bluuebunny/crossref_metadata_2025 huggingface dataset:
The price of polarization: Estimating task prices under routine‐biased technical change
Authors: Böhm Michael J.
Published: May 2020

This paper proposes a new approach to estimate task prices per efficiency unit of skill in the Roy model. I show how the sorting of workers into tasks and their associated wage growth can be used to identify changes in task prices under relatively weak assumptions. The estimation exploits the fact that the returns to observable talents will change differentially over time depending on the changes in prices of those tasks that they predict workers to sort into. In the generalized Roy model, also the average non‐pecuniary amenities in each task are identified. I apply this approach to the literature on routine‐biased technical change, a key prediction of which is that task prices should polarize. Empirical results for male workers in U.S. data indicate that abstract and manual tasks' relative prices indeed increased during the 1990s and 2000s.
Application of Blended Learning for Formation of Project Competence of Future Engineers
Authors: Galustyan Olga Vladimirovna , Solyankin Alexey Viktorovich , Skripkina Alina Vjacheslavovna , Shchurov Evgeny Andreevich , Semeshkina Tatyana Vladimirovna , Ledeneva Anastasia Vladimirovna
Published: May 2020

The article is devoted to application of blended learning for formation of project competence of future engineers. The article identifies the main characteristics of blended learning as means of development of project competence of future engineers. Project competence is considered as an integrative characteristic of future specialist which is expressed in ability and readiness for theoretical and practical activities in the development and implementation of projects in various fields. Cognitive, operational, communicative, reflexive components within the structure of project competence are identified. The authors conclude that application of blended learning within engineering education satisfies the needs of modern educational process.
Educating Engineers Under a Social Justice Perspective
Authors: P. Jiménez Patricia , Pascual Jimena , Mejía Andrés
Published: May 2020

Although the need for an engineering education oriented to public welfare and social justice has been acknowledged for many years, the efforts to put it in practice seem insufficient and a culture of disengagement still appears dominant. The aim of this article is twofold: (1) to examine beliefs and motivations of university faculty towards the social responsibility of engineers, and (2) to develop pedagogical principles to deal with the culture of disengagement in engineering. A survey-based quantitative study was conducted among faculty from a university in Chile. A factor analysis revealed two dimensions of social justice in their conceptions, with significantly higher scores for the first one: environmental/ethical versus public/community. Additionally, faculty value less the humanities and social sciences than other non-technical topics in the curriculum. Results, for this university, confirm the prevailing cultural features reported elsewhere. Some guidelines to counteract the cultural pillars of disengagement are based on critical thinking, context-based learning or situated practice, and interdisciplinary learning. These are illustrated in a course on Systems Simulation.
Numerical Analysis of an Isovolumetric Thermal Desorption Experiment
Authors: von der Weth Axel , Arbeiter Frederik , Nagatou Kaori , Pasler Volker , Klimenko Dmitri , Schulz Marvin
Published: May 2020

Our research group is currently investigating a new kind of thermal desorption experiment (TDE), which uses a hydrogen isotope by loading-unloading process yielding transport parameters. Safety issues are limiting the hydrogen loading content to 3 % at 105 Pa, while former experiments are using pure hydrogen for the loading process at nearly same pressure e. g. [1]. Especially the thermal elongation coefficient (TDE operating conditions 300° to 500 °C compatibility to stainless steel) forces to think about an alternative material of boron silicate glass for specimen containment, in this paper copper will be discussed.
The analysis of TDE concerns the amount of hydrogen stored in the specimen, stored in the time variable gas phase as well as stored in the containment material. These three phases are coupled by phase equilibrium.
The here developed analysis procedure can currently only be performed numerically for a two dimensional geometry. However a two dimensional analytical solution regarding the same boundary condition is currently under investigation. One part of the solution results of this problem can be compared to an additional analytical solution with simpler boundary conditions, e.g. a vanishing hydrogen amount inside the specimen containment observed in steady state. The numerical results will be used to check the suitability of several experimental scenarios, for example the usability of a copper based specimen containment. The approach currently practiced in many experiments is to simply subtract the zero rate of hydrogen without considering the phase equilibrium between the three mentioned phases. The main goal of this analysis procedure consists in the solution of the inverse problem, namely the extraction of the transport parameters like Sieverts ́-and diffusion-constant from a measured time dependent desorption pressure increase.
Numerical Modeling of Heat and Mass Transport with Inner Heat Exchange in Unsaturated Porous Media
Authors: Kačur Jozef , Mihala Patrik
Published: May 2020

We are focused to the numerical modelling of heat, contaminant and water transport in unsaturated porous media in 3D. The heat exchange between water and porous media matrix is taken into the account. The determination of heat energy transmission coefficient and matrix heat conductivity is solved by means of inverse problem methods. The mathematical model represents the conservation of heat, contaminant and water mass balance. It is expressed by coupled non-linear system of parabolic-elliptic equations. Mathematical model for water transport in unsaturated porous media is represented by Richard's type equation. Heat transport by water includes water flux, molecular diffusion and dispersion. A successful experiment scenario is suggested to determine the required parameters including heat transmission and matrix heat conductivity coefficients. Additionally we investigate contaminant transport with heat transmission and contaminant adsorption. The obtained experiments support our method suitable for solution of direct and inverse problems. This problem we have discussed previously in 1D model, but preferential streamlines in 1D thin tubes shadow accurate results in determination of required parameters. In our presented setting we consider a cylindrical sample which is suitable in laboratory experiments for inverse problems.
Transport Coefficients of Ammonia Gas in Thermoplastic Polymers and Nanocomposites Used for Microelectronic Substrates Containers
Authors: Tran Minh Phuong , González-Aguirre Paola , Beitia Carlos , Lundgren Jorgen , Moon Sung In , Fontaine Hervé
Published: May 2020

Polymeric plastic boxes (named Front Opening Unified Pods (FOUP)) were widely used in semiconductor manufacture to maintain the cleanliness of processed wafer substrates in a controlled mini-environment. Polymeric materials, however, are able to sorb airborne molecular contaminants (AMCs) and subsequently to outgas the sorbed AMCs backward to FOUP’s atmosphere, causing the transfer of AMCs to sensitive stored substrates, named cross-contamination. As a type of AMCs, the NH3 cross-contamination could cause a severe yield loss to integrated circuits (crystals (haze), resist-development defects (T-topping) or metallic corrosion). Experiments were carried out to establish the NH3 sorption and desorption kinetics in polyetherimide (PEI), Entegris Barrier Material (EBM)), and EBM/carbon nanotubes (EBMCNT) at NH3 concentration of 800-ppbv, 21°C, and relative humidity of 40%. The transport coefficients i.e. solubility and diffusivity (DNH3 and SNH3) were then determined. The study on NH3 provides an additional guideline to choose the best raw materials for FOUP formulation in taking into account the potential cross-contamination of AMCs. Numerical simulation model based on obtained solubility and diffusivity values was conducted to demonstrate NH3 concentration profiles in FOUP walls during contamination and FOUP decontamination, which are inaccessible by conventional experiments.
Scanning Electron Microscope in Rocks and their Comparison with Physical-Mechanical Properties
Authors: Seras Marco Antonio Navarrete , Mota Francisco Javier Domínguez , Guzmán Elia Mercedes Alonso , Molina Wilfrido Martínez , Chávez-García Hugo Luis , Tinoco Ruiz José Gerardo , Torres José Alberto Guzmán
Published: May 2020

. Banks of stone materials from Michoacán, Mexico were characterized, since they are used in the construction of infrastructure in the area. With these materials are made hydraulic concrete mixtures or asphalt mixtures, foundations, paving stones and in restoration of historical monuments. The rocks analyzed and characterized, come from banks of volcanic stone materials and banks of crushed stone materials, which were subjected to mechanical tests such as uniaxial compression resistance (UCR), in addition was used scanning electron microscope (SEM), by means of which the characterization was carried out, obtaining morphological information of the material. The comparison of physical-mechanical properties with the elements they possess is important to estimate their behavior within ceramic matrices or as a structural element.
Natural Additive to Retard the Setting of a Mortar and Increase its Resistance
Authors: Díaz-González Noel , Luna Luis Alberto González , Guzmán Elia Mercedes Alonso , Molina Wilfrido Martínez , Chávez-García Hugo Luis , Perez Judith Alejandra Velázquez
Published: May 2020

The use of better materials is essential for the development of a country, that is why in this work we analyze a mixture of cement-based mortar with an addition of mucilage from a plant called Maralfalfa, said plant is used as feed for cattle and it is thought that its hydrate content can improve the water-cement reaction. Two mixtures were made, one control and another with the addition. The material used was: volcanic sand from Michoacán, cement CPC 30R RS, drinking water and the addition of mucilage. Cubic specimens (5x5x5 cm), prismatic specimens (4x4x16 cm) and briquettes were made, which were tested at 7, 14, 21, 28, 45 and 70 days of age. The tests performed were non-destructive (density, ultrasonic pulse rate and electrical resistivity) and destructive (simple compression, flexion and tension). The density results indicate that the mixture with addition densifies the cement matrix, the ultrasonic pulse velocity results are very similar between the mixtures, the results of electrical resistivity indicate that the control mixture is slightly higher. In terms of simple compression and flexion, it is indicated that the mixture with the addition was higher than the control, whereas the voltage results indicate the opposite. In addition, it was found that the addition retards the setting time of the mixture.
Failure Analysis of Spur Gears Used in Transmission System Applied on a Hand Tractor
Authors: Husaini Husaini , Dawud Dzikra M. , Putra Teuku Edisah , Ali Nurdin
Published: May 2020

Damage or failure frequently occurs on gearbox gears. If this occurs in the gearbox of tractors, this can be severe. This study aimed to determine the cause of the spur gear fracture through empirical and simulation studies. The hardness test was undertaken employing the Rockwell method where the fracture surface was observed using a scanning electron microscope (SEM) in order to identify crack initiation and the type of fracture. The stress intensity factor was next analysed using the finite element method (FEM). The results of the chemical composition testing indicated that the material used was according to the AISI 8620 standard containing an element of Carbon (C) of about 0.142 %.The hardness value of the gear was 109 HRB. The observation of the fracture surface showed a brittle fracture surface, suggesting that an impact load had occurred. The simulation results using the FEM also showed that the maximum stress intensity factor and KI value occurred at the centre of the tooth. The value of KI was shown to be larger than the fracture toughness and (KIC). Therefore, this result indicates that a crack will continue to propagate until final failure.
Hemp Fiber Reinforced Geopolymer Composites: Effects of NaOH Concentration on Fiber Pre-Treatment Process
Authors: Maichin Phattharachai , Suwan Teewara , Jitsangiam Peerapong , Chindaprasirt Prinya
Published: May 2020

High demand for using parts of natural materials, e.g., cores, fibers or leaves, as alternative additives are being increased. The main reasons are that natural materials can be served as renewable and eco-friendly choices such a sustainable development. Nevertheless, some limitations of applying those natural products, such as biodegradation, UV degradation, or weak bonding, are raised and need to be modified before further handling. One of the modification techniques for bio-based materials is chemical treatment by using alkaline solution (alkalization). Treatment process allows the plant's fiber to have fewer impurities as well as to increase the bonding on its contacting surface area. This research focuses on (i) effects of NaOH solution concentration on the pre-treatment properties of hemp fibers and (ii) self-treatment behavior of hemp fiber in geopolymer composites. The results show that the concentration of NaOH solution directly affected the pre-treatment process of hemp fiber as higher concentration from 1, 3, 5, 8, 10 to 12 Molar provided more vanishing level of fiber impurities, indicated by Contact Angle (CA) measurement and Fourier Transform Infrared (FT-IR) Spectroscopy analysis. With the concept of alkaline treatment, the self-treatment process was therefore applied for hemp fiber incorporated in alkaline-activated geopolymer matrix. The results illustrate the self-treatment behavior of hemp fiber in geopolymer composites, which could improve the final performances of the hardened products without conventional pre-treatment process.
Crushed Rock Geopolymer as a Future Road Construction Material: An Evaluation on Strength Performance and Compaction Characteristics
Authors: Kwunjai Sararat , Jitsangiam Peerapong , Suwan Teewara , Rinchumphu Damrongsak , Thongchua Hemwadee , Chindaprasirt Prinya , Sampattagul Sate
Published: May 2020

To be more sustainable in the road construction industry, the rock-based geopolymer concept should be applied with an aim to create a geopolymer-based road structural layer. The research program studied on the geopolymer for road construction was newly established at Chiang Mai University, Thailand. This study concentrated in a preliminarily evaluation of strength performance and compaction characteristics of crushed rock-based geopolymer (CR-GP) to partially or totally replace the usage of ordinary Portland cement (OPC) as a road stabilizing agent. The standard crushed rock (CR), complying with the standard of road base materials, was obtained from a real construction field. The experiment on CR gradation, compaction and compressive strength were carried out. The results showed that CR of a finer grading curve with higher surface areas tended to better react with alkaline activators, resulting in relatively high compressive strength. The mechanical modification with compaction is one of the simplest methods for strength improvement. It found that higher compactive efforts (the modified compaction), higher densification than that of the standard compaction, corresponding to the compaction theory of soil mechanics. CR-GP having an ideal (reconstituted) grading curve achieved higher compressive strength than that of the standard grading one of a well-graded pattern. Overall, it could be concluded CR-GP has intrinsic compaction characteristics of which at its optimum point of compaction, CR-GP could address the minimum requirement for road standard in terms of compressive strength, by which it could be used as an alternative material in replacing the consumption of OPC.
Study of Properties of 3D Printed Short Carbon Fiber Composite
Authors: Saithongkum Nathathai , Tuchinda Karuna
Published: May 2020

The properties of composite materials do not depend only on the properties of raw materials but also other parameters such as volume fraction, geometry, dimension and material distribution etc. Carbon fiber reinforced polymer is one of the top choices of composite material because carbon fiber has light weigh with high tensile strength. For fiber-based composite such as carbon fiber composite, directions of carbon fiber with respect to loading direction could also affect to the strength of composite material under load. In this work, the properties of short carbon fiber-resin composite were investigated (fiber length of 0.2 mm.) with two different fiber orientations, i.e. 0 and 90 degrees to applied load. The 3D printing technique was employed in order to control carbon fiber direction and minimize material loss leading to material cost reduction. It was found that 3D printing technique could control direction of fiber in most case. However, at area with high curvature, the unexpected fiber direction was observed due to post hot process during which material flow was expected. It should also be noted that fiber path during 3D printing process may be very crucial as it could result in low strength local area due to low fiber density. This area could promote stress concentration leading to final fracture.
Evaluation of the Electrical Resistivity, Ultrasonic Pulse Velocity and Mechanical Properties in Portland Cement Pastes Type II
Authors: Perez Judith Alejandra Velázquez , Guzmán Elia Mercedes Alonso , Molina Wilfrido Martínez , Chávez-García Hugo Luis , Moreno Ioscany Talingo , Sánchez Mauricio Arreola
Published: May 2020

This research is focused on cement pastes with w/c ratio of 0.5. The cementing material is Portland cement type II. The main aim is to estimate the mechanical properties based on non-destructive tests such as ultrasonic pulse velocity, and electrical resistivity by a correlation with the destructive tests such as compressive strength, flexural strength, and tensile strength at ages of 3,7,14,21,28 and 45 days. The results suggest that there is a good correlation between evaluated properties.
Characterization of Hydraulic Concrete with Polystyrene-Based Emulsion
Authors: Chiquito Maybelin Carolina García , Guzmán Elia Mercedes Alonso , Molina Wilfrido Martínez , Chávez-García Hugo Luis , Díaz-González Noel
Published: May 2020

The following investigation was carried out with the objective of characterizing a concrete added with an emulsion based on reused polystyrene. The tests that were carried out for this characterization are: compression resistance, resistivity and ultrasonic pulse speed, in addition to the proper characterization of the stone material. A control mixture was also made and one in which a fluidiser is added in order to compare the results of these mixtures against the results of the concrete added with emulsion. The proportions of the emulsion are 1% and 4% because in the setting times [1], made in previous research results in that 1% is the beginning of setting and 4% the end of it. Values greater than 4% exceed the time allowed in the NMX-C-177-1997 ONNCCE standard.
Preparation and Performance Study of Fluorosilicone Oligomer Anti-Sticking Coatings
Authors: Guan Dong Bo , Zhai Xiao Jie , Biansai Ying Nan , Cao Bo Jun , Zhu Yong Fu , Li Jin Liang
Published: May 2020

In this paper, fluorosilicone oligomer and its curing agent are used as the main film-forming materials, and fluorosilicone POSS is added to reduce the surface energy of the composites to prepare a coating with certain anti-sticking effect. The changes of molecular structure before and after the reaction were obtained by infrared spectroscopy. The contact angle and anti-sticking property of the coating surface were studied by changing the content of POSS containing fluorine. It was found that the contact angle of fluorine-containing POSS reached 98.7° when the content of fluorine-containing POSS was 3 Wt.%. With the increase of POSS content, the anti-sticking force of composites changed little, but with the increase of the contact time of tape, the anti-sticking force showed an increasing trend.
Rejection Rate Reduction of the Automotive Thermoplastic Parts in Injection Moulding Using Response Surface Methodology
Authors: Ong Huei Ruey , Shah Ifwat Mohd , Iskandar Wan Mohd Eqhwan , Khan Md. Maksudur Rahman , Hong Shein , Ramli Ridzuan , Mohamed Muhammad Khairul Anuar
Published: May 2020

Plastic injection moulding is widely used for manufacturing due to variety of plastic product. In this study, plastic part defects such as air bubble and gas mark defect are commonly occurs in thermoplastic part, specifically acrylonitrile butadiene styrene (ABS). In order to optimize the process parameters of injection moulding, design of experiment (DOE) with Response Surface Methodology (RSM) model was used. Process parameters such as melt temperature, mould temperature and injection pressure were selected for the DOE development. The experiments were conducted with melt temperature range from 200 °C to 240 °C, mould temperature from 60 °C to 80 °C and injection pressure from 90 to 99%. The result indicates that, all the selected parameters were significantly influence the rejection rate of the automotive ABS part. The optimum melt temperature, mould temperature and injection pressure were 220 °C, 70 °C and 98% respectively, in obtaining minimum rejection rate.
Simulation of Gap Flow Field in EDM Process Uesd Oil-in-Water Working Fluid
Authors: Chang Wei Jie , Xi Yan Ying , Li Hao Wei
Published: May 2020

Electric Discharge Machining (EDM) working fluid as a medium can control electrical discharges occur, carry away the heat, compress discharge channel and help remove the corrosion products out of the gap. The main working fluids used in EDM are oil-based working fluid, gas-based working fluid, powder mixed working fluid, gas mixed working fluid and water-based working fluid. In order to improve the green and safety of EDM working fluid, an oil-in-water working fluid is proposed. A gap flow field model of EDM is established by using external flushing fluid. The flow field distribution, pressure distribution and corrosion products distribution of the machining gap are analyzed by using computational fluid dynamics. The effects of inlet pressure, processing depth and electrode size on the flow field are studied. The simulated results show that within a certain range, removal effect of the corrosion products will increase with inlet velocity and the size of electrode and decrease with processing depth.
Characterization of Adsorbents Derived from Palm Fiber Waste and its Potential on Methylene Blue Adsorption
Authors: Zulkania Ariany , Iqbal Muhammad , Syamsumarlin Syamsumarlin
Published: May 2020

In this study, two types of adsorbent including activated carbon and bio-sorbent were produced from Palm fiber wastes (PFW), which were activated by phosphoric acid. The influence of adsorbent type and phosphoric acid concentration on methylene blue adsorption was investigated. The most optimum adsorbent was determined based on adsorption capacity and removal percentage of each adsorbent. The result shows that 9.984 mg/g of adsorption capacity and 99.84% of removal percentage were achieved in 90 minutes’ adsorption, which demonstrates the huge potential of bio-sorbent and was chosen to be the most optimum adsorbent based on methylene blue removal. The characterization of bio-sorbent was then investigated using FTIR and SEM. FTIR result shows that bio-sorbent contains cellulose which affected the adsorption process while SEM result shows the cleaner pores and surface compared to bio-sorbent before activation.
Effect of Cr and Si Contents on the Magnetic and Mechanical Properties of Fe-Cr-Si Alloys by MIM Process
Authors: Kimura Masahiro , Shimizu Toru , Watari Hisaki
Published: May 2020

In recent years, metal injection molding (MIM) has been adopted as a process of manufacturing a solenoid valve which is a component of an electronic fuel injector, and PB permalloy component has been commercialized. However, Ni that is an element of PB permalloy is expensive material, and it makes difficult to produce the injector component in low cost. To reduce the production cost, we can use Fe-Cr alloys, although there are few studies on Fe-Cr alloys by MIM process. In this study, Fe-Cr-Si alloy specimens were manufactured by MIM process and the magnetic and mechanical properties were investigated. From these results, we found that high performance Fe-Cr-Si alloy can be obtained by setting Si content to 3% and reducing Cr content.
Investigation on Mechanical Behavior of Sisal Fiber Reinforced Polylactic Acid and Sisal/Epoxy Composites
Authors: Dhannush S. , Aushwin S. , Arunagiri Adhithian R. , Senthamaraikannan Chinnasamy
Published: May 2020

. Natural fibers have been found to be an alternative resource for synthetic materials. Natural composites are found to be a one hundred percent bio degradable product. Natural composites are also found to be having a great strength to weight ratio. In this process, hybrid sisal and polylactic bio composites are reinforced together by using the hand layup method. The ratio of sisal and polylactic element is in the ratio of 1:1 that are subjected to a compressive force with simultaneous heating process. Tensile strength and Flexural strength are evaluated as per the ASTM standards. Results shown that the there is good improvement in polylactic acid based biocomposite due to good interfacial between fiber and matrix.
Evaluation of Mechanical Properties of Sugarcane Reinforced Hybrid Natural Fibre Composites by Conventional Fabrication and Finite Element Method
Authors: S Ram Dhiwakar , Kumar P.N. Bharath , Kumar R. Sandeep , Ramnath B. Vijaya
Published: May 2020

Natural Fibre composites are being widely used as a replacement to non-bio-degradable polymer composites. The unavailability of proper processes to treat the natural fibres and the errors in fabrication result in less accurate mechanical properties. The accuracy that is obtained by machine-based processes is not possible in Hand layup method, which is employed in fabrication of natural fibre composites. Finite Element method packages which are specially intended in modelling composite structures give more accurate result of properties than experimental setup, by avoiding fabrication errors. This paper evaluates Impact energy and then the tensile strength, flexural strength of a sugarcane fibre GFRP reinforced polymer matrix both by conventional Hand Layup method and also by Finite Element method.
Estimation of Cold Roll Forming Characteristics of Wrought Magnesium Alloy with Tension-Compression Asymmetry
Authors: Kobayashi Harunori , Tozuka Hotaka , Watari Hisaki
Published: May 2020

In recent years, the movement for banning the sale of gasoline cars and diesel vehicles, especially in Europe, and allowing only electric passenger cars has been accelerated. For examples, Germany’s federal council, the Bundesrat, has passed a resolution calling for a ban on combustion engine cars by 2030. If the ban were to go through, German citizens would only be permitted to purchase electric or hydrogen-fueled cars. In Norway, until 2025 there is a movement for legislation prohibiting the registration of new gasoline passenger cars and diesel cars. Beginning in 2025 in the Netherlands, a bill prohibiting the sale of new cars gasoline and diesel vehicles was submitted to Congress. Under the circumstances, the demand for light-weight products for automotive industries has increased due to global trends in environmental preservation. Although demands for magnesium has risen dramatically, production of magnesium alloy sheet still remains at a very low level. This study seeks to establish a guideline for roll design in the roll forming of wrought magnesium alloys to extend practical use of roll-formed products of wrought magnesium alloys. A three-dimensional elasto-plastic analysis by the finite-element method has been conducted to express exact roll-forming behavior of wrought magnesium alloys that have different stress-strain curves in tension and compression. Simple V-sections were formed by a tandem six-stand roll forming machine to demonstrate the effectiveness of the simulation methods with different stress-strain curves in the case of tension and compression. Also, spring-back analysis has been performed to investigate the exact cold roll-forming phenomenon for wrought magnesium alloy sheets.
Surface Roughness Prediction Based on Acoustic Emission Signals in High-Precision Diamond Turning of Rapidly Solidified Optical Aluminum Grade (RSA443)
Authors: Hweju Zvikomborero , Abou-El-Hossein Khaled
Published: May 2020

Acoustic emission signal-based prediction of surface roughness has been utilized widely, yet little work has been done in this regard on RSA443. This paper seeks to study the correlation between acoustic emission (AE) signal parameters and surface roughness. Estimation of surface roughness using AE signal parameters and subsequent examination of the influence of AE signal parameters (root mean square, peak rate and prominent frequency) on the accuracy of the RSM model in surface roughness prediction are carried out. The experiment is designed using the Taguchi L9 orthogonal array to minimize the number of experiments. Emitted acoustic signals are captured using a Piezotron sensor. Three RSM models are formulated and compared in this study: a model that uses only critical machining parameters (cutting speed, depth of cut and feed rate), a model that uses only AE signal parameters (root mean square, peak rate and prominent frequency) and a model that uses both critical machining parameters and AE signal parameters. An assessment based on the models’ mean absolute percentage error (MAPE) is made to see if AE signal parameters have any contribution towards surface roughness prediction accuracy. The order of parameter significance in the most accurate model is investigated in this paper. The mean absolute percentage error results for the models indicate that the model in which AE signal parameters are utilized in conjunction with critical machining parameters has the highest prediction accuracy of 97.32%. The model that utilizes only critical machining parameters has a prediction accuracy of 96.35% while the one that utilizes only AE signal parameters has a prediction accuracy of 84.43%. It is observed that the order of parameter significance from the most to the least significant is as follows: feed rate, cutting speed, peak rate, AErms, depth of cut and prominent frequency.
Flow Field Analysis and Experimental Investigation of Electrochemical Etching
Authors: Chen Yuan Long , Guo Chao Hao , Chen Pei Xuan , Liu Zhi , Lv An Sheng
Published: May 2020

. Electrochemical etching is widely used to process refractory metals such as tungsten and molybdenum. Flow field is one of the crucial factors that influence the surface quality in electrochemical etching. In this paper, the electrochemical etching flow field was analyzed via FLUENT, the characteristics of flow field in electrochemical etching are studied, furthermore, the effects of four different outlet forms of electrolyte on flow field uniformity, electrolyte velocity and pressure distribution are investigated. Under the same electrolyte flow rate, the flow field characteristics of different outlet forms are analyzed by velocity vector diagram, pressure distribution nephogram, velocity and pressure curve diagram. The simulation results indicate that stable electrolyte velocity and uniform pressure distribution of flow field are obtained when the outlet form of electrolyte adopts the optimized flat. Finally, the fixture for this outlet form is designed and fabricated, and experimental verification is carried out, which shown that the flow field is uniform and the crystal plane of the workpiece is well-distributed which according with the process requirements.
Design and Optimization of Die Body for Polymer Extrusion
Authors: Saparov Torekhan , Belgibay Ualikhan , Zhang Di Chuan , Wei Dong Ming , Sun Chen Nan , Mentbayeva Almagul , Perveen Asma
Published: May 2020

Polymer extrusion is one of the largest material manufacturing processes, which is deployed substantially in productions. The variety of the output product types is greatly attributed to the die part of the extruder because it is one of the essential components that shapes the material. The main purpose of this paper is to create a feasible and efficient design of the extrusion die, which would meet the design requirements and would be more convenient to use as well as have better performance compared to the existing design. In order to obtain adequate results, CAD model of the die bodies were created and simulated in the SolidWorks Plastics and COMSOL software. It is found from the results of the simulation that, proposed design demonstrated better performance in terms of uniformity of the flow at the outlet as well as pressure and temperature distributions.
Solvent Absorption and Dissolution Kinetics Modelling for the Chemical Recycling of Waste Plastic Laminates
Authors: Deang Michael Sean P. , Alindayu Ricardo II C. , Escasa Karl Vincent H. , Riña Gabrielle Mae G. , Tumolva Terence
Published: May 2020

The Philippines is expected to have an increase in consumption of waste plastic laminates known as sachets, composed of polyethylene (PE) and polyethylene terephthalate (PET) and used in various food and non-food consumer goods. The increase in demand of these sachets has led the country to become one of the top ocean polluters worldwide. Chemical recycling- specifically selective dissolution and reprecipitation- is seen as one viable option for the recovery of these polymers. In this study, the absorption and dissolution kinetics of D-limonene, a potential candidate solvent, in the two-layer (2LL) and three-layer (3LL) laminates were modelled and analyzed for the design of separation equipment to recovery PE. The absorption of limonene for both laminates was observed to initially follow Fickian diffusion, but plateaus when the dissolution rate becomes comparable with the solvent diffusion rate. The dissolution of the 3LL almost closely follows Fickian behavior, while 2LL initially follows Fickian behavior. Deviations from Fickian dissolution may be attributed to the difference in swelling behavior between the non-uniform solvent-polymer diffusion layer and the glassy polymer layer.
Influence of Nano-Silica Dosage on Properties of Cement Paste Incorporating with High Calcium Fly Ash
Authors: Suwan Teewara , Jitsangiam Peerapong , Chindaprasirt Prinya
Published: May 2020

Nanotechnology is receiving widespread attention in many industrial sectors, including construction material industry. One of the nano-scale admixtures, which has the potential to enhance the performance of cement and concrete, is known as Nano-silica (n-SiO2). In general, fly ash (FA) is currently used in cement and concrete industry for replacing the consumption of Portland cement (OPC) to reduce its production cost as well as to improve some specific required properties, e.g., workability or low internal heat liberation. However, the strength of hardened Portland cement is normally decreased when a higher amount of fly ash is presented. This research article is therefore pointed on the influence of nano-silica dosage on the properties of cement paste incorporating with high calcium fly ash. Seven different proportions of OPC:FA were prepared viz. 100:0, 80:20, 60:40, 50:50, 40:60, 20:80 and 0:100 by weight. The commercial grade nano-silica (in liquid form) was used as an admixture in those mixes by 0.0, 0.5, 1.0 and 1.5 wt% of the mixing water with a water-to-binder (w/b) ratio of 0.30. The results indicated that the addition of n-SiO2 improved the compressive strength of all mixtures (with and without high calcium FA) as the presence of n-SiO2 can be a source of silica and easily contribute to an additional formation of CSH in the cementing system, confirmed by the results of XRD analysis. The main findings show a potential approach of using n-SiO2 as an admixture for cement and concrete construction.
3D Reconstruction of Microstructure for Centrifugal Casting Babbitt Lining of Bimetallic Bearing Based on Mimics
Authors: Dong Qin , Yin Zhong Wei , Li Hu Lin , Mao Yang , Gao Geng Yuan
Published: May 2020

Babbitt alloys are the most commonly used bearing materials for low speed diesel engines due to their excellent attributes. An understanding of microstructures in these alloys is important, especially quantifying microstructure in 3D. In this study, we used serial sectioning technique to reconstruct 3D microstructure of tin-based Babbitt lining of bimetallic bearing made by centrifugal casting based on medical software Mimics. The morphologies and volume fraction of hard phase particles and α-Sn matrix were obtained. The volume fraction of the reconstructed microstructures was verified by the area fraction of the metallographic sections, which proved a higher reliability of 3D reconstruction. The results of 3D microstructural characterization and analysis will enable a comprehensive understanding the structure–property relationships of these materials.
X-Ray Powder Diffraction Data and Crystal Refinement of Ternary Compound Ti4ZrSi3
Authors: Liang Liu Qing , Wei Yan Ying , Li De Gui
Published: May 2020

Ternary compound Ti4ZrSi3 was prepared by arc melting using a non-consumable tungsten electrode under argon atmosphere, then annealed at 1023K for 30 days, the X-ray powder diffraction data of Ti4ZrSi3 was collected on a Rigaku SmartLab X-ray powder diffractometer. The powder patterns of the compound were indexed and structure refinement by using Rietveld method indicate that the Ti4ZrSi3 compound crystallizes in the hexagonal structure, space group P6/mcm (No.193) with Mn5Si3 structure type, a=b=7.5759(3) Ǻ, c=5.2162(2) Ǻ, V=259.28Ǻ3, Z=2, ρx=4.779g cm-3, the Smith–Snyder FOM F30=148.7(0.0064, 46) and the intensity ratio RIR=1.37. The Rietveld refinement results were Rp = 0.0836, Rwp= 0.1092.
Monitoring Polar Sea Ice Using Optical and SAR Data
Authors: Sun Hequan , Li Chunhua , Cheng Yifeng
Published: May 2020

AbstractWith the movement and destructiveness of sea ice, conventional in situ instruments are restricted or unavailable for polar sea ice observation. Satellite remote sensing is a feasible way to monitor sea ice in the polar area. Multispectral imaging spectrometer
and synthetic aperture radar are applied to monitoring the sea ice in this article with high spatial resolution, wide swath, and continuous imaging. The sea ice distribution and motion can be measured by analyzing satellite remote sensing images. The image segmentation method is presented
in the article to obtain the sea ice distribution. Meanwhile, the cross-correlation algorithm to extract sea ice motion is proposed as well as the processed vector results.
Offshore Wind Turbine Coupled Motion in Regular Waves
Authors: Zhang Bao-Ji , Yu Gao , She Wen-Xuan
Published: May 2020

AbstractThis study aims to accurately predict the hydrodynamic performance and motion responses of offshore wind turbines on the basis of computational fluid dynamics (CFD) theory. Continuous and Navier-Stokes (N-S) equations are employed as control equations, and the k-ε
model is used as a turbulence model. The finite difference method is utilized to discretize the equation. The Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm is applied to solve the control equation, and the volume-of-fluid (VOF) method is used to capture the free surface.
The numerical wave tank of irregular wave is also established. The hydrodynamic performances and motion responses of the offshore wind turbines under regular waves are studied. First, we assume a floating foundation without the influence of a rotational fan and examine its motion responses
and wave force in three typical sea conditions, namely, Levels 5, 6, and 7. Thereafter, we use a series of force and torque acting on the rotating center of the offshore to substitute for the influence of the rotational fan on the floating foundation. Then, we study the hydrodynamic performance
influenced by blade rotation of the floating foundation in various sea conditions and three wind speeds, namely, 5, 8, and 11 m/s. Research results can provide usable theoretical principle and technical support for the investigation of the hydrodynamic performance and motion responses of similar
offshore wind turbines.
Genome Topology Control of Antigen Receptor Gene Assembly
Authors: Allyn Brittney M. , Lee Kyutae D. , Bassing Craig H.
Published: May 2020

The past decade has increased our understanding of how genome topology controls RAG endonuclease-mediated assembly of lymphocyte AgR genes. New technologies have illuminated how the large IgH, Igκ, TCRα/δ, and TCRβ loci fold into compact structures that place their numerous V gene segments in similar three-dimensional proximity to their distal recombination center composed of RAG-bound (D)J gene segments. Many studies have shown that CTCF and cohesin protein–mediated chromosome looping have fundamental roles in lymphocyte lineage- and developmental stage–specific locus compaction as well as broad usage of V segments. CTCF/cohesin–dependent loops have also been shown to direct and restrict RAG activity within chromosome domains. We summarize recent work in elucidating molecular mechanisms that govern three-dimensional chromosome organization and in investigating how these dynamic mechanisms control V(D)J recombination. We also introduce remaining questions for how CTCF/cohesin–dependent and –independent genome architectural mechanisms might regulate compaction and recombination of AgR loci.
Effect of Additive on the Performance Characteristics of Centrifugal and Progressive Cavity Slurry Pumps with High Concentration Fly Ash Slurries
Authors: Chandel Sunil , Singh S.N , Seshadri V
Published: May 2020

Slurry pumps that are used in the hydraulic transportation of fly ash slurries through pipes in thermal power plants can be broadly classified into two main categories namely positive displacement and centrifugal pumps. The two types of pumps differ considerably in construction as well as in operating principle compared to the conventional pumps. The present study reports the effect of additive on the performance characteristics of centrifugal and progressive cavity screw pumps with fly ash slurries at high concentrations (above Cw AP 50% by weight). Mixture of sodium carbonate and Henko detergent (5:1) at a concentration of 0.2% by weight has been used as an additive. For each type of pump, the effect of additive on the performance characteristics has been experimentally evaluated at rated speed with fly ash slurries in the concentration range of 50 to 70% by weight. The pump total head, overall efficiency and pump input power as a function of flow rate have been measured. The results obtained from the centrifugal slurry pump performance show that at rated speed, the performance of the pump improves with the addition of drag reducing additive. In the case of progressive cavity screw pump, pump performance characteristics and behavior were completely different as compared to the centrifugal slurry pump. At rated speed, the performance of screw pump deteriorates with the addition of drag reducing soap solution.
Editorial
Authors: Rapôso Cláudio Filipe Lima
Published: May 2020

O ano de 2019 está acabando e estamos contente em lançar nossa primeira edição da IMJBR – INTERNACIONAL MULTIDISCIPLINARY JOURNAL OF THE BRAZIL que inicia suas atividades com a procura de grandes desafios no ramo científico. A proposta da revista é trazer é fundamentalmente a divulgação cientifica onde todos terão o direito de publicar, desde que tenha embasamento científico. Respeitamos o direito ao contraditório e acreditamos que a grande academia tem a capacidade de julgar, consagrar e refutar de forma eficientes os artigos. Venho destaca o artigo “PRÁTICA PEDAGÓGICA EM INTELIGÊNCIA LINGUÍSTICA E SUA RELAÇÃO COM A APRENDIZAGEM DE LÍNGUA PORTUGUESA” que vem trazer questionamentos importantes e relevantes sobre a nossa língua. Por outro lado, temos a presença de dois artigos oriundos de apresentações do CONEDU 2018/2019 emitido pelo PhD. Antonio Carlos dos Santos Cruz que trouxe bastante conteúdos sobre a educação. Finalizo agradecendo a todos pela oportunidade e a confiança de destacar seus projetos em uma revista que hoje está indexada na BASE e Worldcat sendo encontrada em diversas universidades do mundo todo e pela adesão de todo Instituto Arca Educacional como signatário do acordo de DORA sobre as boas práticas na pesquisa cientifica. Finalizo informando que semestralmente todos os artigos poderão com a permissão dos respectivos autores se torna um capítulo da “Coletânea de Artigos do Instituto Arca Educacional” que será publicado em janeiro com acesso a diversas fontes, até o GOOGLE PLAY com ISBN.
Türkiye’de İnşaat Projelerinde Çalışanların İşçi Sağlığı ve Güvenliği Tutumlarının Değerlendirilmesi
Authors: AVCI Muhammed , SELÇUK Eda
Published: May 2020

Ekonomik anlamda etkin bir role sahip olan inşaat sektörü, iş sağlığı ve güvenliği bakımından en fazla riski barındıran faaliyet alanlarından birisidir. Bu nedenle inşaat sektöründe oluşabilecek kazaların ve olumsuz etkilerinin en aza indirilmesi, geçici ya da kalıcı iş göremezlik ya da ölümden kaynaklanan iş gücü kayıplarına neden olabilecek ekonomik kayıpların önüne geçilmesi gerekmektedir. Günümüzde Türkiye’de inşaat sektöründe iş sağlığı ve güvenliği konusunda gerçekleşen düzenlemelere bağlı olarak iş kazalarının yaşanma sıklığında düzelmelerin olduğu görülmektedir. Fakat son zamanlarda gerek Türkiye’de meydana gelen iş kazaları, gerekse de bu kazalarda hayatını yitiren çalışanlar bakımından hâlâ iyi bir performans sergilenmediği görülmektedir. Dolayısıyla sektörde yasal düzenlemelerle alınan önlemler tek başına yeterli olmamakta; çalışanların da iş sağlığı ve güvenliğine yönelik karşı tutumlarının da değerlendirilmesi gerekmektedir. Yapılan Çalışmada, Türkiye’de İstanbul, Van ve Malatya illerinde yapımı süren inşaat projelerindeki çalışanların iş sağlığı ve güvenliği ile ilgili algılarının hangi düzeyde olduğunun tespiti ve elde edilen bulguların değerlendirilerek öneriler sunulması amaçlanmıştır. Bu kapsamda elde edilen sonuçların Türk inşaat sektöründeki firmalara işçi sağlığı ve güvenliği konusunda ışık tutacağı düşünülmektedir.
Consecuencias del feminicidio en violencia machista. Análisis de necesidades de hijos, hijas y familiares en Cataluña
Authors: Zafra Aparici Eva , Anleu Hernández Claudia Maria , Forns i Fernández Ma. Victòria
Published: May 2020

Si bien todas las muertes producen un gran impacto social y emocional en la familia de la víctima, cuando se trata de violencia machista el efecto es aún mayor; y en el caso de los hijos y las hijas podemos hablar de un impacto emocional doble. Uno corresponde a la pérdida de la madre como figura protectora y el otro tiene que ver con el hecho de que sea la otra figura paternal quien le ha quitado la vida. Nuestro objetivo es presentar los resultados preliminares de una investigación cualitativa, realizada en Cataluña, que analiza las necesidades de cuidado que tienen los hijos, hijas y familiares de víctimas mortales de violencia machista. Se han estudiado tres casos entrevistando a lxs hijxs, familiares y profesionales que intervinieron en cada caso, y se han analizado las sentencias judiciales de los mismos. Pretendemos así, visibilizar muchas de las situaciones de injusticia y desigualdad "silenciada" en la que se encuentran estas personas. Asimismo, buscamos, promover el debate político e institucional para el diseño de estrategias de intervención integrales que tengan en cuenta la voz de las personas afectadas y eviten su "polivictimización”.
Presentación
Authors: Puchades Pla Rosa
Published: May 2020

Presentación del cuarto número de la revista Ciencia, Técnica y Mainstreaming Social (CITECMA).