Search results for: iron electrode

Authors: Ajay Biswas, Swapan Bhaumik, Abhijit Bhowmik

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Present experiment has been carried out to study the microstructure of weldment obtained by submerged arc welding on mild steel plate at zero degree Celsius. To study this, bead on plate welding is done by submerged arc welding on the sample plate of heavy duty mild steel of designation IS 2062 grade B, fitted on the special fixture ensuring the plate temperature at zero degree Celsius. Sixteen numbers of such samples are welded by varying the most influencing parameters viz. travel speed, voltage, wire feed rate and electrode stick-out at four different levels. Taguchi’s design of experiment is applied by selecting Taguchi's L16 orthogonal array to restrict the number of experimental runs. Cross sectioned samples are polished and etched to view the weldment. Finally, different zone of the weldment is observed by optical microscope. From the type of microstructure of weldment it is concluded that submerged arc welding is feasible at zero degree Celsius on mild steel plate.

Keywords: Submerged Arc Welding, zero degree Celsius, Taguchi’s design of experiment, microstructure of weldment

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Authors: Phumlani Msomi, Patrick Nonjola, Patrick Ndungu, James Ramontja

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A series of quaternized poly (2.6 dimethyl – 1.4 phenylene oxide)/ polysulfone (QPPO/PSF) blend anion exchange membrane (AEM) were successfully fabricated and characterized for methanol alkaline fuel cell application. Zinc Oxide (ZnO) nanoparticles were introduced in the polymer matrix to enhance the intrinsic properties of the AEM. To confirm successful fabrication, FT-IR spectroscopy and nuclear magnetic resonance (¹H NMR and HMBC ¹⁵N NMR) were used. The membrane properties were enhanced by the addition of ZnO nanoparticles. The addition of ZnO nanoparticles resulted to a higher ion exchange capacity (IEC) of 3.72 mmol.g⁻¹and a 30-fold ion conductivity (IC) increase of the nanocomposite due to no (zero (0)) methanol permeability at 30 °C and increased water uptake. The QPPO/PSF/2% ZnO composite retained over 80 % of its initial IC when evaluated for alkaline stability at room temperature. The maximum power output reached for the membrane electrode assembly (MEA) constructed with QPPO/PSF/2%ZnO is 69 mW.cm⁻², which is about three times more than the parent QPPO membrane. The above results indicate that QPPO/PSF-ZnO is a good candidate as an anion exchange membrane for fuel cell application.

Keywords: anion exchange membrane, fuel cell, zinc oxide, nanocomposite

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Authors: S. Ghorbani, N. I. Polushin

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The machinability of workpieces (AISI 1045 Steel, AA2024 aluminum alloy, A48-class30 gray cast iron) in turning operation has been carried out using different types of cutting tool (conventional, cutting tool with holes in toolholder and cutting tool filled up with composite material) under dry conditions on a turning machine at different stages of spindle speed (630-1000 rpm), feed rate (0.05-0.075 mm/rev), depth of cut (0.05-0.15 mm) and tool overhang (41-65 mm). Experimentation was performed as per Taguchi’s orthogonal array. To evaluate the relative importance of factors affecting surface roughness the single decision tree (SDT), Decision tree forest (DTF) and Group method of data handling (GMDH) were applied.

Keywords: decision tree forest, GMDH, surface roughness, Taguchi method, turning process

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Authors: Issa S. Oweis, Gary Gartenberg, Luma J. Oweis

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The site for a residential apartment building overlies an abandoned iron mine in granitic gneiss in northern New Jersey. The mine stope is about 137 m (450 long) and dipping over 344m (800 feet) at 450 to 500. As the building footprint straddles, the mine site needed remediation. The remediation scheme consisted of compaction grouting a minimum 10 m (30 ft.) depth of the mine stope in rock to establish a buttress for the hanging wall and allow support of the building foundation. The rock strength parameters (friction and cohesion) were established based on Hoek Geologic Strength Index (GSI). The derived strength parameters were used in the wedge analysis to simulate rock cave-in. It was concluded that a cave-in would be unlikely. Verification holes confirmed the effectiveness of grouting. Although post grouting micro gravity survey depicted a few anomalies, no anomalies were found to exist by further drilling and excavation.

Keywords: grout, stope, rock, properties

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Authors: Orose Rugchati, Sarawut Wattanawongpitak

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This research studied the analysis of the thermal conductivity and heat transfer in porcine meat due to the electric current flowing between the electrode plates in parallel. Hot-boned pork sample was prepared in 2*1*1 cubic centimeter. The finite element method with ANSYS workbench program was applied to simulate this heat transfer problem. In the thermal simulation, the input thermoelectric energy was calculated from measured current that flowing through the pork and the input voltage from the dc voltage source. The comparison of heat transfer in pork according to two voltage sources: DC voltage 30 volts and dc pulsed voltage 60 volts (pulse width 50 milliseconds and 50 % duty cycle) were demonstrated. From the result, it shown that the thermal conductivity trends to be steady at temperature 40C and 60C around 1.39 W/mC and 2.65 W/mC for dc voltage source 30 volts and dc pulsed voltage 60 volts, respectively. For temperature increased to 50C at 5 minutes, the appearance color of porcine meat at the exposer point has become to fade. This technique could be used for predicting of thermal conductivity caused by some meat’s characteristics.

Keywords: thermal conductivity, porcine meat, electricity, finite element method

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Authors: M. D. Dogara, G. C. Afuwai, O. O. Esther, A. M. Dawai

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The geology of Northern Nigeria is under intense investigation particularly that of the northwest believed to be of the basement complex. The variability of the lithology is consistently inconsistent. Hence, the need for a close range study, it is, in view of the above that, two geophysical techniques, the vertical electrical sounding employing the Schlumberger array and seismic refraction methods, were used to delineate the geoelectric and geovelocity parameters of the basement complex of northwestern Nigeria. A total area of 400,000 m² was covered with sixty geoelectric stations established and sixty sets of seismic refraction data collected using the forward and reverse method. From the interpretation of the resistivity data, it is suggestive that the area is underlain by not more than five geoelectric layers of varying thicknesses and resistivities when a maximum half electrode spread of 100m was used. The result of the interpreted seismic data revealed two geovelocity layers, with velocities ranging between 478m/s to 1666m/s for the first layer and 1166m/s to 7141m/s for the second layer. The results of the two techniques, suggests that the area of study has an undulating bedrock topography with geoeletric and geovelocity layers composed of weathered rock materials.

Keywords: basement complex, delineation, geoelectric, geovelocity, Nigeria

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Authors: S. Ghorbani, N. I. Polushin

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In this study, an approach to identify factors affecting on surface roughness in a machining process is presented. This study is based on 81 data about surface roughness over a wide range of cutting tools (conventional, cutting tool with holes, cutting tool with composite material), workpiece materials (AISI 1045 Steel, AA2024 aluminum alloy, A48-class30 gray cast iron), spindle speed (630-1000 rpm), feed rate (0.05-0.075 mm/rev), depth of cut (0.05-0.15 mm) and tool overhang (41-65 mm). A single decision tree (SDT) analysis was done to identify factors for predicting a model of surface roughness, and the CART algorithm was employed for building and evaluating regression tree. Results show that a single decision tree is better than traditional regression models with higher rate and forecast accuracy and strong value.

Keywords: cutting condition, surface roughness, decision tree, CART algorithm

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Authors: N. Degui, Y. Daoud

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The study investigates the assessment of micronutrient bioavailability and behavior in saline soils based on the determination of three cations and one anion on three soil profiles affected by secondary salinization in Lower Cheliff. The chemical fractionation method was used for the speciation study (different forms) of micronutrients in these soils. The results show that total form quantities of cations are height than norms in agricultural soils, thus the quantities of anion are lows. At the other hand, the quantities of available forms are lows. Statistical analysis reveals that cationic micronutrients localize preferentially in the coarse fraction of the soil in salty conditions and that sodicity causes a decrease in the iron reserve in the soil. The pH range ‘7.49 - 8.76’ represents a constraint for the complexation of micronutrients by organic matter. The study concluded that quantities of total and available forms of micronutrients in salty soils are influenced by soil properties such as: pH, electrical conductivity and exchangeable sodium.

Keywords: chemical fractionation, micronutrients, salty soils, speciation

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Authors: Sudkate Chaiyo, Weena Siangproh, Orawon Chailapakul, Kurt Kalcher

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In the present work, a simple and sensitive non-enzymatic electrochemical detection of glucose in disposable paper-based sensor was developed at ionic liquid/graphene/cobalt phthalocyanine composite (IL/G/CoPc) modified electrode. The morphology of the fabricated composite was characterized and confirmed by scanning electron microscopy and UV-Vis spectroscopy. The UV-Vis spectroscopy results confirmed that the G/CoPc composite formed via the strong π–π interaction between CoPc and G. Amperometric i-t technique was used for the determination of glucose. The response of glucose was linear over the concentration ranging from 10 µM to 1.5 mM. The response time of the sensor was found as 30 s with a limit of detection of 0.64 µM (S/N=3). The fabricated sensor also exhibited its good selectivity in the presence of common interfering species. In addition, the fabricated sensor exhibited its special advantages such as low working potential, good sensitivity along with good repeatability and reproducibility for the determination of glucose.

Keywords: glucose, paper-based sensor, ionic liquid/graphene/cobalt phthalocyanine composite, electrochemical detection

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Authors: Abirham Simeneh Ayalew, Seada Hussen Adem, Frie Ayalew Yimam

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Battery energy storage has a great role on storing energy harnessed from different alternative resources and greatly benefit the power sector by supply energy back to the system during outage and regular operation in power sectors. Most of the study shows that there is an exponential increase in the quantity of lithium - ion battery energy storage system due to their power density, economical aspects and its performance. But this lithium ion battery failures resulted in fire and explosion due to its having flammable electrolytes (chemicals) which can create those hazards. Hazards happen in these energy storage system lead to minimize battery life spans or efficiency. Identifying the real cause of these hazards and its mitigation techniques can be the solution to improve the efficiency of battery technologies and the electrode materials should have high electrical conductivity, large surface area, stable structure and low resistance. This paper asses the real causes of chemical hazards, its impact on efficiency, proposed solution for mitigating those hazards associated with efficiency improvement and summery of researchers new finding related to the field.

Keywords: battery energy storage, battery energy storage efficiency, chemical hazards, lithium ion battery

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Authors: Razyeh Behbahani, Martin L. Plumer, Ivan Saika-Voivod

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Micromagnetic simulations based on the stochastic Landau-Lifshitz-Gilbert equation are used to calculate dynamic magnetic hysteresis loops relevant to magnetic hyperthermia applications. With the goal to effectively simulate room-temperature loops for large iron-oxide based systems at relatively slow sweep rates on the order of 1 Oe/ns or less, a coarse-graining scheme is proposed and tested. The scheme is derived from a previously developed renormalization-group approach. Loops associated with nanorods, used as building blocks for larger nanoparticles that were employed in preclinical trials (Dennis et al., 2009 Nanotechnology 20 395103), serve as the model test system. The scaling algorithm is shown to produce nearly identical loops over several decades in the model grain sizes. Sweep-rate scaling involving the damping constant alpha is also demonstrated.

Keywords: coarse-graining, hyperthermia, hysteresis loops, micromagnetic simulations

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Authors: Leila Maleki, Ahmad Esmali Kooraneh, Hossein Taghi Derakhshi

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Neural activity in the human brain starts from the early stages of prenatal development. This activity or signals generated by the brain are electrical in nature and represent not only the brain function but also the status of the whole body. At the present moment, three methods can record functional and physiological changes within the brain with high temporal resolution of neuronal interactions at the network level: the electroencephalogram (EEG), the magnet oencephalogram (MEG), and functional magnetic resonance imaging (fMRI); each of these has advantages and shortcomings. EEG recording with a large number of electrodes is now feasible in clinical practice. Multichannel EEG recorded from the scalp surface provides a very valuable but indirect information about the source distribution. However, deep electrode measurements yield more reliable information about the source locations، Intracranial recordings and scalp EEG are used with the source imaging techniques to determine the locations and strengths of the epileptic activity. As a source localization method, Low Resolution Electro-Magnetic Tomography (LORETA) is solved for the realistic geometry based on both forward methods, the Boundary Element Method (BEM) and the Finite Difference Method (FDM). In this paper, we review The findings EEG- LORETA about epilepsy.

Keywords: epilepsy, EEG, EEG-LORETA

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Authors: Chih-Chia Lin, Ching-Ying Huang, Cheng-Hong Liu, Wen-Lin Wang

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A complete fuel cell stack comprises several single cells with end plates, bipolar plates, gaskets and membrane electrode assembly (MEA) components. Electrons generated from cells are conducted through bipolar plates. The amount of cells' components increases as the stack voltage increases, complicating the fuel cell assembly process and mass production. Stack assembly error influence cell performance. PEM fuel cell stack importing laser welding technique could eliminate transverse deformation between bipolar plates to promote stress uniformity of cell components as bipolar plates and MEA. Simultaneously, bipolar plates were melted together using laser welding to decrease interface resistance. A series of experiments as through-plan and in-plan resistance measurement test was conducted to observe the laser welding effect. The result showed that the through-plane resistance with laser welding was a drop of 97.5-97.6% when the contact pressure was about 1MPa to 3 MPa, and the in-plane resistance was not significantly different for laser welding.

Keywords: PEM fuel cell, laser welding, through-plan, in-plan, resistance

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Authors: Ariangelo Hauer Dias Filho, Gustavo Antoniácomi de Carvalho, Benjamim de Melo Carvalho

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The work´s purpose was to evaluate the possibility of manufacturing casting tools utilizing Fused Filament Fabrication, a 3D printing technique, without any post-processing on the printed part. Taguchi Orthogonal array was used to evaluate the influence of extrusion temperature, bed temperature, layer height, and infill on the dimensional accuracy of a 3D-Printed Polymer Model. A Zeiss T-SCAN CS 3D Scanner was used for dimensional evaluation of the printed parts within the limit of ±0,2 mm. The mold capabilities were tested with the printed model to check how it would interact with the green sand. With little adjustments in the 3D model, it was possible to produce rapid tools without the need for post-processing for iron casting. The results are important for reducing time and cost in the development of such tools.

Keywords: additive manufacturing, Taguchi method, rapid tooling, fused filament fabrication, casting mold

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Authors: Iman Atighi, Jalal Soleimannejad, Ahmad Akbarinasab, Saeid Moradpour

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In the past, we could increase profit by increasing product prices. But in the new decade, a competitive market does not let us to increase profit with increase prices. Therefore, the only way to increase profit will be reduce costs. A significant percentage of production costs are the maintenance costs, and analysis of these costs could achieve more profit. Most maintenance strategies such as RCM (Reliability-Center-Maintenance), TPM (Total Productivity Maintenance), PM (Preventive Maintenance) etc., are trying to reduce maintenance costs. In this paper, decreasing the maintenance costs of Concentration Plant of Golgohar Company (GEG) was examined by using of MTBF (Mean Time between Failures) and MTTR (Mean Time to Repair) analyses. These analyses showed that instead of buying new machines and increasing costs in order to promote capacity, the improving of MTBF and MTTR indexes would solve capacity problems in the best way and decrease costs.

Keywords: Golgohar Iron Ore Mining and Industrial Company, maintainability, maintenance costs, reliability-center-maintenance

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Authors: Wan-Tzu Yen, Yu-Chen Luo, I-Ping Liu, Po-Hsuan Yeh, Sheng-Hsun Fu, Yuh-Lang Lee

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Self-assembled characteristics and adsorption performance of 1-dodecylamine molecules on gold (Au) (111) surfaces were characterized via cyclic voltammetry (CV), surface-enhanced infrared absorption spectroscopy (SEIRAS) and scanning tunneling microscopy (STM). The present study focused on the formation of 1-dodecylamine (DDA) on a gold surface with respect to the ex-situ arrangement of an adlayer on the Au(111) surface, and phase transition at potential dynamics carried out by EC-STM. This study reveals that alkyl amine molecules were formed an adsorption pattern with highly regular “lie down shape” on Au(111) surface, even in an extreme acid system (pH = 1). Acidic electrolyte (HClO₄) could protonate the surface of alkyl amine of a monolayer of the gold surface when potential shifts to negative. The quite stability of 1-dodecylamine on the gold surface maintained the monolayer across the potential window (0.1-0.8V). This transform model was confirmed by EC-STM. In addition, amine-modified Au(111) electrode adlayer used to examine how to affect an electron transfer across an interface using [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ redox pair containing 0.1 M HClO₄ solution.

Keywords: cyclic voltammetry, dodecylamine, gold (Au)(111), scanning tunneling microscopy, self-assembled monolayer, surface-enhanced infrared absorption spectroscopy

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Authors: N. Aliyu, G. Atkinson, N. Stannard

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Compacted insulated iron powder is a key material in high volume electric motors manufacturing. It offers high production rates, dimensionally stable components, and low scrap volumes. It is the aim of this paper to develop a three-phase compact single sided concentrated winding axial flux PM motor with soft magnetic composite (SMC) core for reducing core losses and cost. To succeed the motor would need to be designed in such a way as to exploit the isotropic magnetic properties of the material and open slot constructions with surface mounted PM for higher speed up to 6000 rpm, without excessive rotor losses. Higher fill factor up to 70% was achieved by compacting the coils, which offered a significant improvement in performance. A finite-element analysis was performed for accurate parameters calculation and the simulation results are thoroughly presented and agree with the theoretical calculations very well.

Keywords: SMC core, axial gap motor, high efficiency, torque

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Authors: Imtiaz Ahmed Khan, Sabu John, Sania Waqar, Lijing Wang, Mac Fergusson, Ilija Najdovski

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Evolution of textiles, from its orthodox to more interactive role has stirred the researchers to uncover its application in numerous arenas. The idea of using textile based materials for wearable energy harvesting and storage devices have gained immense popularity. This is mainly due to textile comfort and flexibility features. In this work, nano-carbonous materials were infused on cellulosic fibers using caustic soda treatment. This paper presents the complete procedure of yarn supercapacitors fabrication process through dip coating technique and its characterization method. The main objective is to study, the effect of varying caustic soda concentration on mass loading of activated carbon on yarns and the related capacitance output of the designed yarn supercapacitor. Polyvinyl alcohol and Phosphoric acid were used as electrolyte in a two-electrode cell assembly to measure device electrochemical performance. The results show a promising increase in capacitance value using this technique.

Keywords: yarn supercapacitors, activated carbon, dip coating, caustic soda, electrolyte, electrochemical characterization

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Authors: Muhammad Javed Bhatti, Tariq Ali, Muazz Ali

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Due to growing environmental awareness in Pakistan, the researchers are increasingly turning to assess and analyze properties of industrial waste and finding solutions on using industrial waste as secondary material. Due to industrialization, enormous by-products are produced and to utilize these by-products is the main challenge faced in Pakistan. Induction furnace slag is one of the industrial by-products from the iron and steel making industries. This paper highlights the true utilization of induction furnace slag as partial replacement of fine aggregate. For the experimental investigation, mixes were prepared with fine aggregate replacement using 0 percent, 5 percent, 10 percent, 15 percent, 20 percent, 25 percent, 30 percent, 35 percent and 40 percent induction furnace slag to evaluate the workability, compaction factor, compressive strength, flexural strength, modulus of elasticity.

Keywords: compressive strength, deflection, induction furnace slag, workability

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Authors: Cherief Houria, Fouka Mourad

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In this work, the simulation of the radiation attenuation is carried out in a photon detector consisting of different common shielding material using a Monte Carlo program called PTM. The aim of the study is to investigate the effect of atomic weight and the thickness of shielding materials on the gamma radiation attenuation ability. The linear attenuation coefficients of Aluminum (Al), Iron (Fe), and lead (Pb) elements were evaluated at photons energy of 661:7KeV that are considered to be emitted from a standard radioactive point source Cs 137. The experimental measurements have been performed for three materials to obtain these linear attenuation coefficients, using a Gamma NaI(Tl) scintillation detector. Our results have been compared with the simulation results of the linear attenuation coefficient using the XCOM database and Geant4 codes and reveal that they are well agreed with both simulation data.

Keywords: gamma photon, Monte Carlo program, radiation attenuation, shielding material, the linear attenuation coefficient

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Authors: Roya Moradifar, Naser Agharezaee

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In this paper corrosion in the liquid sulphur storage tank at South pars gas complex phases 2&3 is presented. This full hot insulated field-erected storage tanks are used for the temporary storage of 1800m3 of molten sulphur. Sever corrosion inside the tank roof was observed during over haul inspections, in the direction of roof gradient. Investigation shown, in spite of other parts of tank there was no insulation around these manholes. Internal steam coils do not maintain a sufficiently high tank roof temperature in the vapor space. Sulphur and formation of liquid water at cool metal surface, this combination leads to the formation of iron sulfide. By employing a distributed external heating system, the temperatures of any point of the tank roof should be based on ambient dew point and the liquid storage solidification point. Also other construction and operation of tank is more important. This paper will review potential corrosion mechanism and operational case study which illustrate the importance of heating systems.

Keywords: tank, steam, corrosion, sulphur

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Authors: Emmanuel Ogundimu, Esther Akinlabi, Mutiu Erinosho

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The aim of this paper is to study the effect of welding current on the microstructure and the mechanical properties. Material characterizations were conducted on a 6 mm thick plates of type-304 austenite stainless steel, welded by TIG welding process at two different welding currents of 150 A (Sample F3) and 170 A (Sample F4). The tensile strength and the elongation obtained from sample F4 weld were approximately 584 MPa and 19.3 %; which were higher than sample F3 weld. The average microhardness value of sample F4 weld was found to be 235.7 HV, while that of sample F3 weld was 233.4 HV respectively. Homogenous distribution of iron (Fe), chromium (Cr) and nickel (Ni) were observed at the welded joint of the two samples. The energy dispersive spectroscopy (EDS) analysis revealed that Fe, Cr, and Ni made up the composition formed in the weld zone. The optimum welding current of 170 A for TIG welding of type-304 austenite stainless steel can be recommended for high-tech industrial applications.

Keywords: microhardness, microstructure, tensile, MIG welding, process, tensile, shear stress TIG welding, TIG-MIG welding

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Authors: Linlin Wang, Guangdong Bian, Jifeng Shen, Jingzhu Zeng

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Zinc-aluminum alloys have been applied as alternatives to bronze, aluminum alloys, and cast iron due to their distinguishing features such as high as-cast strength, excellent bearing properties, as well as low energy requirements for melting. In this study, oxide coatings were produced on ZA27 zinc-aluminum alloy by a plasma electrolytic oxidation (PEO) method. Three coatings were deposited by using three various electrolytes, i.e. silicate, aluminate and aluminate/borate composite solutions. The current density is set at 0.1A/cm2, deposition time is 40 mins for all the deposition processes. The surface morphology and phase structure of the three coatings were characterized by scanning electron microscopy （SEM） and X-ray diffraction (XRD). Pin-on-disc sliding wear tests were conducted to test the tribological properties of coatings. The results indicated that the coating produced using the aluminate/borate composite electrolyte had the highest deposition rate and best wear resistance among the three coatings.

Keywords: oxide coating, PEO, tribological properties, ZA27

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Authors: Charmaine Lamiel, Van Hoa Nguyen, Marjorie Baynosa, Jae-Jin Shim

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Electrochemical supercapacitors have attracted considerable attention because of their high potential as an efficient energy storage system. The combination of carbon-based material and transition metal oxides/sulfides are studied because they have long and improved cycle life as well as high energy and power densities. In this study, a hierarchical mesoporous carbon sphere/nickel cobalt sulfide (CS/Ni-Co-S) core/shell structure was synthesized using a facile hydrothermal method without any further sulfurization or post-heat treatment. The CS/Ni-Co-S core/shell microstructures exhibited a high capacitance of 724 F g−1 at 2 A g−1 in a 6 M KOH electrolyte. After 2000 charge-discharge cycles, it retained 86.1% of its original capacitance, with high Coulombic efficiency of 97.9%. The electrode exhibited a high energy density of 58.0 Wh kg−1 at an energy density of 1440 W kg−1, and high power density of 7200 W kg−1 at an energy density of 34.2 Wh kg−1. The successful synthesis was considered to be simple and cost-effective which supports the viability of this composite as an alternative activated material for high performance supercapacitors.

Keywords: carbon sphere, electrochemical, hydrothermal, nickel cobalt sulfide, supercapacitor

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Authors: Alejandra Martin-Dominguez, Javier Canto-Rios, Velitchko Tzatchkov

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Electrocoagulation is a water treatment technology that consists of generating coagulant species in situ by electrolytic oxidation of sacrificial anode materials triggered by electric current. It removes suspended solids, heavy metals, emulsified oils, bacteria, colloidal solids and particles, soluble inorganic pollutants and other contaminants from water, offering an alternative to the use of metal salts or polymers and polyelectrolyte addition for breaking stable emulsions and suspensions. The method essentially consists of passing the water being treated through pairs of consumable conductive metal plates in parallel, which act as monopolar electrodes, commonly known as ‘sacrificial electrodes’. Physicochemical, electrochemical and hydraulic processes are involved in the efficiency of this type of treatment. While the physicochemical and electrochemical aspects of the technology have been extensively studied, little is known about the influence of the hydraulics. However, the hydraulic process is fundamental for the reactions that take place at the electrode boundary layers and for the coagulant mixing. Electrocoagulation reactors can be open (with free water surface) and closed (pressurized). Independently of the type of rector, hydraulic head loss is an important factor for its design. The present work focuses on the study of the total hydraulic head loss and flow velocity and pressure distribution in electrocoagulation reactors with single or multiple concentric annular cross sections. An analysis of the head loss produced by hydraulic wall shear friction and accessories (minor head losses) is presented, and compared to the head loss measured on a semi-pilot scale laboratory model for different flow rates through the reactor. The tests included laminar, transitional and turbulent flow. The observed head loss was compared also to the head loss predicted by several known conceptual theoretical and empirical equations, specific for flow in concentric annular pipes. Four single concentric annular cross section and one multiple concentric annular cross section reactor configuration were studied. The theoretical head loss resulted higher than the observed in the laboratory model in some of the tests, and lower in others of them, depending also on the assumed value for the wall roughness. Most of the theoretical models assume that the fluid elements in all annular sections have the same velocity, and that flow is steady, uniform and one-dimensional, with the same pressure and velocity profiles in all reactor sections. To check the validity of such assumptions, a computational fluid dynamics (CFD) model of the concentric annular pipe reactor was implemented using the ANSYS Fluent software, demonstrating that pressure and flow velocity distribution inside the reactor actually is not uniform. Based on the analysis, the equations that predict better the head loss in single and multiple annular sections were obtained. Other factors that may impact the head loss, such as the generation of coagulants and gases during the electrochemical reaction, the accumulation of hydroxides inside the reactor, and the change of the electrode material with time, are also discussed. The results can be used as tools for design and scale-up of electrocoagulation reactors, to be integrated into new or existing water treatment plants.

Keywords: electrocoagulation reactors, hydraulic head loss, concentric annular pipes, computational fluid dynamics model

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Authors: Rupan Das Chakraborty, Surendra K. Martha

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Hard carbons (HCs) are extensively used as anode materials for sodium-ion batteries due to their availability, low cost, and ease of synthesis. It possesses the ability to store Na ion between stacked sp2 carbon layers and micropores. In this work, hard carbons are synthesized from different concentrations (0.5M to 5M) of dextrose solutions by hydrothermal synthesis followed by high-temperature calcination at 1100 ⁰C in an inert atmosphere. Dextrose has been chosen as a precursor material as it is a eco-friendly and renewable source. Among all hard carbon derived from different concentrations of dextrose solutions, hard carbon derived from 3M dextrose solution delivers superior electrochemical performance compared to other hard carbons. Hard carbon derived from 3M dextrose solution (Dextrose derived Hard Carbon-3M) provides an initial reversible capacity of 257 mAh g-1 with a capacity retention of 83 % at the end of 100 cycles at 30 mA g-1). The carbons obtained from different dextrose concentration show very similar Cyclic Voltammetry and chargedischarging behavior at a scan rate of 0.05 mV s-1 the Cyclic Voltammetry curve indicate that solvent reduction and the solid electrolyte interface (SEI) formation start at E < 1.2 V (vs Na/Na+). Among all 3M dextrose derived electrode indicate as a promising anode material for Sodium-ion batteries (SIBs).

Keywords: dextrose derived hard carbon, anode, sodium-ion battery, electrochemical performance

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Authors: Alpha Matthew

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The Composites of Al-Doped K₂CO₃ activated coconut husk carbon, Al₀.₁:(K₂CO₃C)₀.₉ and AI₀.₃:(K₂CO₃C)₀.₇, were prepared using the hydrothermal method and drop casting deposition technique. The electrochemical performance of the Al-doped K₂CO₃ activated coconut husk carbon composite as a promising anode material for lithium-ion batteries was characterised by cyclic voltammetry analysis, electrochemical impedance spectroscopy, and galvanostatic charge discharge analysis. The charges that are retained in the anode material during charging showed a linear decline in charge capacity as the charging current intensity increased. Ionic polarisation was the reason for the observed drop in the charge and discharge capabilities at the current density of 5 A/g. Having greater specific capacitance and energy density, the composite Al₀.₁:(K₂CO₃C)₀.₉ is a better anode material for electrochemical applications compared to AI₀.₃:(K₂CO₃C)₀.₇, also its comparatively higher power density at a scan rate of 5 mV/s is mostly explained by its lower equivalent series resistance.

Keywords: coconut carbon husk, power density, energy density, battery, anode electrode

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Authors: Oleg Oborin

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This paper is dedicated to the development of the model, which can be used to evaluate the effectiveness of long-term corporate strategies and identify the best strategies. The theoretical model of the relatively homogenous product market (such as iron and steel industry, mobile services or road transport) has been developed. In the model, the market consists of a large number of companies with different internal characteristics and objectives. The companies can perform mergers and acquisitions in order to increase their market share. The model allows the simulation of long-time dynamics of the market (for a period longer than 20 years). Therefore, a large number of simulations on random input data was conducted in the framework of the model. After that, the results of the model were compared with the dynamics of real markets, such as the US steel industry from the beginning of the XX century to the present day, and the market of mobile services in Germany for the period between 1990 and 2015.

Keywords: Economic Modelling, Long-Time Strategy, Mergers and Acquisitions, Simulation

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Authors: Kerim Emre Öksüz, Mehmet Çevik, A. Enbiya Bozdağ, Ali Özer, Mehmet Şimşir

Abstract:

Metal matrix composites (MMCs) have gained a considerable interest in the last three decades. Conventional powder metallurgy production route often involves the addition of reinforcing phases into the metal matrix directly, which leads to poor wetting behavior between ceramic phase and metal matrix and the segregation of reinforcements. The commonly used elements for ceramic phase formation in iron based MMCs are Ti, Nb, Mo, W, V and C, B. The aim of the present paper is to investigate the effect of sintering temperature and V-B addition on densification, phase development, microstructure, and hardness of Fe–V-B composites (Fe-(5-10) wt. %B – 25 wt. %V alloys) prepared by powder metallurgy process. Metal powder mixes were pressed uniaxial and sintered at different temperatures (ranging from 1300 to 1400ºC) for 1h. The microstructure of the (V, B) Fe composites was studied with the help of high magnification optical microscope and XRD. Experimental results show that (V, B) Fe composites can be produced by conventional powder metallurgy route.

Keywords: hardness, metal matrix composite (MMC), microstructure, powder metallurgy

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Authors: M. A. Hasnat, M. Amirul Islam, M. A. Rashed, Jamil. Safwan, M. Mahabubul Alam

Abstract:

Symmetric (Cu–Pt|Nafion|Pt–Cu) and asymmetric(Pt|Nafion|Pt–Cu) assemblies were fabricated to study the nitrate reduction processes at the cathode. The electrocatalytic nitrate reduction reactions were performed in these assemblies in order to investigate the prerequisite for the enhanced catalytic activity, electrochemical cell durability as well as preferable product selectivity resulting from the reduction of nitrate at the cathode. It has been observed for the symmetric assembly that Cu particles were oxidized on the anode surface under an applied potential and the resulting copper ions migrated to the cathode surface through the Nafion membrane, which deposited as copper oxide on the cathode surface. The formation of this copper oxide covering layer on the Pt–Cu cathode surface is attributed as the reason for the deactivation of the cathode that governed the reduced nitrate reduction along with increasing nitrite selectivity. These problems were addressed and resolved with the asymmetric design of the electrocatalytic reactor, where enhanced hydrogen evolution activates the surface by eroding the CuO over layer as well as speeding up the slow rate determining hydrogenation reactions.

Keywords: membrane, nitrate, electrocatalysis, voltammetry, electrolysis

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