Search results for: reverse rolling

Authors: Majid Mokhtari, Masoud Bahrami Alamdarlo, Babak Nazari, Hossein Zakerinya, Mehdi Salehi

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In this study, microstructure, macro, and microhardness of phases for three grades of cast iron rolls with modified chemical composition using a light microscope (OM) and electron microscopy (SEM) were investigated. The grades were chosen from Chodan Sazan Manufacturing Co. (CSROLL) productions for finishing stands of hot strip mills. The percentage of residual austenite was determined with a ferrite scope magnetic device. Thermal susceptibility testing was also measured. The results show the best oxidation resistance at high temperatures is graphitic high chromium white cast iron alloy. In order to evaluate the final properties of these grades in rolling lines, the results of the Pin on Disk abrasion test showed the superiority of the abrasive behavior of the white chromium graphite cast iron alloy grade sample at the same hardness compared to conventional alloy grades and the enhanced grades.

Keywords: hot roller, wear, behavior, microstructure

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Authors: Arthur Baraov

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Nearly all rocket and spacecraft propulsion concepts in existence today can be linked one way or the other to one of the two ancient warfare devices: the gun and the sling. Chemical, thermoelectric, ion, nuclear thermal and electromagnetic rocket engines – all fall into the first group which, for obvious reasons, can be categorized as “hot” space propulsion concepts. Space elevator, orbital tower, rolling satellite, orbital skyhook, tether propulsion and gravitational assist – are examples of the second category which lends itself for the title “cold” space propulsion concepts. The “hot” space propulsion concepts skyrocketed – literally and figuratively – from the naïve ideas of Jules Verne to the manned missions to the Moon. On the other hand, with the notable exception of gravitational assist, hardly any of the “cold” space propulsion concepts made any progress in terms of practical application. Why is that? This article aims to show that the right answer to this question has the potential comparable by its implications and practical consequences to that of transition from Jules Verne’s stillborn and impractical conceptions of space flight to cogent and highly fertile ideas of Konstantin Tsiolkovsky and Yuri Kondratyuk.

Keywords: propulsion, rocket, rollet, spacecraft

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Authors: Anas H. Aljemely, Jianping Xuan

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Rolling bearing fault diagnosis plays a pivotal issue in the rotating machinery of modern manufacturing. In this research, a raw vibration signal and improved deep learning method for bearing fault diagnosis are proposed. The multi-dimensional scales of raw vibration signals are selected for evaluation condition monitoring system, and the deep learning process has shown its effectiveness in fault diagnosis. In the proposed method, employing an Exponential linear unit (ELU) layer in a convolutional neural network (CNN) that conducts the identical function on positive data, an exponential nonlinearity on negative inputs, and a particular convolutional operation to extract valuable features. The identification results show the improved method has achieved the highest accuracy with a 100-dimensional scale and increase the training and testing speed.

Keywords: bearing fault prognostics, developed CNN model, multiple-scale evaluation, deep learning features

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Authors: Yuksel Akinay, Fatih Hayat

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The influence of the alloying element on mechanical properties and micro structures of the Fe-22Mn-0.6C-0,6Si twinning induced plasticity (TWIP) steel were investigated at different temperatures. This composition was fabricated by a vacuum induction melting method. This steel was homogenized at 1200◦C for 8h. After heat treatment it was hot-rolled at 1100◦C to 6 mm thickness. The hot rolled plates were cold rolled to 3 mm and annealed at 700 800 and 900 °C for 60 and 150 minute and then air-cooled. X-ray diffractometry (XRD), optic microscope and field emission scanning electron microscope (FESEM), hardness and tensile tests were used to analyse the relationship between mechanical properties and micro structure after annealing process. The results show that, the excellent mechanical properties were obtained after heat treatment process. The tensile strength of material was decreased and the ductility of material was improved with increasing annealing temperature. Ni element were increased the mechanical resistance of specimens and because of carbide precipitation the hardness of specimen annealed at 700 C is higher than others.

Keywords: high manganese, heat treatment, SEM, XRD, cold-rolling

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Authors: Aman Patidar, Dipankar Sarkar, Manish Pal

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Due to rapid development, increase in the traffic load, higher traffic volume and seasonal variation in temperature, asphalt pavement shows distresses like rutting, fatigue and thermal cracking etc. because of this pavement fails during service life so that bitumen needs to be modified with some additive. In this study VG30 grade bitumen modify with addition of nanosilica with 1% to 5% (increment of 1%) by weight of bitumen. Hot mix asphalt (HMA) have higher mixing, laying and rolling temperatures which leads to higher consumption of fuel. To address this issue, a nano material named ZycoTherm which is chemical warm mix asphalt (WMA) additive is added to bitumen. Nanosilica modification (NSMB) results in the increase in stability compared to unmodified bitumen (UMB). WMA modified mix shows slightly higher stability than UMB and NSMB in a lower bitumen content. The Retained stability and tensile strength ratio (TSR) is more than 75% and 80% respectively for both mixes. Nanosilica with WMA has more resistant to temperature susceptibility, moisture susceptibility and short term aging than NSMB.

Keywords: HMA, nanosilica, NSMB, temperature, TSR, UMB, WMA

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Authors: Jung-Ho Moon, Tae Kwon Ha

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M2 steels, the typical Co-free high speed steel (HSS) possessing hardness level of 63~65 HRc, are most widely used for cutting tools. On the other hand, Co-containing HSS’s, such as M35 and M42, show a higher hardness level of 65~67 HRc and used for high quality cutting tools. In the fabrication of HSS’s, it is very important to control cleanliness and eutectic carbide structure of the ingot and it is required to increase productivity at the same time. Production of HSS ingots includes a variety of processes such as casting, electro-slag remelting (ESR), forging, blooming, and wire rod rolling processes. In the present study, electro-slag rapid remelting (ESRR) process, an advanced ESR process combined by continuous casting, was successfully employed to fabricate HSS billets of M2, M35, and M42 steels. Distribution and structure of eutectic carbides of the billets were analysed and cleanliness, hardness, and composition profile of the billets were also evaluated.

Keywords: high speed tool steel, eutectic carbide, microstructure, hardness, fracture toughness

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Authors: Tony See

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Although much has been devoted to Deleuze’s ethics of difference, relatively little has been focused on how his political perspective is informed by his appropriation of religious ideas and theological concepts. The bulk of the scholarly works have examined his political views with the assumption that they have little or nothing to do with his ideas of religions at all. This is in spite of the fact that Deleuze has drawn heavily from religious and theological thinkers such as Duns Scotus, Spinoza and Nietzsche. This dimension can also be traced in Deleuze’s later works, when he collaborated with Felix Guattari in creating an anti-Oedipal philosophy of difference after May 68. This paper seeks to reverse the tendency in contemporary scholarship ignore Deleuze’s ‘religious’ framework in his understanding of the ethical and the political. Towards this aim, we will refer to key texts in Deleuze’s corpus such as Expressionism in Philosophy, A Thousand Plateaus and others.

Keywords: difference, haeccities, identity, religion, theology

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Authors: Moridi Fatemeh, Dasineh Mehdi, Jafari Narges

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The aim of this study was to investigate the relationship between dividends and investment in a condition of cash flow uncertainty. Previous studies have also found some evidence that there is N-shaped relationship between dividends and investment given different levels of cash uncertainly. Thus, this study examines this relationship over the period 2009-2014 in Tehran Stock Exchange (TSE). Based on our sample and new variables, we found reverse N-shaped relationship in different levels of cash flow uncertainly. This shape was descending in cash flow certainly and uncertainly but it is ascending in medial position.

Keywords: dividends, investment, nonlinear relationship, uncertainty of cash flow

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Authors: Yapegue Bayogo, Ahmadou Halassi Dicko, Brahima Songore

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In developing countries, the road transportation system occupies an important place because of its flexibility and the low prices of infrastructure and rolling stock. While road transport is necessary for economic development, the movement of people and their goods, it is urgent to use transportation systems that minimize carbon emissions in order to ensure sustainable development. One of the main objectives of OEDC and the Word Bank is to ensure sustainable economic’ development. This paper aims to develop a road transport network taking into account environmental impacts. The methodology adopted consists of formulating a model optimizing the flow of goods and then collecting information relating to the transport of products. Our model was tested with data on product transport in CMDT areas in the Republic of Mali. The results of our study indicate that emissions from the transport sector can be significantly reduced by minimizing the traffic volume. According to our study, optimizing the transportation network, we benefit from a significant amount of tons of CO₂.

Keywords: road transport, transport sustainability, pollution, flexibility, optimized network

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Authors: Murad A. Channa, Mehdi Khiadani. Yasir Al-Abdeli

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Considering the severity of water scarcity around the world and its widening at an alarming rate, practical improvements in desalination techniques need to be engineered at the earliest. Atomization is the major aspect of flashing phenomena, yet it has been paid less attention to until now. There is a need to test efficient ways of atomization for the flashing process. Flash evaporation together with reverse osmosis is also a commercially matured desalination technique commonly famous as Multi-stage Flash (MSF). Even though reverse osmosis is massively practical, it is not economical or sustainable compared to flash evaporation. However, flashing evaporation has its drawbacks as well such as lower efficiency of water production per higher consumption of power and time. Flash evaporation is simply the instant boiling of a subcooled liquid which is introduced as droplets in a well-maintained negative environment. This negative pressure inside the vacuum increases the temperature of the liquid droplets far above their boiling point, which results in the release of latent heat, and the liquid droplets turn into vapor which is collected to be condensed back into an impurity-free liquid in a condenser. Atomization is the main difference between pool and spray flash evaporation. Atomization is the heart of the flash evaporation process as it increases the evaporating surface area per drop atomized. Atomization can be categorized into many levels depending on its drop size, which again becomes crucial for increasing the droplet density (drop count) per given flow rate. This review comprehensively summarizes the selective results relating to the methods of atomization and their effectiveness on the evaporation rate from earlier works to date. In addition, the reviewers propose using centrifugal atomization for the flashing application, which brings several advantages viz ultra-fine droplets, uniform droplet density, and the swirling geometry of the spray with kinetically more energetic sprays during their flight. Finally, several challenges of using rotary bell atomizer (RBA) and RBA Sprays inside the chamber have been identified which will be explored in detail. A schematic of rotary bell atomizer (RBA) integration with the chamber has been designed. This powerful centrifugal atomization has the potential to increase potable water production in commercial multi-stage flash evaporators, where it would be preferably advantageous.

Keywords: atomization, desalination, flash evaporation, rotary bell atomizer

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Authors: A. Hossein Madadi-Najafabadi, Masoud Nasiri

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The discrete element method is a powerful technique for numerical modeling the flow of granular materials such as direct reduced iron. It would enable us to study processes and equipment related to the production and handling of the material. However, the characteristics and properties of the granules have to be adjusted precisely to achieve reliable results in a DEM simulation. The main properties for DEM simulation are size distribution, density, Young's modulus, Poisson's ratio and the contact coefficients of restitution, rolling friction and sliding friction. In the present paper, the mentioned properties are determined for DEM simulation of DRI pellets. A reliable DEM simulation would contribute to optimizing the handling system of DRIs in an iron-making plant. Among the mentioned properties, Young's modulus is the most important parameter, which is usually hard to get for particulate solids. Here, an especial method is utilized to precisely determine this parameter for DRI.

Keywords: discrete element method, direct reduced iron, simulation parameters, granular material

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Authors: S. M. Yasir Arafat

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Driving models are needed by many researchers to improve traffic safety and to advance autonomous vehicle design. To be most useful, a driving model must state specifically what information is needed and how it is processed. So we developed an “Obstacle Avoidance and Detection Autonomous Car” based on sensor application. The ever increasing technological demands of today call for very complex systems, which in turn require highly sophisticated controllers to ensure that high performance can be achieved and maintained under adverse conditions. Based on a developed model of brakes operation, the controller of braking system operation has been designed. It has a task to enable solution to the problem of the better controlling of braking system operation in a more accurate way then it was the case now a day.

Keywords: automobile, obstacle, safety, sensing

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Authors: Grmay Kassa Brhane, Hailemariam Siyum Mekonen

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This study was designed to identify the hydrogeochemical and anthropogenic processes controlling the evaluation of groundwater chemistry in the Ellala catchment which covers about 296.5 km2 areal extent. The chemical analysis revealed that the major ions in the groundwater are Ca2+, Mg2+, Na+, and K+ (cations) and HCO3-, PO43-, Cl-, NO3-, and SO42-(anions). Most of the groundwater samples (68.42%) revealed that the groundwater in the catchment is non-alkaline. In addition to the contribution of aquifer material, the solid materials and liquid wastes discharged from different sources can be the main sources of pH and EC in the groundwater. It is observed that the EC of the groundwater is fairly correlated with the DTS. This indicates that high mineralized water is more conductor than water with low concentration. The degree of salinity of the groundwater increases along the groundwater flow path from East to West; then, areas surrounding Mekelle City are highly saline due to the liquid and solid wastes discharged from the city and the industries. The groundwater facies in the catchment are predominated with calcium, magnesium, and bicarbonate which are labeled as Ca-Mg-HCO3 and Mg-Ca-HCO3. The main geochemical process controlling the evolution of the groundwater chemistry in the catchment is rock-water interaction, particularly carbonate dissolution. Due to the clay layer in the aquifer, the reverse is ion exchange. Non-significant silicate weathering and halite dissolution also contribute to the evolution of groundwater chemistry in the catchment. The groundwater in the catchment is dominated by the meteoritic origin although it needs further groundwater chemistry study with isotope dating analysis. The groundwater is under-saturated with calcite, dolomite, and aragonite minerals; hence, the more these minerals encounter the groundwater, the more the minerals dissolve. The main source of calcium and magnesium in groundwater is the dissolution of carbonate minerals (calcite and dolomite) since carbonate rocks are the dominant aquifer materials in the catchment. In addition to this, the weathering of dolerite rock is a possible source of magnesium ions. The relatively higher concentration of sodium over chloride indicates that the source of sodium-ion is reverse ion exchange and/or weathering of sodium-bearing materials, such as shale and dolerite rather than halite dissolution. High concentration of phosphate, nitrate, and chloride in the groundwater is the main anthropogenic source that needs treatment, quality control, and management in the catchment. From the Base Exchange Index Analysis, it is possible to understand that, in the catchment, the groundwater is dominated by the meteoritic origin, although it needs further groundwater chemistry study with isotope dating analysis.

Keywords: Ellala catchment, factor, chemistry, geochemical, groundwater

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Authors: Seok-Hyeon Park, Joon-Hong Park, Mok-Tan-Ahn, Seong-Hun Ha

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Clad Pipe is made of a different kind of material, which is different from the internal and external materials, for the corrosive crude oil transportation tube. Most of the clad pipes are produced by hot rolling. However, problems arise due to high product prices and excessive process numbers. Therefore, in this study, the hot drawing process with excellent product cost, process number and productivity is applied. Due to the nature of the drawing process, the shape of the mold greatly influences the formability of the material and the bonding pressure of the two materials because it is a process of drawing the material to the die and reducing the cross-sectional area. Also, in case of hot drawing, if the mold shape is not suitable due to the increased fluidity of the material, it may cause problems such as tearing and stretching. Therefore, in this study, we try to find the shape of the mold which suppresses the occurrence of defects in the hot drawing process and maximizes the bonding pressure between the two materials through the mold shape optimization design by FEM analysis.

Keywords: clad pipe, hot drawing, bonding pressure, mold shape

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Authors: Supaporn Yamuangmorn, Chanakan Prom-U-Thai

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Wetland and upland purple rice are the two major types classified by its original ecotypes in Northern Thailand. Wetland rice is grown under flooded condition from transplanting until the mutuality, while upland rice is naturally grown under well-drained soil known as aerobic cultivations. Both ecotypes can be grown and adapted to the reverse systems but little is known on its responses of grain yield and qualities between the 2 ecotypes. This study evaluated responses of grain yield as well as anthocyanin and antioxidant capacity between the wetland and upland purple rice genotypes grown in the submerged and aerobic conditions. A factorial arrangement in a randomized complete block design (RCBD) with two factors of rice genotype and water condition were carried out in three replications. The two wetland genotypes (Kum Doi Saket: KDK and Kum Phayao: KPY) and two upland genotypes (Kum Hom CMU: KHCMU and Pieisu1: PES1) were used in this study by growing under submerged and aerobic conditions. Grain yield was affected by the interaction between water condition and rice genotype. The wetland genotypes, KDK and KPY grown in the submerged condition produced about 2.7 and 0.8 times higher yield than in the aerobic condition, respectively. The 0.4 times higher grain yield of upland genotype (PES1) was found in the submerged condition than in the aerobic condition, but no significant differences in KHCMU. In the submerged condition, all genotypes produced higher yield components of tiller number, panicle number and percent filled grain than in the aerobic condition by 24% and 32% and 11%, respectively. The thousand grain weight and spikelet number were affected by water condition differently among genotypes. The wetland genotypes, KDK and KPY, and upland genotype, PES1, grown in the submerged condition produced about 19-22% higher grain weight than in the aerobic condition. The similar effect was found in spikelet number which the submerged condition of wetland genotypes, KDK and KPY, and the upland genotype, KHCMU, had about 28-30% higher than the aerobic condition. In contrast, the anthocyanin concentration and antioxidant capacity were affected by both the water condition and genotype. Rice grain grown in the aerobic condition had about 0.9 and 2.6 times higher anthocyanin concentration than in the submerged condition was found in the wetland rice, KDK and upland rice, KHCMU, respectively. Similarly, the antioxidant capacity of wetland rice, KDK and upland rice, KHCMU were 0.5 and 0.6 times higher in aerobic condition than in the submerged condition. There was a negative correlation between grain yield and anthocyanin concentration in wetland genotype KDK and upland genotype KHCMU, but it was not found in the other genotypes. This study indicating that some rice genotype can be adapted in the reverse ecosystem in both grain yield and quality, especially in the wetland genotype KPY and upland genotype PES1. To maximize grain yield and quality of purple rice, proper water management condition is require with a key consideration on difference responses among genotypes. Increasing number of rice genotypes in both ecotypes is needed to confirm their responses on water management.

Keywords: purple rice, water condition, anthocyanin, grain yield

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Authors: S. G. Vasantharaju, Viswanath Guptha, Raghavendra Shetty

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Introduction: Aminophylline is a methylxanthine derivative belonging to the class bronchodilator. From the literature survey, reported methods reveals the solid phase extraction and liquid liquid extraction which is highly variable, time consuming, costly and laborious analysis. Present work aims to develop a simple, highly sensitive, precise and accurate high-performance liquid chromatography method for the quantification of Aminophylline in rat plasma samples which can be utilized for preclinical studies. Method: Reverse Phase high-performance liquid chromatography method. Results: Selectivity: Aminophylline and the internal standard were well separated from the co-eluted components and there was no interference from the endogenous material at the retention time of analyte and the internal standard. The LLOQ measurable with acceptable accuracy and precision for the analyte was 0.5 µg/mL. Linearity: The developed and validated method is linear over the range of 0.5-40.0 µg/mL. The coefficient of determination was found to be greater than 0.9967, indicating the linearity of this method. Accuracy and precision: The accuracy and precision values for intra and inter day studies at low, medium and high quality control samples concentrations of aminophylline in the plasma were within the acceptable limits Extraction recovery: The method produced consistent extraction recovery at all 3 QC levels. The mean extraction recovery of aminophylline was 93.57 ± 1.28% while that of internal standard was 90.70 ± 1.30%. Stability: The results show that aminophylline is stable in rat plasma under the studied stability conditions and that it is also stable for about 30 days when stored at -80˚C. Pharmacokinetic studies: The method was successfully applied to the quantitative estimation of aminophylline rat plasma following its oral administration to rats. Discussion: Preclinical studies require a rapid and sensitive method for estimating the drug concentration in the rat plasma. The method described in our article includes a simple protein precipitation extraction technique with ultraviolet detection for quantification. The present method is simple and robust for fast high-throughput sample analysis with less analysis cost for analyzing aminophylline in biological samples. In this proposed method, no interfering peaks were observed at the elution times of aminophylline and the internal standard. The method also had sufficient selectivity, specificity, precision and accuracy over the concentration range of 0.5 - 40.0 µg/mL. An isocratic separation technique was used underlining the simplicity of the presented method.

Keywords: Aminophyllin, preclinical pharmacokinetics, rat plasma, RPHPLC

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Authors: Nagesh Vangala, Rayudu Mannam

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Soft switching has attracted the interest of various researchers constantly. Many techniques are in vogue to achieve soft switching (ZVS and/or ZCS) in Boost converters. These techniques utilize an auxiliary switch to incorporate the ZCS/ZVS. Such schemes require additional control circuit and induce complexity in design. This paper proposes an elegant fly back approach which guarantees zero current switching of the main Switch without the need for any additional active device. A simple flyback transformer scheme is implemented which absorbs the initial turn ON energy (or the Reverse recovery energy of Boost diode) and delivers to the output.

Keywords: boost converter, complete energy transfer, flyback, zero current switching

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Authors: Sou Watanabe, Hiromichi Ogi, Atsuhiro Shibata, Kazunori Nomura

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As a part of STRAD project conducted by JAEA, condensation of radioactive liquid waste containing various chemical compounds using reverse osmosis (RO) membrane filter was examined for efficient and safety treatment of the liquid wastes accumulated inside hot laboratories. NH₄⁺ ion in the feed solution was successfully concentrated, and NH₄⁺ ion involved in the effluents became lower than target value; 100 ppm. Solidification of simulated aqueous and organic liquid wastes was also tested. Those liquids were successfully solidified by adding cement or coagulants. Nevertheless, optimization in materials for confinement of chemicals is required for long time storage of the final solidified wastes.

Keywords: condensation, radioactive liquid waste, solidification, STRAD project

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Authors: Jimin Yun, Yebeen Ji, Kwonhoo Kim

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Magnesium and Mg-Ag system alloys are known to be promising biomaterials due to their high specific strengths and biocompatibility. Because the limited numbers of slip systems were activated in the HCP structure at room temperature, their formability was low. To solve these problems, much research about the improvement of room-temperature formability has been studied, but the microstructure development behaviors of Mg-Ag alloys were still limited. Therefore, this study was conducted to investigate the texture development behaviors of Mg-Ag alloy during high-temperature plane strain deformation. The Ag content of the Mg-Ag alloy used in this study was 3.0, 5.0, and 9.0 wt%. Hot rolling was performed at a temperature of 673K with a reduction ratio of 25%, and these specimens were annealed for 1H at 773K, followed by water quenching at room temperature. High-temperature plane strain deformation was performed under temperatures of 623K and 723K, with strain rates from 0.1/s to 0.05/s and strain from -0.4 to –1.0. As a result, it showed a microstructure and texture similar to the AZ61 alloy, which had been studied previously. It was confirmed that the basal texture became stronger with increasing strains at high-temperature plane strain deformation.

Keywords: Mg-Ag, texture, microstructure development behavior, AZ61

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Authors: Shengqi Yu, Jinwei Zhao

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This paper presents a kind of analog circuit based temperature control system, which is mainly composed by threshold control signal circuit, synchronization signal circuit and trigger pulse circuit. Firstly, the temperature feedback signal function is realized by temperature sensor TS503F3950E. Secondly, the main control circuit forms the cycle controlled pulse signal to control the thyristor switching model. Finally two reverse paralleled thyristors regulate the output power by their switching state. In the consequence, this is a modernized and energy-saving domestic electric heating system.

Keywords: time base circuit, automatic control, zero-crossing trigger, temperature control

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Authors: F. Amin, S. Feizi

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Big data has the potential to improve the quality of services; enable infrastructure that businesses depend on to adapt continually and efficiently; improve the performance of employees; help organizations better understand customers; and reduce liability risks. Analytics and marketing models of fixed and mobile operators are falling short in combating churn and declining revenue per user. Big Data presents new method to reverse the way and improve profitability. The benefits of Big Data and next-generation network, however, are more exorbitant than improved customer relationship management. Next generation of networks are in a prime position to monetize rich supplies of customer information—while being mindful of legal and privacy issues. As data assets are transformed into new revenue streams will become integral to high performance.

Keywords: big data, next generation networks, network transformation, strategy

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Authors: Jessyca A. Bessa, Darlan A. Barroso, Jonas P. Reges, Auzuir R. Alexandria

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This work aims to study the rocker. This is a device of the suspension of Formula SAE vehicle that receives efforts from the motion scrolling of the vehicle and transmits them to the chassis frame minimized by a momentum ratio and smoothed by the set spring - damper. A review of parameters used in vehicle dynamics and a geometric analysis of the forces and stresses caused by such was carried out. The main function of the rocker is to reduce the force transmitted to the frame due to movement of rolling and subsequent application of the suspension. This functions is taken as satisfactory, since the force applied to the wheel and which would be transmitted to the chassis is reduced from 3833.9N to 3496.48N. From these values can be further more detailed simulations using the finite element method aimed at mass reduction or even rocker manufacturing feasibility aluminum. Then, the analysis by the finite element method was applied. This analysis uses the theory of discretization of systems and examines the strength of the component based on the distortion energy, determining the maximum straining experienced by the component and the region of higher demand.

Keywords: rocker, suspension, the finite element method, mechatronics engineering

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Authors: Aleksandr I. Korobov, Natalia V. Shirgina, Aleksey I. Kokshaiskiy, Vyacheslav M. Prokhorov

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The paper presents the results of an experimental study of the effect of reverse mechanical load-unloading on the mechanical, linear, and nonlinear elastic properties of n-AMg6/C60 nanocomposite. Samples for experimental studies of n-AMg6/C60 nanocomposite were obtained by grinding AMg6 polycrystalline alloy in a planetary mill with 0.3 wt % of C60 fullerite in an argon atmosphere. The resulting product consisted of 200-500-micron agglomerates of nanoparticles. X-ray coherent scattering (CSL) method has shown that the average nanoparticle size is 40-60 nm. The resulting preform was extruded at high temperature. Modifications of C60 fullerite interferes the process of recrystallization at grain boundaries. In the samples of n-AMg6/C60 nanocomposite, the load curve is measured: the dependence of the mechanical stress σ on the strain of the sample ε under its multi-cycle load-unloading process till its destruction. The hysteresis dependence σ = σ(ε) was observed, and insignificant residual strain ε < 0.005 were recorded. At σ≈500 MPa and ε≈0.025, the sample was destroyed. The destruction of the sample was fragile. Microhardness was measured before and after destruction of the sample. It was found that the loading-unloading process led to an increase in its microhardness. The effect of the reversible mechanical stress on the linear and nonlinear elastic properties of the n-AMg6/C60 nanocomposite was studied experimentally by ultrasonic method on the automated complex Ritec RAM-5000 SNAP SYSTEM. In the n-AMg6/C60 nanocomposite, the velocities of the longitudinal and shear bulk waves were measured with the pulse method, and all the second-order elasticity coefficients and their dependence on the magnitude of the reversible mechanical stress applied to the sample were calculated. Studies of nonlinear elastic properties of the n-AMg6/C60 nanocomposite at reversible load-unloading of the sample were carried out with the spectral method. At arbitrary values of the strain of the sample (up to its breakage), the dependence of the amplitude of the second longitudinal acoustic harmonic at a frequency of 2f = 10MHz on the amplitude of the first harmonic at a frequency f = 5MHz of the acoustic wave is measured. Based on the results of these measurements, the values of the nonlinear acoustic parameter in the n-AMg6/C60 nanocomposite sample at different mechanical stress were determined. The obtained results can be used in solid-state physics, materials science, for development of new techniques for nondestructive testing of structural materials using methods of nonlinear acoustic diagnostics. This study was supported by the Russian Science Foundation (project №14-22-00042).

Keywords: nanocomposite, generation of acoustic harmonics, nonlinear acoustic parameter, hysteresis

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Authors: Hyunseo Choi, Jaewan Hong, Seil Lee, Yang Mo Koo

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Non-oriented (NO) electrical steel is one of the most important soft magnetic materials for rotating machines. Si has usually been added to electrical steels to reduce eddy current loss by increasing the electrical resistivity. Si content more than 3.5 wt% causes cracks during cold rolling due to increase of brittleness. Al also increases the electrical resistivity of the materials as much as Si. In addition, cold workability of Fe-Al is better than Fe-Si, so that Al can be added up to 6.0 wt%. However, the effect of Al contents on magnetic properties of electrical steels has not been studied in detail. Magnetic domains of {100} grains in electrical steels, ranging from 1.85 to 6.54 wt% Al, were observed by magneto-optic Kerr microscopy. Furthermore, the correlation of magnetic domains with magnetic properties was investigated. As Al contents increased, the magnetic domain size of {100} grains decreased due to lowered domain wall energy. Reorganization of magnetic domain structure became more complex as domain size decreased. Therefore, the addition of Al to electrical steel caused hysteresis loss to increase. Anomalous loss decreased and saturated after 4.68% Al.

Keywords: electrical steel, magnetic domain structure, Al addition, core loss, rearrangement of domains

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Authors: Shuhua Lai, Kairui Chen

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In this paper, we present a fast and efficient mesh coarsening algorithm for 3D triangular meshes. Theis approach can be applied to very complex 3D meshes of arbitrary topology and with millions of vertices. The algorithm is based on the clustering of the input mesh elements, which divides the faces of an input mesh into a given number of clusters for clustering purpose by approximating the Centroidal Voronoi Tessellation of the input mesh. Once a clustering is achieved, it provides us an efficient way to construct uniform tessellations, and therefore leads to good coarsening of polygonal meshes. With proliferation of 3D scanners, this coarsening algorithm is particularly useful for reverse engineering applications of 3D models, which in many cases are dense, non-uniform, irregular and arbitrary topology. Examples demonstrating effectiveness of the new algorithm are also included in the paper.

Keywords: coarsening, mesh clustering, shape approximation, mesh simplification

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Authors: Jui-Pui Hung, Yong-Run Chen, Wei-Cheng Shih, Chun-Wei Lin

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This study was aimed to assess the variations of the modal characteristics of the feeding stage with different linear guide modulus. The dynamic characteristics of the feeding stage were characterized in terms of the modal stiffness, modal frequency and modal damping, which are assessed from the vibration tests. According to the experimental measurements, the actual preload of the linear guide modulus was found to deviate from the rated values as setting in factory. This may be due to the assemblage errors of guide modules. For the stage with linear guides, the dynamic stiffness was affected to change by the preload set on the rolling balls. The variation of the dynamic stiffness at first and second modes is 20.8 and 10.5%, respectively when the linear guide preload is adjusted from medium and high amount. But the modal damping ratio is reduced by 8.97 and 9.65%, respectively. For high-frequency mode, the modal stiffness increases by 171.2% and the damping ratio reduced by 34.4%. Current results demonstrate the importance in the determining the preloaded amount of linear guide modulus in practical application.

Keywords: contact stiffness, feeding stage, linear guides, modal characteristics, pre-load

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Authors: Stacey Pollard, Henry Baraket, Girish Ganesan, Natalie Kim

Abstract:

One year after U.S.-led coalition operations liberated ISIS-held territories in Iraq and Syria and killed ISIS core leader Abu Bakr al-Baghdadi, ISIS is resurging. Taking a page from its old playbook, the organization is capitalizing on social unrest and a rapidly deteriorating security environment—exacerbated by the COVID-19 pandemic—to reconstitute in permissive areas of Iraq and Syria. This Short examines ISIS’s pandemic-era ground and information operations through the lens of its state- and nation-making efforts to help analysts and decisionmakers better understand the imminence and scope of the threat. ISIS is rapidly overcoming U.S.-supported counterterrorism gains and, without direct pressure to reverse these advances, is poised for recovery.

Keywords: Terrorism, COVID-19, Islamic State, Instability, Iraq, Syria, Global, Resurgence

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Authors: Yehya Abdellatif, Ahmed Alsalaymeh, Iyad Muslih, Ali Alshduifat

Abstract:

Photovoltaic (PV) power generation systems, mainly small scale, are rapidly being deployed in Jordan. The impact of these systems on the grid has not been studied or analyzed. These systems can cause many technical problems such as reverse power flows and voltage rises in distribution feeders, and real and reactive power transients that affect the operation of the transmission system. To fully understand and address these problems, extensive research, simulation, and case studies are required. To this end, this paper studies the cloud shadow effect on the power generation of a ground mounted PV system installed at the test field of the Renewable Energy Center at the Applied Science University.

Keywords: photovoltaic, cloud effect, MPPT, power transients

Procedia PDF Downloads 599

Authors: Samira Taleb, Sakina Aoun, Slimane Ziani, Zoheir Mentouri, Adel Boudiaf

Abstract:

Rolling is a pressure treatment technique that modifies the shape of steel ingots or billets between rotating rollers. During this process, defects may form on the surface of the rolled sheets and are likely to affect the performance and quality of the finished product. In our study, we developed a method for detecting surface hole defects using a pixel classification approach. This work includes several steps. First, we performed image preprocessing to delimit areas with and without hole defects on the sheet image. Then, we developed the histograms of each area to generate the gray level membership intervals of the pixels that characterize each area. As we noticed an intersection between the characteristics of the gray level intervals of the images of the two areas, we finally performed a learning step based on a series of detection tests to refine the membership intervals of each area, and to choose the defect detection criterion in order to optimize the recognition of the surface hole.

Keywords: classification, defect, surface, detection, hole

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Authors: Linh Thi Truc Doan, Yousef Amer, Sang-Heon Lee, Phan Nguyen Ky Phuc

Abstract:

During the last few decades, with the high-speed upgrade of electronic products, electronic waste (e-waste) has become one of the fastest growing wastes of the waste stream. In this context, more efforts and concerns have already been placed on the treatment and management of this waste. To mitigate their negative influences on the environment and society, it is necessary to establish appropriate strategies for e-waste management. Hence, this paper aims to review and analysis some useful strategies which have been applied in several countries to handle e-waste. Future perspectives on e-waste management are also suggested. The key findings found that, to manage e-waste successfully, it is necessary to establish effective reverse supply chains for e-waste, and raise public awareness towards the detrimental impacts of e-waste. The result of the research provides valuable insights to governments, policymakers in establishing e-waste management in a safe and sustainable manner.

Keywords: e-waste, e-waste management, life cycle assessment, recycling regulations

Procedia PDF Downloads 275