Search results for: active thermal control system

Authors: Ahmad E. Aldousaria, Abdulla Al Kafy

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Urbanization is an incessant process that involves the transformation of land use/land cover (LULC), resulting in a reduction of cool land covers and thermal comfort zones (TCZs). This study explores the directional shrinkage of TCZs in Kuwait using Landsat satellite data from 1991 – 2021 to predict the future LULC and TCZ distribution for 2026 and 2031 using cellular automata (CA) and artificial neural network (ANN) algorithms. Analysis revealed a rapid urban expansion (40 %) in SE, NE, and NW directions and TCZ shrinkage in N – NW and SW directions with 25 % of the very uncomfortable area. The predicted result showed an urban area increase from 44 % in 2021 to 47 % and 52 % in 2026 and 2031, respectively, where uncomfortable zones were found to be concentrated around urban areas and bare lands in N – NE and N – NW directions. This study proposes an effective and sustainable framework to control TCZ shrinkage, including zero soil policies, planned landscape design, manmade water bodies, and rooftop gardens. This study will help urban planners and policymakers to make Kuwait an eco–friendly, functional, and sustainable country.

Keywords: land cover change, thermal environment, green cover loss, machine learning, remote sensing

Procedia PDF Downloads 222

Authors: Krzysztof Skiba, Zbigniew Czyz, Ksenia Siadkowska, Piotr Borowiec

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The article presents selected concepts of technologies that use intelligent materials in aircraft in order to improve their performance. Most of the research focuses on solutions that improve the performance of fixed wing aircraft due to related to their previously dominant market share. Recently, the development of the rotorcraft has been intensive, so there are not only helicopters but also gyroplanes and unmanned aerial vehicles using rotors and vertical take-off and landing. There are many different technologies to change a shape of the aircraft or its elements. Piezoelectric, deformable actuator systems can be applied in the system of an active control of vibration dampening in the aircraft tail structure. Wires made of shape memory alloys (SMA) could be used instead of hydraulic cylinders in the rear part of the aircraft flap. The aircraft made of intelligent materials (piezoelectrics and SMA) is one of the NASA projects which provide the possibility of changing a wing shape coefficient by 200%, a wing surface by 50%, and wing deflections by 20 degrees. Active surfaces made of shape memory alloys could be used to control swirls in the flowing stream. An intelligent control system for helicopter blades is a method for the active adaptation of blades to flight conditions and the reduction of vibrations caused by the rotor. Shape memory alloys are capable of recovering their pre-programmed shapes. They are divided into three groups: nickel-titanium-based, copper-based, and ferromagnetic. Due to the strongest shape memory effect and the best vibration damping ability, a Ni-Ti alloy is the most commercially important. The subject of this work was to prepare a conceptual design of a rotor blade with SMA actuators. The scope of work included 3D design of the supporting rotor blade, 3D design of beams enabling to change the geometry by changing the angle of rotation and FEM (Finite Element Method) analysis. The FEM analysis was performed using NX 12 software in the Pre/Post module, which includes extended finite element modeling tools and visualizations of the obtained results. Calculations are presented for two versions of the blade girders. For FEM analysis, three types of materials were used for comparison purposes (ABS, aluminium alloy 7057, steel C45). The analysis of internal stresses and extreme displacements of crossbars edges was carried out. The internal stresses in all materials were close to the yield point in the solution of girder no. 1. For girder no. 2 solution, the value of stresses decreased by about 45%. As a result of the displacement analysis, it was found that the best solution was the ABS girder no. 1. The displacement of about 0.5 mm was obtained, which resulted in turning the crossbars (upper and lower) by an angle equal to 3.59 degrees. This is the largest deviation of all the tests. The smallest deviation was obtained for beam no. 2 made of steel. The displacement value of the second girder solution was approximately 30% lower than the first solution. Acknowledgement: This work has been financed by the Polish National Centre for Research and Development under the LIDER program, Grant Agreement No. LIDER/45/0177/L-9/17/NCBR/2018.

Keywords: aircraft, helicopters, shape memory alloy, SMA, smart material, unmanned aerial vehicle, UAV

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Authors: Samart Rungjarean, Benchalak Muangmeesri, Dechrit Maneetham

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Monks' and Novices' chimes may have some restrictions, such as during the rain when a structure or location chimes or at a certain period. Alternately, certain temple bells may be found atop a tall, difficult-to-reach bell tower. As a result, the concept of designing a brass bell for use with a mobile phone over great distances was proposed. The Internet of Things (IoT) system will be used to regulate the bell by testing each of the three beatings with a wooden head. A stone-beating head and a steel beater. The sound resonates nicely, with the distance and rhythm of the hit contributing to this. An ESP8266 microcontroller is used by the control system to manage its operations and will communicate with the pneumatic system to convey a signal. Additionally, a mobile phone will be used to operate the entire system. In order to precisely direct and regulate the rhythm, There is a resonance of roughly 50 dB for this test, and the operating distance can be adjusted. Timing and accuracy were both good.

Keywords: automatic ring-bell, microcontroller, ring-bell, iot

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Authors: Sajjad Shojaeidoust, Mohsen Ghanbarzadeh, Abdolhamid Habibi

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Exercise-induced bronchospasm (EIB) is a transitory condition of airflow obstruction that is associated with physical activities. It is noted that high ventilation can lead to an increase in the heat and reduce in the moisture in airways resistance of trachea. Also causes of pathophysiological mechanism are EIB. Accordingly, studying some parameters of pulmonary function (FVC, FEV1) among active people seems quintessential. The aim of this study was to analyze bronchospasm following the implementation of a program of maximum aerobic exercise in active men at Chamran University of Ahwaz. Method: In this quasi-experimental study, the population consisted of all students at Chamran University. Among from 55 participants, of which, 15 were randomly selected as the experimental group. In this study, the size of the maximum oxygen consumption was initially measured, and then, based on the maximum oxygen consumed, the active individuals were identified. After five minutes’ warm-up, Strand treadmill exercise test was taken (one session) and pulmonary parameters were measured at both pre- and post-tests (spirometer). After data normalization using KS and non-normality of the data, the Wilcoxon test was used to analyze the data. The significance level for all statistical surveys was considered p≤0/05. Results: The results showed that the ventilation factors and bronchospasm (FVC, FEV1) in the pre-test and post-test resulted in no significant difference among the active people (p≥0/05). Discussion and conclusion: Based on the results observed in this study, it appears that pulmonary indices in active individuals increased after aerobic test. The increase in this indicator in active people is due to increased volume and elasticity of the lungs as well. In other words, pulmonary index is affected by rib muscles. It is considered that progress over respiratory muscle strength and endurance has raised FEV1 in the active cases.

Keywords: aerobic active maximum, bronchospasm, pulmonary function, spirometer

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Authors: Ming-Yeh Lu, Shiao-Shing Chen, Saikat Sinha Ray, Hung-Te Hsu

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The submerged anaerobic osmotic membrane bioreactor (AnOMBR) integrated with periodic microfiltration (MF) extraction for simultaneous phosphorus and clean water recovery from wastewater was evaluated. A laboratory-scale AnOMBR used cellulose triacetate (CTA) membranes with effective membrane area of 130 cm² was fully submerged into a 5 L bioreactor at 30-35 ℃. Active layer was orientated to feed stream for minimizing membrane fouling and scaling. Additionally, a peristaltic pump was used to circulate magnesium sulphate (MgSO₄) solution applied as draw solution (DS). Microfiltration membrane periodically extracted about 1 L solution when the TDS reaches to 5 g/L to recover phosphorus and simultaneously control the salt accumulation in the bioreactor. During experiment progress, the average water flux was around 1.6 LMH. The AnOMBR process showed greater than 95% removal of soluble chemical oxygen demand (sCOD), nearly 100% of total phosphorous whereas only partial of ammonia was removed. On the other hand, the average methane production of 0.22 L/g sCOD was obtained. Subsequently, the overall performance demonstrates that a novel submerged AnOMBR system is potential for simultaneous wastewater treatment and resource recovery from wastewater. Therefore, the new concept of this system can be used to replace for the conventional AnMBR in the future.

Keywords: anaerobic treatment, forward osmosis, phosphorus recovery, membrane bioreactor

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Authors: B. Arzhanov, A. Correia, P. Delgado, J. Meireles

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Due to the higher power loss levels in electronic components, the thermal design of PCBs (Printed Circuit Boards) of an assembled device becomes one of the most important quality factors in electronics. Nonetheless, some of leading causes of the microelectronic component failures are due to higher temperatures, the leakages or thermal-mechanical stress, which is a concern, is the reliability of microelectronic packages. This article presents an experimental approach to measure the junction temperature of exposed pad packages. The implemented solution is in a prototype phase, using a temperature-sensitive parameter (TSP) to measure temperature directly on the die, validating the numeric results provided by the Mechanical APDL (Ansys Parametric Design Language) under same conditions. The physical device-under-test is composed by a Thermal Test Chip (TTC-1002) and assembly in a QFN cavity, soldered to a test-board according to JEDEC Standards. Monitoring the voltage drop across a forward-biased diode, is an indirectly method but accurate to obtain the junction temperature of QFN component with an applied power range between 0,3W to 1.5W. The temperature distributions on the PCB test-board and QFN cavity surface were monitored by an infra-red thermal camera (Goby-384) controlled and images processed by the Xeneth software. The article provides a set-up to monitorize in real-time the junction temperature of ICs, namely devices with the exposed pad package (i.e. QFN). Presenting the PCB layout parameters that the designer should use to improve thermal performance, and evaluate the impact of voids in solder interface in the device junction temperature.

Keywords: quad flat no-Lead packages, exposed pads, junction temperature, thermal management and measurements

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Authors: Waleed Ahmed, Huang Xiaohua, Wilayat Ali

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The wheelchair users are generally exposed to physical and psychological health problems, e.g., pressure sores and pain in the hip joint, associated with seating posture or being inactive in a wheelchair for a long time. Reclining Wheelchair with back, thigh, and leg adjustment helps in daily life activities and health preservation. The seat elevating function of an electric wheelchair allows the user (lower limb amputation) to reach different heights. An electric wheelchair is expected to ease the lives of the elderly and disable people by giving them mobility support and decreasing the percentage of accidents caused by users’ narrow sight or joystick operation errors. Thus, this paper proposed the design, analysis and obstacle avoidance control of an electric wheelchair with sit-sleep-seat elevation functions. A 3D model of a wheelchair is designed in SolidWorks that was later used for multi-body dynamic (MBD) analysis and to verify driving control system. The control system uses the fuzzy algorithm to avoid the obstacle by getting information in the form of distance from the ultrasonic sensor and user-specified direction from the joystick’s operation. The proposed fuzzy driving control system focuses on the direction and velocity of the wheelchair. The wheelchair model has been examined and proven in MSC Adams (Automated Dynamic Analysis of Mechanical Systems). The designed fuzzy control algorithm is implemented on Gazebo robotic 3D simulator using Robotic Operating System (ROS) middleware. The proposed wheelchair design enhanced mobility and quality of life by improving the user’s functional capabilities. Simulation results verify the non-accidental behavior of the electric wheelchair.

Keywords: fuzzy logic control, joystick, multi body dynamics, obstacle avoidance, scissor mechanism, sensor

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Authors: Mohammadreza Akbari, Leila Abdollahpour, Sara Akbari, Pooya Soleimani

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Transferring thermo at the field of solid materials for instance tube-shaped structures, causing dynamical vibration at them. Majority of thermal and fluid processes are done engineering science at solid materials, for example, thermo-transferred pipes, fluids, chemical and nuclear reactors, include thermal processes, so, they need to consider the moment solid-fundamental structural strength unto these thermal interactions. Fluid and thermo retentive materials in front of external force to it like thermodynamical force, hydrodynamical force and static force continuously according to a function of time vibrated, and this action causes relative displacement of the structural materials elements, as a result, the moment resistance analysis preservation materials in thermal processes, the most important parameters for design are discussed. Including structural substrate holder temperature and fluid of the administrative and industrial center, is a cylindrical tube that for vibration analysis of cylindrical cells with heat and fluid transfer requires the use of vibration differential equations governing the structure of a tubular and thermal differential equations as the vibrating motive force at double-glazed cylinders.

Keywords: heat transfer, elements in cylindrical coordinates, analytical solving the governing equations, structural vibration

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Authors: A. Lakrim, D. Tahri

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This paper sets out a behavioral macro-model of a Merged PiN and Schottky (MPS) diode based on silicon carbide (SiC). This model holds good for both static and dynamic electrothermal simulations for industrial applications. Its parameters have been worked out from datasheets curves by drawing on the optimization method: Simulated Annealing (SA) for the SiC MPS diodes made available in the industry. The model also adopts the Analog Behavioral Model (ABM) of PSPICE in which it has been implemented. The thermal behavior of the devices was also taken into consideration by making use of Foster’ canonical network as figured out from electro-thermal measurement provided by the manufacturer of the device.

Keywords: SiC MPS diode, electro-thermal, SPICE model, behavioral macro-model

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Authors: Naveed Ejaz, Liaqat Ali, Amer Nusair

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Thermal barrier coatings (TBCs) serve as thermal barriers against the high temperature of the hot regions of the aircraft turbine engines keeping the surface of the turbine blades, vanes and combustion chamber at comparatively lower temperature. The life of these coatings depends on many in-service environmental factors. Among these factors, the behavior of the bond coat as well as the top coat at high temperature aggravated by the corrosive environments having S, V, Na and Cl plays a key role. The incorporation of the 5-15% CaZrO3 in YSZ coatings was studied after hot corrosion in vanadium oxide environment. It was observed that the reactivity of the V gradually switched from Y to Ca making CaV2O4 instead of YVO4; the percentage of CaV2O4 increased with the increase of CaZrO3 in YSZ. It eventually prevented leaching out of the Y from YSZ leaving the YSZ without any harmful phase change. The thermal insulation was found to be improved in case of CaZrO3 incorporated YSZ coatings as compared to only YSZ coating.

Keywords: hot corrosion, thermal barrier coatings, yttria stabilized zirconia, calcium zirconate

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Authors: Athena Nguyen, Rojin Belganeh

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Detecting and identifying differences in like polymer materials are key factors in deformulation, comparative analysis as well as reverse engineering. Pyrolysis-GC/MS is an easy solid sample introduction technique which expands the application areas of gas chromatography and mass spectrometry. The Micro-furnace pyrolyzer is directly interfaced with the GC injector preventing any potential of cold spot, carryover, and cross contamination. This presentation demonstrates the study of two similar polymers by performing different mode of operations in the same system: Evolve gas analysis (EGA), Flash pyrolysis, Thermal desorption analysis, and Heart-cutting analysis. Unknown polymer materials and their chemical compositions are identified.

Keywords: gas chromatography/mass spectrometry, pyrolysis, pyrolyzer, thermal desorption-GC/MS

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Authors: Sakti Mandal

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Varying distribution of land surface temperature in an urbanized environment is a globally addressed phenomenon. Usually has been noticed that criticality of surface temperature increases from the periphery to the urban centre. As the centre experiences maximum severity of heat throughout the year, it also represents most critical zone in terms of thermal condition. In this present study, an attempt has been taken to propose a quantitative approach of thermal critical zonation (TCZ) on the basis of seasonal temperature variation. Here the zonation is done by calculating thermal critical value (TCV). From the Landsat 8 thermal digital data of summer and winter seasons for the year 2014, the land surface temperature maps and thermally critical zonation has been prepared, and corresponding dataset has been computed to conduct the overall study of that particular study area. It is shown that TCZ can be clearly identified and analyzed by the help of inter-seasonal temperature range. The results of this study can be utilized effectively in future urban development and planning projects as well as a framework for implementing rules and regulations by the authorities for a sustainable urban development through an environmentally affable approach.

Keywords: thermal critical values (TCV), thermally critical zonation (TCZ), land surface temperature (LST), Landsat 8, Kolkata Municipal Corporation (KMC)

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Authors: Marcin Zieliński, Marcin Dębowski, Mirosław Krzemieniewski

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The purpose of the present work was to assess the impact of using electromagnetic microwave radiation as a means of stimulating the thermal conditions in anaerobic reactors on biomethanation efficiency of different plant substrates, as measured by the quantity and quality of the resultant biogas. Using electromagnetic microwave radiation to maintain optimal thermal conditions during biomethanation allows for achievement of much higher technological effects in comparison with a conventional heating system. After subjecting different plant substrates to fermentation in the model fermentation chambers, the largest improvements in regard to biogas production efficiency and biogas quality were recorded in the series with corn silage and grass silage. In the first case, the quantity of methane produced in the microwave-stimulated technological system exceeded by 15.26% the quantities produced in reactors heated conventionally. When grass silage was utilized as the organic substrate in the process of biomethanation, anaerobic reactors treated with microwave radiation produced 12.62% more methane.

Keywords: microwave radiation, biogas, methane fermentation, biomass

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Authors: Małgorzata Golonka, Jadwiga Laska

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Self-healing polymers are one of the most investigated groups of smart materials. As materials engineering has recently focused on the design, production and research of modern materials and future technologies, researchers are looking for innovations in structural, construction and coating materials. Based on available scientific articles, it can be concluded that most of the research focuses on the self-healing of cement, concrete, asphalt and anticorrosion resin coatings. In our study, a method of obtaining and testing the properties of several types of microcapsules for use in self-healing polymer materials was developed. A method to obtain microcapsules exhibiting various mechanical properties, especially compressive strength was developed. The effect was achieved by using various polymer materials to build the shell: urea-formaldehyde resin (UFR), melamine-formaldehyde resin (MFR), melamine-urea-formaldehyde resin (MUFR). Dicyclopentadiene (DCPD) was used as the core material due to the possibility of its polymerization according to the ring-opening olefin metathesis (ROMP) mechanism in the presence of a solid Grubbs catalyst showing relatively high chemical and thermal stability. The ROMP of dicyclopentadiene leads to a polymer with high impact strength, high thermal resistance, good adhesion to other materials and good chemical and environmental resistance, so it is potentially a very promising candidate for the self-healing of materials. The capsules were obtained by condensation polymerization of formaldehyde with urea, melamine or copolymerization with urea and melamine in situ in water dispersion, with different molar ratios of formaldehyde, urea and melamine. The fineness of the organic phase dispersed in water, and consequently the size of the microcapsules, was regulated by the stirring speed. In all cases, to establish such synthesis conditions as to obtain capsules with appropriate mechanical strength. The microcapsules were characterized by determining the diameters and their distribution and measuring the shell thickness using digital optical microscopy and scanning electron microscopy, as well as confirming the presence of the active substance in the core by FTIR and SEM. Compression tests were performed to determine mechanical strength of the microcapsules. The highest repeatability of microcapsule properties was obtained for UFR resin, while the MFR resin had the best mechanical properties. The encapsulation efficiency of MFR was much lower compared to UFR, though. Therefore, capsules with a MUFR shell may be the optimal solution. The chemical reaction between the active substance present in the capsule core and the catalyst placed outside the capsules was confirmed by FTIR spectroscopy. The obtained autonomous repair systems (microcapsules + catalyst) were introduced into polyethylene in the extrusion process and tested for the self-repair of the material.

Keywords: autonomic self-healing system, dicyclopentadiene, melamine-urea-formaldehyde resin, microcapsules, thermoplastic materials

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Authors: Mariyappan Shanmugam, Bin Yu

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Schottky-barrier solar cells are demonstrated employing 2D-layered MoS2 and WS2 semiconductor nanofilms as photo-active material candidates synthesized by chemical vapor deposition method. Large area MoS2 and WS2 nanofilms are stacked by layer transfer process to achieve thicker photo-active material studied by atomic force microscopy showing a thickness in the range of ~200 nm. Two major vibrational active modes associated with 2D-layered MoS2 and WS2 are studied by Raman spectroscopic technique to estimate the quality of the nanofilms. Schottky-barrier solar cells employed MoS2 and WS2 active materials exhibited photoconversion efficiency of 1.8 % and 1.7 % respectively. Fermi-level pinning at metal/semiconductor interface, electronic transport and possible recombination mechanisms are studied in the Schottky-barrier solar cells.

Keywords: two-dimensional nanosheet, graphene, hexagonal boron nitride, solar cell, Schottky barrier

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Authors: I. Kadek Candra Parmana Wiguna, Wiwik Budiawan, Heru Prastawa

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Semarang has become not only a metropolitan city but also a centre of government that has experienced significant changes in urban land use. Temperature increases in urban areas result from the expansion of development. The average temperature in Semarang reached 27.10°C to 29.60°C in 2022. The state of thermal sensation is very dependent on the mode of operation; Industrial Engineering building is mostly equipped with an air conditioner (AC). This study aims to analyze the thermal comfort level and energy consumption of air conditioners in classroom of industrial engineering. Participants in this study amounted to 31 students with data collection for 4 weeks. Results of the physical environment are Ta in: 25.52°C, Ta out: 32.71 °C, Rh in: 61.14%, Rh out: 59.43%, and Av in: 0.037 m/s. The results of clothing insulation are 41% of the respondents belonged to the categories 0.31 - 0.5 clo (summer domming) and 0.51 - 0.70 clo (spring clothing). Regarding the predicted mean vote (PMV), the average value is 0.63, and only 14.85% result of the predicted percentage dissatisfied (PPD). The neutral temperature with measurement Griffith’s constant 0.5/°C was 27.16°C, but the statistical test results show that the comfort temperature to use TSV ≤ 0 which is 28.55°C. The highest average power (watt) measurement results during week 3, which is 1613.65 watts. It is concluded in this study that the thermal comfort conditions in the classroom are adequate and acceptable to more than 90% of respondents.

Keywords: thermal comfort, PMV/PPD, air conditioner, TSV

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Authors: Amil Daraz, Suheel Abdullah Malik, Tahir Saleem, Sajid Ali Bhati

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In this paper, Integral Proportional (I-P) controller is employed for superheated steam temperature control system. The Ziegler-Nichols (Z-N) method is used for the tuning of I-P controller. The performance analysis of Z-N based I-P controller is assessed on superheated steam system of 500-MW boiler. The comparison of transient response parameters such as rise time, settling time, and overshoot is made with Z-N based Proportional Integral (PI) controller. It is observed from the results that Z-N based I-P controller completely eliminates the overshoot in the output response.

Keywords: superheated steam, process reaction curve, PI and I-P controller, Ziegler-Nichols Tuning

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Authors: M. Zasada, A. Markiewicz, A. Erkiert-Polguj, E. Budzisz

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The epidermis is a keratinized stratified squamous epithelium covered by the hydro-lipid barrier. Therefore, active substances should be able to penetrate through this hydro-lipid coating. L-ascorbic acid is one of the vitamins which plays an important role in stimulation fibroblast to produce collagen type I and in hyperpigmentation lightening. Vitamin C is a water-soluble antioxidant, which protects skin from oxidation damage and rejuvenates photoaged skin. No-needle mesotherapy is a non-invasive rejuvenation technique depending on electric pulses, electroporation, and ultrasounds. These physicals factors result in deeper penetration of cosmetics. It is important to increase the penetration of L-ascorbic acid, thereby increasing the spectrum of its activity. The aim of the work was to assess the effectiveness of pure L-ascorbic acid activity in anti-aging therapy using a needle-free and micro-needling mesotherapy. The study was performed on a group of 35 healthy volunteers in accordance with the Declaration of Helsinki of 1964 and agreement of the Ethics Commissions no RNN/281/16/KE 2017. Women were randomized to mesotherapy or control group. Control group applied topically 2,5 ml serum containing 20% L-ascorbic acid with hydrate from strawberries, every 10 days for a period of 9 weeks. No-needle mesotherapy, on the left half of the face and micro-needling on the right with the same serum, was done in mesotherapy group. The pH of serum was 3.5-4, and the serum was prepared directly prior to the facial treatment. The skin parameters were measured at the beginning and before each treatment. The measurement of the forehead skin was done using Cutometer® (measurement of skin elasticity and firmness), Corneometer® (skin hydration measurement), Mexameter® (skin tone measurement). Also, the photographs were taken by Fotomedicus system. Additionally, the volunteers fulfilled the questionnaire. Serum was tested for microbiological purity and stability after the opening of the cosmetic. During the study, all of the volunteers were taken care of a dermatologist. The regular application of the serum has caused improvement of the skin parameters. Respectively, after 4 and 8 weeks improvement in hydration and elasticity has been seen (Corneometer®, Cutometer® results). Moreover, the number of hyper-pigmentated spots has decreased (Mexameter®). After 8 weeks the volunteers has claimed that the tested product has smoothing and moisturizing features. Subjective opinions indicted significant improvement of skin color and elasticity. The product containing the L-ascorbic acid used with intercellular penetration promoters demonstrates higher anti-aging efficiency than control. In vivo studies confirmed the effectiveness of serum and the impact of the active substance on skin firmness and elasticity, the degree of hydration and skin tone. Mesotherapy with pure L-ascorbic acid provides better diffusion of active substances through the skin.

Keywords: anti-aging, l-ascorbic acid, mesotherapy, promoters

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Authors: Adriano Pinargote, Josue Mosquera, Eduardo Montero, Dalton Noboa, Jenny Venegas, Genesis Vasquez Escuela

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In the framework of Pre University learning of the Polytechnic School of the Litoral, Guayaquil, Ecuador, the methodology of Active Learning (Flipped Classroom) has been implemented for applicants who wish to obtain a quota within the university. To complement the Active Learning cycle, it has been proposed that the respective students influence the qualification of their work groups, for which a web platform has been created that allows them to evaluate the performance of their peers through a digital coevaluation that measures through statistical methods, the group and individual performance score that can reflect in numbers a weighting score corresponding to the grade of each student. Their feedback provided by the group help to improve the performance of the activities carried out in classes because the note reflects the commitment with their classmates shown in the class, within this analysis we will determine if this implementation directly influences the performance of the grades obtained by the student.

Keywords: active learning, coevaluation, flipped classroom, pre university

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Authors: Folorunso Omoniyi, Peter Olubambi, Rotimi Sadiku

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Thermal barrier coating (TBC) system is used in both aero engines and other gas turbines to offer oxidation protection to superalloy substrate component. In the present work, it shows the ability of a new fabrication technique to develop rapidly new coating composition and microstructure. The compact powders were prepared by Powder Metallurgy method involving powder mixing and the bond coat was synthesized through the application of Spark Plasma Sintering (SPS) at 10500C to produce a fully dense (97%) NiCrAl bulk samples. The influence of sintering temperature on the hardness of NiCrAl, done by Micro Vickers hardness tester, was investigated. And Oxidation test was carried out at 1100oC for 20h, 40h, and 100h. The resulting coat was characterized with optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX) and x-ray diffraction (XRD). Micro XRD analysis after the oxidation test revealed the formation of protective oxides and non-protective oxides.

Keywords: high-temperature oxidation, powder metallurgy, spark plasma sintering, thermal barrier coating

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Authors: Fatemeh Keshavarz

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Background: Schizophrenia is a disease of the nervous system, and immune system disorders can affect its pathogenesis. Activation of microglia, proinflammatory cytokines, disruption of the blood-brain barrier (BBB) due to inflammation, activation of autoreactive B cells, and consequently the production of autoantibodies against system antigens are among the immune processes involved in neurological diseases. interleukin 32 (IL-32) a proinflammatory cytokine that important player in the activation of the innate and adaptive immune responses. This study aimed to measure the serum level of IL-32 as well as the frequency of autoantibody positivity against several nervous system antigens in patients with schizophrenia. Material and Methods: This study was conducted on 40 patients with schizophrenia and 40 healthy individuals in the control group. Serum IL-32 levels were measured by ELISA. The frequency of autoantibodies against Hu, Ri, Yo, Tr, CV2, Amphiphysin, SOX1, Zic4, ITPR1, CARP, GAD, Recoverin, Titin, and Ganglioside antigens were measured by indirect immunofluorescence method. Results: Serum IL-32 levels in patients with schizophrenia were significantly higher compared to the control group. Autoantibodies were positive in 8 patients for GAD antigen and 5 patients for Ri antigen, which showed a significant relationship compared to the control group. Autoantibodies were also positive in 2 patients for CV2, in 1 patient for Hu, and in 1 patient for CARP. Negative results were reported for other antigens. Conclusion: Our findings suggest that elevated the serum IL-32 level and autoantibody positivity against several nervous system antigens may be involved in the pathogenesis of schizophrenia.

Keywords: schizophrenia, microglia, autoantibodies, IL-32

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Authors: Ikbal Eski, Turan Gürgenç

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After nearly more than a century of research and development, internal combustion engines have become almost perfect. Along with such improvement in internal combustion engines, automotive manufacturers are conducting research on design of alternative fuel vehicles. Nevertheless an ideal interim solution is to increase overall efficiency of internal combustion vehicles. A potential solution to achieve that is using continuously variable transmission system which, despite being an old idea, has recently become a hope for automotive manufacturers. CVT system, by continuously varying speed ratio, raises vehicle efficiency. In this study, fuzzy logic controller is used in speed ratio control of pulley based CVT system.

Keywords: continuously variable transmission system, variator, speed ratio, fuzzy logic

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Authors: Anastasia Stamatiou, Markus Odermatt, Dominic Leemann, Ludger J. Fischer, Joerg Worlitschek

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The successful integration of thermal energy storage in industrial processes is expected to play an important role in the energy turnaround. Latent heat storage technologies can offer more compact thermal storage at a constant temperature level, in comparison to conventional, sensible thermal storage technologies. The focus of this study is the development of latent heat storage solutions based on the Phase Change Slurry (PCS) concept. Such systems promise higher energy densities both as refrigerants and as storage media while presenting better heat transfer characteristics than conventional latent heat storage technologies. This technology is expected to deliver high thermal power and high-temperature stability which makes it ideal for storage of process heat. An evaluation of important batch processes in industrial applications set the focus on materials with a melting point in the range of 55 - 90 °C. Aluminium ammonium sulfate dodecahydrate (NH₄Al(SO₄)₂·12H₂O) was chosen as the first interesting PCM for the next steps of this study. The ability of this material to produce slurries at the relevant temperatures was demonstrated in a continuous mode in a laboratory test-rig. Critical operational and design parameters were identified.

Keywords: esters, latent heat storage, phase change materials, thermal properties

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Authors: Snehal R. Pathak, Sachin S. Munnoli

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Evaluation of dynamic earth pressure on retaining wall is a topic of primary importance. In present paper, dynamic active earth pressure and displacement of flexible cantilever retaining wall has been evaluated analytically using 2-DOF mass-spring-dashpot model by incorporating both wall and backfill properties. The effect of wall flexibility on dynamic active earth pressure and wall displacement are studied and presented in graphical form. The obtained results are then compared with the various conventional methods, experimental analysis and also with PLAXIS analysis. It is observed that the dynamic active earth pressure decreases with increase in the wall flexibility while wall displacement increases linearly with flexibility of the wall. The results obtained by proposed 2-DOF analytical model are found to be more realistic and economical.

Keywords: earth pressure, earthquake, 2-DOF model, Plaxis, retaining walls, wall movement

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Authors: Rafik Balti, Mohamed Ben Mansour, Abdellah Arhaliass, Anthony Masse

Abstract:

Unfortunately, shrimps are highly perishable and they start deteriorating immediately after death owing to their high water content and nutritional components. Currently, there has been an increasing interest in bioactive edible films and coatings to preserve the freshness and quality of foods. In this study, active edible coatings from microalgal exopolysaccharides (EPS) enriched with different concentrations of Red Seaweed Extract (RSE) (0.5, 1 and 1.5 % (w/v)) were developed and their effects on the quality changes of white shrimp during refrigerated storage (4 ± 1 °C) were examined over a period of 8 days. The control and the coated shrimp samples were analyzed periodically for microbiological (total viable bacteria, psychrotrophic bacteria, and enterobacteriaceae counts), chemical (pH, TVB-N, TMA-N, PV, TBARS), textural and sensory characteristics. The results indicated that the coating with a mixture of EPS and RSE could significantly decrease the total volatile basic nitrogen (TVB-N), trimethylamine (TMA) and thiobarbituric acid reactive substances (TBARS) (p < 0.05). With storage, EPS coatings containing RSE at both levels (1 and 1.5 %) were more effective in inhibiting the microbial species studied, specially psychrotrophic bacteria. Also, EPS + RSE coated samples had lower polyphenol oxidase (PPO) activity and lipid oxidation (p < 0.05) toward the end of storage. Textural and color properties of coated shrimp were generally more acceptable. Sensory scores indicated no significant changes in all samples during storage. The obtained results indicate that the edible EPS coating solutions enriched with RSE have noticeable effects on the quality and shelf life of shrimps when compared to control group. Finally, the present work demonstrates the effectiveness of EPS enriched coatings, offering a promising alternative to preserve more better the quality characteristics and to extend the shelf life of shrimp during the refrigerated storage

Keywords: active coating, exopolysaccharides, red seaweed, refrigerated storage, white shrimp

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Authors: Shing-Cheng Chang, Cheng-Hao Yang, Wen-Sheng Chang, Chih-Chia Lin, Chun-Han Li

Abstract:

The solid oxide fuel cell (SOFC) is a promising green technology which can achieve a high electrical efficiency. Due to the high operating temperature of SOFC stack, the off-gases at high temperature from anode and cathode outlets are introduced into an afterburner to convert the chemical energy into thermal energy by combustion. The heat is recovered to preheat the fresh air and fuel gases before they pass through the stack during the SOFC power generation system operation. For an afterburner of the SOFC system, the temperature control with a good thermal uniformity is important. A burner with a well-designed geometry usually can achieve a satisfactory performance. To design an afterburner for an SOFC system, the computational fluid dynamics (CFD) simulation is adoptable. In this paper, the hydrogen combustion characteristics in an afterburner with simple geometry are studied by using CFD. The burner is constructed by a cylinder chamber with the configuration of a fuel gas inlet, an air inlet, and an exhaust outlet. The flow field and temperature distributions inside the afterburner under different fuel and air flow rates are analyzed. To improve the temperature uniformity of the afterburner during the SOFC system operation, the flow paths of anode/cathode off-gases are varied by changing the positions of fuels and air inlet channel to improve the heat and flow field synergy in the burner furnace. Because the air flow rate is much larger than the fuel gas, the flow structure and heat transfer in the afterburner is dominated by the air flow path. The present work studied the effects of fluid flow structures on the combustion characteristics of an SOFC afterburner by three simulation models with a cylindrical combustion chamber and a tapered outlet. All walls in the afterburner are assumed to be no-slip and adiabatic. In each case, two set of parameters are simulated to study the transport phenomena of hydrogen combustion. The equivalence ratios are in the range of 0.08 to 0.1. Finally, the pattern factor for the simulation cases is calculated to investigate the effect of gas inlet locations on the temperature uniformity of the SOFC afterburner. The results show that the temperature uniformity of the exhaust gas can be improved by simply adjusting the position of the gas inlet. The field synergy analysis indicates the design of the fluid flow paths should be in the way that can significantly contribute to the heat transfer, i.e. the field synergy angle should be as small as possible. In the study cases, the averaged synergy angle of the burner is about 85̊, 84̊, and 81̊ respectively.

Keywords: afterburner, combustion, field synergy, solid oxide fuel cell

Procedia PDF Downloads 132

Authors: J. P. Reges, L. C. S. Mazza, E. J. Braga, J. A. Bessa, A. R. Alexandria

Abstract:

This paper proposes the development of control and automation of irrigation system located sunflower harvest in the Teaching Unit, Research and Extension (UEPE), the Apodi Plateau in Limoeiro do Norte. The sunflower extraction, which in turn serves to get the produced oil from its seeds, animal feed, and is widely used in human food. Its nutritional potential is quite high what makes of foods produced from vegetal, very rich and healthy. The focus of research is to make the autonomous irrigation system sunflower crop from programmable logic control energized with alternative energy sources, solar photovoltaics. The application of automated irrigation system becomes interesting when it provides convenience and implements new forms of managements of the implementation of irrigated cropping systems. The intended use of automated addition to irrigation quality and consequently brings enormous improvement for production of small samples. Addition to applying the necessary and sufficient features of water management in irrigation systems, the system (PLC + actuators + Renewable Energy) will enable to manage the quantitative water required for each crop, and at the same time, insert the use of sources alternative energy. The entry of the automated collection will bring a new format, and in previous years, used the process of irrigation water wastage base and being the whole manual irrigation process.

Keywords: automation, control, sunflower, irrigation, programming, renewable energy

Procedia PDF Downloads 397

Authors: Xinke Huang, Huan Wang, Lidong Guo, Changbin Ju, Runbiao Liu, Guoen Cao, Yibo Wang, Honghua Xu

Abstract:

Grid connected photovoltaic (PV) power system is to be developed in the direction of large-scale, clustering. Large-scale PV generation systems connected to HVDC grid have many advantages compared to its counterpart of AC grid, and DC connection is the tendency. DC/DC converter as the most important device in the system, has become one of the hot spots recently. The paper proposes a Quasi Z-Source(QZS) based Boost Full Bridge Isolated DC/DC Converter(BFBIC) topology as a basis power module and combination through input parallel output series(IPOS) method to improve power capacity and output voltage to match with the HVDC grid. The topology has both traditional voltage source and current source advantages, it permit the H-bridge short through and open circuit, which adopt utility duty cycle control and achieved input current and output voltage balancing through input current sharing control strategy. A ±10kV/200kW system model is built in MATLAB/SIMULINK to verify the proposed topology and control strategy.

Keywords: PV Generation System, Cascaded DC/DC converter, HVDC, Quasi Z Source Converter

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Authors: Henni Mansour Abdelwaheb

Abstract:

This study discusses the design of a bounded position/force feedback controller developed to ensure position and force tracking for bilateral teleoperation arms operating with variable delay, and actuator saturation. Also, an adaptive robust Radial Basis Function (RBF) neural network is used to estimate the environment torque. The parameters of the environment torque are then sent from the slave site to the master site as a non-power signal to avoid passivity problems. Moreover, a nonlinear function is applied to each controller term as a smooth saturation function, providing a bounded control signal and preserving the system’s actuators. Lastly, the Lyapunov approach demonstrates the global stability of the controlled system, and numerical experiment results further confirm the validity of the presented strategy.

Keywords: teleoperation manipulators system, time-varying delay, actuator saturation, adaptive robust rbf neural network approximation, uncertainties

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Authors: Arber Sejdiji, Jan Schmitz-Huebsch, Christian Mittelstedt

Abstract:

Due to its use in a broad range of temperatures, the prediction of elastic properties of fiber composite materials under thermal load is significant. Especially the transversal stiffness dominates the potential of use for fiber-reinforced composites (FRC). A numerical study on the influence of thermal stress on transversal stiffness of fiber-reinforced composites is presented. In the numerical study, a representative volume element (RVE) is used to estimate the elastic properties of a unidirectional ply with finite element method (FEM). For the investigation, periodic boundary conditions are applied to the RVE. Firstly, the elastic properties under pure mechanical load are derived numerically and compared to results, which are obtained by analytical methods. Thereupon thermo-mechanical load is implemented into the model to investigate the influence of temperature change with low temperature as a key aspect. Regarding low temperatures, the transversal stiffness increases intensely, especially when thermal stress is dominant over mechanical stress. This paper outlines the employed numerical methods as well as the derived results.

Keywords: elastic properties, micromechanics, thermal stress, representative volume element

Procedia PDF Downloads 101