Mechanical stress and deformation analyses of pressurized cylindrical shells based on a higher-order modeling

In this research,mechanical stress,static strain and deformation analyses of a cylindrical pressure vessel subjected to mechanical loads are presented.The kinematic relations are developed based on higherorder sinusoidal shear deformation theory.Thickness stretching formulation is accounted for more accurate analysis.The total transverse deflection is divided into bending,shear and thickness stretching parts in which the third term is responsible for change of deflection along the thickness direction.The axisymmetric formulations are derived through principle of virtual work.A parametric study is presented to investigate variation of stress and strain components along the thickness and longitudinal directions.To explore effect of thickness stretching model on the static results,a comparison between the present results with the available results of literature is presented.As an important output,effect of micro-scale parameter is studied on the static stress and strain distribution.

Multi-stage rodingitization of ophiolitic bodies from Northern Apennines(Italy): Constraints from petrography, geochemistry and thermodynamic modelling

The investigated mantle bodies from the External Ligurians(Groppo di Gorro and Mt.Rocchetta)show evidences of a complex evolution determined by an early high temperature metasomatism,due to percolating melts of asthenospheric origin,and a later metasomatism at relatively high temperature by hydrothermal fluids,with formation of rodingites.At Groppo di Gorro,the serpentinization and chloritization processes obliterated totally the pyroxenite protolith,whereas at Mt.Rocchetta relics of peridotite and pyroxenite protoliths were preserved from serpentinization.The rodingite parageneses consist of diopside+vesuvianite+garnet+calcite+chlorite at Groppo di Gorro and garnet+diopside+serpentine±vesuvianite±prehnite±chlorite±pumpellyite at Mt.Rocchetta.Fluid inclusion measurements show that rodingitization occurred at relatively high temperatures(264-334℃ at 500 bar and 300-380℃ at 1 kbar).Garnet,the first phase of rodingite to form,consists of abundant hydrogarnet component at Groppo di Gorro,whereas it is mainly composed of grossular and andradite at Mt.Rocchetta.The last stage of rodingitization is characterized by the vesuvianite formation.Hydrogarnet nucleation requires high Ca and low silica fluids,whereas the formation of vesuvianite does not need CO2-poor fluids.The formation of calcite at Groppo di Gorro points to mildly oxidizing conditions compatible with hydrothermal fluids;the presence of andradite associated with serpentine and magnetite at Mt.Rocchetta suggests Fe^3+-bearing fluids with fO2 slightly higher than iron-magnetite buffer.We propose that the formation of the studied rodingite could be related to different pulses of hydrothermal fluids mainly occurring in an oceancontinent transitional setting and,locally,in an accretionary prism associated with intra-oceanic subduction.

Simulating the Turbulent Hydrothermal Behavior of Oil/MWCNT Nanofluid in a Solar Channel Heat Exchanger Equipped with Vortex Generators

Re-engineering the channel heat exchangers(CHEs)is the goal of many recent studies,due to their great importance in the scope of energy transport in various industrial and environmental fields.Changing the internal geometry of the CHEs by using extended surfaces,i.e.,VGs(vortex generators),is the most common technique to enhance the efficiency of heat exchangers.This work aims to develop a newdesign of solar collectors to improve the overall energy efficiency.The study presents a new channel design by introducing VGs.The FVM(finite volume method)was adopted as a numerical technique to solve the problem,with the use of Oil/MWCNT(oil/multi-walled carbon nano-tubes)nanofluid to raise the thermal conductivity of the flow field.The study is achieved for a Re number ranging from12×10^(3) to 27×10^(3),while the concentration(φ)of solid particles in the fluid(Oil)is set to 4%.The computational results showed that the hydrothermal characteristics depend strongly on the flow patterns with the presence of VGs within the CHE.Increasing the Oil/MWCNT rates with the presence of VGs generates negative turbulent velocities with high amounts,which promotes the good agitation of nanofluid particles,resulting in enhanced great transfer rates.

Mineral fibres and environmental monitoring:A comparison of different analytical strategies in New Caledonia

Covered by ultrabasic units for more than a third of its surface,the New Caledonia(South West Pacific)is one of the largest world producers of Ni-ore from lateritic deposits.Almost all outcrops of geological units and open mines contain serpentine and amphibole,also as asbestos varieties.In this geological context,in which weathering processes had a great contribution in the production and dispersion of mineral fibres into the environment,the development of a routinely analytical strategy,able to discriminate an asbestiform fibre from a non-harmful particle,is a pivotal requisite.However,the acquisition of all these parameters is necessary for determining the risk associated to fibres exposition.A multidisciplinary routinely approach,based on the use of complementary simply-to-use but reliable analytical methods is the only possible strategy.In addition,the instrumental apparatus must be easily transportable on the field,directly on the mining site.The employment of specialized tools such as Polarized Light Microscopy associated to Dispersion Staining method(PLM/DS)and portable Raman spectroscopy for identification of environmental asbestos,are proved extremely effective in the improvement of the performance and rapidity of data acquisition and interpretation.Both PLM/DS and handheld Raman devices confirmed to be discriminant in the detection and characterization of asbestos fibres for both serpentine and amphibole.Furthermore,these techniques proved extremely effective even in the presence of strongly fibrous and altered samples.

Modified couple stress and thickness-stretching included formulation of a sandwich micro shell subjected to electro-magnetic load resting on elastic foundation

This paper studies electromagnetoelastic static investigation of a sandwich doubly curved microshell subjected to multi-field loading based on a new thickness stretching included refined higher order shear/normal deformable model.Modified-couple-stress-theory(MCST)is used for accounting small-scaledependency.The numerical results are derived using an analytical method.The effect of small scale parameter in micro scale,initial electric and magnetic potentials and foundation parameters is studied on the electromagnetoelastic bending results.It is confirmed an enhancing in stiffness of small scale shell with an increase in micro length scale parameter.

New Caledonia Ophiolite, Marginal Rifting to Fore-arc Evolution

The New Caledonia Ophiolite(Peridotite Nappe), represents about one third of the island’s surface(i.e. 5 500 km2). The ophiolite is composed of harzburgites, dunites, lherzolites, minor mafic-ultramafic cumulates, and various dykes and sills. The mantle section underwent a polyphase evolution, which involved prominent depletion and re-fertilization. The oldest events are probably recorded by abyssal-type lherzolites of the northern massifs, which bear traces of moderate partial melting. Plagioclase lherzolites were formed by shallow entrapment of highly depleted MORB melt in residual spinel lherzolites. Nd isotope compositions are consistent with derivation from an asthenospheric mantle source that experienced a recent MORB-producing depletion. This evolution was most likely accomplished during the late Cretaceous breakup of the eastern Australian margin. The harzburgite-dunite association, which forms the bulk of Peridotite Nappe was probably formed through a multistage magma-producing process. Harzburgites composition may have be obtained by a first phase of ~15% dry fractional melting, followed by 15%–18% hydrous melting in a supra-subduction zone setting. Variable εNd negatively correlate with 87Sr/86Sr, while Pb isotopes cover a wide range, trending from depleted mantle towards enriched, sediment-like, compositions. Such signatures likely reflect the evolution of a highly depleted forearc mantle wedge variably modified by different fluid and melt inputs during Eocene subduction. The harzburgite-dunite set is overlain by a dunite transition zone ~300 m thick, in turn discontinuously covered by cumulate lenses consisting of layered pyroxenites, dunites, and wherlites at the base and gabbronorites/websterites on top. The mafic cumulates crystallized from primitive, ultra-depleted melts in the nascent lower fore-arc crust. In particular, FME enrichments and Nd-Pb isotopes support an origin from a refractory mantle source modified by slab fluids for the gabbronorite-forming melts. The Peridotite Nappe has been extensively serpentinized(40% to 100%) with extremely scarce occurrences of unserpentinized rocks. Lizardite, brucite, magnetite and minor chrysotile developed from joints and intra-granular cooling cracks in a near-static environment. Serpentine-coated joints and peridotite foliation have been thereafter reopened and injected by various felsic, mafic and ultramafic supra-subduction melts emplaced within a narrow time interval(55–50 Ma), immediately after subduction inception at 56 Ma, i.e. the age of granulite-facies metamorphic sole. The youngest magmatic event is represented by island-arc tholeiite dykes dated at 50 Ma. A widespread set of antigorite and tremolite-bearing veins crosscut all previous structures in a progressively cooling forearc environment. The former are synkinematic crack seals, which display highly radiogenic, sediment-like 87Sr/86Sr ratios suggesting direct derivation of fluids from the subduction zone, while the latter bear mantle-like isotopic signatures and probably originated from the interaction of wall rocks with Ca-rich fluids released by Eocene dykes or fluids that leached them. Finally, continental subduction and obduction occurred during the 44–34 Ma interval and were accompanied by the development of the HP-LT metamorphic belt of northern New Caledonia, which constrains the polarity of subduction.

Palladium-Catalyzed Carbonylation of Multifunctionalized Substituted Alkynes to Quinolinone Derivatives under Mild Conditions

A highly selective palladium-catalyzed carbonylation of 2-alkynylanilines bearing an amide moiety to condensed six-membered heterocyclic structures has been developed under mild conditions(room temperature and atmospheric pressure of CO).The carbonylative protocol is also compatible with CO surrogates,such as benzene-1,3,5-triyl triformate(TFBen)or the newly developed calix[6]arenes functionalized with six formate groups(CLX[6]CO),which are both capable to release CO in situ.A series of tricyclic fused heterocycles containing the important oxazino-quinolinone scaffold have been selectively obtained(only the 6-endo-dig cyclization mode has been observed)in good to excellent yields(up to 99%).

Palladium Iodide-Catalyzed Selective Carbonylative Double Cyclization of 4-(2-Aminophenyl)-3-yn-1-ols to Dihydrofuroquinolinone Derivatives

The PdI_(2)/KI-catalyzed oxidative carbonylation of 4-(2-aminophenyl)-3-yn-1-ols,bearing two potential nucleophilic groups in suitable position selectively leads to dihydrofuroquinolinone derivatives in fair to high yields(60%—89%)and excellent turnover numbers(180—267 mol of product per mol of Pd)over 19 examples,through a mechanistic pathway involving initial O-cyclization followed by N-cyclocarbonylation.In such process,the selective catalytic construction of two rings and three new bonds is achieved in one synthetic step to afford high value added fused heterocyclic structures starting from readily available materials.

Synthesis and Characterization of Iron-Rich Glass Ceramic Materials：A Model for Steel Industry Waste Reuse

Wastes deriving from steel industry, containing large amounts of iron oxides and heavy metals, when collected in landfills are subjected to atmospheric agents, with consequent release of toxic substances in the soil and groundwater. The reuse of these wastes as raw materials for the production of advanced materials is a viable way both to overcome the environmental impact and to reduce the disposal costs,proposing new technologically advanced materials. This work aims to simulate these interesting glassceramics by using glass cullet coming from recycled municipal waste and high amount of iron（III） oxide（from 25 wt% to 50 wt%）, the prevalent component of steel waste. The oxide was mixed with glass cullet and vitrified. The samples composition and the microstructure were investigated by scanning electron microscopy（SEM）, and X-ray diffraction（XRD） was used to evaluate the nature of the crystalline phases.The chemical stability of the materials, in terms of ionic release into saline solution, was assessed. The electrical behavior of the samples was also investigated by varying the iron ions content and controlling the crystallization process. It is possible to obtain chemically stable materials with a nearly semiconducting behavior.

Galerkin finite element analysis of magneto-hydrodynamic natural convection of Cu-water nanoliquid in a baffled U-shaped enclosure

In this paper,single-phase homogeneous nanofluid model is proposed to investigate the natural convection of magneto-hydrodynamic(MIID)flow of Newtonian Cu—H20 nanoli­quid in a baffled U-shaped enclosure.The Brinkman model and Wasp model are considered to measure the effective dynamic viscosity and effective thermal conductivity of the nanoliquid coreespondingly.Nanoliquid's effective properties such as specific heat,density and thermal expansion coefficient are modeled using mixture theory.The complicated PDS(partial differ­ential system)is treated for numeric solutions via the Galerkin finite element method.The perti­nent parameters Hartmann number(1≤Ha≤60),Rayleigh number(10^(3)≤Ra≤10^(6))and nanoparticles volume fraction (0% ≤Ф≤4%) are taken for the parametric analysis, and it is conducted via streamlines and isotherms. Excellent agreement between numerical results and open literature. It is ascertained that heat transfer rate enhances with Rayleigh number Ra and volume fraction 0, however it is diminished for laiger Hartmann number Ha.

In Vivo Phenotyping for the Early Detection of Drought Stress in Tomato

Drought stress imposes a major constraint over a crop yield and can be expected to grow in importance if the climate change predicted comes about.Improved methods are needed to facilitate crop management via the prompt detection of the onset of stress.Here,we report the use of an in vivo OECT(organic electrochemical transistor)sensor,termed as bioristor,in the context of the drought response of the tomato plant.The device was integrated within the plant’s stem,thereby allowing for the continuous monitoring of the plant’s physiological status throughout its life cycle.Bioristor was able to detect changes of ion concentration in the sap upon drought,in particular,those dissolved and transported through the transpiration stream,thus efficiently detecting the occurrence of drought stress immediately after the priming of the defence responses.The bioristor’s acquired data were coupled with those obtained in a high-throughput phenotyping platform revealing the extreme complementarity of these methods to investigate the mechanisms triggered by the plant during the drought stress event.