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Number of results: 3348
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Abstract

The paper presents the impact of exceeding the railway rails lifespan which usually causes a railway structural failure, thus an accident. The research highlights the rails’s high degradation, especially on the running area, consisting in 60-70% weight loss by advanced wear of the rail, followed by fatigue fracture caused by alternating cyclic stresses that initiates the crack and also by tensile stresses resulting in the crack growth. The chemical composition, structural and mechanical properties were analyzed in order to establish the causes that led to the railway rails rupture.
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Authors and Affiliations

A.C. Berbecaru
1
ORCID: ORCID
G. Coman
1
ORCID: ORCID
S. Ciucă
1
ORCID: ORCID
I.A. Gherghescu
1
ORCID: ORCID
M.G. Sohaciu
1
ORCID: ORCID
C. Grădinaru
1
ORCID: ORCID
C. Predescu
1
ORCID: ORCID

  1. Politehnica University of Bucharest, Faculty of Materials Science and Engineering, 313 Splaiul Independenței, 060042 Bucharest, Romania
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Abstract

Machining with tool that have cutting edge radius provides components with high fatigue strength, microhardness of a large surface layer and plastic deformation. Finite element simulations of the cutting process give a better knowledge of the chip generation phenomenon, heat generation in the machining area, stress and temperature field results. This study emphasizes the true importance of the mathematical model that underlies the shape of the tool in the pre-processing steps of finite element analysis. The argument is that its achievement and definition depend on the network difficulty. This research purpose is to perform simulations series of orthogonal machining with different radius and depth of cut. In this way, conclusions on the impact of these variations on the whole cutting process were drawn. The finite element application used is Deform 2D, the Lagrange incremental method and the Johnson-Cook material model. The temperature distribution, stress distribution, von Mises stress distribution, effects on specific tool pressure and wear, and fluctuations in the cutting resistance of the tool tip and C45 workpiece were analyzed.
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Authors and Affiliations

A.B. Pop
1
ORCID: ORCID
A.V. Sandu
2 3
ORCID: ORCID
A. Sachelarie
4
ORCID: ORCID
Mihail Aurel Țîțu
ORCID: ORCID

  1. Technical University of Cluj-Napoca, North University Center of Baia Mare, 62A, Victor Babeș Street, Baia Mare, Romania
  2. Gheorghe Asachi Technical University, Faculty of Materials Science and Engineering, Blvd. D. Mangeron 71, 700050 Iasi, Romania
  3. Romanian Inventors Forum, Str. Sf. P. Movila 3, 700089 Iasi, Romania
  4. Gheorghe Asachi Technical University of Iasi, Faculty of Mechanical Engineering, D. Mangeron 41, 70050, Iasi, Romania
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Abstract

The most common means to analyze redox gradients in sediments is by push/pulling electrochemical probes through sediment’ strata while repeating measurements. Yet, as electrodes move up and down they disrupt the texture of the sediment layers thus biasing subsequent measurements. This makes it difficult to obtain reproducible measurements or to study the evolution of electrochemical gradients. One solution for solving this problem is to eliminate actuators and electrode movements altogether, while instead deploying probes with numerous electrodes positioned at various depths in the sediment. This mode of operation requires electrode switching. We discuss an electrode-switching solution for multi-electrode probes, based on Complementary Metal-Oxide-Semiconductor (CMOS) multiplexors. In this solution, electrodes can be individually activated in any order, sequence or time frame through digital software commands. We discuss constraints of CMOS-based multilayer electrochemical probes during cyclic voltammetry.
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Authors and Affiliations

V.M. Cimpoiasu
1
ORCID: ORCID
F. Radulescu
2
K.H. Nealson
3
ORCID: ORCID
I.C. Moga
4
ORCID: ORCID
R. Popa
4
ORCID: ORCID

  1. University of Craiova, Frontier Biology and Astrobiology Research Center, Biology and Environmental Engineering Department, Craiova, 200585, Romania
  2. Portland, OR, 97229
  3. University of Southern California, Department of Biological Sciences, 3616, Trousdale Parkway, Los Angeles, 90089, USA
  4. DFR Systems SRL, R&D Department, Bucharest, Romania
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Abstract

Geopolymer is synthesized by polycondensation of SiO4 and AlO4 aluminosilicate complexes, tetrahedral frames linked with shared sialate oxygen. This paper studies the effect of the solids-to-fluids (S/L) and Na2SiO3/NaOH proportions on the preparing of metakaolin inorganic membrane geopolymer. By consolidating a mixture of metakaolin with sodium hydroxide, sodium silicate and foaming agent, the geopolymer membrane was made in required shape about 1 cm and cured at 80°C for 24 hours. After the curing process, the properties of the samples were tested on days 7. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solution were utilized as an alkaline activator with a NaOH fixation fixed at 10 M. The geopolymer inorganic membrane tests were set up with various S/L proportions (0.8, 1.0, 1.2 and 1.4) and Na2SiO3/NaOH proportions (0.5, 1.0, 1.5, 2.0 and 2.5). Aluminium (Al) powder as a foaming agent was used to create bubbles in porous structure and provide details on the development of membrane geopolymers. This metakaolin membrane, based on the geopolymer, was synthesized by a suspension that depends on the fast cementing mechanism of high-temperature slurries. Porous geopolymeric circles provided a homogeneous composition and quantitative distribution of pores. The water absorption, density, impact toughness testing and microstructure analyses were studied. However, considering the promising results, an adjustment in the mix design of the metakaolin inorganic membrane geopolymer mixtures could increase their mechanical properties without negatively affecting the mechanical properties and porosity, making these sustainable materials a suitable alternative to traditional porous cement concrete.
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Authors and Affiliations

Masdiyana Ibrahim
1 2
ORCID: ORCID
Wan Mastura Wan Ibrahim
2 3
ORCID: ORCID
Mohd Mustafa Al Bakri Abdullah
1 2
ORCID: ORCID
Ahmad Syauqi Sauffi
1 2
ORCID: ORCID
Petrica Vizureanu
4
ORCID: ORCID

  1. Universiti Malaysia Perlis (UniMAP), Faculty of Chemical Engineering Technology, 02100, Padang Besar, Perlis, Malaysia
  2. Universiti Malaysia Perlis (UniMAP), Center of Excellence Geopolymer & Green Technology (CeGeoGTech), 02600, Arau, Perlis, Malaysia
  3. Universiti Malaysia Perlis (UniMAP), Faculty of Mechanical Engineering Technology, 02600, Arau, Perlis, Malaysia
  4. Gheorghe Asachi Technical University of Iasi, Faculty of Materials Science and Engineering, 700050, Iasi, Romania
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Abstract

Herein, the effects of multi-walled carbon nanotubes (CNTs) on the mechanical and dielectric performance of hybrid carbon nanotube-woven glass fiber (GF) reinforced epoxy laminated composited are investigated. CNTs are deposited on woven GF surface using an electrospray deposition method which is rarely reported in the past. The woven GF deposited with CNT and without deposited with CNT are used to produce epoxy laminated composites using a vacuum assisted resin transfer moulding. The tensile, flexural, dielectric constant and dielectric loss properties of the epoxy laminated composites were then characterized. The results confirm that the mechanical and dielectric properties of the woven glass fiber reinforced epoxy laminated composited increases with the addition of CNTs. Field emission scanning electron microscope is used to examine the post damage analysis for all tested specimens. Based on this finding, it can be prominently identified some new and significant information of interest to researchers and industrialists working on GF based products.
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Authors and Affiliations

Muhammad Razlan Zakaria
1 2
ORCID: ORCID
Nur Aishahatul Syafiqa Mohammad Khairuddin
3
ORCID: ORCID
Mohd Firdaus Omar
1 2
ORCID: ORCID
Hazizan Md Akil
3
ORCID: ORCID
Muhammad Bisyrul Hafi Othman
4
ORCID: ORCID
Mohd Mustafa Al Bakri Abdullah
1 2
ORCID: ORCID
Shayfull Zamree Abd Rahim
2
ORCID: ORCID
Sam Sung Ting
1 2
ORCID: ORCID
Azida Azmi
1
ORCID: ORCID

  1. Universiti Malaysia Perlis (UniMAP), Faculty of Chemical Engineering Technology, Perlis, Malaysia
  2. Universiti Malaysia Perlis (UniMAP), Geopolymer & Green Technology, Centre of Excellent (CEGeoGTech), Perlis, Malaysia
  3. Universiti Sains Malaysia, School of Materials and Mineral Resources Engineering, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang, Malaysia
  4. Universiti Sains Malaysia, School of Chemical Sciences, 11800 Minden, Penang, Malaysia
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Abstract

This study compares the mechanical properties of recycled high-density polyethylene (r-HDPE)/rice husk (RH) composites from a twin-screw extruder and a heated two-roll mill, and the effect of different filler loadings using different melt blending processes on the mechanical properties of r-HDPE/RH composites. Polyethylene-graft-maleic anhydride (MAPE) acts as the coupling agent to enhance interfacial bonding between the fibre and the polymer matrix. The filler loading used was in the range of 10-40 wt. %. In this work, r-HDPE/RH blends were prepared using a twin-screw extruder and a heated two-roll mill. The ratio of 70/30 twin-screw extruder compounded composites significantly showed higher tensile based on improved to about 45.5% at 11 MPa compared to those compounded in the heated two-roll mill. The same ratio showed an increment almost up to 9% of elongation at break. It has also been verified that the higher filler loading used reduced the tensile strength and elongation at break, while the Young’s modulus increased. The result was evidenced by the increase in water absorption and longer burning time as the filler loading increased.
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Authors and Affiliations

Mohd Nazry Salleh
1 2
ORCID: ORCID
Roslaili Abdul Aziz
1 3
ORCID: ORCID
Chen Ruey Shan
4 2
ORCID: ORCID
Luqman Musa
1 2
ORCID: ORCID
Mohd Fairul Sharin Abdul Razak
1 2
ORCID: ORCID
Marcin Nabiałek
5
ORCID: ORCID
Bartłomiej Jeż
5
ORCID: ORCID

  1. Universiti Malaysia Perlis, Faculty of Chemical Engineering, TechnologyKompleksPusatPengajian Taman Muhibah, 02600 Arau, Perlis, Malaysia
  2. Universiti Malaysia Perlis, Advanced Polymer Group, Center of Excellence Geopolymer and Green Technology (CEGeoGTech), 02600 Arau, Perlis, Malaysia
  3. Universiti Malaysia Perlis, Center of Excellence for Biomass Utilization (COEBU), 02600 Arau, Perlis, Malaysia
  4. Universiti Kebangsaan Malaysia, Faculty of Science and Technology, School of Applied Physics, Material Science Programme, 43600 Bangi, Selangor, Malaysia
  5. Częstochowa University of Technology, Department of Physics, 21 Armii Krajowej Av., 42-200 Częstochowa, Poland
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Abstract

The introduction of carbon nanotubes (CNTs) onto glass fibre (GF) to create a hierarchical structure of epoxy laminated composites has attracted considerable interest due to their merits in improving performance and multifunctionality. Field emission scanning electron microscopy (FESEM) was used to analyze the woven hybrid GF-CNT. The results demonstrated that CNT was successfully deposited on the woven GF surface. Woven hybrid GF-CNT epoxy laminated composites were then prepared and compared with woven GF epoxy laminated composites in terms of their tensile properties. The results indicated that the tensile strength and tensile modulus of the woven hybrid GF-CNT epoxy laminated composites were improved by up to 9% and 8%, respectively compared to the woven hybrid GF epoxy laminated composites.
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Authors and Affiliations

Muhammad Razlan Zakaria
1 2
ORCID: ORCID
Mohd Firdaus Omar
1 2
ORCID: ORCID
Hazizan Md Akil
3
ORCID: ORCID
Muhammad Bisyrul Hafi Othman
4
ORCID: ORCID
Mohd Mustafa Al Bakri Abdullah
1 2
ORCID: ORCID

  1. Universiti Malaysia Perlis (UniMAP), Faculty of Chemical Engineering Technology Perlis, Malaysia
  2. Universiti Malaysia Perlis (UniMAP), Geopolymer & Green Technology, Centre of Excellent (CEGeoGTech), Perlis, Malaysia
  3. Universiti Sains Malaysia, School of Materials and Mineral Resources Engineering, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang, Malaysia
  4. Universiti Sains Malaysia, School of Chemical Sciences, 11800 Minden, Penang, Malaysia
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Abstract

For ages, concrete has been used to construct underwater structures. Concrete laying underwater is a very complex procedure important to the success or failure of underwater projects. This paper elucidates the influence of alkali activator ratios on geopolymers for underwater concreting; focusing on the geopolymer concrete synthesized from fly ash and kaolin activated using sodium hydroxide and sodium silicate solutions. The geopolymer mixtures were designed to incorporate multiple alkali activator ratios to evaluate their effects on the resulting geopolymers’ properties. The fresh concrete was molded into 50 mm cubes in seawater using the tremie method and tested for its engineering properties at 7 and 28 days (curing). The control geopolymer and underwater geopolymers’ mechanical properties, such as compressive strength, water absorption density, and setting time were also determined. The differences between the control geopolymer and underwater geopolymer were determined using phase analysis and functional group analysis. The results show that the geopolymer samples were optimally strengthened at a 2.5 alkali activator ratio, and the mechanical properties of the control geopolymer exceeded that of the underwater geopolymer. However, the underwater geopolymer was determined to be suitable for use as underwater concreting material as it retains 70% strength of the control geopolymer.
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Authors and Affiliations

Fakhryna Hannanee Ahmad Zaidi
1
ORCID: ORCID
Romisuhani Ahmad
1 2
ORCID: ORCID
Mohd Mustafa Al Bakri Abdullah
3 2
ORCID: ORCID
Wan Mastura Wan Ibrahim
1 2
ORCID: ORCID
Ikmal Hakem Aziz
3 2
ORCID: ORCID
Subaer Junaidi
4
ORCID: ORCID
Salmabanu Luhar
5 2
ORCID: ORCID

  1. Universiti Malaysia Perlis, Faculty of Engineering Technology, Sungai Chuchuh, 02100 Padang Besar, Perlis, Malaysia
  2. Universiti Malaysia Perlis (UniMAP), Geopolymer & Green Technology, Centre of Excellence (CEGeoGTech), Perlis, Malaysia
  3. Universiti Malaysia Perlis, Faculty of Chemical Engineering Technology, Taman Muhibbah, 02600 Jejawi, Arau, Perlis, Malaysia
  4. Universitas Negeri Makassar, Geopolymer & Green Material Group, Physics Department, FMIPA, Indonesia
  5. Frederick Research Center, P.O Box 24729, 1303 Nicosia, Cyprus
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Abstract

An alternative for Ordinary Portland cement (OPC) consumption is the production and integration of green cement. In other words, the clinker consumption has to be replaced with new low-carbon binders. A possible solution was introduced by the geopolymerisation technology. However, the alkaline activation of geopolymers offers the possibility of obtaining greener materials with high properties, superior to OPC, but due to the high price of sodium silicate, their industrial use is limited. In the past few years, a new activator has been discovered, namely phosphoric acid. This study approaches the obtaining of coal ash-based geopolymers activated with acid solution cured at room temperature. Accordingly, phosphoric acid, 85% by mass, was diluted in distilled water to obtain a corresponding activation solution for H3PO4/Al2O3 ratio of 1.0 and two types of geopolymers were ambient cured (22°C ±2°C). Moreover, to evaluate the geopolymerisation potential of this system (coal ash – phosphoric acid), SEM and EDS analysis was performed to investigate their morphologic characteristics.
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Authors and Affiliations

D.D. Burduhos Nergis
1
ORCID: ORCID
P. Vizureanu
1 2
ORCID: ORCID
S. Lupescu
1
ORCID: ORCID
D.P. Burduhos Nergis
1
ORCID: ORCID
M.C. Perju
1
ORCID: ORCID
A.V. Sandu
1 2
ORCID: ORCID

  1. "Gheorghe Asachi” Technical University of Iasi, Blvd . Mangeron, No. 51, 700050, Iasi, Romania
  2. Universiti Malaysia Perlis (UniMAP), Center of Excellence, Geopolymer & Green Technology (CeGeoGTech), School of Material Engineering, Perlis, Malaysia

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