Search results for: heating rate

Authors: D. K. Soni

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A study of engineering properties of stones, i.e. compressive strength, tensile strength, modulus of elasticity, density, hardness were carried out to explore the possibility of optimum utilization of stone. The laboratory test results on equally dimensioned discs of the stone show a considerable variation in computed split tensile strength with varied rates of deformation. Hence, the effect of strain rate on the tensile strength of a sand stone and lime stone under wet and dry conditions has been studied experimentally using the split tensile strength test technique. It has been observed that the tensile strength of these stone is very much dependent on the rate of deformation particularly in a dry state. On saturation the value of split tensile strength reduced considerably depending upon the structure of rock and amount of water absorption.

Keywords: sedimentary rocks, split tensile test, deformation rate, saturation rate, sand stone, lime stone

Procedia PDF Downloads 380

Authors: Mas Aji Rizki Widjayanto, Rizka Yunita

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The building which has an efficient and low-energy today followed by the developers. It’s not because trends on the building nowaday, but rather because of its positive effects in the long term, where the cost of energy per month to be much cheaper, along with the high price of electricity. The use of solar power (Photovoltaic System) becomes one source of electrical energy for the apartment so that will efficiently use energy, water, and other resources in the operations of the apartment. However, more than 80% of the solar radiation is not converted into electrical energy, but reflected and converted into heat energy. This causes an increase on the working temperature of solar panels and consequently decrease the efficiency of conversion to electrical energy. The high temperature solar panels work caused by solar radiation can be used as medium heat exchanger or heating water for the apartments, so that the working temperature of the solar panel can be lowered to reduce the reduction on the efficiency of conversion to electrical energy.

Keywords: photovoltaic system, efficient, heat energy, heat exchanger, efficiency of conversion

Procedia PDF Downloads 331

Authors: Piyush Sharma, Laltu Chandra, P. S. Ghoshdastidar, Rajiv Shekhar

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Metals processing operations such as melting and heat treatment of metals are energy-intensive, requiring temperatures greater than 500oC. The desired temperature in these industrial furnaces is attained by circulating electrically-heated air. In most of these furnaces, electricity produced from captive coal-based thermal power plants is used. Solar thermal energy could be a viable heat source in these furnaces. A retrofitted solar convective furnace (SCF) concept, which uses solar thermal generated hot air, has been proposed. Critical to the success of a SCF is the design of an open volumetric air receiver (OVAR), which can heat air in excess of 800oC. The OVAR is placed on top of a tower and receives concentrated solar radiation from a heliostat field. Absorbers, mixer assembly, and the return air flow chamber (RAFC) are the major components of an OVAR. The absorber is a porous structure that transfers heat from concentrated solar radiation to ambient air, referred to as primary air. The mixer ensures uniform air temperature at the receiver exit. Flow of the relatively cooler return air in the RAFC ensures that the absorbers do not fail by overheating. In an earlier publication, the detailed design basis, fabrication, and characterization of a 2 kWth open volumetric air receiver (OVAR) based laboratory solar air tower simulator was presented. Development of an experimentally-validated, CFD based mathematical model which can ultimately be used for the design and scale-up of an OVAR has been the major objective of this investigation. In contrast to the published literature, where flow and heat transfer have been modeled primarily in a single absorber module, the present study has modeled the entire receiver assembly, including the RAFC. Flow and heat transfer calculations have been carried out in ANSYS using the LTNE model. The complex return air flow pattern in the RAFC requires complicated meshes and is computational and time intensive. Hence a simple, realistic 1-D mathematical model, which circumvents the need for carrying out detailed flow and heat transfer calculations, has also been proposed. Several important results have emerged from this investigation. Circumferential electrical heating of absorbers can mimic frontal heating by concentrated solar radiation reasonably well in testing and characterizing the performance of an OVAR. Circumferential heating, therefore, obviates the need for expensive high solar concentration simulators. Predictions suggest that the ratio of power on aperture (POA) and mass flow rate of air (MFR) is a normalizing parameter for characterizing the thermal performance of an OVAR. Increasing POA/MFR increases the maximum temperature of air, but decreases the thermal efficiency of an OVAR. Predictions of the 1-D mathematical are within 5% of ANSYS predictions and computation time is reduced from ~ 5 hours to a few seconds.

Keywords: absorbers, mixer assembly, open volumetric air receiver, return air flow chamber, solar thermal energy

Procedia PDF Downloads 172

Authors: Jay P. Sipani, Riki H. Patel, Trushit Upadhyaya

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Today there is a demand to monitor environmental factors almost in all research institutes and industries and even for domestic uses. The analog data measurement requires manual effort to note readings, and there may be a possibility of human error. Such type of systems fails to provide and store precise values of parameters with high accuracy. Analog systems are having drawback of storage/memory. Therefore, there is a requirement of a smart system which is fully automated, accurate and capable enough to monitor all the environmental parameters with utmost possible accuracy. Besides, it should be cost-effective as well as portable too. This paper represents the Wireless Sensor (WS) data communication using DHT11, Arduino, SIM900A GSM module, a mobile device and Liquid Crystal Display (LCD). Experimental setup includes the heating arrangement of DHT11 and transmission of its data using Arduino and SIM900A GSM shield. The mobile device receives the data using Arduino, GSM shield and displays it on LCD too. Heating arrangement is used to heat and cool the temperature sensor to study its characteristics.

Keywords: wireless communication, Arduino, DHT11, LCD, SIM900A GSM module, mobile phone SMS

Procedia PDF Downloads 259

Authors: Bin Su

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This study focuses on the impact of school building design factors on winter extra energy consumption which mainly includes space heating, water heating and other appliances related to winter indoor thermal conditions. A number of Auckland schools were randomly selected for the study which introduces a method of using real monthly energy consumption data for a year to calculate winter extra energy data of school buildings. The study seeks to identify the relationships between winter extra energy data related to school building design data related to the main architectural features, building envelope and elements of the sample schools. The relationships can be used to estimate the approximate saving in winter extra energy consumption which would result from a changed design datum for future school development, and identify any major energy-efficient design problems. The relationships are also valuable for developing passive design guides for school energy efficiency.

Keywords: building energy efficiency, building thermal design, building thermal performance, school building design

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Authors: S. Reaz Ahmed, M. S. Kaiser

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The tribological behavior of commercially used Perspex was evaluated under dry and wet sliding condition using a pin-on-disc wear tester with different applied loads ranging from 2.5 to 20 N. Experiments were conducted with varying sliding distance from 0.2 km to 4.6 km, wherein the sliding velocity was kept constant, 0.64 ms^-1. The results reveal that the weight loss increases with applied load and the sliding distance. The nature of the wear rate was very similar in both the sliding environments in which initially the wear rate increased very rapidly with increasing sliding distance and then progressed to a slower rate. Moreover, the wear rate in wet sliding environment was significantly lower than that under dry sliding condition. The worn surfaces were characterized by optical microscope and SEM. It is found that surface modification has significant effect on sliding wear performance of Perspex.

Keywords: Perspex, wear, friction, SEM

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Authors: Jian Gu, Sea-Hoon Lee, Jun-Seop Kim

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SiC particulate-reinforced SiC ceramic composites (SiCp/SiC) were successfully fabricated using polymer impregnation and pyrolysis (PIP) method. The effects of green density, infiltrated method, pyrolytic temperature, and heating rate on the densification behavior of the composites were investigated. SiCp/SiC particulate reinforced composites with high relative density up to 88.06% were fabricated after 4 PIP cycles using SiC pellets with high green density. The pellets were prepared by drying 62-70 vol.% aqueous SiC slurries, and the maximum relative density of the pellets was 75.5%. The hardness of the as-fabricated SiCp/SiCs was 21.05 GPa after 4 PIP cycles, which value increased to 23.99 GPa after a heat treatment at 2000℃. Excellent mechanical properties, thermal stability, and short processing time render the SiCp/SiC composite as a challenging candidate for the high-temperature application.

Keywords: high green density, mechanical property, polymer impregnation and pyrolysis, structural application

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Authors: L. O. Luengas, E. V. Morales, L. F. G. De Souza, I. S. Bott

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Duplex Stainless Steels are well known for its good mechanical properties, and corrosion resistance. However, when submitted to heating, these features can be lost since the good properties are strongly dependent on the austenite-ferrite phase ratio which has to be approximately 1:1 to keep the phase balance. In a welded joint, the transformation kinetics at the heat affected zone (HAZ) is a function of the cooling rates applied which in turn are dependent on the heat input. The HAZ is usually ferritized at these temperatures, and it has been argued that small variations of the chemical composition can play a role in the solid state transformation sequence of ferrite to austenite during cooling. The δ → γ transformation has been reported to be massive and diffusionless due to the fast cooling rate, but it is also considered a diffusion controlled transformation. The aim of this work is to evaluate the effect of different heat inputs on the HAZ of two duplex stainless steels UNS S32304 and S32750, obtained by physical simulation.

Keywords: duplex stainless steels, HAZ, microstructural characterization, physical simulation

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Authors: Laura Elena De León Prado, Dora Alicia Cortés Hernández, Javier Sánchez

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Among the different cancer treatments that are currently used, hyperthermia has a promising potential due to the multiple benefits that are obtained by this technique. In general terms, hyperthermia is a method that takes advantage of the sensitivity of cancer cells to heat, in order to damage or destroy them. Within the different ways of supplying heat to cancer cells and achieve their destruction or damage, the use of magnetic nanoparticles has attracted attention due to the capability of these particles to generate heat under the influence of an external magnetic field. In addition, these nanoparticles have a high surface area and sizes similar or even lower than biological entities, which allow their approaching and interaction with a specific region of interest. The most used magnetic nanoparticles for hyperthermia treatment are those based on iron oxides, mainly magnetite and maghemite, due to their biocompatibility, good magnetic properties and chemical stability. However, in order to fulfill more efficiently the requirements that demand the treatment of magnetic hyperthermia, there have been investigations using ferrites that incorporate different metallic ions, such as Mg, Mn, Co, Ca, Ni, Cu, Li, Gd, etc., in their structure. This paper reports the synthesis of nanosized Mg_xMn_1-xFe₂O₄ (x = 0.3 and 0.4) ferrites by sol-gel method and their evaluation in terms of heating capability and in vitro hemolysis to determine the potential use of these nanoparticles as thermoseeds for the treatment of cancer by magnetic hyperthermia. It was possible to obtain ferrites with nanometric sizes, a single crystalline phase with an inverse spinel structure and a behavior near to that of superparamagnetic materials. Additionally, at concentrations of 10 mg of magnetic material per mL of water, it was possible to reach a temperature of approximately 45°C, which is within the range of temperatures used for the treatment of hyperthermia. The results of the in vitro hemolysis assay showed that, at the concentrations tested, these nanoparticles are non-hemolytic, as their percentage of hemolysis is close to zero. Therefore, these materials can be used as thermoseeds for the treatment of cancer by magnetic hyperthermia.

Keywords: ferrites, heating capability, hemolysis, nanoparticles, sol-gel

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Authors: Reginald Umunakwe, Obinna Chibuzor Okoye, Uzoma Samuel Nwigwe, Damilare John Olaleye, Akinlabi Oyetunji

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The potential for the development of PPS-AlMMCs as light weight material for industrial applications was investigated. Periwinkle shells were milled and the density of the particles determined. Particulate periwinkle shell of particle size 75µm was used to reinforce aluminium 6063 alloy at 10wt% filler loading using two-step stir casting technique. The composite materials were stirred for five minutes in a semi-solid state and the stirring time varied as 3, 6 and 9 minutes at above the liquidus temperature. A specimen was also produced with pre-heated filler. The effect of variation in stirring time and reinforcement pre-heating on the porosity of the composite materials was investigated. The results of the analysis show that a composition of reinforcement pre-heating and stirring for 3 minutes produced a composite material with the lowest porosity of 1.05%.

Keywords: composites, periwinkle shell, two-step casting, porosity

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Authors: Serdar Yaman, Hanzade Haykiri-Acma

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Biomass is a CO₂-neutral fuel that is renewable and sustainable along with having very huge global potential. Efficient use of biomass in power generation and production of biomass-based biofuels can mitigate the greenhouse gasses (GHG) and reduce dependency on fossil fuels. There are also other beneficial effects of biomass energy use such as employment creation and pollutant reduction. However, most of the biomass materials are not capable of competing with fossil fuels in terms of energy content. High moisture content and high volatile matter yields of biomass make it low calorific fuel, and it is very significant concern over fossil fuels. Besides, the density of biomass is generally low, and it brings difficulty in transportation and storage. These negative aspects of biomass can be overcome by thermal pretreatments that upgrade the fuel property of biomass. That is, torrefaction is such a thermal process in which biomass is heated up to 300ºC under non-oxidizing conditions to avoid burning of the material. The treated biomass is called as biochar that has considerably lower contents of moisture, volatile matter, and oxygen compared to the parent biomass. Accordingly, carbon content and the calorific value of biochar increase to the level which is comparable with that of coal. Moreover, hydrophilic nature of untreated biomass that leads decay in the structure is mostly eliminated, and the surface properties of biochar turn into hydrophobic character upon torrefaction. In order to investigate the effectiveness of torrefaction process on biomass properties, several biomass species such as olive milling residue (OMR), Rhododendron (small shrubby tree with bell-shaped flowers), and ash tree (timber tree) were chosen. The fuel properties of these biomasses were analyzed through proximate and ultimate analyses as well as higher heating value (HHV) determination. For this, samples were first chopped and ground to a particle size lower than 250 µm. Then, samples were subjected to torrefaction in a horizontal tube furnace by heating from ambient up to temperatures of 200, 250, and 300ºC at a heating rate of 10ºC/min. The biochars obtained from this process were also tested by the methods applied to the parent biomass species. Improvement in the fuel properties was interpreted. That is, increasing torrefaction temperature led to regular increases in the HHV in OMR, and the highest HHV (6065 kcal/kg) was gained at 300ºC. Whereas, torrefaction at 250ºC was seen optimum for Rhododendron and ash tree since torrefaction at 300ºC had a detrimental effect on HHV. On the other hand, the increase in carbon contents and reduction in oxygen contents were determined. Burning characteristics of the biochars were also studied using thermal analysis technique. For this purpose, TA Instruments SDT Q600 model thermal analyzer was used and the thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), and differential thermal analysis (DTA) curves were compared and interpreted. It was concluded that torrefaction is an efficient method to upgrade the fuel properties of biomass and the biochars from which have superior characteristics compared to the parent biomasses.

Keywords: biochar, biomass, fuel upgrade, torrefaction

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Authors: S. Hachemi, A. Ounis, S. Chabi

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This paper presents the results of an experimental study on the effects of elevated temperature on compressive and flexural strength of Normal Strength Concrete (NSC), High Strength Concrete (HSC) and High Performance Concrete (HPC). In addition, the specimen mass and volume were measured before and after heating in order to determine the loss of mass and volume during the test. In terms of non-destructive measurement, ultrasonic pulse velocity test was proposed as a promising initial inspection method for fire damaged concrete structure. 100 Cube specimens for three grades of concrete were prepared and heated at a rate of 3°C/min up to different temperatures (150, 250, 400, 600, and 900°C). The results show a loss of compressive and flexural strength for all the concretes heated to temperature exceeding 400°C. The results also revealed that mass and density of the specimen significantly reduced with an increase in temperature.

Keywords: high temperature, compressive strength, mass loss, ultrasonic pulse velocity

Procedia PDF Downloads 326

Authors: Jarek Krajewski, David Daxberger

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We propose a stress detection method based on an RGB camera using heart rate detection, also known as Photoplethysmography Imaging (PPGI). This technique focuses on the measurement of the small changes in skin colour caused by blood perfusion. A stationary lab setting with simulated video conferences is chosen using constant light conditions and a sampling rate of 30 fps. The ground truth measurement of heart rate is conducted with a common PPG system. The proposed approach for pulse peak detection is based on a machine learning-based approach, applying brute force feature extraction for the prediction of heart rate pulses. The statistical analysis showed good agreement (correlation r = .79, p<0.05) between the reference heart rate system and the proposed method. Based on these findings, the proposed method could provide a reliable, low-cost, and contactless way of measuring HR parameters in daily-life environments.

Keywords: heart rate, PPGI, machine learning, brute force feature extraction

Procedia PDF Downloads 107

Authors: Misbahuddin Mahammad, P. Chandra Sekhar, Metuku Shyamsunder

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The oversampled output of a sigma-delta modulator is decimated to Nyquist sampling rate by decimation filters. The decimation filters work twofold; they decimate the sampling rate by a factor of OSR (oversampling rate) and they remove the out band quantization noise resulting in an increase in resolution. The speed, area and power consumption of oversampled converter are governed largely by decimation filters in sigma-delta A/D converters. The scope of the work is to design a decimation filter for sigma-delta ADC and simulation using MATLAB. The decimation filter structure is based on cascaded-integrated comb (CIC) filter. A second decimation filter is using CIC for large rate change and cascaded FIR filters, for small rate changes, to improve the frequency response. The proposed structure is even more hardware efficient.

Keywords: sigma delta modulator, CIC filter, decimation filter, compensation filter, noise shaping

Procedia PDF Downloads 442

Authors: O.Ofoegbu, S. Roongnapa, A.N. Eboatu

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Most polluted environments, most challengingly, aerosol types, contain a cocktail of different toxicants. Multi-templating of matrices have been the recent target by researchers in a bid to solving complex mixed-toxicant challenges using single or common remediation systems. This investigation looks at the effect of such multi-templated system vis-a-vis the synthesis by non-covalent interaction, of a molecularly imprinted polymer architecture using nicotine and its structural analogue Phenylalanine amide individually and, in the blend, (50:50), as template materials in a Chitosan-Methacrylic acid functional monomer matrix. The temperature for polymerization is 60OC and time for polymerization, 12hrs (water bath heating), 4mins for (microwave heating). The characteristic thermal properties of the molecularly imprinted materials are investigated using Simultaneous Thermal Analysis (STA) profiling, while the absorption and separation efficiencies based on the relative retention times and peak areas of templates were studied amongst other properties. Transmission Electron Microscopy (TEM) results obtained, show the creation of heterogeneous nanocavities, regardless, the introduction of Caffeine a close structural analogue presented near-zero perfusion. This confirms the selectivity and specificity of the templated polymers despite its dual-templated nature. The STA results presented the materials as having decomposition temperatures above 250OC and a relative loss in mass of less than19% over a period within 50mins of heating. Consequent to this outcome, multi-templated systems can be fabricated to sequester specifically and selectively targeted toxicants in a mixed toxicant populated system effectively.

Keywords: chitosan, dual-templated, methacrylic acid, mixed-toxicants, molecularly-imprinted-polymer

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Authors: Aynur Aker, Hasan Kaya

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In recent years, the use of the aluminum based alloys in the industry and technology are increasing. Alloying elements in aluminum have further been improving the strength and stiffness properties that provide superior compared to other metals. In this study, investigation of physical properties (microstructure, microhardness, tensile strength, electrical conductivity and thermal properties) in the Al-12.6wt.%Si-%2wt.Ni ternary alloy were investigated. Al-Si-Ni alloy was prepared in a graphite crucible under vacuum atmosphere. The samples were directionally solidified upwards with different growth rate (V) at constant temperature gradient G (7.73 K/mm). The microstructures (flake spacings, λ), microhardness (HV), ultimate tensile strength, electrical resistivity and thermal properties enthalpy of fusion and specific heat and melting temperature) of the samples were measured. Influence of the growth rate and flake spacings on microhardness, ultimate tensile strength and electrical resistivity were investigated and relationships between them were experimentally obtained by using regression analysis. According to results, λ values decrease with increasing V, but microhardness, ultimate tensile strength, electrical resistivity values increase with increasing V. Variations of electrical resistivity for cast samples with the temperature in the range of 300-1200 K were also measured by using a standard dc four-point probe technique. The enthalpy of fusion and specific heat for the same alloy was also determined by means of differential scanning calorimeter (DSC) from heating trace during the transformation from liquid to solid. The results obtained in this work were compared with the previous similar experimental results obtained for binary and ternary alloys.

Keywords: electrical resistivity, enthalpy, microhardness, solidification, tensile stress

Procedia PDF Downloads 356

Authors: Madeleine Nicole G. Bernardo, Katrina T. Feliciano, Marcelo Nonato A. Nacionales III, Diane Frances M. Peralta, Denise Nicole V. Profeta

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This study aims to find out if heart rate variability and valence of emotion have an effect on perceived intensity of emotion. Psychology undergraduates (N = 60) from the University of the Philippines Diliman were shown 10 photographs from the Japanese Female Facial Expression (JAFFE) Database, along with a corresponding questionnaire with a Likert scale on perceived intensity of emotion. In this 3 x 2 mixed subjects factorial design, each group was either made to do a simple exercise prior to answering the questionnaire in order to increase the heart rate, listen to a heart rate of 120 bpm, or colour a drawing to keep the heart rate stable. After doing the activity, the participants then answered the questionnaire, providing a rating of the faces according to the participants’ perceived emotional intensity on the photographs. The photographs presented were either of positive or negative emotional valence. The results of the experiment showed that neither an induced fast heart rate or perceived fast heart rate had any significant effect on the participants’ perceived intensity of emotion. There was also no interaction effect of heart rate variability and valence of emotion. The insignificance of results was explained by the Philippines’ high context culture, accompanied by the prevalence of both intensely valenced positive and negative emotions in Philippine society. Insignificance in the effects were also attributed to the Cannon-Bard theory, Schachter-Singer theory and various methodological limitations.

Keywords: heart rate variability, perceived intensity of emotion, Philippines , valence of emotion

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Authors: Mohammed Adamu Musa, Shehu Saminu Babba

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The technological trend towards waste utilization and cost reduction in industrial processing has attracted use of Rice Husk as a value added material. Both rice husk (RH) and Rice Husk Ash (RHA) has been found suitable for wide range of domestic as well as industrial applications. Therefore, the purpose of this research is to produce high grade sodium silicate from rice husk ash by considering the effect of temperature and time of heating as the process variables. The experiment was performed by heating the rice husk at temperatures 500 °C, 600 °C, 700 °C and 800 °C and time 60min, 90min, 120min and 150min were used to obtain the ash. 1.0M of aqueous sodium hydroxide solution was used to dissolve the silicate from the ash, which contained crude sodium silicate. In addition, the ash was neutralized by adding 5M of HCL until the pH reached 3.5 to give silica gel. At 6000C and 120mins, 94.23% silica was obtained from the RHA. At higher temperatures (700 °C and 800 °C) the percentage yield of silica reduced due to surface melting and carbon fixation in the lattice caused by presence of potassium. For this research, 600 °C is considered to be the optimum temperature for silica production from RHA. Silica produced from RHA can generate aggregate value and can be used in areas such as pulp and paper, plastic and rubber reinforcement industries.

Keywords: burning, rice husk, rice husk ash, silica, silica gel, temperature

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Authors: Manjit Singh

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Multiscale entropy (MSE) is an extensively used index to provide a general understanding of multiple complexity of physiologic mechanism of heart rate variability (HRV) that operates on a wide range of time scales. Accurate selection of electrocardiogram (ECG) sampling frequency is an essential concern for clinically significant HRV quantification; high ECG sampling rate increase memory requirements and processing time, whereas low sampling rate degrade signal quality and results in clinically misinterpreted HRV. In this work, the impact of ECG sampling frequency on MSE based HRV have been quantified. MSE measures are found to be sensitive to ECG sampling frequency and effect of sampling frequency will be a function of time scale.

Keywords: ECG (electrocardiogram), heart rate variability (HRV), multiscale entropy, sampling frequency

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Authors: Paulo Teodoro De Luna Carada, Toru Fujii, Kazuya Okubo

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Natural fibers have wide variety of uses (e.g., rope, paper, and building materials). One specific application of it is in the field of composite materials (i.e., green composites). Huge amount of research are being done in this field due to rising concerns in the harmful effects of synthetic materials to the environment. There are several natural fibers used in this field, one of which can be extracted from a plant called kenaf (Hibiscus cannabinus L.). Kenaf fiber is regarded as a good alternative because the plant is easy to grow and the fiber is easy to extract. Additionally, it has good properties. Treatments, which are classified as mechanical or chemical in nature, can be done in order to improve the properties of the fiber. The aim of this study is to assess the effects of heat treatment in kenaf fiber. It specifically aims to observe the effect in the tensile strength and modulus of the fiber. Kenaf fiber bundles with an average diameter of at most 100μm was used for this purpose. Heat treatment was done using a constant temperature oven with the following heating temperatures: (1) 160̊C, (2) 180̊C, and (3) 200̊C for a duration of one hour. As a basis for comparison, tensile test was first done to kenaf fibers without any heat treatment. For every heating temperature, three groups of samples were prepared. Two groups of which were for doing tensile test (one group was tested right after heat treatment while the remaining group was kept inside a closed container with relative humidity of at least 95% for two days). The third group was used to observe how much moisture the treated fiber will absorb when it is enclosed in a high moisture environment for two days. The results showed that kenaf fiber can retain its tensile strength when heated up to a temperature of 160̊C. However, when heated at a temperature of about 180̊C or higher, the tensile strength decreases significantly. The same behavior was observed for the tensile modulus of the fiber. Additionally, the fibers which were stored for two days absorbed nearly the same amount of moisture (about 20% of the dried weight) regardless of the heating temperature. Heat treatment might have damaged the fiber in some way. Additional test was done in order to see if the damage due to heat treatment is attributed to changes in the viscoelastic property of the fiber. The findings showed that kenaf fibers can be heated for at most 160̊C to attain good tensile strength and modulus. Additionally, heating the fiber at high temperature (>180̊C) causes changes in its viscoelastic property. The results of this study is significant for processes which requires heat treatment not only in kenaf fiber but might also be helpful for natural fibers in general.

Keywords: heat treatment, kenaf fiber, natural fiber, mechanical properties

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Authors: Sofia N. Gonçalves, Duarte M. S. Albuquerque, José C. F. Pereira

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The energy transition is spurred by structural changes in energy demand, supply, and prices. Microwave technology was first proposed as a faster alternative for cooking food. It was found that food heated instantly when interacting with high-frequency electromagnetic waves. The dielectric properties account for a material’s ability to absorb electromagnetic energy and dissipate this energy in the form of heat. Many energy-intense industries could benefit from electromagnetic heating since many of the raw materials are dielectric at high temperatures. Limestone sedimentary rock is a dielectric material intensively used in the cement industry to produce unslaked lime. A numerical 3D model was implemented in COMSOL Multiphysics to study the limestone continuous processing under microwave heating. The model solves the two-way coupling between the Energy equation and Maxwell’s equations as well as the coupling between heat transfer and chemical interfaces. Complementary, a controller was implemented to optimize the overall heating efficiency and control the numerical model stability. This was done by continuously matching the cavity impedance and predicting the required energy for the system, avoiding energy inefficiencies. This controller was developed in MATLAB and successfully fulfilled all these goals. The limestone load influence on thermal decomposition and overall process efficiency was the main object of this study. The procedure considered the Verification and Validation of the chemical kinetics model separately from the coupled model. The chemical model was found to correctly describe the chosen kinetic equation, and the coupled model successfully solved the equations describing the numerical model. The interaction between flow of material and electric field Poynting vector revealed to influence limestone decomposition, as a result from the low dielectric properties of limestone. The numerical model considered this effect and took advantage from this interaction. The model was demonstrated to be highly unstable when solving non-linear temperature distributions. Limestone has a dielectric loss response that increases with temperature and has low thermal conductivity. For this reason, limestone is prone to produce thermal runaway under electromagnetic heating, as well as numerical model instabilities. Five different scenarios were tested by considering a material fill ratio of 30%, 50%, 65%, 80%, and 100%. Simulating the tube rotation for mixing enhancement was proven to be beneficial and crucial for all loads considered. When uniform temperature distribution is accomplished, the electromagnetic field and material interaction is facilitated. The results pointed out the inefficient development of the electric field within the bed for 30% fill ratio. The thermal efficiency showed the propensity to stabilize around 90%for loads higher than 50%. The process accomplished a maximum microwave efficiency of 75% for the 80% fill ratio, sustaining that the tube has an optimal fill of material. Electric field peak detachment was observed for the case with 100% fill ratio, justifying the lower efficiencies compared to 80%. Microwave technology has been demonstrated to be an important ally for the decarbonization of the cement industry.

Keywords: CFD numerical simulations, efficiency optimization, electromagnetic heating, impedance matching, limestone continuous processing

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Authors: Amar Al-Obaidi, Verena Kräusel, Dirk Landgrebe

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Induction assisted single point incremental forming (IASPIF) is a flexible method and can be simply utilized to form a high strength alloys. Due to the interaction between the mechanical and thermal properties during IASPIF an evaluation for the process is necessary to be performed analytically. Therefore, a numerical simulation was carried out in this paper. The numerical analysis was operated at both room and elevated temperatures then compared with experimental results. Fully coupled dynamic temperature displacement explicit analysis was used to simulated the hot single point incremental forming. The numerical analysis was indicating that during hot single point incremental forming were a combination between complicated compression, tension and shear stresses. As a result, the equivalent plastic strain was increased excessively by rising both the formed part depth and the heating temperature during forming. Whereas, the forming forces were decreased from 5 kN at room temperature to 0.95 kN at elevated temperature. The simulation shows that the maximum true strain was occurred in the stretching zone which was the same as in experiment.

Keywords: induction heating, single point incremental forming, FE modeling, advanced high strength steel

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Authors: Baso Hamdani, Arniati Massinai, Jamaluddin Jompa

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Coral diseases are one of the factors affect reef degradation. This research had analysed the progression rate, incidence, and prevalence of Black Band Disease (BBD) on stony coral (Pachyseris sp.) in relation to the environmental parameters (pH, nitrate, phospate, Dissolved Organic Matter (DOM), and turbidity). The incidence of coral disease was measured weekly for 6 weeks using Belt Transect Method. The progression rate of BBD was measured manually. Furthermore, the prevalence and incidence of BBD were calculated each colonies infected. The relationship between environmental parameters and the progression rate, prevalence and incidence of BBD was analysed by Principal Component Analysis (PCA). The results showed the average of progression rate is 0,07 ± 0,02 cm/ hari. The prevalence of BBD increased from 0,92% - 19,73% in 7 weeks observation with the average incidence of new infected colonies coral 0,2 - 0,65 colony/day The environment factors which important were pH, Nitrate, Phospate, DOM, and Turbidity.

Keywords: progression rate, incidence, prevalence, Black Band Disease, Barranglompo

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Authors: S. K. Ashiquer Rahman

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the paper concentrations on the importance of hourly compensation, emphasizing the significance of the unemployment rate. There are the two most important factors of a nation these are its unemployment rate and hourly compensation. These are not merely statistics but they have profound effects on individual, families, and the economy. They are inversely related to one another. When we consider the unemployment rate that will probably decline as hourly compensations in manufacturing rise. But when we reduced the unemployment rates and increased job prospects could result from higher compensation. That’s why, the increased hourly compensation in the manufacturing sector that could have a favorable effect on job changing issues. Moreover, the relationship between hourly compensation and unemployment is complex and influenced by broader economic factors. In this paper, we use panel data regression models to evaluate the expected link between hourly compensation and unemployment rate in order to determine the effect of hourly compensation on unemployment rate. We estimate the fixed effects model, evaluate the error components, and determine which model (the FEM or ECM) is better by pooling all 60 observations. We then analysis and review the data by comparing 3 several countries (United States, Canada and the United Kingdom) using panel data regression models. Finally, we provide result, analysis and a summary of the extensive research on how the hourly compensation effects on the unemployment rate. Additionally, this paper offers relevant and useful informational to help the government and academic community use an econometrics and social approach to lessen on the effect of the hourly compensation on Unemployment rate to eliminate the problem.

Keywords: hourly compensation, Unemployment rate, panel data regression models, dummy variables, random effects model, fixed effects model, the linear regression model

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Authors: Glauco M. M. M. Lustosa, João Paulo C. Costa, Sonia M. Zanetti, Mario Cilense, Leinig Antônio Perazolli, Maria Aparecida Zaghete

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The contamination of the environment has been one of the biggest problems of our time, mostly due to developments of many industries. SnO2 is an n-type semiconductor with band gap about 3.5 eV and has its electrical conductivity dependent of type and amount of modifiers agents added into matrix ceramic during synthesis process, allowing applications as sensing of gaseous pollutants on ambient. The chemical synthesis by polymeric precursor method consists in a complexation reaction between tin ion and citric acid at 90 °C/2 hours and subsequently addition of ethyleneglycol for polymerization at 130 °C/2 hours. It also prepared polymeric resin of zinc, cobalt and niobium ions. Stoichiometric amounts of the solutions were mixed to obtain the systems (Zn, Nb)-SnO2 and (Co, Nb) SnO2 . The metal immobilization reduces its segregation during the calcination resulting in a crystalline oxide with high chemical homogeneity. The resin was pre-calcined at 300 °C/1 hour, milled in Atritor Mill at 500 rpm/1 hour, and then calcined at 600 °C/2 hours. X-Ray Diffraction (XDR) indicated formation of SnO2 -rutile phase (JCPDS card nº 41-1445). The characterization by Scanning Electron Microscope of High Resolution showed spherical ceramic powder nanostructured with 10-20 nm of diameter. 20 mg of SnO2 -based powder was kept in 20 ml of isopropyl alcohol and then taken to an electrophoretic deposition (EPD) system. The EPD method allows control the thickness films through the voltage or current applied in the electrophoretic cell and by the time used for deposition of ceramics particles. This procedure obtains films in a short time with low costs, bringing prospects for a new generation of smaller size devices with easy integration technology. In this research, films were obtained in an alumina substrate with interdigital electrodes after applying 2 kV during 5 and 10 minutes in cells containing alcoholic suspension of (Zn, Nb)-SnO2 and (Co, Nb) SnO2 of powders, forming a sensing layer. The substrate has designed integrated micro hotplates that provide an instantaneous and precise temperature control capability when a voltage is applied. The films were sintered at 900 and 1000 °C in a microwave oven of 770 W, adapted by the research group itself with a temperature controller. This sintering is a fast process with homogeneous heating rate which promotes controlled growth of grain size and also the diffusion of modifiers agents, inducing the creation of intrinsic defects which will change the electrical characteristics of SnO2 -based powders. This study has successfully demonstrated a microfabricated system with an integrated micro-hotplate for detection of CO and NO2 gas at different concentrations and temperature, with self-heating SnO2 - based nanoparticles films, being suitable for both industrial process monitoring and detection of low concentrations in buildings/residences in order to safeguard human health. The results indicate the possibility for development of gas sensors devices with low power consumption for integration in portable electronic equipment with fast analysis. Acknowledgments The authors thanks to the LMA-IQ for providing the FEG-SEM images, and the financial support of this project by the Brazilian research funding agencies CNPq, FAPESP 2014/11314-9 and CEPID/CDMF- FAPESP 2013/07296-2.

Keywords: chemical synthesis, electrophoretic deposition, self-heating, gas sensor

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Authors: Gustave Semugaza, Anne Zora Gierth, Tommy Mielke, Marianela Escobar Castillo, Nat Doru C. Lupascu

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The generation of Construction and Demolition Waste (CDW) has globally increased enormously due to the enhanced need in construction, renovation, and demolition of construction structures. Several studies investigated the use of CDW materials in the production of new concrete and indicated the lower mechanical properties of the resulting concrete. Many other researchers considered the possibility of using the Hydrated Cement Powder (HCP) to replace a part of Ordinary Portland Cement (OPC), but only very few investigated the use of Recycled Concrete Powder (RCP) from CDW. The partial replacement of OPC for making new concrete intends to decrease the CO₂ emissions associated with OPC production. However, the RCP and HCP need treatment to produce the new concrete of required mechanical properties. The thermal treatment method has proven to improve HCP properties before their use. Previous research has stated that for using HCP in concrete, the optimum results are achievable by heating HCP between 400°C and 800°C. The optimum heating temperature depends on the type of cement used to make the Hydrated Cement Specimens (HCS), the crushing and heating method of HCP, and the curing method of the Rehydrated Cement Specimens (RCS). This research assessed the quality of recycled materials by using different techniques such as X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and thermogravimetry (TG), Scanning electron Microscopy (SEM), and X-ray Fluorescence (XRF). These recycled materials were thermally pretreated at different temperatures from 200°C to 1000°C. Additionally, the research investigated to what extent the thermally treated recycled cement could partially replace the OPC and if the new concrete produced would achieve the required mechanical properties. The mechanical properties were evaluated on the RCS, obtained by mixing the Dehydrated Cement Powder and Recycled Powder (DCP and DRP) with water (w/c = 0.6 and w/c = 0.45). The research used the compressive testing machine for compressive strength testing, and the three-point bending test was used to assess the flexural strength.

Keywords: hydrated cement powder, dehydrated cement powder, recycled concrete powder, thermal treatment, reactivation, mechanical performance

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Authors: Gbenga Martins, Christopher J. Olowookere, Lateef Bamidele, Kehinde O. Olatunji

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The aims of this research are to measure the scattered dose rate during an X-ray examination in an X-ray room, compare the scattered dose rate with exposure parameters based on the body region examined, and examine the X-ray examination done with an over couch tube. The research was carried out using Gamma Scout software installation on the computer system (Laptop) to record the radiation counts, pulse rate, and dose rate. The measurement was employed by placing the detector at 900 to the incident X-ray. Proforma was used for the collection of patients’ data such as age, sex, examination type, and initial diagnosis. Data such as focus skin distance (FSD), body mass index (BMI), body thickness of the patients, the beam output (kVp) were collected at Obafemi Awolowo University, Ile-Ife, Western Nigeria. Total number of 136 patients was considered during this research. Dose rate range between 14.21 and 86.78 µSv/h for the plain abdominal region, 85.70 and 2.86 µSv/h for the lumbosacral region,1.3 µSv/yr and 3.6 µSv/yr in the pelvis region, 2.71 µSv/yr and 28.88 µSv/yr for leg region, 3.06 µSv/yr and 29.98 µSv/yr in hand region. The results of this study were compared with those of other studies carried out in other countries. The findings of this study indicated that the number of exposure parameters selected for each diagnostic examination contributed to the dose rate recorded. Therefore, these results call for a quality assurance program (QAP) in diagnostic X-ray units in Nigerian hospitals.

Keywords: X-radiation, exposure parameters, dose rate, pulse rate, number of counts, tube current, tube potential, diagnostic examination, scattered radiation

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Authors: Indrajeet Singh, Abhishek Gandhi, Smita Mohanty, S. K. Nayak

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In this article, a focused study has been performed to comprehend the influence of change in depressurization rate on microcellular polycarbonate foamed morphological attributes. The depressurization rate considered in this study were 0.5, 0.05, 0.01 and 0.005 MPa/sec and the physical blowing agent utilized was carbon dioxide owing to its high solubility in polycarbonate at room temperature. The study was performed on two distinct saturation pressures, i.e., 3 MPa and 6 MPa to understand if saturation pressure has any effects on it. It is reported that with increase in depressurization rate, a higher amount of thermodynamic instability was induced which resulted in generation of larger number of smaller sized cells. This article puts forward an understanding of how depressurization rate control could be well exploited during the batch foaming process to develop high quality microcellular foamed products with exceedingly well controlled cell size.

Keywords: depressurization, porous polymer, foaming, microcellular

Procedia PDF Downloads 244

Authors: D. Jagath Kumari, K. Srinivasa Rao

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Quality assurance of the structures subjected to high temperatures is now enforcing measure for the Structural Engineers. The existing relations between strength and nondestructive measurements have been established under normal conditions are not suitable to concretes that have been exposed to high temperatures. The scope of the work is to investigate the influence of high temperatures of short durations on the residual properties of reinforced HVFA concrete columns that affect the strength by non-destructive tests (NDT). Fly ash concrete is increasingly used in the design of normal strength, high strength and high performance concretes. In this paper, the authors revealed the influence of high temperatures on HVFA concrete columns. These columns are heated from 100oC to 800oC with increments of 100oC and allowed to cool to room temperature by two methods one is air cooling method and the other immediate water quenching method. All the specimens were tested identically, before heating and after heating for compressive strength and material integrity by rebound hammer and ultrasonic pulse velocity (UPV) meter respectively. HVFA concrete retained more residual strength by water quenching method than air-cooling method.

Keywords: HVFA concrete, NDT methods, residual strength, non-destructive tests

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Authors: Hasan Basri Jumin

Abstract:

Application of crude palm oil waste combined to suitable concentration of benzyl-adenine give the significant effect to mean relative growth rate of vegetable plants and the same pattern in net assimilation rate crude palm oil waste has also significantly increased during 28 days old plants. Combination of treatment of suitable concentration of crude palm oil and benzyl adenine increased the growth and production of vegetable plants. The relative growth rate of vegetable plants was rapid 3 weeks after planting and gradually decreased at the end of the harvest time period. Combination of 400 mg.l-1 CPO with 1.0 mgl-1 till 10mgl-1 BA increased the Mean Relative Growth Rate (MRGR), Net assimilation rate (NAR), Leaf area and dry weight of Brassica juncea, Brassica oleraceae and Lactuca sativa.

Keywords: benzyladenine, crude-palm-oil, nutrient, vegetable, waste

Procedia PDF Downloads 165