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In this paper, a self-tunable energy harvester based on pendulum oscillations with a mechanical motion rectifier (MMR) system, which can convert vibration into electrical energy, is proposed. The harvester is composed of a pendulum excited by a slider-crank mechanism. The pendulum system is designed to automatically adjust its own natural frequency to match that of the imposed base excitation. Frequency adjustment in a proposed pendulum-type energy harvester is achieved by varying the length of the pendulum rod through changing the position of pendulum mass which mounted at its tip. The pendulum mass is driven by a ball screw through a stepper motor which controls the length of the pendulum automatically in accordance with the frequency of the external motion. The base motion frequency is detected by an infrared sensor. An ultrasonic distance sensor is used to detect the length of the pendulum rod and feeds this information to a microcontroller to obtain the corresponding natural frequency from a lookup table. The microcontroller calculates the frequency difference between natural frequency and excitation frequency and converts this value into a length difference through another lookup table. The microcontroller then gives instructions to drive a stepper motor through a sequence of steps to achieve the target length and keeps the device in resonance state to harvest maximum power during operation. Different time detection intervals were studied to investigate their effect on the tuning process. This study showed that the longer time intervals increase the detection accuracy for the calculation of low excitation frequency. The amount of energy consumed during the tuning process to adjust the pendulum length is presented. In this context, the consumed energy is only needed until the resonance of the device matches the excitation frequency. The harvester system was studied numerically and experimentally. Based on the findings of this work, the natural frequency of the harvester is successfully tuned below 0.7 Hz, when the length of pendulum rod is changed from 550 mm to 900 mm, generating power from 1.78 W to 4.1 W at an optimal load resistance value of 10 Ω and 3 Ω respectively at maximum excitation amplitude of 120 mm. Therefore, the proposed pendulum system can be used as an efficient harvester for producing power in low-frequency applications (< 1 Hz).

A relatively successful dissimilar joint between 1050 pure aluminum and annealed low carbon steel is achieved by using friction stir welding. Most studies of joining aluminum to steel have been performed by using low rotational speed with high traverse speed to minimize heat in weld zones and to minimize the thickness of the intermetallic compounds (IMCs). Although the minimized heat may reduce the formation of brittle IMCs but the steel side may not be strongly influenced by this heat which affects the stirring action on both sides. The novelty of this analysis is applying great generated heat by employing a combination of a low traverse speed and a high rotational speed to accomplish the joints. In this study, a high rotational speed of 1550 rpm, a low traverse speed of 17 mm/min, a tilt angle of 1°, a pin length of 1.6 mm, and a deep shoulder surface penetration of 0.2 mm on 1.9 mm sheet thickness is the best set obtained to maximize both the frictional heat and the joint strength. The theory used exhibits more stirring of steel on aluminum than previous studies. The major contribution obtained from this study is knowing a new evaluation of the effect of the thicknesses of the IMCs formed at the interface and on the nugget. It is shown that the effect of the thickness of IMCs formed has a very little impact on the joint strength of about 1.3% at a very high difference in the IMCs thickness obtained between 7.5−8 μm and 8−36 μm. The joint strength depends on how the wide intermixing of steel edge on the aluminum side creates and the size/shape of steel particles.

The present work deals with the development of nanocomposite grease to reduce friction and wear between two contact surfaces such as the components of engine, cams, gears, and bearing. The tribological and rheological characteristics of nano grease with a new design of automated lubricant machine tests were evaluated. In this paper, a manual Reicher test machine is converted to an automatic machine by an electric actuator, which used to convert the load from manual to automatic. Calcium grease containing a different concentration of titanium dioxide and carbon nanotubes TiO2/CNTs (0.5, 1, 2, 3, 4 wt. %) was successfully prepared. The tribological and rheological characteristics of the nano grease were investigated under different temperatures. The morphologies and chemical composition of the worn surface and the wear mechanisms were also discussed at different loads. X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis were used to analyze the microstructure of the nano additives and nano grease. The result shows that the optimal concentration of TiO2 /CNTs was 3 wt%, which reduces the wear and coefficient of friction about 72.3 and 60 %, respectively. Furthermore, the apparent viscosity and shear stress are increased by 48.2 and 74.2 %, respectively. Keywords: Lubricant test, Tribology, Rheology, Nanoparticles additives.

Purpose The purpose of this paper is to evaluate the influence of nanoparticles as an additive on the tribological properties of calcium grease. Design/methodology/approach The nano additives in this research are with different concentration of multi carbon nanotubes (MWCNTs) and Talc powder (1, 2, 3, 3 and 5 per cent). The ratio of MWCNTs to Talc powder is 1:1. The tribological properties of hyper MWCNTs/Talc powder to calcium grease were evaluated using a pin-on-disk wear testing. The results show that the nano additives MWCNTs/Talc to calcium grease exhibit good performance in anti-wear and friction reduction. The action mechanism was estimated through analysis of the worm surface with x-ray diffraction and transmission electron microscope. Findings The result indicates that boundary film mainly composed of MWCNT and Talc powder, and other organic compound was formed on the worm surface during the friction test. In addition, the wear rate and coefficient of friction of nanogreases have shown excellent improvement about 80.62 and 63.44 per cent, respectively, at 4 Wt.% of MWCNTs/Talc powder. Moreover, the thermal conductivity of nanogrease increased about 51.72 per cent. Originality/value This study describes the inexpensive and simple fabrication of nanogrease for improving properties of lubricants, which improve power efficiency and extend lifetimes of mechanical equipment.

The water pollution increases every day due to the increase of the humans needs so a lot of studies were studied for looking the solutions. In this work, we studied the photocatalytic degradation performance of the methylene blue (MB) and the indigo carmine (IC) in an aqueous solution by using the composite nanofiber (PAN-CNTs/ZnO-NH2) under visible light. The electrospinning technique was used to fabricate the PAN-CNTs followed by a chemical crosslinking of ZnO nanoparticles (NPs) on it. FTIR, TEM, SEM and XRD analysis are used to examine the changes of the surface morphology, structure and modification of the fabricated composite nanofiber. This study has proved that PAN-CNTs/ZnO-NH2 get high photodegradation efficiency at a low power intensity (80 lux) and at a short time. A complete degradation has done for the dyes solution after a very short time 29 min and 115 min for IC and MB respectively. There are many factors taking into account during the photodegradation process like the pH of the solution, dyes concentration and the irradiation time.

Muffling devices are essential parts of any vehicle/machine that uses internal combustion engines. From automotive manufacturers point of view, they contribute massive sheet metal processing and production time, especially mufflers that are produced at high rates for commercial vehicles. This paper is concerned with applying manufacturing procedures to reduce the production cost of any commercial automotive mufflers through theoretical studies and experimental measurements verification. Mufflers design parameters such as transmission loss, flow generated noise and pressure drop were selected for performance judgment, parameters were simulated and experimentally measured. The transfer matrix method was used to calculate the propagation of sound waves along the muffler. A commercial automotive muffler with a hybrid combination of dissipation and reflection was selected for application and a new design was proposed for this muffler with a reduced manufacturing cost. The manufacturing processes were reduced by 77.7% and consequently the cost relative to the original muffler. Keywords: Commercial vehicle, Vehicle economics, Perforated muffler, Dissipative muffler, Exhaust system manufacturing

This paper introduces acoustics software for mechanical engineers and architects to aid in the early design stages or later consultations. The software uses governing equations for mechanical equipment and HVAC components in standards such as ASHARE, ASTM E477 and ARI coupled with room acoustics equations. Along the sound propagation path the noise sound pressure levels are calculated starting from the first source to the receiving point. The transmission loss of any obstacles/walls are taken into consideration to give a reliable estimation to the real values. In this paper two case studies are presented to show the efficiency of the software and verify the outputs with measurements. The sound pressure levels and noise criteria of the indoor and outdoor spaces studied showed a variation around 6.4% compared to measured values. Through this software the designer could map and manipulate the design to reach the standard or regulated noise criteria. Keywords: Noise control, Noise mapping, Acoustic software, HVAC noise, Transmission loss

Nanofluids are gaining attention as an attractive solution for the sustainable machining of difficult-to-cut materials. Despite the enormous recent work in the literature, there are still contradictions concerning the effect of different preparation factors on the characteristics of nanofluids and the underlying mechanisms governing them. In the present study, the effect of varying the preparation factors, namely, multi-walled carbon nanotube (MWCNT) concentration, sonication time, and surfactant amount on various nanofluid characteristics and the interactions among these characteristics were studied. The characteristics are divided into two categories: (a) dispersion/stability and (b) viscosity/wettability. The analysis showed strong interactions between these two categories which were mainly attributed to aggregates' formation and dynamics. For the stability/dispersion responses, the effect of aggregation and saturation phenomena is discussed in relation to the different preparation factors. Our analysis shows that the nanofluid viscosity is strongly dependent on aggregate morphology. As for wettability, a novel mechanism is proposed and used to explain the nanoparticles' influence on wettability based on the nanolayering theory. Finally, multi objective optimization (MOO) based on grey relational analysis (GRA) was performed. It was found that moderate MWCNT concentration, high sonication time, and low surfactant amount show the optimal characteristics within the current study design variables search domain. The novelty in the present study lies in its consideration of the simultaneous interaction between the nanofluids' properties and stability. Unlike the common practice in the literature, which focuses on one or two aspects of nanofluids, our approach broadens the analysis and provides in-depth insights into the nanofluid as a complete physical system.

An adaptive, heuristic, nonlinear mathematical model (AHNM) was proposed to optimize the loading path of successful tube hydroforming process through adaptive minimization of the internal pressure and axial load by using Multiple Ridge Regression (Machine learning technique). The AHNM model was implemented, solved, and optimized, and it was found that increasing the number of steps and starting with small increment enables the mathematical model to capture the non-linearity of the real model, which leads to minimizing the system requirements. In this paper Finite Element Modelling (FEM) was developed to verify and test the validity and reality of the implemented loading oaths from the AHNM model for hydroforming of T-shape tube having an elliptical protrusion. The objective function was measured, and the results of minimum thickness, and maximum protrusion height were verified. Besides, the tube was formed with a well wall thickness distribution. Consequently, it is confirmed that developing an adaptive heuristic nonlinear mathematical modelling is effective for obtaining a Loading Path for Hydroforming of a Tube Having an Elliptical Protrusion.

Optimum loading paths for successful tube hydroforming processes have been studied by several researchers. In this paper, an adaptive, heuristic, nonlinear mathematical model (AHNM) was proposed to optimize the loading path of a hydroforming process through adaptive minimization of the internal pressure and axial load of the process. Firstly, Finite Element Analysis (FEA) was used to analyse the hydroforming process where several features of the process were extracted from the FEA for further analyses of the relations among them. To capture these relations and include them in the AHNM, the paper examined several Machine Learning algorithms including Multiple Linear Regression, Multiple Ridge Regression, Decision Tree, and Random Forest. The Multiple Ridge Regression was found to give the highest accuracy to efficiently linear modelling the inputs and outputs of the FEA of the hydroforming process. The AHNM model was implemented, solved, and optimized using several steps of tee protrusion height that create several loading paths. It was found that increasing the number of steps and starting with small increment leads to minimizing the system requirements.

An effective photocatalyst obtained from composite nanofibers CA/GO fabricated by electrospinning technique followed by chemical crosslinking surface modified TiO2 nanoparticles (NPs) was used for removing the organic dyes Indigo carmine (IC) and Methylene blue (MB) from an aqueous solution under UV irradiation light. The crystalline structure and morphologies of CA–GO/TiO2–NH2 composite nanofibers were characterized by SEM, TEM, XRD, and FTIR. The prepared CA–GO/TiO2–NH2 composite nanofibers displayed significantly enhanced photocatalytic activity for photodegradation the organic dyes IC and MB under UV irradiation after 150 and 250 min respectively. The pH value of the solution was studied from 2 to 8 and obtained results showed a clear improvement of photocatalytic activity at pH 2. The results indicated that the activated CA–GO/TiO2–NH2 composite nanofibers functioned as an adsorbent for the removal of IC and MB from aqueous solutions. In addition, the results showed a high adsorption capacity remain up to 65% after five consecutive capacity cycles.

Molded plastic gears have long provided an alternative to metal gears in lightly loaded drives. They transmit power quietly and often without lubrication in numerous applications, furthermore decrease the quantity of parts and oppose chemicals in numerous applications. Previously, plastic gears were restricted to to 0.25 hp because of varieties in their properties and uncertainties about how they react to natural conditions such as moisture, temperature and chemical. Today, better molding controls combined with design practices that more accurately encompass environmental factors have boosted plastic gear drive capacity to 1.5 hp. Using reinforcement this is standout amongst the most practices to enhance the gear performance.This study estimated the effects of multilayer graphene nanoplatelets (MLNGPs) as an additive on polyamide 6 (PA6) spur gear performance. These include strength, elastic modulus, thermal stability, dynamic mechanical analysis, moisture absorption, and wear characteristics.The ...

The objectives of this work are to optimize the process parameters on the mechanical properties (ultimate tensile strength (UTS) and ductility) of dissimilar joints between AA5454 and AA7075 produced by friction stir welding and to determine which of them is significant by using Taguchi L16 optimization method. Seven parameters at two levels were selected in this study. The selected parameters are tool rotational speed, traverse speed, pin profile (based on taper angle), D/d ratio, tool tilt angle, plunge depth, and base metal location. Then, mathematical models are built as function of significant parameters/ interactions using Response Surface Methodology. The results of this work showed that the rotational speed, traverse speed, D/d ratio and plunge depth are significant parameters in determining UTS (Mean, Signal to noise ratio (S/N)) at different confidence levels, but pin profile, location of base metal and tool tilt angle are insignificant parameters at any confidence levels. The traverse speed has the highest contribution to the process for UTS about 18.577 % and 16.943 % for S/N ratio and mean, respectively. The accuracy of the models according to the UTS is 97.678 % and 99.56 %for mean and S/N ratio, respectively. The maximum joint efficiency, compared to the strength of the AA5454, is 85.3%.

The purpose of this research is to use friction stir welding (FSW) to join dissimilar metals, annealed low carbon steel and A1050 pure aluminum. A butt joint with a similar sheet thickness of 1.9 mm was applied. The novelties of the research are relatively using high generated heat produced by a combination of low traverse speed and high rotational speed to perform the dissimilar joints and using a tool material (K107cold work tool steel) which has not been used in FSW with tool cooling. The present work studied the effect of FSW variables such as tilt angle, tool cooling, base metal location on mechanical properties. Tensile tests were used to evaluate the mechanical properties of the dissimilar joints. The microstructure specimens were examined using a scanning electron microscope (SEM). Sound dissimilar joints were successfully produced. The maximum joint efficiency obtained in this study is 51.7% of the aluminum tensile strength. The microstructure images showed that many steel fragments were sheared off from the steel surface by the tool action and scattered in the weld nugget, a continuous intermetallic compound (IMC) layer formed at the interface, the thickness of the IMC layer at the interface decreased in the thickness direction of the weld. FeAl3 IMC phase was only observed at the interface.

Purpose The purpose of this paper is to investigate the rheological characteristics of graphene nanoplatelets (GNPs) and hybridized nanocomposite consisting of multi-walled carbon nanotubes (MWCNTs) and GNPs as an additive on lithium-based grease. The experiments of nanogrease are examined in different values of shear stress, apparent viscosity, temperature and shear rate using Brookfield Programmable Rheometer DV-III ULTRA and characterized by high-resolution transmission electron microscope (HRTEM) and X-ray diffraction (XRD). Design/methodology/approach First, GNPs was mixed well with lithium grease using mechanical stirring at 3,500 rpm for 15 min at room temperature to form a homogenous composite at different concentrations (0.5, 1, 1.5, 2 and 2.5 Wt.%). Afterwards, MWCNTs and GNPs are mixed and dispersed well in the lithium grease using a sonication path for 30 min and mechanical stirring at 3,500 rpm for 15 min at 28°C to form a homogenous nanocomposite. Findings The results indicated that 1 Wt.% of GNPs is the optimum concentration. Subsequently, the weight percentage of additives varying between MWCNTs and GNPs are tested, and the result indicate that the grease containing GNPs had a 75 per cent increase in shear stress and 93.7 per cent increase in apparent viscosity over ordinary grease. Originality/value This work describes the inexpensive and simple fabrication of nanogrease for improving properties of lubricants, which improve power efficiency and extend lifetimes of mechanical equipment.

The objective of this paper is to investigate the effect of Multi-Walled Carbon Nanotubes (MWCNTs) content on microstructure and dry sliding wear behavior of hypo-eutectic A356Al–Si alloy Metal Matrix Nano-Composites (MMNCs). Composites containing 0.5, 1.5, and 2.5 wt.% MWCNTs were prepared by rheocasting technique followed by squeeze casting. Characterization of nanocomposites was done by scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDX), dry sliding wear tests were performed in a pin-on-disk wear tester against a steel disk at various speeds and normal loads. Results revealed that a decrease in both wear rate and friction coefficient of the nanocomposites considerably with the increase of MWCNT's content. The formation of the hard compact transfer layer on the pin surface nanocomposites assisted in increasing the wear resistance of these materials. It is that the transfer layer which was formed under an applied load of 20 N can act as a protective layer and ...

In this work, photocatalytic degradation of organic dyes such as methylene blue (MB) and indigo carmine (IC) have been studied by composite nanofibers systems containing cellulose acetate (CA), multiwall carbon nanotubes (CNT) and TiO2 nanoparticles under UV light. The amino factionalized TiO2–NH2 NPs cross-linked to the CA/CNT composite nanofibers works as a semiconductor catalyst. The morphology and crystallinity were characterized by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, and Fourier transform infrared spectroscopy. It was also seen that many factors affected the photodegradation rate, mainly the pH of the solution and the dye concentration, temperature, etc. The study demonstrated that IC degrades at a higher rate than MB. The maximum photodegradation rate of both organic dyes was achieved at a pH 2. In comparison to other studies, this work achieved high photodegradation rate in lower time and using less power intensity.

This work describes the fabrication of the composite nanofibers containing polyacrylonitrile polymer (PAN) and different weight percentage of carbon nanotubes (CNTs) using electrospinning technique which is simplest and highly versatile method to enhance the mechanical properties by removing the surface defects of the composite nanofibers. The tensile test, X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy measurements are used to find the mechanical properties and the characterization of PAN/CNT composite nanofibers. The result demonstrated that adding CNTs to the polymer enhances the mechanical properties like tensile strengths and Young’s modulus with an average 55 and 60 %, respectively at only 0.1 wt% of CNTs.

Graphene oxide incorporated cellulose acetate composite nanofibers were prepared via an electrospinning technique. The weight percentage of graphene oxide varied from 0.05 to 1.5 wt.% in the polyme...

Purpose This work describes the fabrication of composite nanogrease based on carbon nanotubes (CNTs) as an additive at different volume concentrations 0, 0.5, 1, 2 and 3 Wt.% and investigates the correlation between CNTs and grease rheological behaviour. In addition, study the influence of shear thinning rate at various temperatures and investigates the thermal conductivity of nanogrease. The results demonstrated that grease behaves like a Newtonian viscoelastic material with a narrow linear domain. The thermal conductivity of nanogrease was enhanced by about 31.58 per cent, and the thermal and mechanical stabilities improved. Moreover, the apparent viscosity and dropping point increased by about 93 and 27 per cent, respectively. Design/methodology/approach Grease was dissolved in chloroform (10 Wt.%), at 25°C for 1 h. In parallel, functionalized CNTs with different volume concentrations (0.5, 1, 2 and 3 Wt.%) were dispersed in N,N-dimethylformamide; the dispersion was stirred for 15 min, and then sonicated (40 kHz, 150 W) for 30 min. Grease solution was then added to the CNTs. The nanofluid was magnetically stirred for 15 min and then sonicated for 2 h. This ensured uniform dispersion of nanoparticles in the base fluid. Findings Inexpensive and simple fabrication of nanogrease. Thermal conductivity of nanogrease was typically enhanced compared to other reported studies. Apparent viscosity and dropping point increases with the increase the volume concentration. Originality/value This work describes the inexpensive and simple fabrication of nanogrease for improving properties of lubricants, which improve power efficiency and extend lifetimes of mechanical equipment.

This work describes the enhanced mechanical properties of the composite nanofibers and the photodegradation of two organic dyes using PAN/CNTs under UV irradiation at different volume concentration ...

Carbon nanotubes (CNTs) are used as a nanoadditive due to their unique properties and for improving the lubricant’s properties. In this research, the effect of CNTs in different concentrations (0.1, 0.5, 1 and 2 wt%) on kinematic viscosity, pour point, flash point and thermal conductivity coefficient as four quality parameters which are effective in the functionality of oil is evaluated and compared against the standard Mobil gear 627 and paraffinic mineral oils. The samples were tested according to ASTM D-445, ASTM D-97 and ASTM D-92 standards, respectively. The results indicated that the thermal conductivity, flash point, pour point and kinematic viscosity of nanolubricants with low concentration of CNTs improved with respect to the base oil. Dispersion of CNTs as additive has improved the lubricant properties and operational characteristics of Mobil gear 627 and paraffinic mineral oils.

[EN] Titanium and its alloys have been widely used as biometals due to their excellent biocompatibility, corrosion resistance and moderate mechanical properties. Ti-15Mo-6Zr-based alloys and a series of Ti-15Mo-6Zr-xCr (x = 1, 2, 3, 4 wt.%) alloys were designed and fabricated by powder metallurgy for the first time to develop novel biomedical materials. The microstructure, internal porosity and mechanical properties of the sintered Ti-15Mo-6Zr and Ti-15Mo-6Zr-xCr alloys were investigated using scanning electronic microscopy (SEM) and bending and compression tests. The experimental results indicated that the microstructure and mechanical properties of these alloys changed as different Cr levels were added. The addition of small Cr levels further increased the β-phase stability, improving the properties of the Ti-15Mo-6Zr-xCr alloy. However, all of the alloys had good ductility, and the Ti-15Mo-6Zr-2Cr alloy had lower bending and compression moduli (31 and 23 GPa, respectively) than the Ti-15Mo-6Zr-based alloys (40 and 36 GPa, respectively). Moreover, the Ti-15Mo-6Zr-2Cr alloys exhibited higher bending and compression strength/modulus ratios, which were as large as 48.4 and 52.2, respectively; these were higher than those of the Ti-15Mo-6Zr-based alloy (41.3 and 33.6, respectively). In the search for a better implant material, β phase Ti-15Mo-6Zr-2Cr, with its low modulus, ductile properties and reasonably high strength, is a promising candidate., The authors thank the Ministry of Economy and Competitiveness for financially supporting the research project MAT2014-53764-C3-1-R and the European Commission through the Erasmus Mundus scholarship program WELCOME. The European Commission via FEDER funds allowed for the purchase of equipment for research and Microscopy Service of the Polytechnic University of Valencia.

In this work we report a highly efficient photocatalytic reduction of Cr(VI) based on PAN-CNT/TiO 2 -NH 2 composite nanofibers fabricated by using electrospinning technique followed by chemical crosslinking of surface modified TiO 2 NPs functionalized with amino group. The structure and morphology of the fabricated composite nanofibers were characterized by FTIR, SEM, TEM, TGA, and XPS. The results indicate that the composite nanofibers possess excellent photoreduction performance for Cr(VI) under visible light (125 W) after 30 min, which is much faster than previous reports. The effects of various experimental parameters such as catalyst dose, irradiation time, initial concentration of Cr(VI), and pH on the photoreduction efficiency of Cr(VI) were investigated. The highest photoreduction efficiency of Cr (VI) was obtained at low acidity and low amount of TiO 2 /CNT photocatalyst. The kinetic experimental data was attained and fitted well with a pseudo-first-order model. The UV–vis spectrophotometer and XPS analyses proved that chromate Cr(VI) was reduced to Cr(III). In addition, it can be concluded that the addition of the phenol enhances the photocatalytic reduction of Cr(VI). Furthermore, the photoreduction mechanism has also been discussed. Finally, the fabricated composite nanofibers were found to be stable after at least five regeneration cycles.

This work describes the fabrication of two composite nanofibers systems containing polyacrylonitrile polymer (PAN), Multiwall carbon nanotubes (MWCNT) and Titania (TiO

In recent years, since the discovery of Nano-additives especially carbon nanotubes (CNTs) and graphene, many interesting articles on composites with CNTs have been studied. CNTs have attracted considerable interest in all fields of science because of its unique characteristics. In this study, aluminum (Al) matrix reinforcement by the different volume fraction of Al2O3 and CNTs composites have been manufactured by using a powder metallurgy technique. The effects of tribological behaviors, density, hardness, and compression strength behavior of aluminum matrix Nano-composite were investigated before and after Hot Isostatic pressing (HIP). Transmission Electron Microscopy (TEM) and Scanning Electron Microscope (SEM) were employed to check the CNTs and hybrid composites. Results show that the density of nanocomposites decreased by 38% but after HIP, the density decreased by 45%. In addition, the hardness enhanced by 40% but, after HIP the hardness became 67%. On the other side, the compressive strength enhanced by 38% and 60% before and after HIP respectively. The coefficient of friction of nanocomposites are improved by 39%, 48% with HIP and without HIP while the wear rates improved by the addition of Al2O3 and CNTs at all volume fraction by 20%, but after HIP the enhancement became 45% at all volume concentration.

In this work, Polyacrylonitrile nanofibers were enhanced by graphene oxide and zinc oxide, in terms of enhanced the photocatalytic activity and mechanical properties for the composite nanofibers. Photocatalytic degradation of two organic dyes methylene blue dye and indigo carmine dye from the simulated industrial wastewaters has been investigated under visible light irradiation. Composite nanofibers fabricated by using electrospinning technique followed by chemical cross-linking with zinc oxide. The surface sensitization and morphology changes of the fabricated composite nanofibers were studied using Fourier transform infrared spectroscopy analysis, Scanning Electron Microscopy and transmission electron microscope. Sensitized zinc oxide with graphene oxide showed higher efficiency in the degradation of MB with a 96% of degradation efficiency after 70 min and 98% for IC after merely 27 min. The optimum catalytic parameters such as initial organic dye concentration and pH were discussed. The efficacy of degradation of methylene blue dye and indigo carmine increased as initial concentration decreased. The optimal pH was around 5 where the reaction rate decreases above and under this pH value.

This study examined the tribological properties of two lubricating oils, mobil gear 627 and paraffinic mineral oils, with multi-walled carbon nanotubes (MWCNTs) nanoparticles used as additives with various concentrations (0.1, 0.5, 1, and 2 wt.%). The friction and wear experiments were performed using a four ball tribotester. The samples were tested for their anti-wear, load carrying capacity, and friction coefficients according to ASTM D-2783, ASTM D-2596, and ASTM D-5183 standards. The experimental results show that the addition of MWCNTs to base oils exhibit good friction reduction and anti-wear properties. The wear test results show a decreased wear by 68% and 39% in the case of MWCNTs-based mineral oil as compared with base mobil gear 627 and paraffinic mineral oils, respectively. Furthermore, the friction reduction results show a decrease of friction about 57% and 49% in the case of MWCNTs-based mineral oil as compared with base mobil gear 627 and paraffinic mineral oils, respectively. The w...

Cold-rolled low carbon steel sheets of thicknesses ranging from 0.8 to 2 mm were sheets welded together to form a single part before the formability tests. In this study, the formability of the tailor-welded blanks (TWBs) was evaluated in terms of three measures which are limited dome height (LDH), forming limit diagram (FLD), and minimum major strain. In addition to the mechanical properties, the welded specimens were analyzed experimentally under the effect of thickness ratios. The influence of welding orientation and its relation with the rolling direction on formability and mechanical properties were also studied. The mechanical properties of the welded specimens were investigated by tensile testing and micro-hardness measurements. The metallographic studies were investigated using optical microscope and scanning electron microscope (SEM). The experimental findings in this study showed that the higher the thickness ratio of the TWBs, the lower the forming limits curve level and the lower formability. The minimum major strain was clearly inversely proportional to the thickness ratio of the TWBs. On the other hand, the results of uniaxial tests clearly illustrated that there was no significant difference between the tensile strengths of the TWBs and base metal. The micro-hardness measurements indicated that the hardness in the weld bead increased by about 55 % of the base metal.

This work describes the fabrication of two composite nanofibers systems containing polyacrylonitrile polymer (PAN), Multiwall carbon nanotubes (MWCNT) and Titania (TiO2) nanoparticles. Photodegradation experiments were performed to study the effect of various parameters including pH, catalyst dose, pollutant concentration and reaction time for three model compounds, methylene blue (MB), indigo carmine (IC), and ibuprofen (IBU) under visible light. Morphology and structure of the modified composite nanofibers were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA), Photoluminescence (PL) spectroscopy, Raman spectra, and X-ray Photoelectron Spectra (XPS) analyses. The photocatalytic performance was achieved in a rather short time visible light (

This work aims to study the wear characterization of common types of acetal polymer gears (spur, helical, bevel, and worm) using a new TS universal test rig, in order to obtain reliable results and as a reference when compared with acetal nanocomposite gears later. The TS universal test rig consists of three different units that are connected by a main driver shaft and a pair of constantly meshing metal spur gears, which transfer power to the bevel and worm test units. The first unit is used to test the bevel gears, the second unit is used to test the spur and helical gears, and the third unit is used to test the worm gears. The loading mechanism is similarly designed to block the brake mechanism. Hobbing and milling machines were used to machine an injection-moulded polymer flanges and produce the tested gears. All gear pairs, except the worm gear, have identical gear ratios. The experiments were performed at speed 1420 rpm and the torque was 4 Nm. The results showed that the wear rates (in the form of weight loss) of spur gears were consistent with the previous results and the other gear types had larger wear rates.

Although the applications of nanotechnologies are increasing, there remains a significant barrier between nanotechnology and machine element applications. This work aims to remove this barrier by blending carbon nanotubes (CNT) with common types of acetal polymer gears (spur, helical, bevel and worm). This was done by using adhesive oil (paraffin) during injection molding to synthesize a flange and short bars containing 0.02% CNT by weight. The flanges and short bars were machined using hobbing and milling machines to produce nanocomposite polymer gears. Some defects that surfaced in previous work, such as the appearance of bubbles and unmelted pellets during the injection process, were avoided to produce an excellent dispersion of CNT in the acetal. The wear resistances of the gears were measured by using a TS universal test rig using constant parameters for all of the gears that were fabricated. The tests were run at a speed of 1420 rpm and a torque of 4 Nm. The results showed that the wear resistances of the CNT/acetal gears were increased due to the addition of CNT, especially the helical, bevel and worm gears.

The goal of this paper is to investigate tribological characteristics of nanographene platelets and hybridized nanocomposite of multiwalled carbon nanotubes (MWCNTs)/multilayer nanographene platelets (MLNGPs)/lithium based-grease. Characterization is done through high resolution transmission electron microscopy (TEM) and X-ray diffraction. While grease properties were tested using Falex four-ball testing machine. Scanning electron microscopy (SEM) and energy dispersive X-ray diffraction (EDX) were utilized to characterize the lubrication mechanism and the worn surface. The results showed that 1% of MLNGPs is the optimum concentration. Wear scar diameter (WSD) was reduced by 66%, friction coefficient was reduced by 91%, while maximum nonseizer load was increased by 90 kg over ordinary lithium grease. Hybrid MWCNTs\MLNGPs were studied, and the optimum ratio of MLNGPs to MWCNTs was found to be 4:1.

A novel composites nanofiber was synthesized based on PAN-CNT/TiO2-NH2 nanofibers using electrospinning technique followed by chemical modification of TiO2 NPs. PAN-CNT/TiO2-NH2 nanofiber were characterized by XRD, FTIR, SEM, and TEM. The effects of various experimental parameters such as initial concentration, contact time, and solution pH on As removal were investigated. The maximum adsorption capacity at pH 2 for As(III) and As(V) is 251 mg/g and 249 mg/g, respectively, which is much higher than most of the reported adsorbents. The adsorption equilibrium reached within 20 and 60 min as the initial solution concentration increased from 10 to 100 mg/L, and the data fitted well using the linear and nonlinear pseudo first and second order model. Isotherm data fitted well to the linear and nonlinear Langmuir, Freundlich, and Redlich-Peterson isotherm adsorption model. Desorption results showed that the adsorption capacity can remain up to 70% after 5 times usage. This work provides a simple and an efficient method for removing arsenic from aqueous solution.

An important progress within the last decade in the development of the selectivity model approach to overcome the inconsistent results if the distributi onal assumptions of the errors terms are made this problem is through the use of semi-parametric method. However, the uncertainties and ambiguities exist in the mod els, particularly the relationship between the endogenou s and exogenous variables. A new framework of the relationship between the endogenous and exogenous variables of semi-parametric sample selection model using the concept of fuzzy modelling is introduced. Through this approach, a flexible fuzzy concept hy brid with the semi-parametric sample selection models known as Fuzzy Semi-Parametric Sample Selection Model (FSPSSM). The elements of vagueness and uncertainty in the models are represented in the model construction, as a way of increasing the available information to produce a more accurate model. This led to the development of the convergence theorem presented in the form of triangular fuzzy numbers to be use d in the model. Besides that, proofs of the theorems are presented. An algorithm using the concept of fuzzy modelling is developed. The effectiveness of the es timators for this model is investigated. Monte Carl o simulation revealed that consistency depends on ban dwidth parameter. When bandwidth parameters, c are increased from 0.1, 0.5, 0.75 and 1 as the numbers of N increased (from 100 to 200 and increased to 50 0), the values of mean approaches (closed to) the real para meter. Through the bandwidth parameter also reveals that the estimated parameter is efficient, i.e., the S.D , MSE and RMSE values become smaller as N increased. In particular, the estimated parameter becomes consist ent and efficient as the bandwidth parameters appro aches to infinity, c→∞ as the number of observations, n tend to infinity, n→∞.

This paper proposes two Bose---Chaudhuri---Hocquenghem (BCH) soft decoders suitable for high-rate codes with medium to large word length. The proposed decoders extend the correcting capability by providing a programmable performance gain according to the choice of the extra compensated bits p, with a theoretical maximum likelihood decoding when 2t+p approaches the codeword size n, where t is the correcting capability of the code under algebraic decoding. Our proposed architectures for the proposed algorithms use pipelined arithmetic units, leading to a reduction in the critical paths. This allows for an increase in the operating frequency by up to m/2 times compared to algebraic decoders, where m is the Galois field size. Our proposed decoders operate only on the least reliable bits, which leads to a reduction in the decoder complexity by removing the Chien search procedure.

In last decade, polymeric gears have found wide applications in industrial fields. This is due to their advantages like noise reduction, self-lubricating features, weight reduction, cost savings as well as lower tribological characteristics in term of friction and wear. The main objective of this paper is to study the wear behavior of spur gears that makes polymer blended by carbon nanotubes (CNTs) (acetal). This was made by using appropriate adhesive oil (Paraffin) during injection moulding practice to produce thick flanges with diameter 134 mm and thickness 29 mm. The CNTs were produced by a fully automatic system using arc-discharge technique multi-electrodes. The synthesizing CNT/acetal flanges contain 1% CNTs by weight. The flanges were machined using CNC milling machine to produce spur gears. The dispersion of CNTs in polymer were examined by scanning electron microscope. The experiments were performed at a running speed of 1420 r/min and at torques of 13 and 16 N·m. In addition, the mechanical properties of CNT/acetal have been tested. The results showed that the wear resistances of the CNTs/acetal spur gears increased with the addition of CNT. The strength, Young's modulus and stiffness also increased while the hardness was not affected by the addition of CNT.

The limit behaviour of trajectories of dissipative quadratic stochastic operators on a finite-dimensional simplex is fully studied. It is shown that any dissipative quadratic stochastic operator has either unique or infinitely many fixed points. If dissipative quadratic stochastic operator has a unique point, it is proven that the operator is regular at this fixed point. If it has infinitely many fixed points, then it is shown that ω- limit set of the trajectory is contained in the set of fixed points.