Shell Surface Research Articles

Large deformation Kirchhoff–Love shell hierarchically enriched with warping: Isogeometric formulation and modeling of alternating stiff/soft layups

This paper presents a large deformation Kirchhoff–Love shell model hierarchically enhanced with through-the-thickness warping functions, arbitrarily chosen by the user. Two unknowns are introduced for each of them, representing its amplitudes in two directions tangent to the shell surface. NURBS are used to approximate reference surface displacement and warping amplitudes in the weak form. The transverse shear strains are linear functions of the warping parameters only and naturally free from locking. A patch-wise reduced integration avoids membrane locking and improves efficiency. Particular attention is paid to the modeling of composites made up of multiple stiff layers coupled with soft interlayers. The alternating layup with high stiffness ratios induces a significant sectional warping with transverse shear strains concentrated in the soft layers. Two warping models are investigated: (WI) all stiff layers maintain the same director orthogonal to the deformed surface with independent transverse shear deformations of the soft layers; (WZ) a single zigzag function linking these deformations. The numerical tests confirm the great accuracy of the hierarchic shell model in reproducing the solid solution with a small number of discrete parameters, provided that the correct warping model is chosen. WI is reliable for all alternating layups. WZ reduces the unknowns to five per surface point, regardless of the number of layers, and is accurate for uniform soft layers.

Structurally stable but functionally disrupted marine microbial communities under a future climate change scenario: Potential importance for nitrous oxide emissions

The blue mussel Mytilus edulis is a widespread and abundant bivalve species along the North Sea with high economic and ecological importance as an engineer species. The shell of mussels is intensively colonized by microbial organisms that can produce significant quantities of nitrous oxide (N2O), a potent greenhouse gas. To characterize the impacts of climate change on the composition, structure and functioning of microbial biofilms on the shell surface of M. edulis, we experimentally exposed them to orthogonal combinations of increased seawater temperature (20 vs. 23 °C) and decreased pH (8.0 vs. 7.7) for six weeks. We used amplicon sequencing of the 16S rRNA gene to characterize the alpha and beta diversity of microbial communities on the mussel shell. The functioning of microbial biofilms was assessed by measuring aerobic respiration and nitrogen emission rates. We did not report any significant impacts of climate change treatments on the diversity of mussel microbiomes nor on the structure of these communities. Lowered pH and increased temperature had antagonistic effects on the functioning of microbial communities with decreased aerobic respiration and N2O emission rates of microbial biofilms in acidified seawater compared to increased rates in warmer conditions. An overriding impact of acidification over warming was finally observed on N2O emissions when the two factors were combined. Although acidification and warming in combination significantly reduced N2O biofilm emissions, the promotion of aquaculture activities in coastal waters where shellfish do not normally occur at high biomass and density could nonetheless result in unwanted emissions of this greenhouse gas in a near future.

Myxobolus dumerilii sp. n. (Myxozoa: Myxobolidae) infecting the brain of Chinese longsnout catfish Tachysurus dumerili (Bleeker) in China.

During an investigation of Myxobolus diversity in the Chinese longsnout catfish Tachysurus dumerili (Bleeker), a new species infecting the intracranial epidermis of the host was discovered. Upon opening the cranial cavity, several round whitish plasmodia measuring 0.55-0.80 mm in diameter were observed. Fresh spores (n= 50) were pyriform in the frontal view and fusiform in the sutural view, with a length of 15.4±0.6 (13.9-16.5) μm, width of 9.1±0.4 (8.3-9.8) μm, and thickness of 7.0±0.4 (6.3-7.9) μm. The spores had smooth shell surfaces and transparent membrane sheaths in the posterior. No folds, intercapsular appendix, and caudal appendages were observed. Two equal polar capsules were pyriform and measured 7.5±0.5 (6.7-8.7) μm in length and 3.2±0.3 (2.5-3.6) μm in width. The polar filaments were coiled with five to six turns and perpendicular to the polar capsule length. A BLAST search indicated M. dumerilii sp. n. was closely related to five Myxobolus species (with sequences similarities ranging from 90.54% to 96.52%) found in different organs of yellow catfish Tachysurus fulvidraco (Richardson), rather than the T. dumerili-infecting species M. branchiola Dong and Zhao, 2014 (with 90.5% sequence similarity). Phylogenetic analysis showed that M. dumerilii sp. n. didn't form sister clade with brain-infecting Myxobolus spp, but clustered with M. jianlinensis Gao et Zhao, 2020 and M. voremkhai Akhmerov, 1960 within the Siluriformes-clade with highly supported values, indicating that the host specificity may play a stronger signal than site infections during the evolution of Myxobolus species. Based on the morphological, ecological, and molecular differences observed between the newly discovered species and other available Myxobolus species, M. dumerilii sp. n., is proposed and described in this study.

Electron probe microanalysis and gene expression analysis of melanization caused by summer atrophy virus in the Akoya pearl oyster (Pinctada fucata)

The Akoya pearl oyster, Pinctada fucata, is the major species used for pearl culture in Japan. However, a massive mortality of juvenile and mantle atrophy of adult P. fucata have occurred during summer in Japan's major pearl production areas since 2019, and the symptoms were named “summer atrophy,” where a brown substance was deposited on the inner surface of their shell and mainly at the edge of the mantle. Summer atrophy is caused by a non-enveloped virus with a diameter of <100 nm. This study aimed to reveal whether the deposits are melanin and determine the gene expression in the mantle with the deposition through an infectious experiment. The body fluid of diseased P.fucata containing the causative virus was inoculated into the adductor muscle of three-year-old P. fucata. P. fucata were sampled at 0 (before injection), 1, 3, 6, 10, 14, 21, and 35 days post-injection. First, an electron probe microanalyzer was used to observe the detailed structure and material composition of the deposits of experimentally and spontaneously diseased P. fucata. Protuberances and wrinkled structures differed from a normal inner surface shell. Cluster analysis of these elemental composition ratios revealed that the brown deposits formed a cluster with the melanin standard, a prismatic layer of Mytilus galloprovincialis. Therefore, the brown deposits were considered to be melanin. The gene expression of infected mantles was analyzed by quantitative PCR. RNA was extracted from the mantle and body fluids, and the gene expression of shell matrix protein genes (msi31 and msi60), tyrosinase genes involved in melanin formation (OT47 and pfty1), and superoxide dismutase (SOD), which is an indicator of reactive oxygen species, was analyzed. A general linear model was created using the presence of deposits as an objective variable, with virus gene copy numbers in the body fluid and mantle and expression levels of the above five genes as explanatory variables. Then, an optimal model was selected. As a result, OT47, msi60, and SOD were selected as explanatory variables. The results suggest that virus infection induced the up-regulation of SOD and tyrosinase, inducing the deposits on the inner surface of shells in summer atrophy. Melanization is known in many animals and plays a major role in immunity, particularly in invertebrates. In bivalves, melanization caused by bacterial diseases has been reported, but this is the first report of melanization caused by viral diseases.

Noteworthy Taphonomic Attributes of a Nautiloid Cephalopod from the Middle Silurian (Wenlock) Massie Formation of Southern Indiana

A specimen of the nautiloid cephalopod Dawsonoceras annulatum from the middle Silurian (Wenlock) Massie Formation of southeastern Indiana, USA, is herein described because of its suite of uncommon taphonomic characteristics. Three noteworthy features are observable. First, an articulated calymenid trilobite is preserved in the sediment infill of the cephalopod, having been either swept into the open shell post-mortem or rapidly buried alive while sheltering inside the hollow cavity. Second, a series of small (pinhole-sized) borings, potentially produced by ctenostomate bryozoans, are present on the upward-facing and lateral surfaces of the cephalopod shell, a feature that is otherwise unreported in this fauna. There appears to be a preference for boring into raised portions of the shell. Third, a number of tightly coiled microconchids are encrusting the exterior of the shell, an association not previously documented in this unit. Some of these phenomena represent first reports from a fossil fauna in a region strongly affected by dolomitization and are worthy of description on that basis alone. However, their co-occurrence on a single specimen highlights the fact that relatively common taxa such as cephalopods are still capable of yielding rare and/or significant taphonomic and paleoecological data.

Use of heat recovery technology to increase thermal efficiency of rotary furnaces

The article considers the problem of increasing the energy efficiency of rotary kilns, which are used in various industries for thermal processing of materials, such as metallurgical, chemical, construction, electrode and others. The source of heat for the kilns is gaseous fuel, which is supplied through special burners located at one end of the cylinder. The material for processing is loaded at the opposite end and moves towards the burner due to the force of gravity and rotation of the kiln. One of the important aspects of operating rotary kilns is energy efficiency, which depends on many factors and generally characterizes the degree of use of heat from fuel for heating the material. However, a significant part of the heat from fuel is lost through the kiln shell, which leads to an increase in fuel consumption and a decrease in kiln productivity. Therefore, it is necessary to look for ways to reduce heat losses and use part of the heat for other purposes. In this context, heating secondary air can be one of the important methods for increasing the thermal efficiency of rotary kilns, especially for kilns that operate in a mode for pyrolysis firing of materials such as coal, wood, peat, etc. The aim of the work is to increase the energy efficiency of a rotary kiln using a spiral heat exchanger, using the heat from the external shell of the kiln to heat secondary air. The paper proposes the use of a sectional heat exchanger, which can perform the functions of a cooler, a thermal insulator and a regulator of temperature regimes of the kiln. The heat exchanger consists of several sections that are attached to the outer surface of the kiln shell and have channels for air passage. The air is heated by contact with the hot shell and then supplied to the burner as secondary air. Thus, the heat exchanger allows to reduce the temperature of the shell and provide an additional source of hot air. A mathematical model for numerical calculation of a spiral heat exchanger has been developed, which allows to evaluate its thermal and temperature characteristics. It is shown that by using the heat from the shell it is possible to heat secondary air to a temperature of 270 °C in an amount sufficient to ensure the operation of the burner. An analysis of the location of the heat exchanger and the use of insulation coating has been carried out, which made it possible to significantly reduce its size without changing the total thermal effect compared to a heat exchanger installed along the entire length of the kiln shell. The effectiveness of using thermal insulation has been shown, which makes it possible to increase the temperature of air by 50 °C with its thickness 7 mm. The obtained results can be useful for further development and optimization of projects aimed at improving heat exchange systems and efficient use of thermal resources in rotary kilns.

Quarks species in a cold genesis theory; theoretic implications of a Vortical quark model

By the author’s cold genesis theory (CGT), based on the Galileian relativity, it was argued the possibility to explain the massic spectrum of the elementary particles by two species of preonic quasi-crystalline quarks: A) preonics –formed by basic preons z0(34 me) which form bosonic preons z2(4z0) and zpi(7z0) , and B) quarkonics – formed by 3n preonic quarks (4≥n≥1) (mainly –v- or/and s-quarks) or as crystalline cluster of 7x5 = 35 preonic or quarkonic quarks: (p+;n−) –nucleonic quarks or l±, s±,v± -preonic quarks, or c- or b- quarkonic quarks, (‚charm’, ‚botton’), in two flavors: f=1-of Standard model’s variant and f = 2 –of Souza/CGT’s variant. Because the basic z0-preons are explained as cluster of paired degenerate electrons, the strong forces between quarks and particles can be naturally explained by the existence of a permanent etherono-quantonic vortex around the super-dense kernel of electron generated by etherono-quantonic winds of the quantum vacuum and by an etheronic centripetal force of Magnus type. As consequence, in CGT can be argued a model of‚ gravistar’ having a shell of dark energy but also of photons vortexed around a rotational hard core (HC) of black hole type which –by matter→energy conversion can obtain periodically an antigravitic (pseudo)charge MA, by the releasing of heavy etherons of the destroyed degenerate electrons’ vortices. The antigravitic field of an enough high value of MA, produced by the friction between the surface of an internal hard core (HCi) of HC, of black hole type, and the interior surface of a crystalline shell of current strange cold quarks, HCe, could be –in this case, a natural equivalent of the‚ dilaton’ field considered in the EMD theories.

Paleogene turtles of Eastern Europe: new findings and a revision

The article provides an overview of all known 39 localities of the Paleogene turtles of Eastern Europe. Numerous remains of turtles are described for the first time from 19 localities, of which six are new, and 13 are the localities from which materials were only mentioned previously. Among them are Pan-Trionychidae indet., Pan-Cheloniidae indet., Dermochelyidae indet. and Pan-Testudines indet., as well as pan-cheloniids Argillochelys sp. from the Ypresian Novoivanovka and the Ypresian or Lutetian Gruzinov localities. Several indeterminate specimens from Eocene localities show similarity to pan-cheloniids Argillochelys cuneiceps (Owen, 1849) and Puppigerus camperi (Gray, 1831) or Tasbacka aldabergeni Nessov, 1987, and dermochelyids Natemys peruvianus Wood et al., 1996 or “Psephophorus” rupeliensis van Beneden, 1883. One specimen of costal 1 of Pan-Testudines indet. from the Lutetian Krasnorechenskoe locality resembles that of pleurodires Eocenochelus spp. and Neochelys spp. In addition, new materials of turtles are described from five previously known localities. Among them, new and additionally restored specimens from the Bartonian Ak-Kaya 1 locality of the pan-cheloniid Argillochelys sp., and the dermochelyid Cosmochelys sp., which expand data on their morphology and intraspecific variability. The specimens of pan-cheloniids with deep and dense sculpturing of the external shell surface from the Bakhmutovka, Bulgakovka, Krasnorechenskoe and Tripolye localities clearly belong to a new species, not described due to fragmentary material. It is supposed that Anhuichelys-like pan-testudinoids migrated from Asia in Eastern Europe in the Danian age, and were preserved as relict Dithyrosternon valdense Pictet et Humbert, 1855 until the Priabonian age.

First Report of Peanut Black Pod Rot Caused by Berkeleyomyces rouxiae in China.

Peanut (Arachis hypogaea L.) is an important oilseed and cash crop cultivated in over 100 countries worldwide. The major producers are China, India and USA (Ding et al. 2022). In September 2022, peanut pods exhibiting black necrotic symptoms on the shell surface were observed in Puyang, Henan Province, China. These black spots often merged to form larger necrotic spots on the shell. Disease incidence was 100% in susceptible varieties. Symptomatic shell pieces were surface sterilized with 75% ethanol for 3 min, rinsed three times with sterile water, and then transferred onto PDA medium supplemented with 25 µg/ml chloramphenicol (Long et al. 2022). Isolation frequency of a fungus with similar-appearing colonies from symptomatic pods was 81.7%. A pure culture of a representative isolate, PYHB, was obtained through single-sporing and maintained on PDA plates at 25℃ in darkness. The colony initially appeared white but turned black within 2 days. The isolate produced dark brown, unicellular chlamydospores, which were arranged in club-shaped chains consisting of two to seven cells. The size of the unicellular chlamydospores varied from 3.34 to 15.27 µm (average:6.81, n = 100) in length and 8.30 to 15.51 µm (average:11.29, n = 100) in width. The endoconidia were hyaline and cylindrical, measuring 7.91-22.94 × 1.69-4.81 µm (average: 12.16 × 3.13, n = 100). Based on morphological characteristics, the isolate was tentatively identified as a Berkeleyomyces sp. (Nel et al. 2018; Long et al. 2022). The ITS region of r-DNA, the ribosomal large subunit (LSU), the minichromosome maintenance complex component 7 (MCM7), and the 60S ribosomal protein RPL10 (60S) genes were amplified using ITS1/ITS4, LR0R/LR5, rouxMCM7-F/rouxMCM7-R and roux60s-F/roux60s-R primers, respectively (White et al. 1990; Vilgalys and Hester 1990; Nakane and Usami 2020). The sequences were deposited in GenBank (ITS: OR053803; LSU: OR053818; MCM7: OR058549; 60S: OR060656). Through BLASTn analysis of the NCBI GenBank database, the generated ITS and LSU sequences showed 100% identity to Berkeleyomyces rouxiae (GenBank MF952418.1 and MF948662.1, respectively) and B. basicola (GenBank MT221585.1 and MH868639.1, respectively). Importantly, the MCM7 and 60S sequences were 100% identical to B. rouxiae (GenBank MF967114.1 and MF967077.1, respectively). Phylogenetic analysis combining ITS, LSU, MCM7, and 60S sequences showed that the isolate PYHB clustered with B. rouxiae. To evaluate pathogenicity, surface-sterilized healthy peanut pods (n = 90) were immersed in a 1×106 spore/ml conidial suspension obtained from isolate PYHB for 5 min and placed in Petri dishes containing moistened cotton at 25°C for 10 days. Pods (n = 90) inoculated with sterile water served as controls. Inoculated pods displayed black necrosis 10 days after inoculation (dai), whereas no symptoms were observed on the control pods at 21 dai. The reisolated pathogen was shown to be identical to the original inoculum through morphological and phylogenetic analysis. Black root rot is a fungal disease caused by Berkeleyomyces spp. (syn. Thielaviopsis spp.) and affects various crops and ornamentals, such as cotton, tobacco, carrot, holly, and pansy (Rahnama et al. 2022). The causal agents B. rouxiae and B. basicola have similar morphological characteristics but can be differentiated through molecular characterization (Nel et al. 2018). To our knowledge, this is the first report of black pod rot in peanut caused by B. rouxiae in China. The finding from this study will contribute to the development of monitoring and management strategies to combat this destructive disease in peanut cultivation.

Analysis of regional wear failure of crankshaft pair of heavy duty engine

This study focuses on investigating the underlying causes of localized wear failure on one side of the oil hole in the third crankpin of a straight-six-cylinder internal combustion engine, constructed using 42CrMo material. A comprehensive analysis of this wear phenomenon was conducted through a series of meticulous experimental investigations and advanced finite element analysis. The experimental campaign encompassed macroscopic morphology observation, precise metallographic structure analysis, microscopic structure observation, iron spectrum abrasive particle detection, micro-hardness testing, and rigorous chemical composition analysis. Furthermore, finite element analysis was employed to simulate the stress and strain distribution of the crankshaft under realistic operating conditions, enabling a deeper understanding of the mechanisms driving the localized wear in the third crankpin region. The research results revealed that the primary driver behind the localized wear in the third crankpin region is the ingress of grinding debris and contaminated particles from the oil passage into the contact surface between the third crankpin and the bearing shell, leading to abrasive particle wear. Moreover, the synergistic effects of friction and elevated temperatures facilitate the migration of carbon elements from lubricants or other materials to the surface of the third crankpin, resulting in their accumulation. This carbon accumulation causes non-uniform stress distribution on the surface, exacerbating fatigue wear on the crankshaft crankpin. The finite element simulation outcomes demonstrated that the center of the oil hole on one side of the third crankpin experiences the most pronounced deformation. Under actual operating conditions, the deformation of the crankpin leads to an increase in clearance between the crankpin and the bearing shell, thereby impeding the formation of a complete oil film. Consequently, the occurrence of dry friction and elevated temperatures leads to the melting of the alloy on the bearing shell surface, giving rise to adhesive wear.

Analysis of thermal-vibration coupling modeling of combined conical-cylindrical shell under complex boundary conditions

In this paper, a unified method is proposed to predict the free and forced vibration behavior of the combined conical-cylindrical shell (CCS) structure in the steady-state thermal environment. The first-order shear deformation theory (FSDT) and the thermal strain are utilized to establish the energy equation of the combined structure, and the artificial virtual spring technique is introduced to realize the coupling between the substructures and the arbitrary boundary conditions of the CCS. The displacement function of the structure is constructed by the spectral-geometry method, and the vibration equation is solved by using the Rayleigh–Ritz method. The accuracy of the present model is verified by comparing the numerical results with the finite element method. The factors that may affect the vibration behavior of the CCS under thermal environment are analyzed specifically, and the results demonstrate that point constraints on the shell surface can effectively suppress shell vibration. This paper provides a compelling reference for vibration control of CCS in practical applications.

Molecular and morphological evidence reveals a hidden new taxon in the endemic genus Pseudocuneopsis (Bivalvia, Unionidae) from China.

A new species of freshwater mussel belonging to the genus Pseudocuneopsis, namely Pseudocuneopsiswuanasp. nov., is diagnosed and described from Guangxi Province, China. This paper provides a detailed shell morphological description, soft-body anatomical characteristics, and partial sequences of mitochondrial COI as DNA barcode data for the novel species. The new species can be distinguished from its congeners (Pseudocuneopsissichuanensis, P.yangshuoensis, and P.capitata) by shell shape, beak position, and surface sculpture. Phylogenetic analyses based on the mitochondrial COI gene reveal that Pseudocuneopsiswuanasp. nov. forms a sister group with P.yangshuoensis and exhibits an interspecific genetic distance of 5.1%. Therefore, we provide robust morphological and molecular evidence to support the validity of this new species.

Giant limpets in southern Iberian coastal and continental archaeological sites, from Neanderthals to Copper Age

The use of coastal resources has been crucial for human diet and social behaviour evolution has been extensively documented since the Middle Palaeolithic, mainly in the western Mediterranean and southern Africa. In southern Iberia, the mollusc assemblages associated with archaeological sites show a continuous record regardless of palaeoclimatic conditions. Among these, limpets are uninterruptedly abundant from the Middle Palaeolithic to the Bronze age with the giant limpets (Cymbula safiana and Patella ferruginea) being present since MIS6. To assess their distribution, predominance, and cultural significance this paper presents the results from an exhaustive archeozoological survey of the southern Iberian region. A total of 1628 specimens have been analysed, including 425 modern (333 C. safiana and 91 P. ferruginea) and 1203 from 60 archaeological deposits deriving from 36 sites, both coastal and continental. Giant limpets’ context also has been described and it has been related with a wide variety of deposits ranging from food refuse accumulations to occupations and burials.Detailed morphological and surface analysis allowed us to determine extraction methods and anthropic transformations. On coastal sites, the giant limpet record starts with Neanderthal populations from the Middle Palaeolithic and continues throughout the Upper Palaeolithic, Mesolithic, Neolithic, and Copper Age. On inland sites, giant limpets appear first in reduced numbers during the Late Neolithic and have been often worked into elliptical contours with polished, rib-free, external shell surfaces. In this study, we focus on the Copper Age, when giant limpet use becomes common, and records include tholoi, dolmens and other funerary contexts. The data indicate that the use of P. ferruginea is associated with Los Millares and El Argar cultures. Giant limpets use declines during the Bronze Age probably due to the major cultural shift that occurred during the Chalcolithic to Bronze transition.The data suggest that giant limpets should be considered as proxies of long-range trade during the Chalcolithic. We propose a new hypothesis linking giant limpets symbology with orbital/tidal variations and the ubiquitous use of marine elements as symbolism during this period.Our study highlights the relevance of shells in the reconstruction of the symbolic evolution of prehistoric cultures, as well as their connections with local ecosystem resources and regional commerce networks.

Multilayer Shells Interacting Through Friction

Abstract The corresponding author had the pleasure of attending an excellent symposium titled “Experimental and Theoretical Micro- and Nano-Mechanics: Honoring the Contributions of Prof. Kyung-Suk Kim” organized by Professors Ashraf Bastawros, Wendy Crone, Yanfei Gao, and Ruike (Renee) Zhao as part of the 2022 Society of Engineering Sciences Annual Technical Meeting held in College Station, TX on October 16–19, 2022. The symposium was held in honor of Prof. Kim’s 70th Birthday and celebrated over 40 years of Prof. Kim’s independent research achievements across several areas of Applied Mechanics. The present paper is dedicated to Prof. Kim, a great colleague at Brown University.We present a new formulation for the multilayer isogeometric Kirchhoff–Love (KL) shells, where the individual layers are assumed to interact through no-penetration and frictional contact. This work is largely motivated by the experiments and analysis presented in Poincloux et al. (2021, “Bending Response of a Book With Internal Friction,” Phys. Rev. Lett., 126(21), p. 218004). We utilize a regularized version of Coulomb’s friction law to model the tangential traction between the contacting shell surfaces. To ensure objectivity (i.e., reference-frame invariance) in the frictional model, we propose two different strategies to extrapolate the velocity vectors of the contact pair at the contact interface: (i) using the underlying KL kinematics of the individual shell layers and (ii) using the Taylor series-based extension from Kamensky et al. (2019, “Peridynamic Modeling of Frictional Contact,” J. Peridyn. Nonlocal Model., 1(2), pp. 107–121). We compare the performance of both approaches through a numerical benchmark example. We then validate our multilayer shell formulation using the “bending response of a book with internal friction” experiments of Poincloux et al. (2021, “Bending Response of a Book With Internal Friction,” Phys. Rev. Lett., 126(21), p. 218004).

ПОДГОТОВКА ПОВЕРХНОСТЕЙ ИЗ РАЗЛИЧНЫХ МАТЕРИАЛОВ КОМБИНИРОВАННЫМИ МЕТОДАМИ ДЛЯ ОБЕСПЕЧЕНИЯ КАЧЕСТВА СБОРОК НЕЖЕСТКИХ ОБОЛОЧЕК

The objects of research in this work are technologies for preparing surfaces of non-rigid finned shells of the ogival profile for assembly for soldering with the exception of defects and ele-ments of abrasive caricature on conjugated surfaces

Shell formation in two species of bivalves: the role of mantle cells and haemocytes

Abstract The shell of bivalves acts as structural support, defence against predators, stressors, and maintenance of homeostasis. Haemocytes and mantle epithelial cells participate in shell formation. Mantle epithelial cells produce the organic matrix of the shell and are associated with biomineralization because of their proximity to the shell surface and ability to maintain shell deposition ex vivo. Haemocytes play an immunological role and are involved in Ca2+ and CO32- intracellular transport implicated in shell mineralization. This study aims to evaluate the expression of molecules that play key roles in internal defence and the nervous system, in epithelial cells and haemocytes of the outer mantle margin of two species of bivalves, Polititapes aureus Gmelin, 1791 and Cerastoderma glaucum Bruguière, 1789, to highlight their collaborative role in shell formation. Our data show for the first time the presence of serotonin/S100 protein, and TLR2/iNOS colocalization in the haemocytes and mantle epithelial cells of P. aureus and C. glaucum, suggesting that the mantle cells perform their canonical role of sensory and biomineralizing activity, while the haemocytes perform their typical immune function, and their collaboration in shell formation, providing new information on cellular interactions in shell formation and giving more details for taxonomical studies.

Use of interpolation methods for modeling the stress-strain state of operated oil storage tanks

The aim of the research is the comparison of two approaches for computer modeling of the stress-strain state of thin-walled shells of engineering structures, considering the imperfections of the geometric shapes arising due to their operation. The object of the study is the operated steel vertical cylindrical reservoir with imperfections of the geometric shape intended for storage of petroleum products. The first, so-called classical, approach provides geometric modeling of the surface of the tank's shell with the subsequent import of the geometric model into one of the systems of finite element analysis to calculate the stress-strain state of the structure and determine its technical condition, and the possibility of further operation. The geometric modeling of the shell surface with imperfections was performed using a two-dimensional interpolation method based on the 1st order smoothness outlines implemented in the point calculus. The calculation of the stress-strain state of the shell was carried out in the SCAD Office computer complex, taking into account geometric and structural non-linearity on the basis of the octahedral tangential stress theory. The second approach assumes modeling of an array of functions of vertical deflection of the tank wall by means of interpolation, solution of an array of differential equations of the elastic cylindrical shell under axisymmetric loading, improved by introduction of vertical deflection functions of the wall, followed by two-dimensional interpolation and analysis of the deformed state of the shell based on displacements arising in the tank wall from the hydrostatic load. As a result of the effective use of two-dimensional interpolation in the process of implementing the second approach, it was possible to achieve a significant increase in the speed of the numerical solution while maintaining sufficient accuracy for engineering calculations.

Surfaces with a main framework of three given curves which include one circle

Superellipses are becoming more and more in demand in various branches of science and national economy due to their versatility. They found the most application in shipbuilding. Suggestions for the use of superellips in architecture and construction have appeared recently. The author proposes explicit and parametric equations of surfaces with a main framework of three predetermined superellips lying in three coordinate planes. These equations describe a large set of analytical shapes suitable for the formation middle surfaces of thin building shells. One of the superellipses is taken in a form of a circle. The shells can be designed on circular and rhombic plans, and also on plans in the shape of superellips of general type with convex and concave sides. All recommended surfaces are illustrated in 24 examples using computer graphics. A network of curvilinear non-orthogonal coordinates is generated on the surfaces using dimensionless independent parameters. The considered surfaces can become a part of the reserve of surfaces for further application in real structures and facilities.

Distributed optical fiber sensing technology in operation status monitoring of GIL equipment

Abstract This paper firstly proposes distributed fiber optic sensing technology based on big data technology and physics, distributed fiber optic sensing technology includes distributed fiber optic sensing technology based on interference type and distributed fiber optic sensing technology based on the scattering principle. Then investigated the demand for remote monitoring of distributed fiber optic sensing systems and the demand for large sensing networks in the Internet of Things and designed a long-distance distributed fiber optic sensing-based intelligent monitoring system. Finally, the vibration acceleration signal of the metal shell when partial discharge occurs is collected, and the high-frequency components in the vibration acceleration signal are used to diagnose and analyze the discharging faults caused by the metal particles of GIL. The results show that: when the rated current is loaded on the GIL, the main frequency distribution of the vibration acceleration signal on the surface of the metal shell is from 0 to 1 kHz, and the percentage of the signal energy in this frequency band is greater than 99% of the total energy in the range of 0 to 20 kHz. In the frequency range of 1 kHz to 20 kHz, the percentage of the signal energy in the total energy does not exceed 1%, and there is almost no high-frequency vibration acceleration signal. This study and the combination of these two technologies is a great contribution to the further development of each, but also more favorable for application in work and life.

Hollow STW‐Type Zeolite Single Crystals with Aluminum Gradient for Highly Selective Production of p‐Xylene from Methanol‐Toluene Alkylation

AbstractZeolites with uniform micropores are important shape‐selective catalysts. However, the external acid sites of zeolites have a negative impact on shape‐selective catalysis, and the microporosity may lead to serious diffusion limitation. Herein, we report on the direct synthesis of hierarchical hollow STW‐type zeolite single crystals with a siliceous exterior. In an alkalinous fluoride medium, the nucleation of highly siliceous STW zeolites takes place first, and the nanocrystals are preferentially aligned on the outer surface of the gel agglomerates to grow into single crystalline shells upon crystallization. The lagged crystallization of the internal Al‐rich amorphous gels onto the inner surface of nanocrystalline zeolite shells leads to the formation of hollow cavities in the core of the zeolite crystals. The hollow zeolite single crystals possess a low‐to‐high aluminum gradient from the surface to the core, resulting in an intrinsic inert external surface, and exhibit superior catalytic performance in toluene methylation reactions.