Hexagonal Tubes Research Articles

Mathematical Model Development on the Deformation Behaviour of Symmetric Hexagonal of Various Angles and Square Tubes under Lateral Loading

The purpose of this research is to develop a mathematical model of the collapse behaviour of symmetric hexagonal tubes. For that, a finite element analysis procedure was conducted using ABAQUS software to determine the lateral collapse behaviour of symmetric hexagonal of angles, and square tubes to compare the results with the cylindrical tube. Then, a new predictive mathematical model of the lateral collapse behaviour for the generalized symmetrical geometric tubes is developed based on rigid, perfectly plastic model and the energy balance method. The newly mathematical model was validated with the simulation method results. It was discovered that symmetric hexagonal and square tubes performed different deformation behaviour than the cylindrical tube. Square and symmetric hexagonal with tubes performed Type II deformation behaviour.Symmetric hexagonal tubes with performed Type I with the perfectly plastic collapse behaviour whereas cylindrical tube performed Type I with strain hardening deformation behaviour. The mathematical prediction model had managed to model the deformation behaviour of symmetric hexagonal tubes with but failed to model the square and symmetric hexagonal with tubes because it was the perfectly plastic model which suitable for Type I with perfectly plastic deformation behaviour.

IMPROVEMENT OF ENERGY ABSORPTION OF THIN WALLED HEXAGONAL TUBE MADE OF MAGNESIUM ALLOY BY USING TRIGGER MECHANISMS

This paper describes potentially the using of magne sium alloy as an energy longitudinal member used in crashworthiness applications. Since magnesium alloys are lighter we ight material, they are preferred to use to decreas e the environmental pollution and fuel consumptions. Non-linear finite element wa s used to simulate the crash behaviour of the thin walled hexagonal tube. The tube was subjected to both direct and oblique loading. T rigger mechanism was applied in this study. The aim of using trigger is to decrease the initial peak load and to enhance the energy abs orption capability of the tube and also crash force efficiency. Three trigger geometries have been applied circular, rectangular and elliptical geometry. Three type of trigger dist ribution already have been studied. The positions and the size of triggers are also investigated. It was found that the 10% per creductions with elliptical trigger revealed the best choice; it shows enhancin g in energy absorption and CFE about10 per cent and decreasing in peak force by 10 per cent too.

ENHANCEMENT OF ENERGY ABSORPTION OF THIN WALLED HEXAGONAL TUBE BY USING TRIGGER MECHANISMS

This paper presents the using of non-linear finite element simulations on the crash behavior and to en hance the energy absorption of the thin walled hexagonal tube subjected to dynamic loading and to decrease the peak load to ensure th e occupants safety during front collisions. Triggers have been applied to the thin walled hexagonal tube. Three trigger geometri es have been applied circular, rectangular and elliptical geometry. Three type of trigger distribution already have been studied. The positions and the size of triggers are also investigated. It was found that tper cent reductions with elliptical trigger revealed the best choice, it shows enhancing in energy absorption about 8 percent and CFE about 13 percent and decreasing in peak force bpercent.

РАСЧЕТНОЕ МОДЕЛИРОВАНИЕ РАДИАЦИОННОГО ФОРМОИЗМЕНЕНИЯ ТЕПЛОВЫДЕЛЯЮЩЕЙ СБОРКИ РЕАКТОРОВ НА БЫСТРЫХ НЕЙТРОНАХ

A computational analysis problem of deformation of a hexagonal wrapper tube in a fuel assembly (FA) of sodium-cooled fast reactors (the BN-type reactors), accounting for radiation-induced swelling and radiation-induced creep is solved. Determining equations for calculating the radiation-induced shape changes in FA's using the finite-element method are presented. The material parameters of the radiation-induced shape changes in FA's in are obtained based on the experimental data. The results of computational-and-experimental analysis of the shape changes in the wrapper tube of the BT-type reactor FA accounting for the radiation-induced swelling and radiation-induced creep are given. Results of the studies done showed that blocks developed to take account of the radiation-induced swelling and radiation-induced creep make it possible to analyze the FA shape changes in the core. Keywords: radiation-induced swelling, radiation-induced creep, fuel assembly, post-irradiation examination, analysis.

An Evaluation of Samarra City Drinking Water Treatment Plants

Global population increases specially in developing countries such Iraq requires more effort and investment in water and sanitation facilities to enhance the welfare of people in meeting the MDG objectives. The competition for water resources coupled with the generation of wastewater is creates additional pressure on the available supplies and increasing pollution level. To address such challenges it has become necessary to build new or enhance existing treatment systems. In different part of Iraq including in Samarra City effort is being made to enhance the water quality in regard to its physical, chemical, and biological characteristics as well as the minerals and organic substances which may produce adverse physiological effects. In order to evaluate different aspect of water quality this study focused on evaluating the drinking water quality and also the performance of the two treatment plants in Samarra City located on the left bank of Tigris River to the north of Baghdad City. The investigation covered the period of December, 2004 to May, 2005. The first is the main conventional water treatment plant with a capacity of 2400m3/hr. and the second is a compact unit with a capacity of 200m3/hr. The collected water data cover some of the important physical and chemical parameters of water quality; covering temperature, TDS, turbidity, pH and residual chlorine. While the bacteriological parameters covered total plate count (TPC) and E-coli for stages of treatment plants. The results show that turbidity of raw water is not high (3.84-425) NTU compared with Al-Karkh water project in Baghdad City (6-1400) NTU, because the intakes of WTPs are located in the downstream of Samarra barrage which serves as a pre-sedimentation tank. Low clarifiers turbidity removal efficiencies of (48.323 %) and (32.09 %) were obtained for treatment plant and compact unit respectively, while for filters removal efficiencies were (63.2 %) and (39.05 %) respectively. The monthly average turbidity of supplied water for conventional water treatment plant and compact unit were (4.3 and 18.2) NTU, the percent of violation to Iraqi Specifications were (29.4 % and 64.7%) respectively. Not always, increasing in raw water turbidity result in an increase in turbidity removal efficiency. pH values and TDS concentrations of supplied water are within Iraqi, EPA and WHO Specifications. Low amount and interrupted chlorination in WTP and CU, so, irregular chlorination results in frequent outbreak of waterborne diseases. It can be recommend to improve the water quality monitoring program through the application of; coagulant aids to overcome the high turbidity of raw water during the rainy season, the hexagonal tube settler in the sedimentation tank of the compact unit to get the designed SOR and anthracite with sand as a dual porous media to increase the filtration rate to overcome the shortage in hot seasons. Also periodic systematic maintenance for different units of treatment plants is required.

Electrochemical synthesis and surface characterization of hexagonal Cu–ZnO nano-funnel tube films

An electrochemical deposition technique was used to synthesis hexagonal nano-funnel tube films on zinc foil, utilizing an electrolyte of ZnCl 2 +H 2 O 2 under ambient conditions. The structures, morphologies, chemical compositions, and optical properties of the synthesized films were characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible diffuse reflectance spectrometry (UV-vis-DRS), photoluminescence (PL) spectrometry, and energy-dispersive X-ray spectrometry (EDS) techniques. The XRD pattern showed a set of diffraction peaks that were indexed to the ZnO, Zn(OH) 2 , and Cu phases. The SEM observations revealed a cauliflower-like morphology consisting of branches in the form of nano-funnel tubes. The TEM results demonstrated that the synthesized film was comprised of several branches. The EDS studies confirmed the presence of only Cu, Zn, and O atoms. The UV-vis-DRS spectrum showed the onset of the band gap absorption peak at ∼375 nm. The PL studies evaluated various emission bands that originated from different defect mechanisms. In addition, the hexagonal nano-funnel tube film showed a good superhydrophobicity, with a water contact angle of ∼153°. ► Large-scale Cu–ZnO nano-funnel tubes were synthesized by an electrochemical deposition technique. ► Key factor for obtaining funnel tube shape is use of specific voltage without electrolyte stirring. ► The results suggest the suitability of this material for device applications.

Systematic morphology and phase control of Mg-ptcda coordination polymers by Ostwald ripening and self-templating

Mg-ptcda (ptcda = perylene-3,4,9,10-tetracarboxylic dianhydride) coordination polymer particles (CPPs) with special hexagonal tubes morphology were manufactured by a self-assembly and hydrothermal method. The growth process from unstable nanoribbons to metastable hexagonal rods to a core–shell structure and finally to the stable hexagonal tubes was achieved and investigated by SEM and XRD characterizations. The morphology of Mg-ptcda is mainly controlled by Ostwald ripening and self-templating mechanism. Mg-ptcda CPPs with various morphologies, such as hexagonal rings and snowflakes, and particle sizes from micro to nanoscale can be finely tuned using organic solvent as additives. The optical properties of Mg-ptcda CPPs show that incorporation of ptcda dyes in coordination polymers can efficiently reduce their aggregation and interaction in the solid state. Furthermore, porous MgO nanomaterials with various morphologies can be fabricated from Mg-ptcda CPP precursors by a simple thermal treatment process.

Experimental study on convective heat transfer coefficient around a vertical hexagonal rod bundle

Research on convective heat transfer coefficient around a rod bundle has many diverse applications in industry. So far, many studies have been conducted in correlations related to internal and turbulent fully-developed flow. Comparison shows that Dittus-Boelter, Sieder-Tate and Petukhov have so far been the most practical correlations in fully-developed turbulent fluid flow heat transfer. The present study conducts an experimental examination of the validity of these frequently-applied correlations and introduces a manufactured test facility as well. Due to its generalizibility, the unique geometry of this test facility (hexagonal arranged, 7 vertical rods in a hexagonal tube) can fulfil extensive applications. The paper also studies the major deviation sources in data measurements, calibrations and turbulence of fluid flow in this. Finally, regarding to sufficient number of experiments in a vast fluid mean velocity range (3,800 < Re < 40,000), a new curve and correlation are presented and the results are compared with the above mentioned commonly-applied correlations.

Structure determination of neutral MgO clusters—hexagonal nanotubes and cages

Structural information for neutral magnesium oxide clusters has been obtained by a comparison of their experimental vibrational spectra with predictions from theory. (MgO)(n) clusters with n = 3-16 have been studied in the gas phase with a tunable IR-UV two-color ionization scheme and size-selective infrared spectra have been measured. These IR spectra are compared to the calculated spectra of the global minimum structures predicted by a hybrid ab initio genetic algorithm. The comparison shows clear evidence that clusters of the composition (MgO)(3k) (k = 1-5) form hexagonal tubes, which confirm previous theoretical predictions. For the intermediate sizes (n≠ 3k) cage-like structures containing hexagonal (MgO)(3) rings are identified. Except for the cubic (MgO)(4) no evidence for bulk like structures is found.

Characterization of ZnO Nanotube Fabricated by the Plasma Decomposition of Zn(OH)2 Via Dielectric Barrier Discharge

Here, we report a new and rapid way to decompose Zn(OH)2 for the fabrication of ZnO nanotube using dielectric barrier discharge (DBD) plasma initiated at ambient condition. X-ray diffraction, field emission scanning electron microscope and high-resolution transmission electron microscopy were employed to characterize the fabricated ZnO nanotube. The results show that hexagonal hollow tubes in a wurtzite phase are obtained. Compared to the ZnO powder prepared by the thermal calcination, the DBD plasma made ZnO nanotube shows an enhanced performance for H2S removal at low temperature.

Multiscale modeling of lymphatic drainage from tissues using homogenization theory

Lymphatic capillary drainage of interstitial fluid under both steady-state and inflammatory conditions is important for tissue fluid balance, cancer metastasis, and immunity. Lymphatic drainage function is critically coupled to the fluid mechanical properties of the interstitium, yet this coupling is poorly understood. Here we sought to effectively model the lymphatic-interstitial fluid coupling and ask why the lymphatic capillary network often appears with roughly a hexagonal architecture. We use homogenization method, which allows tissue-scale lymph flow to be integrated with the microstructural details of the lymphatic capillaries, thus gaining insight into the functionality of lymphatic anatomy. We first describe flow in lymphatic capillaries using the Navier–Stokes equations and flow through the interstitium using Darcy's law. We then use multiscale homogenization to derive macroscale equations describing lymphatic drainage, with the mouse tail skin as a basis. We find that the limiting resistance for fluid drainage is that from the interstitium into the capillaries rather than within the capillaries. We also find that between hexagonal, square, and parallel tube configurations of lymphatic capillary networks, the hexagonal structure is the most efficient architecture for coupled interstitial and capillary fluid transport; that is, it clears the most interstitial fluid for a given network density and baseline interstitial fluid pressure. Thus, using homogenization theory, one can assess how vessel microstructure influences the macroscale fluid drainage by the lymphatics and demonstrate why the hexagonal network of dermal lymphatic capillaries is optimal for interstitial tissue fluid clearance.

Crushing Behavior of Composite Hexagonal Ring System

An extensive experimental investigation of inplane crushing of composite hexagonal ring system between platens has been carried out. Woven roving glass/epoxy hexagonal ring system with different angles and arrangement were employed. The rings angles are varying between 45 and 70°. The wet winding process was used to fabricate the woven E-glass fabric /epoxy specimens. Four layers of woven E-glass fabric/epoxy wrapped over wooden mandrel to get thickness of about 3 mm. The composite hexagonal tubes were then cured at room temperature (32oC) for 24 hours to provide optimum hardness and shrinkage. Repeatability of the results was ensuring by performing the experiments on three identical specimens. Typical histories of their crushing mechanism are presented. Behavior of ring as regards the initial crushing load, post crushing load, energy absorbed and mode of crushing has been presented and discussed. Results showed that the crush failure loads and energy absorption capability are greatly affected by the hexagonal ring geometry, arrangement and loading conditions. As the ring angle increases the energy absorption capacity increases. Composite hexagonal ring with 70 degree exhibited the highest energy absorption capability among tested specimens. It is also found that energy absorption capability for systems crushed in-plane X2 higher than X1.

Desktop Magnetic Shielding System for the Calibration of High-Sensitivity Magnetometers

The objective of the study is a development of desk-top magnetic shielding system for the calibration of high-sensitive magnetometers, and the evaluation of their ability to produce a uniform magnetic field. This system consists of hexagonal tubes and a cylinder. The hexagonal tubes have a double-layered structure, an opening and an advantage in axial shielding performance. The cylinder has openings and an advantage in transverse shielding performance. A solenoid-like coil is wound around the hexagonal tubes to produce a uniform magnetic field. From the experimental results, the magnetic shielding and the calibration field properties are demonstrated. Within the half length of the system, the achieved total magnetic field (dc component) is less than 200 nT within ± 50 nT deviation, and the measured shielding factor is larger than 250. For producing a uniform magnetic field up to 10 kHz, we can use the 1/3 length of the system.

Structural types of boron nitride particles produced by carbothermal synthesis

Transmission electron microscopy and microdiffraction are used to examine boron nitride produced by carbothermal synthesis (using saccharose as a carbon-containing component) in the temperature range 1000–1450°C in nitrogen. It is established that onion-like particles form during structural ordering of turbostratic boron nitride in the range 900 − 1000°C. The structural types of BN particles are classified according to: 1) crystal morphological features (onion-like particles, cylindrical and faceted tubes, and lamellas), 2) formation mechanisms (structures of growth formed through nucleation and structures of breakdown formed through structural transitions), and 3) synthesis temperatures. The tubes grow from the gas phase and their crystal morphological forms differ in phase composition (cylindrical tubes consist of the hexagonal BN phase and faceted tubes of the rhombohedral one). At T ≥ 1350°C, rhombohedral–hexagonal phase transition and transformation into multilayered polytypes occur in faceted tubes due to a highly anisotropic thermal expansion coefficient of graphite-like modifications of boron nitride.

Experimental qualification of subassembly design for Prototype Fast Breeder Reactor

The Prototype Fast Breeder Reactor (PFBR) which is under construction at Kalpakkam, India, is a 500 MWe sodium cooled pool type reactor. The core of the PFBR consists of 1758 free standing subassemblies supported on the grid plate. The entire core is divided into 15 different flow zones and the flow rate required through each zone is calculated based on the fission heat generation. The coolant sodium flows from the bottom of the subassembly to top and the design of the subassembly for each flow zone is quite complex. There are 181 fuel subassemblies in PFBR core with 217 fuel pins in each subassembly, vertically held in the form of bundle within a hexagonal wrapper tube. The pins are separated by spacer wires wound around the pins helically. Analytical prediction of subassembly pressure drop, vibration and determination of inception of cavitation for this complex geometry is very difficult. So experiments were conducted extensively to get a more accurate evaluation of the design and for its qualification for the use in PFBR, which is designed for 40 years of operation. Pressure drop and cavitation experiments were carried out in water on full scale (1:1) subassemblies of all flow zones. The overall pressure drop of the subassembly determines the ratings of the pump. Cavitation of the pressure drop devices lead to erosion damage of fuelpins and may also result in reactivity fluctuation due to sodium-void effect. So it is essential to confirm that the subassembly is not cavitating in the operating regime of the reactor. Subassembly can vibrate in cantilever mode due to the turbulence in the flow and can result in reactivity fluctuation, reactor control problem and can even lead to the failure of the fuel pins. So vibration measurements were carried out in water on the maximum rated subassembly. This paper discusses various experiments carried out on PFBR subassembly, the similarity criteria followed, instrumentation, results and conclusion.

Crushing Behavior of Thin-Walled Hexagonal Tubes with Partition Plates

The crushing behaviour of hexagonal thin-walled tube with partition plates subjected to axial compression is studied by using finite element method. It is found that, in the crushing process, the folds, which generate along the full length of the tube, come to be crushed simultaneously and the compressive load will not descend, since the compressive load produced in the central part does not descend with the folds forming on outer walls. Therefore, in order to suppress a fluctuation of the compression load in crushing of the tube and to raise its average compression load, it is an effective method to introduce corner parts, especially corner parts where three plates intersect, in the geometry of the thin-walled tube.

Electrochemistry of tin in the 1-ethyl-3-methylimidazolium dicyanamide room temperature ionic liquid

The electrochemistry of Sn(II) was studied in the room temperature ionic liquid 1-ethyl-3-methylimidazolium dicyanamide (EMI-DCA) on a glassy carbon (GC) and a polycrystalline Pt electrode at 40 °C. The Sn(II) species was introduced into the ionic liquid by either dissolution of SnCl 2 or anodizing a Sn wire. The reduction potential of the Sn(II)/Sn couple produced in these two solutions was found to be different, indicating that different Sn(II) species may be present. The order of the reduction potential of the two Sn(II) species indicates that the Gutmann donor ability of the anions is likely to be DCA − > Cl −. Cyclic voltammetry indicates the stripping efficiency is >90% on the Pt but only 40% on the GC electrode. Analysis of the chronoamperometric transient behavior during electrodeposition suggests that the deposition of Sn on the GC electrode involves a three dimensional progressive nucleation on a finite number of active sites. The diffusion coefficient of SnCl 2 dissolved in the EMI-DCA was found to be 9.8 × 10 −7 cm 2 s −1 which is in the same order of magnitude as those reported for SnCl 2 in several other ionic liquids. Depending on the deposition potentials, potentiostatic electrolysis produced Sn deposits with various unusual morphologies such as hexagonal tubes, spiral nanowires, and dendrite.

Shape-controlled synthesis and luminescence properties of yttria phosphors

Y(OH)3 hexagonal tubes with embedded polyhedrons (HTEPs) were successfully prepared by a facile hydrothermal method using sodium citrate as the crystal modifier, and as-synthesized products exhibit uniform diameter and length of about 2 μm and 2–3 μm, respectively. An oriented aggregation and subsequent dissolution-recrystallization process was proposed to explain the growth mechanism of obtained products. Y2O3 : Eu3+ microstructures with similar morphologies were obtained after thermal treatment of the as-prepared Y(OH)3 : Eu3+ microstructures at 1000 °C for 2 h. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fluorescence spectrometer were used to characterize the samples. The photoluminescence properties investigation reveals that Y2O3 : Eu3+ HTEPs show a strong red emission with the strongest peak centered at 614 nm under the excitation of 259 nm ultraviolet light.

Adsorption of H2 on MgO clusters studied by ab initio method

Based on the most stable structures of the magic MgO clusters, the adsorption of H2 onto the rocksalt and hexagonal tube (MgO)9,12 is studied using first principal method. The results show that physical adsorption can be formed on Mg+q or O-q ions at different sites of the clusters. On the top of the Mg+q ions, H2 is adsorbed in the side-on manner and donates electrons to the ions. On the top of the O-q ions, H2 is adsorbed in the end-on manner and the molecule is polarized. The strength of the adsorption depends mainly on the location of the Mg/O ions, and the smaller the coordination number of the ions, the stronger the adsorption of H2 is. For the Mg/O ions with the same coordination number, the adsorption formed onto the Mg+q is stronger. According to the Mg or O ions and their locations, the adsorption energy ranges from 0.03 eV to 0.08 eV.

ICONE19-43857 Investigation on Velocity Distribution in an Inner Subchannel of Wire Wrapped Fuel Pin Bundle of Sodium-cooled Fast Reactor

A sodium cooled fast reactor is designed to attain a high burn-up of core fuel in commercialized fast reactor cycle systems. In high burn-up fuel subassemblies, deformation of fuel pin due to the swelling and thermal bowing may decrease local flow velocity via change of flow area in the subassembly and influence the heat removal capability. Therefore, it is important to obtain the detail of flow velocity distribution in a wire wrapped pin bundle. In this study, water experiments were carried out to investigate the detailed velocity distribution in a subchannel of nominal pin geometry as the first step. These basic data are not only useful for understanding of pin bundle thermal hydraulics but also a code validation. A wire-wrapped 3-pin bundle water model was applied to investigate the detailed velocity distribution in the subchannel which is surrounded by 3 pins with wrapping wire. The test section consists of an irregular hexagonal acrylic duct tube and three pins made of fluorinated resin pins which has nearly the same refractive index with that of water and a high light transmission rate. This enables to visualize the central subchannel through the pins. The velocity distribution in the central subchannel with the wrapping wire was measured by PIV (Particle Image Velocimetry) through a side wall of the duct tube. Typical flow velocity conditions in the pin bundle were 0.36m/s (Re=2,700) and 1.6m/s (Re=13,500). Influence of the wrapping wire on the velocity distributions in vertical and horizontal directions was confirmed. A clockwise swirl flow around the wire was found in subchannel. Significant differences were not recognized between the two cases of Re=2,700 and 13,500 concerning flow patterns.