Contact Zone Research Articles

Groundwater Exploration Within Shallow Depths Around Distinct Litho-Petrological Contact Zones

The world’s increasing demand for freshwater has put a strain on existing reserves in recent years, necessitating further exploration of new groundwater reserves. However, geologic provinces located within the contact boundary of Sedimentary Basin-Basement Complex region are somewhat faced with the problem of shallow sediment thickness. As a result, exploring for groundwater poses a challenge as the sediment thickness might be insufficient to host productive aquifers. Hence, exploring for faults and fractures zones that are embedded on the hard rock underneath the sediment is very essential and complimentary. In this study, high resolution aeromagnetic data over a litho-petrological contact zone of the Middle Benue Trough (MBT) and the Adamawa Massif were analyzed to delineate groundwater exploration areas using a simplified qualitative and quantitative approach. Visual inspection of isolated and aggregate anomalies is performed by analyzing their shapes, dimensions, lateral extents, and discontinuities. Lineaments were then extracted from the residual magnetic map to determine faults, fractures, and joints. A two-source-depth model is indicated by the Spectral Analysis technique used to determine the thickness of the sediments in the area. The deeper source (Z1) has a thickness of 0.9 - 3.6 km, while the shallow source (Z2) has a thickness of 0.1 - 0.8 km. While in some areas the overburden thickness may be sufficient for groundwater exploration, in others it was not, as indicated by the shallow magnetic depth, Z2. Nonetheless, areas of shallow thickness but with aggregates of faults, fractures, and joints were identified as possible locations for groundwater accumulation through magnetic lineament exploration.

Research on the calculation method of grinding temperature field of spiral bevel gear based on generative machining

At present, the process parameter setting of spiral bevel gear grinding is mainly based on an empirical method, and the tooth surface temperature is difficult to estimate effectively during grinding, which may lead to excessive tooth surface temperature and surface burn caused by improper selection of process parameters. Aiming at the above problems, this paper presents a method for calculating the temperature field of spiral bevel gear forming based on a combination of analytical and numerical methods. The motion equation of spiral bevel gear grinding is derived based on the method of tooth surface development. The time-varying heat flow calculation method in tooth surface grinding was developed through the discrete and two-dimensional contact zone. The time-varying temperature field analysis method of spiral bevel gear forming is developed using the time-varying heat flow and finite element calculation method. The related research can realize the temperature prediction of grinding tooth surfaces and provide the basis for improving grinding technology.

Implementation of bio-inspired organic/inorganic layer structures as interphase in carbon fiber reinforced concrete

Biological materials found in nacre or glass sponges reveal specific layered organic and inorganic structures known for their fracture toughness caused by crack deflection and −bridging. This work aims to bio-mimic the brick-and-mortar (BnM) structure from nacre and the layer-by-layer (LbL) structure from the glass sponge filaments to incorporate these effects into the contact zone of carbon fiber-reinforced concrete (CFRC) in order to prevent brittle composite failure. To build up BnM- and LbL-structure materials such as nanoclays, sodium water–glass and polymer dispersions were selected since they are well-established low-cost materials in building. Nanoclays were analyzed regarding their size, dispersibility and exfoliation. Montmorillonite (MMT) was used to be mixed with polymers to produce self-assembled BnM-structured films and coatings. Also, LbL structures were formed by alternating layers of sodium water glass and polymer. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to verify the morphology. The MMT-containing coatings demonstrated enhanced nucleation potential when exposed to cementitious eluate. Micromechanical pull-out tests on single carbon fibers with BnM- and LbL-coatings embedded in concrete demonstrate the potential to increase composite toughness. The successful implementation of the bio-inspired structures using affordable materials lays the groundwork for their scalability and integration into composite structures for building.

Indirect measurement of process parameters in peripheral end milling based on acoustic emission signals

In machining, current methods for online estimation of cutting parameters heavily rely on piezoelectric dynamometers. Albeit their high precision, integration into industrial environments is limited due to high cost and practical machine mounting constraints. To address this challenge, this study presents an indirect measurement method of the cutting depths in peripheral milling based on acoustic emission sensors. The proposed method involves extracting time-based features from a tailor-made envelope of the acoustic emission signal, identifying transitions between cutting phases from its waveform, and using these features to estimate radial and axial depths of cut through a geometric model of the tool-workpiece contact zone. Experiments show that this method can achieve relative errors below 5% in measuring the depths of cut, approaching the precision levels of piezoelectric dynamometers. This suggests that acoustic emission is an alternative process variable, enriching the spectrum of monitoring systems traditionally dependent on the measurement of cutting forces.

Adaptive alien genes are maintained amid a vanishing introgression footprint in a sea squirt

Abstract Human transport of species across oceans disrupts natural dispersal barriers and facilitates hybridization between previously allopatric species. The recent introduction of the North Pacific sea squirt, Ciona robusta, into the native range of the North Atlantic sea squirt, Ciona intestinalis, is a good example of this outcome. Recent studies have revealed an adaptive introgression in a single chromosomal region from the introduced into the native species. Here, we monitored this adaptive introgression over time, examining both the frequency of adaptive alleles at the core and the hitchhiking footprint in the shoulders of the introgression island by studying a thousand Ciona spp. individuals collected in 22 ports of the contact zone, 14 of which were sampled 20 generations apart. For that purpose, we developed a KASP multiplex genotyping approach, which proved effective in identifying native, nonindigenous and hybrid individuals and in detecting introgressed haplotypes. We found no early generation hybrids in the entire sample, and field observations suggest a decline in the introduced species. At the core region of the introgression sweep, where the frequency of C. robusta alleles is the highest and local adaptation genes must be, we observed stable frequencies of adaptive alien alleles in both space and time. In contrast, we observed erosion of C. robusta ancestry tracts in flanking chromosomal shoulders on the edges of the core, consistent with the second phase of a local sweep and a purge of hitchhiked incompatible mutations. We hypothesize that adaptive introgression may have modified the competition relationships between the native and invasive species in human-altered environments.

Distribution, diversity and genetic structure of alders (Alnus lusitanica and A. glutinosa) in Spain

Alders (Alnus spp., Betulaceae) are keystone pioneer species in riparian habitats. In the Mediterranean Basin, where the diploid Alnus glutinosa coexists with the recently discovered tetraploid A. lusitanica, the distribution, diversity and genetic structure of alder species is unknown. The main objectives of this study were to report the distribution of A. glutinosa and A. lusitanica, quantify the local genetic diversity of populations and explore the presence of putative hybrids resulting from the coexistence of A. lusitanica and A. glutinosa individuals in Spain. We assessed 627 individuals from 22 natural alder populations by combining chromosome counts, flow cytometry and microsatellite markers (SSRs) analyses. The ploidy analysis, validated through chromosome counts, revealed the presence of 92 diploid and 535 tetraploid trees from three A. glutinosa and 18 A. lusitanica pure populations, respectively. Notably, no hybrids were detected, not even in Assa, the only population where both species co-occur. The occurrence of mixed ploidy level in alder is reported for the first time in Spain (Assa, Logroño, within the Ebro basin). SSR analysis revealed robust genetic differentiation between the two species and distinctive patterns of variation within A. glutinosa. The high level of differentiation observed was supported by the most probable population clustering determined through pca and structure analyses, along with the identification of a high number of private alleles. For A. lusitanica, the results revealed three distinct genetic groups, geographically distributed. Positive genetic and geographical distance correlations indicated that differentiation could have been driven by isolation by distance. In light of the results, A. lusitanica is the most representative, widespread and genetically variable alder species in Spain, and A. glutinosa is restricted to the north-east of the country. The Ebro riverbank is a contact zone between A. lusitanica and A. glutinosa species, in which no evidence of hybridization was detected yet. Finally, with focus on management, our findings may suggest considering A. lusitanica as a new species, which should be regulated by the forest reproductive material legislation.

A study of fretting fatigue in a contact pair of DZ125/GH4169: its mechanical behavior and life prediction

In this paper, the fretting fatigue test of DZ125/GH4169 contact pair was carried out. Observation and analysis of the wear and fracture were needed to get the fretting damage law. A hardness parameter was introduced to modify the existing life prediction model. The specimen was exposed to both normal and fatigue loads, as indicated by the results, which resulted in the formation of a black oxide layer that stuck to the contact zone's edge. Oxide spalling formed grits and abrasive wear, accelerating the loss of fatigue resistance. At high temperatures, the oxidation was intensified. The life prediction results were all within the double error band. The error range was reduced and the life prediction effect was significantly improved.

Modelling and application of dissolved air flotation for efficient separation of microplastics from sludges and sediments

The pervasive presence of microplastics in our environment necessitates urgent measures to prevent further release and address existing contamination hotspots. This work focuses on the removal of microplastics from sludges and sediments through the application of dissolved air flotation (DAF). In addition to experimental investigations, the study presents the development of a predictive model for the formation of aggregates comprising air bubbles and microplastics in the DAF contact zone. First an empirical model was established to predict the attachment efficiency between air bubbles and particles (αdb). To this end, the experimental attachment efficiency was determined for various plastics, with varying particle sizes and shape factors, and system conditions. The obtained data set was utilized to establish an empirical model by PLS regression describing αdb based on particle size, bubble size, density, Hamaker constant, contact angle, solid load, aspect ratio, circularity, and sphericity, resulting in an MSPE of 0.011 and adjusted-R² of 0.64. Secondly, a semi-deterministic model based on the XDLVO theory was developed using MLR, where αdb was described by the natural logarithm of the Van der Waals, electrostatic and hydrophobic forces acting between the particle and air bubble, and the solid load, with an RSE of 0.067 and adjusted-R² of 0.63. Finally, the applicability of these models was demonstrated in a case study on industrial sludge consisting of sediment and PVC microplastics. Validation of the attachment efficiency and the dimensioning of a DAF unit for processing this sludge at a capacity of 20 m³.h−1 emphasize the practical implications of the developed models.

Simulation Analysis and Experimental Study on the Fluid–Solid–Thermal Coupling of Traction Motor Bearings

The traction motor is a crucial component of high-speed electric multiple units, and its operational reliability is directly impacted by the temperature increase in the bearings. To accurately predict and simulate the temperature change process of traction motor bearings during operation, a fluid–solid–thermal simulation analysis model of grease-lubricated deep groove ball bearings was constructed. This model aimed to simulate the temperature rise of the bearing and the grease flow process, which was validated through experiments. The results from the simulation analysis and tests indicate that the temperature in the contact zone between the bearing rolling element and the raceway, as well as the ring temperature, initially increases to a peak and then gradually decreases, eventually stabilizing once the bearing’s heat generation power and heat transfer power reach equilibrium. Furthermore, the established fluid–solid–thermal coupling simulation analysis model can accurately predict the amount of grease required for effective lubrication in the bearing cavity, which stabilizes along with the bearing temperature. The findings of this research can serve as a theoretical foundation and technical support for monitoring the health status of high-speed EMU traction motor bearings.

SNP‐based analysis of European Thymallus spp. (Salmonidae) reveals extensive mito‐nuclear discordance relevant for biogeographic inferences, taxonomy and conservation

AbstractAimPaleohydrological dynamics are well‐documented for European river systems, promoting shifting phases of isolation and connectivity of their aquatic fauna. These conditions coupled with high rates of hybridisation found in freshwater fishes may introduce considerable complexity and potential mito‐nuclear discordance of phylogenetic patterns. We evaluate this hypothesis using the first large‐scale analysis of nuclear SNPs in European species of grayling (Thymallus) compared to mtDNA data with the aim of reassessing the evolutionary history of this group of rheophilic fishes.LocationFreshwater systems in Europe.MethodsBased on mitochondrial (mitogenomes, control region) and nuclear (ddRADseq) data, we applied population‐genetic, phylogenetic, and biogeographic tools to evaluate lineage diversity in the context of paleohydrological alterations.ResultsThe results corroborated previously recognised high levels of lineage diversity, but revealed several cases of mito‐nuclear discordance and signals of both historical (natural) and human‐mediated introgression among major inter‐ and intraspecific lineages of Thymallus in Europe. A time‐calibrated phylogeny and ancestral area estimation, based on nuclear SNP data, supported a late Pliocene diversification of the genus in Europe and suggested an early colonisation of the Black Sea basin with subsequent dispersal into Central and Western Europe.Main ConclusionsThe genetic structure of Thymallus in Europe recovered by nuclear SNPs contrasts considerably with that supported by mtDNA. Several instances of mito‐nuclear discordance underscore frequent contact of allopatric lineages in a dynamic paleohydrological landscape and reveal the weakness of basing both taxonomic and conservation decisions on inferences based on mtDNA alone. The Danube and Rhine drainages were inferred as important zones of contact between divergent phylogeographic lineages. Additionally, our data cast doubt on the genetic integrity of the endangered T. aeliani. Its divergence from T. thymallus, using nuclear SNPs, appears minimal as samples of T. aeliani group within Danubian lineages, despite carrying highly divergent reciprocally monophyletic mtDNA.

Hydrodynamic processes in designing diamond drilling tools

Relevance. The rational choice of drilling tools is one of the components of a positive result of exploration, mining, drilling operations. The function of a complex solution of problems arising when drilling wells is assigned to a modern drilling tool. Today there is a great variety of designs of rock cutting drilling tools. However, scientific achievements in improving the material and technical production base contribute to the development of drilling technology and creation of new, more efficient tool designs. The most promising and effective in various mining conditions is a diamond drilling tool. During the operation of such a tool, flushing fluid circulation is of great importance, especially in the bottomhole zone of the well being constructed. When designing the structures of a diamond rock cutting tool, it is necessary to take into account not only the strength, cutting, and stabilizing properties, but also the possibility of an effective fluid flow in its circulation system, i.e. without flow energy consumption to overcome resistance, with sufficient capacity for cuttings removal and the necessary level of cooling, lubrication and implementation of other functions of the flushing fluid, which contribute to improving drilling results. At the same time, modern methods of designing a drilling tool should take into account the influence of the drilling fluid, its properties, and the nature of the flow on the rock destruction mechanism, i. e. require a thorough study of the nature of the fluid flow in the contact zone of the tool cutters with the rock. The article proposes the position of considering the design of a diamond drilling tool cutting surface from the point of view of the influence of hydrodynamic processes on the nature of cutters rock interaction. The results of the study of both the author herself and well-known world manufacturers of diamond drilling tools are given as arguments. Aim. To study the influence of the design features of the existing diamond drilling tool on the nature of the fluid flow in the bottomhole zone of the well during drilling. Objects. Designs of diamond drilling tools, hydrodynamic processes associated with drilling. Methods. Analytical method, computer simulation method. Results. Differences in fluid circulation in certain types of diamond drilling tools are determined. The zones of the diamond rock-cutting tool are distinguished. They differ in the nature of the fluid flow. Directions for reducing hydraulic resistance in the bottomhole zone of the well due to changes in the design features of the drilling tool were established.

A Degraded Finger Vein Image Recovery and Enhancement Algorithm Based on Atmospheric Scattering Theory.

With the development of biometric identification technology, finger vein identification has received more and more widespread attention for its security, efficiency, and stability. However, because of the performance of the current standard finger vein image acquisition device and the complex internal organization of the finger, the acquired images are often heavily degraded and have lost their texture characteristics. This makes the topology of the finger veins inconspicuous or even difficult to distinguish, greatly affecting the identification accuracy. Therefore, this paper proposes a finger vein image recovery and enhancement algorithm using atmospheric scattering theory. Firstly, to normalize the local over-bright and over-dark regions of finger vein images within a certain threshold, the Gamma transform method is improved in this paper to correct and measure the gray value of a given image. Then, we reconstruct the image based on atmospheric scattering theory and design a pixel mutation filter to segment the venous and non-venous contact zones. Finally, the degraded finger vein images are recovered and enhanced by global image gray value normalization. Experiments on SDUMLA-HMT and ZJ-UVM datasets show that our proposed method effectively achieves the recovery and enhancement of degraded finger vein images. The image restoration and enhancement algorithm proposed in this paper performs well in finger vein recognition using traditional methods, machine learning, and deep learning. The recognition accuracy of the processed image is improved by more than 10% compared to the original image.

Modeling and experiments on flexible side-electrodes electrostatic actuators: Influence of the contact interface on the available force

This paper presents an in-depth study of electrostatic actuators based on flexible side-electrodes focusing on the available electrostatic force and the derived useful force. A design tool is proposed considering technological aspects as aspect ratio, insulating layer material and voltage level. A space discretized mechanical approach based on Euler-Bernoulli beam theory is developed to model the bending deflection of the flexible movable electrode and “zipping” contact. Analytical developments and simplifications are achieved, rapidly and efficiently implemented in a proposed algorithm. ANSYS® simulations validate the procedure for updating the contact zone through the updating of the electrostatic pressure distribution. Optimum movable electrode width and appropriate “opposable” stiffness for guiding system are discussed. A “residual air thickness” parameter is introduced to address imperfect contact between the electrodes. Experimentalcharacterization studies various prototypes with different structural parameters as thickness (50 µm and 200 µm), gaps (5 µm and 15 µm) and material for insulating layers (silicon oxide and parylene C). The metrology campaign highlights the impact of aspect ratio and oxidation/deoxidation on electrode sidewall quality and hence mechanical performance.A comparison with well-known comb-drive shows higher electrostatic force for flexible side-electrode actuators. As an example, for a 10 µm stroke, the available electrostatic force for flexible electrodes with irregular sidewalls (residual air thickness 0.6 µm) is 2.2 times greater and rises to 7.3 times greater for perfect sidewalls (no residual air).

A New Nephrite Occurrence in Jiangxi Province, China: Its Characterization and Gemological Significance

Nephrite is a very precious gemstone material. As a non-renewable resource, the discovery of new nephrite deposits and the study of the genesis of nephrite have aroused great interest. A new occurrence of nephrite known as Xinyu nephrite was discovered in Xinyu Country, Jiangxi province, China. Field investigations reveal that nephrite appears in a contact zone between the Mengshan composite granitic pluton and Permian carbonate rock. The carbonate rock is calcic marble that underwent diopsidization and tremolitization. Nephrites have a light yellow-green color, weak greasy luster, are slightly-translucent to translucent, and are fine-grained. Their refractive index (RI) ranges from 1.60 to 1.61, and their specific gravity (SG) value ranges from 2.90 to 2.91, falling within the range of nephrites from Xinjiang, China. Their Mohs hardness (Hm) ranges from 5.78 to 5.83. Petrographic observations and electron probe micro analyzer (EPMA) data indicated that analyzed nephrites mainly comprise tremolite, with minor diopside, calcite, quartz, and apatite. Tremolite has a ratio of Mg/(Mg + Fe2+) greater than 0.99. The tremolite grains show microscopic fibrous-felted and columnar textures. Scanning electron microscope (SEM) images show some tremolite fibers interwoven in different crystallographic orientations, and some arranged in parallel. Fourier transform infrared and Raman spectroscopy features reveal the bands of minerals typical for nephrite composition. The petrographic characteristics and geological background of the Mengshan area indicate that nephrite formed through a replacement of calcic marble, which differs from the two known types (D-type: dolomite-related; S-type: serpentinite-related). Mineral replacements were common in nephrite, including diopside by tremolite, calcite by tremolite, and recrystallization of coarse by fine tremolite grains. The discovery of Xinyu nephrite occurrence complements the resource and provides an updated case for the in-depth study of the diversity of nephrite deposits.

Geometric deviation during incremental sheet forming process: Analytical modeling and experiment

Incremental sheet forming (ISF), a promising and flexible forming method, is generally restricted by the unsatisfied geometric deviation for industrial applications; therefore, effective control and accurate prediction of geometric deviation in ISF are essential for quality improvement. However, the geometric deviation in ISF is extremely sensitive to the geometric shape, toolpath, and process parameters, which is challenging to predict and control. In this study, the comprehensive geometric-related mechanisms in ISF were analyzed, including springback after local bending of the bent and contact zones, and the elastic deflection of the inclined wall, particularly the associated deformation in the weak-stiffness region. Through a creative equivalent mapping method for calculating the elastic deflection of complex structures and modeling the bending moment distribution in different zones, an analytical model was developed to accurately and universally predict the geometric deviations of parts by ISF. Based on the results of the experiments and comparative studies using a response surface model, the proposed model provided superior capability for predicting the geometric accuracies of parts made using ISF with different sheet materials, process parameters, and geometric shapes, even for complex parts with non-axisymmetric structures and stepped features. The geometric-related mechanisms, forming characteristics, and influences of crucial parameters in ISF are discussed by adopting an analytical model combined with numerical simulations, demonstrating that the elastic deflection on the inclined wall, particularly the associated deformation in the weak-stiffness region, plays a primary role in the geometric deviation of complex parts compared with other geometric-related mechanisms.

Existence results for variational–hemivariational inequality systems with nonlinear couplings

In this paper we investigate a system of coupled inequalities consisting of a variational–hemivariational inequality and a quasi-hemivariational inequality on Banach spaces. The approach is topological, and a wide variety of existence results is established for both bounded and unbounded constraint sets in real reflexive Banach spaces. Applications to Contact Mechanics are provided in the last section of the paper. More precisely, we consider a contact model with (possibly) multivalued constitutive law whose variational formulation leads to a coupled system of inequalities. The weak solvability of the problem is proved via employing the theoretical results obtained in the previous section. The novelty of our approach comes from the fact that we consider two potential contact zones and the variational formulation allows us to determine simultaneously the displacement field and the Cauchy stress tensor.

Moving contact problem of a functionally graded orthotropic coated half plane

AbstractThis paper develops a frictional moving contact model for a functionally graded (FG) orthotropic layer pressed by a rigid cylindrical punch. The FG orthotropic layer is fully bonded to the isotropic half-plane. The punch moves to the left on the layer at a constant subsonic velocity and a shear stress arises in the contact zone according to the Coulomb friction law. General expressions of displacements and stresses are derived with the help of the Fourier transform and Galilean transformation. Using boundary conditions, the moving contact problem is reduced to a Cauchy-type singular integral equation, the unknowns of which are contact stress and contact width. Gauss–Jacobi integration formula is used to solve the obtained singular integral equation. The effect of some parameters and material properties on the contact width, contact stress and in-plane stress are given in graphical forms and detailed numerical interpretations are presented.

Effects of Pressure Rollers with Variable Compliance in the Microfinishing Process Utilizing Abrasive Films.

This article presents a comprehensive investigation into pressure rollers utilized in the microfinishing process, covering aspects such as design, experimental properties, compliance, and finite element simulation. Prototype pressure rollers with unconventional elastomer configurations were designed and analyzed to explore their effectiveness in achieving superior surface finishes. Experimental analysis and finite element simulations were conducted to gain insights into the performance and behavior of these pressure rollers under various loading conditions. This study addresses the validation of constitutive material models used in finite element simulations to ensure accuracy and reliability. The results indicate that the applied material model, validated through experimental analysis, accurately predicts pressure roller behavior. Finite element simulations reveal distinct contact zone patterns and stress distributions across the contact surfaces, highlighting the importance of considering deflection-induced variations in contact behavior. Additionally, the investigation evaluates the effectiveness of different pressure rollers in removing surface irregularities during the microfinishing process. Roller R3 demonstrates the highest efficacy in removing surface peaks, suggesting its potential for achieving superior surface finishes. Overall, this research contributes to the advancement of microfinishing techniques by providing insights into pressure roller design, performance, and behavior, thereby optimizing microfinishing processes to produce high-quality components. The urgency of this study arises from the growing need for exceptional surface finishes in various industrial sectors. With manufacturing industries increasingly pursuing high-precision components boasting flawless surface quality, the significance of microfinishing processes is highlighted.

ON THE PROBLEM OF EASTERN BORDER OF SAKA CULTURE OF ALAI

Introduction. The article is devoted to the problem of establishing the eastern border of the Saka culture of Alai. An important role in understanding of this problem is played by the Touyun burial ground, located in the southwestern part of Xinjiang, close to Kyrgyzstan. Materials and methods. This burial ground has specific funeral rites, which demonstrate the characteristic features peculiar to the Saka culture of Alai. In particular, these are burials in stone boxes, crypt-like stone structures and at the level of the ancient surface, constructed under low stone-earth burial mounds. Burials in them were both single and multi-act. The buried people in these burials were in an elongated position with orientation of the sculls to the west and northwest direction. The funeral inventory from Touyun was relatively poor and represented by a couple of ceramic vessels, jewelry items (earring, bracelet, and beads), a belt garment (belt buckle), household items (sumac, awls) and clothing items (plaques). Results and discussion. These funeral objects, based on analogies, allowed us to establish the time of existence of the Touyun burial ground, which fits into the chronological framework of the end of the 5th - 3rd centuries BC. It is evident, that this necropolis appears as a result of the migration of the Saka population from the eastern part of the Alai Valley. The occupying this territory group of Alai Saka was appeared in the contact zone with the population of the Saka culture of Tien Shan region, with which, apparently, they established marital ties. Currently, the Touyun burial ground is the easternmost site of the Saka culture of Alai, which makes it possible to expand the border of this culture by more than 130 km to the east than previously thought. It also made it possible to significantly clarify the real areas of the main archaeological cultures in the southwestern part of Xinjiang such as the Saka cultures of Alai, Pamir and Tien Shan region.

Скінченно-елементна модель вертикального резервуара на жорсткій основі

This study addresses the problem of finite element modeling of a 20,000 m3 vertical steel tank subjected to static loads. The structure includes a cylindrical wall of total height 17,880 mm and diameter 39,900 mm. The shell thicknesses of the cylindrical wall are determined according to strength and buckling design standards. The geometric model is axisymmetric. The analysis involves the calculation of the stress and strain fields of the cylindrical wall and the contact zone between the flat bottom and the rigid foundation under various combinations of external loads, namely, excessive and hydrostatic pressures. The ANSYS Mechanical software is used for finite element analysis. Three-dimensional SOLID186 and SHELL281 elements are used for axisymmetric modeling of the shell structure in a three-dimensional formulation. To simulate the contact zone, CONTA174 and TARGE170 finite elements are used to model the moving contact surface of the bottom and the fixed surface of the rigid foundation, respectively. The model is verified by comparing the radial displacements calculated numerically and analytically. The discrepancy does not exceed 4%, thus evidencing the adequacy of the finite element model. The contact zone is analyzed for non-standard service conditions, such an excessive internal pressure in the tank (2.5 and 3 kPa compared to 2 kPa under normal conditions). The unilaterally constrained "bottom–foundation" contact zone model allows the bottom to detach from the foundation, thus leading to contact opening. A full detachment occurs under a certain combination of the excessive and the hydrostatic pressure. For certain liquid levels in the tank, the gap decreases, which may be due to a reduced effect of the excessive pressure. This is accompanied by the development of internal detachment caused by the increasing moment from the hydrostatic pressure. The internal detachment increases the bending moment at the wall–bottom junction, which, under certain conditions, may cause plastic deformations followed by the development of an emergency state.