite Belt, Spain. Copper isotopic data show that the lower isotopic ratios (δ65Cu ≈ −9.2 ± 0.11 ‰, the lowest value measured worldwide in a supergene environment) are found in the upper part of the cementation zone, the same zone where the maximum copper grades are found and where there is direct evidence of extremophilic microbial activity. There is a tendency towards higher values downwards through the cementation zone (−9.2 ± 0.11 ‰ to + 1.67 ± 0.11 ‰ δ65Cu) and upwards into the former Cu-depleted gossan that originally capped the cementation zone (−7.79 ± 0.11 ‰ to −1.32 ± 0.11 ‰ δ65Cu). As microbes preferentially sequester the lighter isotope when incorporating intracellular Cu, this distribution indicates that microbes played a major role in the formation of the high-grade zones. Water arrives to the deposit enriched in isotopically heavy copper, likely because it has leached other ore bodies upstream. δ65Cu values of water currently flowing into the system are remarkably more positive than those in the ore, indicating that microbial activity is a major cause of copper isotope fractionation. At least half of the copper transported by the incoming waters remains within the ore body. Our best interpretation is that the large and high-grade cementation zone at Las Cruces is of biogenic origin, and that the primary mineralization acted as a trap for copper transported by groundwater, leading to the formation of an exotic mineralization distal to sub-eroded massive sulfides located upstream.

Detached eddy simulation of traffic-induced air pollution in an urban highway with complex surrounding morphology

Air pollution caused by traffic is a major contributor to unhealthy ambient air quality in the vicinity of urban highways and puts the health of residents and pedestrians at risk. Therefore, it is imperative to examine local pollution reduction methods. The present paper is concerned with Detached Eddy Simulation (DES) of an urban area with high concentration of air pollutants. As an example of a complex surrounding morphology, the studied domain encompasses a 2.5 km stretch of high-traffic highway, a bus terminal, and the nearby residential buildings. The numerical procedure is validated with some benchmark wind tunnel and numerical data. The locations of pollution accumulation have been identified and the effect of the ambient wind speed on the change of the maximum pollution concentration points has been investigated. Furthermore, potential pollution reduction strategies for such complex morphologies have been proposed based on the geometry change to prevent the formation of critical zones of pollution accumulation. The results show that critical zones are generally formed behind the walls of upstream buildings, adjacent to the upstream wall of the highway, and in front of the walls of downstream buildings. It was also found that changes in the ambient wind speed do not significantly alter the location of these critical zones. Furthermore, increasing the distance between adjacent buildings and the highway from 21 m to 30 m, can result in an average reduction of 76% in maximum carbon monoxide concentration values. An investigation into the impact of upstream buildings height indicates that reducing the height of certain buildings can effectively diminish pollution concentration to zero in residential areas and surrounding sidewalks. Additionally, increasing the depth of the highway and erecting 2 m solid barriers on either side of the highway are identified as two other effective techniques for reducing pollution concentration on both sides of the highway. The findings can be utilised to develop novel strategies aimed at enhancing air quality for residents and pedestrians.

Evolution of Power‐Law Particle‐Size Distributions in Dense Grain‐Flow Experiments

AbstractUnderstanding particle fragmentation and its resulting particle‐size distribution is essential for comprehending shear zone formation, structure, and frictional behavior in faults and landslides, particularly at high normal stresses. 3‐D fractal dimension (D3) is used as a measure of particle‐size distribution, and for the potential self‐similarity physics. Previous research suggests D3 – 2.58 based on the “constrained comminution” model, or D3 = 3.00 considering large shear displacement. However, field data from rock avalanches reveal scattered D3 that deviate from these predictions, possibly due to the neglection of the underlying fragmented physics, such as the particle‐size‐dependent fragmentation probability. Herein, we conducted rotary shear experiments to investigate the evolution of D3 under varying normal stresses, velocities, and mineral compositions. Experimental results demonstrate that D3 monotonically increases with shear displacement and converges to an ultimate value, significantly influenced by mineral composition but less affected by shear velocity and confining stress within the experimental conditions. A modified large‐strain model that considered size‐dependent grain‐breakage probability was proposed, which may explain the observed divergence of D3 from previous predictions. This model highlights the complex mechanisms involved in particle breakage within dense grain‐flows, resulting in the high but scattered D3 observed in natural shear zones. Furthermore, we recognize that additional mechanisms, such as abrasion and grinding, can contribute to the particle size reduction and influence the ultimate fractal dimension. This study provides valuable insights into the dynamics of particle fragmentation in shear zones and has implications for understanding various geological processes.

Effect of dispersoid formation on age hardening and precipitation behavior of an Al-Si-Mg(-Cu) alloy with Mn and Cr addition

In the present study, Mn and Cr elements were added to the alloy to induce the formation of the α-AlFeMnCrSi dispersoids during solution treatment. The effect of the dispersoids on subsequent age-hardening response and precipitation behavior was investigated. The results indicate that there is a partially coherent structure between the dispersoid and the α-Al matrix, but the coherence is weak. The precipitation of dispersoids resulted in accelerated age-hardening response and precipitation kinetics, but weakened peak-aged hardening effect. With the aging time increasing from 0 to 16 h, a new precipitation sequence was proposed in Mn+Cr modified Al-Si-Mg(-Cu) alloy: Supersaturated solid solution (SSSS) → GP zones (under-aged) → β'' + β' (peak-aged) → Si + β'' + β' + Mg2Si + Q + α (over-aged). Among them, the extra precipitates were heterogeneous nucleated on the dispersoids, which depended on the orientation relationship between the dispersoid and the precipitation, the interfacial energy of the dispersoid/matrix/precipitation, and the local solute element concentration. Heterogeneous precipitation of coarse particles on dispersoids resulted in the formation of precipitation-free zones (PFZ), which was mainly responsible for the weakened peak-age hardening effect. Moreover, compared to the base alloy, finer and denser precipitates were obtained in the matrix of the modified alloy, due to the increased density of dislocations induced by the dispersoids and the higher Mg supersaturation.

The Impact of Fly Ash on the Properties of Cementitious Materials Based on Slag-Steel Slag-Gypsum Solid Waste.

This paper presents a novel low-carbon binder formulated from fly ash (FA), ground granulated blast furnace slag, steel slag, and desulfurization gypsum as a quaternary solid waste-based material. It specifically examines the influence of FA content on the mechanical properties and hydration reactions of the quaternary solid waste-based binder. The mortar test results indicate that the optimal FA content is 10%, which yields a 28-day compressive strength 11.28% higher than that of the control group without FA. The spherical particles of fly ash reduce the overall water demand and provide a "lubricating" effect to the paste due to their continuous gradation, improving the fluidity of the slag-steel slag-gypsum cementitious materials. The micro test results indicate that fly ash has minimal effect on the early hydration products and process of the solid waste-based cementitious materials, but after 7 days, it continuously dissolves silicon-oxygen tetrahedrons or aluminum-oxygen tetrahedrons, consuming Ca2+ and OH- in the system. After 28 days, the amount of ettringite and C-(A)-S-H gel generated increases significantly. The pozzolanic activity of fly ash is mainly stimulated by the Ca(OH)2 from steel slag in the later hydration stage. Additionally, spherical fly ash particles can fill the voids in the hardened paste, reducing the formation of cracks and weak zones, and thereby contributing to a denser overall structure of the hydrated binder. The findings of this paper provide data support for the development of low-carbon cement-free binders using fly ash in conjunction with metallurgical slags, thereby contributing to the low-carbon advancement of the construction materials industry.

Hydrogen leakage and diffusion in the operational cabin of hydrogen tube bundle containers：A CFD study

The operational cabin of hydrogen tube bundle containers (HTBCs) is susceptible to vibration and fatigue loads during transportation, which may result in hydrogen leakage and deflagration accidents. In this paper, a three-dimensional (3D) computational fluid dynamics (CFD) model is developed to simulate the effects of leakage diameter, leakage pressure, leakage direction and position on hydrogen leakage and diffusion in the operational cabin of HTBCs. The results demonstrate that the formation of vortex recirculation zones leads to the accumulation of flammable gas cloud (FGC) in the operational cabin. The medium leakage diameter (1.5 mm) and higher leakage pressure (20 MPa, 35 MPa) cause the operational cabin to be filled with FGC within 5 s, requiring the operational cabin to be designed with no possible ignition source inside. In addition, when hydrogen leaks from the +Z direction, the sensor responds within 0.31 s, which is 1.7 s earlier than the response time in the -Z direction, indicating that the existing sensor layout cannot meet the requirements of fast response. When the leak position (L3) is close to the vent, the FGC volume proportion at 2 s is 19.3 % and 15.88 % lower than that of L1 and L2, respectively, indicating that the leak position close to the vent can effectively slow down the accumulation of FGC. The research results have implications for the safety design of operational cabin of HTBCs, the layout of hydrogen sensors and vents, and the emergency response measures for hydrogen leakage.

Performance analysis and design method of strengthening beam-column welded connections against progressive collapse

To address the insufficient collapse resistance of the beam-column welded connection (BWC), this study proposes a strengthening beam-column welded connection with truss elements (BWCTE). A static test on a BWCTE specimen with a composite slab was conducted to investigate its failure pattern, final deflection, and the evolution of axial force, bending moment, and collapse resistance. The results indicate that the addition of truss elements increases the peak load and corresponding deformation of BWCTE by 108.6 % and 27.3 %, respectively, compared to BWC. Moreover, the axial force in the composite beam of the BWCTE specimen achieved the yield axial force, facilitating the complete development of catenary action and optimizing beam performance. Subsequently, primary parameters of the truss element were analyzed using refined numerical models. It is recommended that the projected length of the inside leaning limb is within 0.5 to 0.7 times the height of the steel beam, and the thickness of each limb is within 0.6 to 1.2 times the thickness of the beam flange. Then, the working mechanism of BWCTE was explored through theoretical analysis. The resistance process of BWCTE can be divided into elastic, elastic-plastic, plastic, transition, and catenary stages. The loading and deformation synergies between truss elements and composite beams enable the formation of double plastic zones and double strengthening zones at the beam root, effectively delaying the rupture of the stretched beam flange. Finally, a design method for BWCTE is proposed according to theoretical and numerical analysis.

Study of the microhardness ensuring the contact endurance of structural materials

The strength of the working surfaces of gears depends on the mechanical properties of the material and the quality of parts. We present the results of studying the strength of materials and working surfaces of a gear mechanism due to structural changes attributed to chemical and thermal treatment. The surface strength of the gears of gas turbine engines was studied. Nitrocementation and ion nitriding were used for chemical and thermal treatment of the contacting surfaces of steel samples under study (20Kh3MVF-Sh, 16Kh3NVFMB-Sh, 18Kh2H4MA, and 12Kh2H4A). Changes in the microhardness of the component layers (diffusion, transition and basic) of the toothed crown were analyzed. Metallographic analysis of the structure of materials was carried out to describe the factors determining the surface strength of working surfaces. Systematized data on the change in the microhardness of materials obtained experimentally in conditions of mass production are presented. Presented experimental results on changes in the mechanical properties of materials are based on data on the microhardness and structural state of the surface layers of the working profiles of gears. A comparative assessment of the surface strength of the studied samples during contact interaction was performed. The dependence of the surface strength on the multifactorial volumetric structure and structure formation of the material in the process of operation is determined. It is shown that the method of surface saturation forms the structure of a material with different mechanical properties accompanied with the formation of a transition zone having characteristic distinctive values of the hardness. The results obtained can be used in the design of gears, taking into account changes in the mechanical properties and structure of materials to ensure the necessary operational requirements.

STRATIGRAPHY AND DIAGENESIS OF THE THAMAMA‐B RESERVOIR ZONE AND ITS SURROUNDING DENSE ZONES IN ABU DHABI OILFIELDS AND EQUIVALENT OMAN OUTCROPS

We review published studies characterizing the Thamama‐B reservoir zone in the upper Kharaib Formation (late Barremian) in Abu Dhabi oilfields and at outcrops in Oman. Available data for oxygen and carbon isotope compositions, fluid inclusion measurements, cement abundance and formation water composition are interpreted in terms of a paragenetic model for the Thamama‐B in field F in Abu Dhabi where the interval is deeply buried. The present synthesis provides a useful basis for understanding and predicting reservoir quality in static models and undrilled prospects, as well as for planning promising directions for further research. The goals of this study were to summarize the geologic setting and petrology of the Thamama‐B reservoir and its surrounding dense zones, and to examine how sedimentology, stratigraphy and diagenesis have interacted to control porosity and permeability. Results that may have useful applications for similar microporous limestone reservoirs in general include: the depositional environments and stratigraphy of the subject strata; a model for how porosity variations result mainly from calcite cementation sourced from stylolites, with little dependence on lithofacies other than the localization of chemical compaction by depositional clay linked to sequence stratigraphy; the use of solidity (rock thickness with porosity removed) as a check on porosity creation by burial dissolution; observations linking high‐permeability streaks with storm lag beds and fractures; the concept of strata being gradually buried through a relatively static salinity‐stratified water column; integration of conventional and clumped stable‐isotope data with petrologic observations to constrain the timing of porosity evolution.

The role of clinopyroxenes in the process of formation of subalkaline olivine-basaltic magma of the Talysh zone (Azerbaijan)

Based on the study of the compositions, relationships of coexisting minerals, as well as the minal components of clinopyroxenes of trachybasalt-trachyandesibasalt-phono- lite formation of the Talysh zone, it was established that they characterize different stages of crystallization of subalkali In addition, the role of clinopyroxenes in the process of formation of subalkaline olivine-basaltic magma of the Talysh zone was determined. The characteristics of the Eocene volcanism of trachyba- salt-trachyandesite-basalt-phonolite formation of the Talysh zone were studied. Using new analytical data of author’s materials, the composition of rocks and minerals of the trachybasalt-trachyandesite-basalt-phonolite formation of the Talysh zone were analyzed. Analyses of rocks and parts of clinopyroxenes were carried out in the chemical laboratory “Uralgeology” of the Ministry of Geology of the Russian Federation (Ekaterinburg). The composition of clinopyroxenes and the melt inclusions they contain were determined by microprobe analysis (Camebax-micro) in the corresponding laboratories of the United Institute of Mineralogy of the Russian Academy of Sciences (Novosibirsk). It was determined that in the complex, under the conditions of the Astara uplift, the rise of subalkaline olivine-basaltic melt into the upper horizons of the earth’s crust was solidified and the early accumulative cumulates of rock minerals in intermediate sources had time to completely dissolve. In the Gosmolyan-Pilachai trough, with the mobility of its transverse mag- ma-supplying faults, such a melt did not have time to crystallize and fractionate. As a result, the transition between petrographic types of rocks in this case is gradual and accumulative inclusions of rocks, minerals were preserved in the melt. The first case is noted by crystallized melt microinclusions, represented by biotite, potassium feldspar, residual glass, the composition belonging to trachydacite and trachyrhyolite, their homogeneous temperature genesis fluctuates between 900-1000oC. In the second case, crystallites of leucite, phlogopite, olivine, etc. were found and molten microinclusions in composition are close to the main alkaline varieties of rocks of the complex under consideration.

Resolving spatially complex interactions between hydrodynamics and biogeochemical processing in a large reservoir with metalimnetic oxygen deficits

Deoxygenation in the deep water of stratified lakes and reservoirs due to climate warming and human activities poses a threat to crucial limnetic ecosystem services. Metalimnetic oxygen minima (MOM) typically occurs during the mid to late stages of limnetic stratification. To investigate the mechanism of MOM during stably stratified periods in the Panjiakou Reservoir, northern China, four years of in-situ monitoring was conducted in parallel with longitudinal-vertical 2D modeling. The model simulated the hydrodynamic, water quality, algal, and DO processes in 2017 and 2020, and was calibrated and verified by the measurements. Three scenarios were designed to test the impact of hydrological processes and the high oxygen-consuming sedimentation zones (HOCSZ). We concluded that the stratification and the corresponding advection generated in the metalimnion are the driving forces of MOM in the reservoir, and the limnetic eutrophication-related benthic HOCSZ are the seedbeds of the metalimnetic hypoxia. This unique spatial setting driving the biogeochemical processing and MOM dynamics required a new generation of modelling, incorporating spatial inhomogeneities of sediment characteristics and a sophisticated resolution of hydrodynamics. Metalimnetic horizontal advection, hypolimnetic upwelling currents, sedimentation hot spots and the formation of high oxygen consumption zones became the major initiation processes leading to MOM. The numerical modeling not only represented the occurrence, development, and extinction of MOM but also comprehensively explained the spatial differences in the vertical morphology of MOM and its inter-annual variations. Our studies help to identify management strategies to mitigate the impacts of MOM on aquatic ecological security and drinking water quality, thus supporting the optimization of reservoir regulations.

Analysis of Structures at the Boundary of Contact Melting Al–Mg–Mn and Zn Based Alloys

The processes of contact melting of the AMg6 (Al-6%Mg-1%Mn) alloy with Zn–Cu–Al solder and the model Zn–Al alloy, as well as the structure of the contact fusion zone, are studied. Samples were obtained in two stages. At the first step, the solder was mechanically applied (tinned) to the surface of the AMg6 plates. Аt the second step, the resulting composite samples were subjected to heat treatment with a varied exposure time in the liquid state. According to the data of metallographic and X-ray diffraction analyses, as well as differential scanning calorimetry, it was shown that already at the tinning stage the active interaction between Zn and Al occurs, which leads to the formation of a developed microstructure in the joint zone. The presence of copper in the solder HTS-2000 reduces the melting point of the Zn-Al alloy by 30-40°C and improves the conditions for contact interaction with the grade AMg6 matrix. Active diffusion of zinc ensures the formation of an extensive melting zone during heat treatment, while zinc-rich areas during crystallization contain the Zn5Cu intermetallic phase, which prevents the formation of intermetallic ZnxMgy compounds, which does not lead to embrittlement of the contact zone.

Geodynamic development of structures of the North Absheron uplift zone within the South Caspian megadepression and oil-gas-bearing

The article discusses the geodynamic development of the structures of the North Absheron uplift zone. The Pirallahi-Kelkor trough is a polyfocal sub-basin due to the fact that in its sedimentary section, at least the Jurassic, Lower Cretaceous, Lower Pliocene and Quaternary deposits, are characterized by favorable conditions for the accumulation and burial of organic matter. It follows from this that, in accordance with its paleogeotemperature regime, several main stages of hydrocarbon migration could have taken place here. For identifying the formation and further structural-tectonic development , the Absheron bank, the Arzu, Chilov, Palchig Pilpilasi, Chirag and Garabag uplifts have been studied. To solve this issue, paleoprofiles for the end of the Jurassic, Early Cretaceous, Miocene and Pliocene based on the seismic geological profile across the strike of the Pirallahi-Kelkor trough have been compiled. As a result of these studies we established that the uplifts are of syndepositional origin, formed simultaneously with the sedimentation process. The sedimentation and geotemperature regime of the subbasin play a significant role . İt was found that by the end of the Pliocene, the main oil formation zone (MOFZ) contained sediments from the second half of the Lower Cretaceous to the second half of the Lower Pliocene, and both Lower Cretaceous and Lower Pliocene deposits took part in the main stage of hydrocarbon migration. Finally, the MOFZ currently contains sediments from the tops of the Lower Cretaceous to the bottoms of the Upper Pliocene. As can be seen, the main stage of migration covered both Lower Cretaceous and Lower Pliocene deposits. İn addition, we concluded that the natural reservoirs of local uplifts that formed within the Absheron archipelago, regardless of the time of their formation, could be saturated with hydrocarbons depending on the level of their development, position in the structural-tec- tonic plan and reservoir characteristics of the strata. Due to the fact that the uplifts were formed no later than the Miocene, it was even considered that they began to appear by the end of the earlier Miocene, and that they could have captured hydrocarbons of the Lower and Later Cretaceous period.

Microstructure Refinement via Nucleation of Intragranular Acicular Ferrite Stimulated by Ti-Containing Core-Shell Structured Particles in Low-Carbon Steel.

This study investigated the microstructure, mechanical properties, and nucleation mechanism of acicular ferrite (AF) present in hot-rolled Ti deoxidized steel. In our experiments, the impact toughness of Ti deoxidized steel is significantly increased to 144 J at -20 °C, while those Mn and Al deoxidized steels are only 9 J and 18 J, respectively. Interlocked AF is the primary microstructure of Ti deoxidized steel. The second-phase particles of the core-shell-type structure, in which Ti2O3 is the nucleus and TiO is the outermost shell, act as effective nucleating agents to stimulate AF nucleation. The low lattice disregistry between TiO and AF is the main factor contributing to the production of AF. It is also revealed that Ti2O3 and MnS fulfill the particular orientation relationship, contributing to the formation of an Mn-depleted zone (MDZ) adjacent to MnS, proposed to be one of the possible mechanisms for promoting AF nucleation.