DESIGN, MECHANICAL MODELING AND 3D PRINTING OF KOCH FRACTAL CONTACT AND INTERLOCKING

Topological interlocking is an effective joining approach in both natural and engineering systems. Especially, hierarchical/fractal interlocking were found in many biological systems and can significantly enhance the system mechanical properties. Inspired by the hierarchical/fractal topology in nature, mechanical models for Koch fractal interlocking were developed as an example system to better understand the mechanics of fractal interlocking. In this investigation, Koch fractal interlocking with and without adhesive layers were designed for different number of iterations N. Theoretical contact mechanics model was used to capture the deformation mechanisms of the fractal interlocking with no adhesive layers under relatively small deformation. Then finite element (FE) simulations were performed to study the mechanical behavior of fractal interlocking under finite deformation. The designs were also fabricated via a multi-material 3D printer (Objet Connex 260) and mechanical experiments were performed to further explore the mechanical performance of the new designs. It was found that the load-bearing capacity of Kotch fractal interlocking can be effectively increased via fractal design. In general, when the fractal complexity (it is specifically represented as number of hierarchy N in the present Koch fractal design) increases, the stiffness of the fractal interlocking will increase significantly. Also, when N increases, the stress are more uniformly distributed along the fractal boundary of the top and bottom pieces of the fractal interlocking, which efficiently reduce local stress concentration, and therefore the overall strength of the interlocking also increases. However, the mechanical responses of fractal interlocks are also sensitive to imperfections, such as the gap between the interlocked pieces and the rounded tips. When fractal complexity increases, the mechanical properties will become more and more sensitive to the imperfection and eventually, the negative influences from imperfection can even become dominant. Therefore, considering the imperfection, there is an optimal level of fractal complexity to reach the maximum mechanical performance. This result is in consistent with fractal interlocks in different biological systems. Except topology, the influences of friction, material properties and damage evolution, and the adhesive layer on the mechanical performance of Koch fractal interlocking were also evaluated via non-linear FE simulations and mechanical experiments on 3D printed Koch interlocking specimens. It was found that the adhesive layer can significantly improve the load transmission of the fractal interlocking and therefore can effectively amplify the interlocking efficiency

Removal of Reactive Red 74 Dye from Textile Industrial Waste using Zinc Oxide Nanoparticle

Global population growth and industrial activities in recent decades has been caused to enter excessive amount of pollutants to water resources. Industrial textile dyes are an important class of the pollutants in the sewage system. Disposal of the dyes in precious water resources must be avoided, however, and for that various treatment technologies are in use. Considering the toxicity of the pollutants, their removal from water resources is necessary. In this research, removal of reactive red 74, RR47, from aqueous solution by zinc oxide nanoparticles was investigated and the affecting parameters such as pH, contact time and adsorbent mass on removal efficiency were determined. Langmuir and Freundlich isotherms were studied and the results indicated that the adsorption process obey the Langmuir and Freundlich isotherms. The experimental results also showed that the pseudo-second order kinetic equation could nicely describe the sorption kinetics

Determination of Trace Amount of Cadmium in Real Water And Baby Food Samples By Microinjection Flame Atomic Absorption Spectrometry After Cloud Point Extraction Using Selective Synthesis Ligand

A cloud point extraction procedure was used for preconcentration and determination of trace amount of cadmium ion in real water and baby food samples by microinjection flame atomic absorption spectrometry and with using new synthesis dithiocarbamate ligand. The method is based on cloud point extraction of cadmium using triton X-114 as nonionic surfactant. A certain amount of ligand (Complexing Agent) and surfactant was added to samples and after pH adjustment; the sample was heated in a water bath. A hydrophobic complex was formed between cadmium and [N-(2-phenylethyl) dithiocarbamate] ligand and followed by its extraction into triton X-114 surfactant-rich phase.The surfactant-rich phase was diluted with suitable solvent and was separated with using centrifugation, and then measurements were performed with a micro-injection flame atomic absorption spectrometry. Extraction conditions such as pH, amount of Ligand (Complexing Agent) and Surfactant, equilibrium temperature and time, diluent volume and type were optimized. Also ionic strength effect and limit of interferences were studied. Under the optimum conditions, the limit of detection (3Sb/m) of 0.2 µg L-1, an enhancement factor of 116 and the relative standard deviation (5 µg L-1, n=5) of 4.5% were obtained. The calibration curve was linear for the concentration range of 0.5 to 20 µg L-1 with correlation coefficient of 0.9992. The proposed method was applied to determination of cadmium ion in water samples including tap water, mineral water, river water and sea water also baby food samples including infant formula powder (milk-based) and infant cereal Powder (wheat and milk-based).Â

Synthesis of nickel ferrite nanoparticles as an efficient magnetic sorbent for removal of an azo-dye: Response surface methodology and neural network modeling

In this research, nickel ferrite (NiFe2O4) nanoparticles (NFNs) are prepared through coprecipitation method, and applied for adsorption removal of a model organic pollutant, methyl orange (MO). The characterization of the prepared NFNs was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM). Optimization and modeling of the removal of MO applying NFNs were performed via central composite design (CCD) and the influential parameters including nano-sorbent amount, dye initial concentration, contact time and pH were considered as input variables for CCD. A dye removal percentage of 99 % was achieved under the optimum condition established for MO removal that was in agreeing with the predicted value. Additionally, multi-layer artificial neural network (ML-ANN) was applied to acquire a predictive model of MO removal. The isothermal investigation of MO adsorption was performed by developing Langmuir, Freundlich and Temkin models, and results showed that experimental data were best fit in Freundlich model. Based on the adsorption kinetics studies, the pseudo-second-order kinetic model was the best model to describe the adsorption mechanism of MO onto NFNs

Design, microstructure and mechanical characterization of Ti6Al4V reinforcing elements for cement composites with fractal architecture

This paper presents a study on the design, and microstructural and mechanical characterization of additively manufactured reinforcing elements for composite materials exhibiting fractal geometry, with a focus on the flexural reinforcement of cement-matrix composites. The examined elements are manufactured via an additive process, electron beam melting, from the Ti6Al4V titanium alloy, using a Koch curve construction ruled by three complexity parameters. Koch fibers and meshes are designed, additively manufactured and experimentally tested, through the use of the proposed fractal design procedure. Laser scanning tests illustrate the correspondence between the CAD objects and the additively manufactured samples. The experimental characterization of the surface properties of the Koch fibers is conducted through optical microscopy and contact angle tests, while their mechanical performance is analyzed through Vickers hardness and bending tests on a fiber-reinforced reinforced mortar. The given mechanical tests highlight that reinforcing fibers with fractal architecture significantly enhance the first crack strength and the residual loading capacity of cement mortar specimens subject to three-point bending tests. This is due to the relevant interlocking mechanisms acting at the interface between the matrix and the ribs of such reinforcing elements, which delay the macroscopic cracking of the mortar

Magnetic Solid Phase Extraction of Au(III) using Fe3O4 Nanoparticles Prior to its Flame Atomic Absorption Spectrometric Determination

A simple solid phase extraction procedure has been proposed for determination of Au(III) based on separation and preconcentration using magnetite nanoparticles (MNPs) prior to its determination by flame atomic absorption spectrometry. The influences of experimental parameters including sample pH, sorbent mass, contact time, volume and type of eluent, and interference of some ions with extraction of Au(III) ions were investigated using batch procedure. The maximum adsorption capacity of the sorbent for Au(III) was found to be 45.0 mg g-1. The sorption of Au(III) ions was quantitative in the pH range of 4.0–5.0 and quantitative desorption was achieved using 10 mL of thiourea (0.5 mol L-1)/hydrochloric acid (1 mol L-1) solution. In the initial solution, the calibration curve was linear in the range of 8.8 - 666.0 μg L-1 with R2 = 0.9994 (n = 8), the detection limit (3Sb, n = 8) was 6.2 μg L-1, relative standard deviation (R.S.D) of 20 μg mL-1 of Au(III) was 3.9% (n = 8), and the preconcentration factor was 30. The proposed method has been applied to the determination of Au(III) in water and wastewater samples with good recoveries in the range of 95% –103%

Simulation of High-Voltage Board with power electronics in Fuel cell Electric Truck

Environment and sustainability are getting more and more important these days and a simple way to contribute positively to the ecosystem is to improve humans’ everyday life in a way to reduce emission as much as possible, therefore, having a zero-emission truck may have a huge impact on this matter due to the large consumption of this trucks in conjunction with mass transportation that takes place with these trucks. MAN truck took a big step aiming at this problem by introducing zero-emission trucks. Fuel cell electric trucks that work with Hydrogen with zero emission tailpipes. In this report, the main components of fuel cell trucks will be introduced and analyzed, in addition to wiring, and analyzing techniques. The circuit analysis takes place in Lt-spice, with the focus on testing the voltages in order to ensure functionality. The work began with cable analysis and continued by introducing the inverter and converters step by step