Search results for: vertical hall device

Authors: Intan Izafina Idrus, Mardina Abdullah, Alina Marie Hasbi, Asnawi Husin

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This paper presents the result of large-scale traveling ionospheric disturbance (LSTID) observation during moderate magnetic storm event on 25 October 2011 with SYM-H ~ -160 nT and Kp ~ 7 over Peninsular Malaysia at equatorial region using vertical total electron content (VTEC) from the Global Positioning System (GPS) observation measurement. The propagation of the LSTID signatures in the TEC measurements over Peninsular Malaysia was also investigated using VTEC map. The LSTID was found to propagate equator-ward during this event. The results showed that the LSTID propagated with an average phase velocity of 526.41 m/s and average periods of 140 min. The occurrence of this LSTID was also found to be the subsequent effects of substorm activities in the auroral region.

Keywords: Global Positioning System (GPS), large-scale traveling ionospheric disturbance (LSTID), moderate geomagnetic storm, vertical total electron content (VTEC)

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Authors: Gizachew Belay Adugna, Yu-Tai Tao

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Perovskite solar cells (PSCs) have been gaining impressive progress with excellent power conversion efficiency (PCE) of 25.5% in small-area devices. However, the conventional film coating approach is not applicable to large-area module fabrication. Meniscus-guided coating, including blade coating, slot-die coating, and bar coating, is solution processing and promising for large-area and cost-effective film coating to industrial-scale PSCs. Here, we develop simple and scalable solution shearing (SS) and bar coating (BC) methods to coat all layers on large-area (10x10 cm²) substrate in FTO/c-TiO₂/mp-TiO₂/ CH₃NH₃PbI₃/Spiro-OMeTAD/Ag device structure, except the Ag electrode. All solution-sheared PSC exhibited a champion power conversion efficiency of 15.89% in the conational DMF/DMSO solvent. Whereas a very high PCE of 20.30% compared to the controlled spin-coated device (SC, 17.60%) was achieved from the large area sheared perovskite film in a green ACN/MA solvent. Similarly, a remarkable PCE of 18.50% was achieved for a device fabricated from a large-area perovskite film in a simpler and more compatible Bar-coating system. This strategy demonstrates the huge potential for module fabrication and future PSC commercialization.

Keywords: Perovskite solar cells, larger area film coating, meniscus-guided film coating, solution-shearing, bar-coating, power conversion efficiency

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Authors: Saeid Seddegh, Xiaolin Wang, Alan D. Henderson, Dong Chen, Oliver Oims

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The main objective of this research is to study the heat transfer processes and phase change behaviour of a phase change material (PCM) in shell and tube latent heat thermal energy storage (LHTES) systems. The thermal behaviour in a vertical and horizontal shell-and-tube heat energy storage system using a pure thermal conduction model and a combined conduction-convection heat transfer model is compared in this paper. The model is first validated using published experimental data available in literature and then used to study the temperature variation, solid-liquid interface, phase distribution, total melting and solidification time during melting and solidification processes of PCMs. The simulated results show that the combined convection and conduction model can better describe the energy transfer in PCMs during melting process. In contrast, heat transfer by conduction is more significant during the solidification process since the two models show little difference. Also, it was concluded that during the charging process for the horizontal orientation, convective heat transfer has a strong effect on melting of the upper part of the solid PCM and is less significant during melting of the lower half of the solid PCM. However, in the vertical orientation, convective heat transfer is the same active during the entire charging process. In the solidification process, the thermal behavior does not show any difference between horizontal and vertical systems.

Keywords: latent heat thermal energy storage, phase change material, natural convection, melting, shell and tube heat exchanger, melting, solidification

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Authors: Amina Sultan, Mohamed Ghonim, Eman Oweida, Aya Abdelaziz

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Objective: To assess the diagnostic reliability of multi-detector CT in pre and post-operative evaluation of cochlear implant candidates. Material and Methods: The study includes 40 patients (18 males and 22 females); mean age 5.6 years. They were classified into two groups: Group A (20 patients): cochlear implant device was Nucleus-22 and Group B (20 patients): the device was MED-EL. Cochlear length (CL) and cochlear height (CH) were measured pre-operatively by 128-multidetector CT. Electrode length (EL) and insertion depth angle (α) were measured post-operatively by MDCT. Results: For Group A mean CL was 9.1 mm ± 0.4 SD; mean CH was 4.1 ± 0.3 SD; mean EL was 18 ± 2.7 SD; mean α angle was 299.05 ± 37 SD. Significant statistical correlation (P < 0.05) was found between preoperative CL and post-operative EL (r²=0.6); as well as EL and α angle (r²=0.7). Group B's mean CL was 9.1 mm ± 0.3 SD; mean CH was 4.1 ± 0.4 SD; mean EL was 27 ± 2.1 SD; mean α angle was 287.6 ± 41.7 SD. Significant statistical correlation was found between CL and EL (r²= 0.6) and α angle (r²=0.5). Also, a strong correlation was found between EL and α angle (r²=0.8). Significant statistical difference was detected between the two devices as regards to the electrode length. Conclusion: Multidetector CT is a reliable tool for preoperative planning and post-operative evaluation of the outcomes of cochlear implant operations. Cochlear length is a valuable prognostic parameter for prediction of the depth of electrode array insertion which can influence criteria of device selection.

Keywords: angle of insertion (α angle), cochlear implant (CI), cochlear length (CL), Multidetector Computed Tomography (MDCT)

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Authors: Seyed Abbas Tabatabaei, Afshin Ghanbarzadeh, Mehdi Abidizadeh

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Nowadays the subject of road traffic accidents and the high social and economic costs due to them is the most fundamental problem that experts and providers of transport and traffic brought to a challenge. One of the most effective measures is to enhance the skid resistance of road surface. This research aims to study the intersection of one case in Ahwaz and the effect of increasing the skid resistance in reducing pedestrian injuries in accidents at intersections. In this research the device was developed to measure the coefficient of friction and tried the rules and practices of it have a high similarity with the Locked Wheel Trailer. This device includes a steel frame, wheels, hydration systems, and force gauge. The output of the device is that the force gauge registers. By investigate this data and applying the relationships relative surface coefficient of friction is obtained. Friction coefficient data for the current state and the state of the new pavement are obtained and plotted on the graphs based on the graphs we can compare the two situations and speed at the moment of collision between the two modes are compared. The results show that increasing the coefficient of friction to what extent can be effective on the severity and number of accidents.

Keywords: intersection, coefficient of friction, skid resistance, locked wheels, accident, pedestrian

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Authors: Jae-Chang Kwak, Yong-Seo Koo

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The high efficiency power management IC (PMIC) with switching device is presented in this paper. PMIC is controlled with PFM control method in order to have high power efficiency at high current level. Dynamic Threshold voltage CMOS (DT-CMOS) with low on-resistance is designed to decrease conduction loss. The threshold voltage of DT-CMOS drops as the gate voltage increase, resulting in a much higher current handling capability than standard MOSFET. PFM control circuits consist of a generator, AND gate and comparator. The generator is made to have 1.2MHz oscillation voltage. The DC-DC converter based on PFM control circuit and low on-resistance switching device is presented in this paper.

Keywords: DT-CMOS, PMIC, PFM, DC-DC converter

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Authors: Nima Farshidfar, Navid Daryasafar

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In this paper, the seismic stability of reinforced soil slopes is studied using pseudo-dynamic analysis. Equilibrium equations that are applicable to the every kind of failure surface are written using Horizontal Slices Method. In written equations, the balance of the vertical and horizontal forces and moment equilibrium is fully satisfied. Failure surface is assumed to be log-spiral, and non-linear equilibrium equations obtained for the system are solved using Newton-Raphson Method. Earthquake effects are applied as horizontal and vertical pseudo-static coefficients to the problem. To solve this problem, a code was developed in MATLAB, and the critical failure surface is calculated using genetic algorithm. At the end, comparing the results obtained in this paper, effects of various parameters and the effect of using pseudo - dynamic analysis in seismic forces modeling is presented.

Keywords: soil slopes, pseudo-dynamic, genetic algorithm, optimization, limit equilibrium method, log-spiral failure surface

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Authors: Saleh Alzahrani

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The studies in the field of International Comparative Education in the Arabic world and the middle east are scarcity. However, some International Comparative Education Researchers and post graduates face a challenge concerning of a selection of a distinguished study to improve their national education system. It requires a considerable effort. According to that, the matrix of scientific research in comparative and international education is designed to help specialists, researchers and graduate students in generating a variety of research ideas in a short time in this field. The matrix is built by using content analysis method of comparative education research published in the Arab journals from 1980 to 2017. Then, qualitative input with the in-depth focus analysis tool is utilized according to the root theory. The matrix consists of two axes; vertical (X) and horizontal (Y). The number of fields in the vertical axis are 6 domains, including 105 variables. The horizontal axis is two fields which are pre-university education that incorporate educational stages and contemporary formulations including (23) variables. The second field is the university education in its public universities and contemporary formulas including (15) variables. The researcher can access topics, ideas and research points through the matrix of scientific research in comparative and international education by selecting of any subject on the vertical axis (X) from (1) to (105) and selecting of any subject on the horizontal axis (Y) from (B) to (U). The cell where the axes intersect with the chosen fields can generate an idea or a research point conveniently and easily through the words that have been monitored by the user. These steps can be repeated to generate new ideas and research points. Many graduate researchers have been trained on using of this matrix which gave them more potential to generate an appropriate study serving the national education.

Keywords: content analysis method, comparative education, international education, matrix, root theory

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Authors: Samson Mil'shtein, Dhawal Asthana, Benjamin Sullivan

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The wide energy gap of GaN is the major parameter justifying the design and fabrication of high-power electronic components made of this material. However, the existence of a piezo-electrics in nature sheet charge at the AlGaN/GaN interface complicates the control of carrier injection into the intrinsic channel of GaN HEMTs (High Electron Mobility Transistors). As a result, most of the transistors created as R&D prototypes and all of the designs used for mass production are D-mode devices which introduce challenges in the design of integrated circuits. This research presents the design and modeling of an E-mode GaN HEMT with a very low turn-on voltage. The proposed device includes two critical elements allowing the transistor to achieve zero conductance across the channel when Vg = 0V. This is accomplished through the inclusion of an extremely thin, 2.5nm intrinsic Ga₀.₇₄Al₀.₂₆N spacer layer. The added spacer layer does not create piezoelectric strain but rather elastically follows the variations of the crystal structure of the adjacent GaN channel. The second important factor is the design of a gate metal with a high work function. The use of a metal gate with a work function (Ni in this research) greater than 5.3eV positioned on top of n-type doped (Nd=10¹⁷cm⁻³) Ga₀.₇₄Al₀.₂₆N creates the necessary built-in potential, which controls the injection of electrons into the intrinsic channel as the gate voltage is increased. The 5µm long transistor with a 0.18µm long gate and a channel width of 30µm operate at Vd=10V. At Vg =1V, the device reaches the maximum drain current of 0.6mA, which indicates a high current density. The presented device is operational at frequencies greater than 10GHz and exhibits a stable transconductance over the full range of operational gate voltages.

Keywords: compound semiconductors, device modeling, enhancement mode HEMT, gallium nitride

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Authors: Foad Hassaninejadafarahani, Scott Ormiston

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Reflux condensation occurs in a vertical channels and tubes when there is an upward core flow of vapor (or gas-vapor mixture) and a downward flow of the liquid film. The understanding of this condensation configuration is crucial in the design of reflux condensers, distillation columns, and in loss-of-coolant safety analyses in nuclear power plant steam generators. The unique feature of this flow is the upward flow of the vapor-gas mixture (or pure vapor) that retards the liquid flow via shear at the liquid-mixture interface. The present model solves the full, elliptic governing equations in both the film and the gas-vapor core flow. The computational mesh is non-orthogonal and adapts dynamically the phase interface, thus produces sharp and accurate interface. Shear forces and heat and mass transfer at the interface are accounted for fundamentally. This modeling is a big step ahead of current capabilities by removing the limitations of previous reflux condensation models which inherently cannot account for the detailed local balances of shear, mass, and heat transfer at the interface. Discretisation has been done based on a finite volume method and a co-located variable storage scheme. An in-house computer code was developed to implement the numerical solution scheme. Detailed results are presented for laminar reflux condensation from steam-air mixtures flowing in vertical parallel plate channels. The results include velocity and pressure profiles, as well as axial variations of film thickness, Nusselt number and interface gas mass fraction.

Keywords: Reflux, Condensation, CFD-Two Phase, Nusselt number

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Authors: Alessandro Marano

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The author describes the use of deep plane face lifting and platysmaplasty to treat sagging neck with minimal scars. Series of case study. The author uses a selective deep plane face lift with a minimal access scar that not extend behind the ear lobe, neck liposuction and platysmaplasty to restore the sagging neck; the scars are minimal and no require drainage post-op. The deep plane face lifting can achieve a good result restoring vertical vectors in aging and sagging face, neck district can be treated without cutting the skin behind the ear lobe combining the SMAS vertical suspension and platysmaplasty; surgery can be performed in local anesthesia with sedation in day surgery and fast recovery. Restoring neck sagging without extend scars behind ear lobe is possible in selected patients, procedure is fast, safe, no drainage required, patients are satisfied and healing time is fast and comfortable.

Keywords: face lifting, aesthetic, face, neck, platysmaplasty, deep plane

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Authors: Mina Mortazavi, Hamid Ronagh, Pezhman Sharafi

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The new concept of a cold formed-hot rolled hybrid steel wall panel system is introduced to overcome the deficiency in lateral load resisting capacity of cold-formed steel structures. The hybrid system is composed of a cold-formed steel part laterally connected to hot rolled part. The hot rolled steel part is responsible for carrying the whole lateral load; while the cold formed steel part is only required to transfer the lateral load to the hot rolled part without any local failure. The vertical load is beared by both hot rolled, and cold formed steel part, proportionally. In order to investigate the lateral performance of the proposed system, it should be tested under simultaneous lateral and vertical load. The main concern is to deliver the loads to each part during the test to simulate the real load distribution in the structure. In this paper, a detailed description of the proposed wall panel system and the designed testing rig is provided.

Keywords: cold-formed steel, hybrid system, wall panel system, testing rig design

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Authors: Tuqa Abdulrazzaq, Hussein Togun, M. K. A. Ariffin, S. N. Kazi, A. Badarudin, N. M. Adam, S. Masuri

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Numerical study of heat transfer and fluid flow over vertical double forward facing step were presented. The k-w model with finite volume method was employed to solve continuity, momentum, and energy equations. Different step heights were adopted for range of Reynolds number varied from 10000 to 40000, and range of temperature varied from 310K to 340 K. The straight side of duct is insulated while the side of double forward facing step is heated. The result shows augmentation of heat transfer due to the recirculation region created after and before steps. Effect of step length and Reynolds number observed on increase of local Nusselt number particularly at recirculation regions. Contour of streamline velocity is plotted to show recirculation regions after and before steps. Numerical simulation in this paper done by used ANSYS Fluent 14.

Keywords: turbulent flow, double forward, heat transfer, separation flow

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Authors: Sirajdin Olagoke Adeshina, Haidi Ibrahim, Akeem Salawu

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large lecture theatres cannot be covered by a single camera but rather by a multicamera setup because of their size, shape, and seating arrangements. Although, classroom capture is achievable through a single camera. Therefore, a design and implementation of a multicamera setup for a large lecture hall were considered. Researchers have shown emphasis on the impact of class attendance taken on the academic performance of students. However, the traditional method of carrying out this exercise is below standard, especially for large lecture theatres, because of the student population, the time required, sophistication, exhaustiveness, and manipulative influence. An automated large classroom attendance system is, therefore, imperative. The common approach in this system is face detection and recognition, where known student faces are captured and stored for recognition purposes. This approach will require constant face database updates due to constant changes in the facial features. Alternatively, face counting can be performed by cropping the localized faces on the video or image into a folder and then count them. This research aims to develop a face localization-based approach to detect student faces in classroom images captured using a multicamera setup. A selected Haar-like feature cascade face detector trained with an asymmetric goal to minimize the False Rejection Rate (FRR) relative to the False Acceptance Rate (FAR) was applied on Raspberry Pi 4B. A relationship between the two factors (FRR and FAR) was established using a constant (λ) as a trade-off between the two factors for automatic adjustment during training. An evaluation of the proposed approach and the conventional AdaBoost on classroom datasets shows an improvement of 8% TPR (output result of low FRR) and 7% minimization of the FRR. The average learning speed of the proposed approach was improved with 1.19s execution time per image compared to 2.38s of the improved AdaBoost. Consequently, the proposed approach achieved 97% TPR with an overhead constraint time of 22.9s compared to 46.7s of the improved Adaboost when evaluated on images obtained from a large lecture hall (DK5) USM.

Keywords: automatic attendance, face detection, haar-like cascade, manual attendance

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Authors: P. Gil, F. Charrua-Santos, A. A. Baptista, S. Azevedo, A. Espirito-Santo, J. Páscoa

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Lean manufacturing is a philosophy of industrial management that aims to identify and eliminate any waste that exists in the companies. The augmented reality is a new technology that stills being developed in terms of software and hardware. This technology consists of an image capture device, a device for data processing and an image visualization equipment to visualize collected and processed images. It is characterized by being a technology that merges the reality with the virtual environment, so there is an instantaneous interaction between the two environments. The present work intends to demonstrate that the use of the augmented reality will contribute to improve some tools and methods used in Lean manufacturing philosophy. Through several examples of application in industry it will be demonstrated that the technological impact of the augmented reality on the Lean Manufacturing philosophy contribute to added value improvements.

Keywords: lean manufacturing, augmented reality, case studies, value

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Authors: Zainuddin Zakaria, Sun Woh Lye

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Despite the continuous advancements in automated conflict resolution tools, there is still a low rate of adoption of automation from Air Traffic Control Officers (ATCOs). Trust or acceptance in these tools and conformance to the individual ATCO preferences in strategy execution for conflict resolution are two key factors that impact their use. This paper proposes a methodology to unearth and classify ATCO conflict resolution strategies from simulator data of trained and qualified ATCOs. The methodology involves the extraction of ATCO executive control actions and the establishment of a system of strategy resolution classification based on ATCO radar commands and prevailing flight parameters in deconflicting a pair of aircraft. Six main strategies used to handle various categories of conflict were identified and discussed. It was found that ATCOs were about twice more likely to choose only vertical maneuvers in conflict resolution compared to horizontal maneuvers or a combination of both vertical and horizontal maneuvers.

Keywords: air traffic control strategies, conflict resolution, simulator data, strategy classification system

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Authors: Jun Young Moon, Hyeonggeon Lee, Jong Tae Kim

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In this paper, we present Cortex-M3 based virtual platform which can virtualize wearable hardware platform and evaluate hardware performance. Cortex-M3 is very popular microcontroller in wearable devices, hardware sensors and display devices. This platform can be used to implement software layer for specific hardware architecture. By using the proposed platform the software development process can be parallelized with hardware development process. We present internal mechanism to implement the proposed virtual platform and describe how to use the proposed platform to develop software by using case study which is low cost wearable device that uses Cortex-M3.

Keywords: electronic system level design, software development, virtual platform, wearable device

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Authors: Branimir Jurun, Elza Jurun

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The focus of this paper is the description of an instrument called 'Quattuor 45' and defining of wave pressure measurement. Special attention is given to measurement of wave pressure created by the wind speed increasing obtained with the instrument 'Quattuor 45' in the investigated area. The study begins with respect to theoretical attitudes and numerous up to date investigations related to the waves approaching the coast. The detailed schematic view of the instrument is enriched with pictures from ground plan and side view. Horizontal stability of the instrument is achieved by mooring which relies on two concrete blocks. Vertical wave peak monitoring is ensured by one float above the instrument. The synthesis of horizontal stability and vertical wave peak monitoring allows to create a representative database for wave pressure measuring. Instrument ‘Quattuor 45' is named according to the way the database is received. Namely, the electronic part of the instrument consists of the main chip ‘Arduino', its memory, four load cells with the appropriate modules and the wind speed sensor 'Anemometers'. The 'Arduino' chip is programmed to store two data from each load cell and two data from the anemometer on SD card each second. The next part of the research is dedicated to data processing. All measured results are stored automatically in the database and after that detailed processing is carried out in the MS Excel. The result of the wave pressure measurement is synthesized by the unit of measurement kN/m². This paper also suggests a graphical presentation of the results by multi-line graph. The wave pressure is presented on the left vertical axis, while the wind speed is shown on the right vertical axis. The time of measurement is displayed on the horizontal axis. The paper proposes an algorithm for wind speed measurements showing the results for two characteristic winds in the Adriatic Sea, called 'Bura' and 'Jugo'. The first of them is the northern wind that reaches high speeds, causing low and extremely steep waves, where the pressure of the wave is relatively weak. On the other hand, the southern wind 'Jugo' has a lower speed than the northern wind, but due to its constant duration and constant speed maintenance, it causes extremely long and high waves that cause extremely high wave pressure.

Keywords: instrument, measuring unit, waves pressure metering, wind seed measurement

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Authors: Adnan Kedir Jarso, Mesfin Megra Rorisa, Haftom Gebreslassie Gebregwergis, Frie Ayalew Yimam, Seada Hussen Adem

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A microgrid is a small-scale power grid that can operate independently or in conjunction with the main power grid. It is a promising solution for providing reliable and sustainable energy to remote areas. The integration of solar and vertical axis wind turbines (VAWTs) in a microgrid can provide a stable and efficient source of renewable energy. This paper provides a comprehensive overview of the integration of solar and VAWTs in a microgrid. The paper discusses the design, operation, and control of a microgrid that integrates solar and VAWTs. The paper also examines the performance of the microgrid in terms of efficiency, reliability, and cost-effectiveness. The paper highlights the advantages and disadvantages of using solar and VAWTs in a microgrid. The paper concludes that the integration of solar and VAWTs in a microgrid is a promising solution for providing reliable and sustainable energy to remote areas. The paper recommends further research to optimize the design and operation of a microgrid that integrates solar and VAWTs. The paper also recommends the development of policies and regulations that promote the use of microgrids that integrate solar and VAWTs. In conclusion, the integration of solar and VAWTs in a microgrid is a promising solution for providing reliable and sustainable energy to remote areas. The paper provides a comprehensive overview of the integration of solar and VAWTs in a microgrid and highlights the advantages and disadvantages of using solar and VAWTs in a microgrid. The paper recommends further research and the development of policies and regulations that promote the use of microgrids that integrate solar and VAWTs.

Keywords: hybrid generation, intermittent power, optimization, photovoltaic, vertical axis wind turbine

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Authors: Getnet Ayele Kebede, Tasew Tadiwose Zewdie

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In this study, a novel design of a wind-powered water pump for small-scale irrigation application by using the Savonius wind turbine of Vertical Axis Wind Turbine(VAWT) with 2 blades has been used. Calculations have been made on the energy available in the wind and an energy analysis was then performed to see what wind speed is required for the system to work. The rotor has a radius of 0.53 m giving a swept area of 1.27 m2 and this gives a solidity of 0.5, which is the minimum theoretical optimum value for wind turbine. The average extracted torque of the wind turbine is 0.922 Nm and Tip speed ratio is one this shows, the tips are moving at equal the speed of the wind and by 2 rotating of blades. This is sufficient to sustain the desired flow rate of (0.3125X 10-3) m3 per second with a maximum head of 10m and the expected working is 4hr/day, and also overcome other barriers to motion such as friction. Based on this novel design, we are able to achieve a cost-effective solution and simultaneously effective in self-starting under low wind speeds and it can catch the wind from all directions.

Keywords: Savonius wind turbine, Small-scale irrigation, Vertical Axis Wind Turbine, Water pump

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Authors: Shin-Jer Yang, Kai-Tai Yang

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In response to a changing world and the fast growth of the Internet, more and more enterprises are replacing web-based services with cloud-based ones. Multi-tenancy technology is becoming more important especially with Software as a Service (SaaS). This in turn leads to a greater focus on the application of Identity and Access Management (IAM). Conventional Near-Field Communication (NFC) based verification relies on a computer browser and a card reader to access an NFC tag. This type of verification does not support mobile device login and user-based access management functions. This study designs an NFC-based third-party cloud identity and access management scheme (NFC-IAM) addressing this shortcoming. Data from simulation tests analyzed with Key Performance Indicators (KPIs) suggest that the NFC-IAM not only takes less time in identity identification but also cuts time by 80% in terms of two-factor authentication and improves verification accuracy to 99.9% or better. In functional performance analyses, NFC-IAM performed better in salability and portability. The NFC-IAM App (Application Software) and back-end system to be developed and deployed in mobile device are to support IAM features and also offers users a more user-friendly experience and stronger security protection. In the future, our NFC-IAM can be employed to different environments including identification for mobile payment systems, permission management for remote equipment monitoring, among other applications.

Keywords: cloud service, multi-tenancy, NFC, IAM, mobile device

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Authors: Ahmad K. Samaila, Basant K. Jha

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This paper presents the effects of suction/injection of transient/steady natural convection flow of reactive viscous fluid in a vertical porous pipe. The mathematical model capturing the time dependent flow of viscous reactive fluid is solved using implicit finite difference method while the corresponding steady state model is solved using regular perturbation technique. Results of analytical and numerical solutions are reported for various parametric conditions to illustrate special features of the solutions. The coefficient of skin friction and rate of heat transfer are obtained and illustrated graphically. The numerical solution is shown to be in excellent agreement with the closed form analytical solution. It is interesting to note that time required to reach steady state is higher in case of injection in comparison to suction.

Keywords: porous pipe, reactive viscous fluid, transient natural-convective flow, analytical solution

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Authors: Ji Chen, Chunhui Zhang, Fanming Zeng, Lei Zhang, Ying Li, Wei Zhang

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Based on the synthetic principle of force, a pre-compressed nonlinear isolator with quasi-zero-stiffness (QZS) is developed for shock isolation of ship equipment. The proposed isolator consists of a vertical spring with positive stiffness and several lateral springs with negative stiffness. An analytical expression of vertical stiffness of the nonlinear isolator is derived and numerical simulation on the effect of the geometric design parameters is carried out. Besides, a pre-compressed QZS shock isolation system model is established. The stiffness characteristic of the system is studied and the effects of excitation amplitude and friction damping on shock isolation performance are discussed respectively. The research results show that in comparison with linear shock isolation system, the pre-compressed QZS shock isolation system could realize constant-force or approximately constant-force function and perform better anti-impact performance.

Keywords: quasi-zero-stiffness, constant-force, pre-compressed, large deformation, shock isolation, friction damping

Procedia PDF Downloads 659

Authors: Vitaliy Petrov, Natalia Shusharina, Vitaliy Kasymov, Maksim Patrushev, Evgeny Bogdanov

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The leading worldwide death reasons are ischemic heart disease and other cardiovascular illnesses. Generally, the common symptom is high blood pressure. Long-time blood pressure control is very important for the prophylaxis, correct diagnosis and timely therapy. Non-invasive methods which are based on Korotkoff sounds are impossible to apply often and for a long time. Implantable devices can combine longtime monitoring with high accuracy of measurements. The main purpose of this work is to create a real-time monitoring system for decreasing the death rate from cardiovascular diseases. These days implantable electronic devices began to play an important role in medicine. Usually implantable devices consist of a transmitter, powering which could be wireless with a special made battery and measurement circuit. Common problems in making implantable devices are short lifetime of the battery, big size and biocompatibility. In these work, blood pressure measure will be the focus because it’s one of the main symptoms of cardiovascular diseases. Our device will consist of three parts: the implantable pressure sensor, external transmitter and automated workstation in a hospital. The Implantable part of pressure sensors could be based on piezoresistive or capacitive technologies. Both sensors have some advantages and some limitations. The Developed circuit is based on a small capacitive sensor which is made of the technology of microelectromechanical systems (MEMS). The Capacitive sensor can provide high sensitivity, low power consumption and minimum hysteresis compared to the piezoresistive sensor. For this device, it was selected the oscillator-based circuit where frequency depends from the capacitance of sensor hence from capacitance one can calculate pressure. The external device (transmitter) used for wireless charging and signal transmission. Some implant devices for these applications are passive, the external device sends radio wave signal on internal LC circuit device. The external device gets reflected the signal from the implant and from a change of frequency is possible to calculate changing of capacitance and then blood pressure. However, this method has some disadvantages, such as the patient position dependence and static using. Developed implantable device doesn’t have these disadvantages and sends blood pressure data to the external part in real-time. The external device continuously sends information about blood pressure to hospital cloud service for analysis by a physician. Doctor’s automated workstation at the hospital also acts as a dashboard, which displays actual medical data of patients (which require attention) and stores it in cloud service. Usually, critical heart conditions occur few hours before heart attack but the device is able to send an alarm signal to the hospital for an early action of medical service. The system was tested with wireless charging and data transmission. These results can be used for ASIC design for MEMS pressure sensor.

Keywords: MEMS sensor, RF power, wireless data, oscillator-based circuit

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Authors: R. Kanthavel, R. Yogesh Kumar, T. Narendrakumar, B. Santhosh, S. Surya Prakash

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This paper primarily focuses on developing an affordable personal assistant and the implementation of it in the field of Artificial Intelligence (AI) to create a virtual assistant/friend. The problem in existing home automation techniques is that it requires the usage of exact command words present in the database to execute the corresponding task. Our proposed work is ATOM a.k.a ‘Artificial intelligence Talking Omnipresent Machine’. Our inspiration came from an unlikely source- the movie ‘Iron Man’ in which a character called J.A.R.V.I.S has omnipresence, and device controlling capability. This device can control household devices in real time and send the live information to the user. This device does not require the user to utter the exact commands specified in the database as it can capture the keywords from the uttered commands, correlates the obtained keywords and perform the specified task. This ability to compare and correlate the keywords gives the user the liberty to give commands which are not necessarily the exact words provided in the database. The proposed work has a higher flexibility (due to its keyword extracting ability from the user input) comparing to the existing work Intelligent Home automation System (IHAS), is more accurate, and is much more affordable as it makes use of WI-FI module and raspberry pi 2 instead of ZigBee and a computer respectively.

Keywords: home automation, speech recognition, voice control, personal assistant, artificial intelligence

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Authors: R. Sri Karthi Krishna, A. Saravana Kumar, Kesava Brahmaji, V. S. Vinoj

Abstract:

The lunar surface may contain rough and non-uniform terrain with dips and peaks. Soft-landing is a method of landing the lander on the lunar surface without any damage to the vehicle. This project focuses on finding a safe landing site for the vehicle by developing a method for the lateral velocity determination of the lunar lander. This is done by processing the real time images obtained by means of an on-board vision sensor. The hazard avoidance phase of the soft-landing starts when the vehicle is about 200 m above the lunar surface. Here, the lander has a very low velocity of about 10 cm/s:vertical and 5 m/s:horizontal. On the detection of a hazard the lander is navigated by controlling the vertical and lateral velocity. In order to find an appropriate landing site and to accordingly navigate, the lander image processing is performed continuously. The images are taken continuously until the landing site is determined, and the lander safely lands on the lunar surface. By integrating this vision-based navigation with the INS a better accuracy for the soft-landing of the lunar lander can be obtained.

Keywords: vision aided INS, image processing, lateral velocity estimation, materials engineering

Procedia PDF Downloads 440

Authors: Maryam Kakavand, Samira Entezari, Sara Khoshjamalfekri, Raghad Mimar

Abstract:

The objective of this study is 1) to compare elite female and beginner taekwondo players in terms of plantar pressure distribution, vertical ground reaction force, contact area, mean pressure, and right and left longitudinal arches, and 2) to compare preferred and non-preferred limbs among elite players. To the best of authors’ knowledge, as of yet, there is no information available about the plantar pressure distribution and arch index among taekwondo players. Material and Methods: An analytical-comparative research method is applied. Therefore seven elite athletes and eight novice athletes were selected. The emed-C50 platform was used to assess plantar pressure distribution, vertical ground reaction force, contact area, mean pressure of different areas, and planter longitudinal arch in a second step protocol. Independent t-test and dependent t-test were used at a level of 0.05 to compare the elites and beginners' right and left feet, and preferred and non-preferred limbs among elite athletes, respectively. Results: In comparing the right and left limbs of elite and beginner groups, findings indicate that there is only a significant difference in the mean pressure of the first metatarsal of the right foot. Findings also showed a significant difference in the contact area of the toes 3, 4, 5 regions between elites’ preferred and non-preferred limbs. However, no significant difference was found between the two groups’ right and left limbs and elites’ preferred and non-preferred limbs in terms of pressure distribution, vertical ground reaction force, and arch index. Conclusion: It seems that taekwondo exercises have affected pressure distribution patterns among advanced players causing some differences in their planter pressure distribution pattern when compared to that of beginners. Therefore, taekwondo exercises may be a factor contributing to asymmetry performance in preferred and non-preferred limbs.

Keywords: planter pressure, arch index, taekwondo, elite

Procedia PDF Downloads 137

Authors: H. V. H. De Soysa, N. D. Hiripitiya, H. S. U. Thrimavithana, B. R. Epitawala, K. A. D. D. Kuruppu, D. J. K. Lokupathirage

Abstract:

This research was based on developing a mechanism in order to optimize the landing distance. Short distance braking and long distance braking may cause several issues for the aircraft including tyre wearing. The worst case occurs with short distance landing. The issues related to short distance landing were identified after conducting interviews with pilots, aeronautical engineers and technicians. A model was constructed in order to optimize the landing distance. The device started to function at the point where the main wheels of the aircraft touchdown the runway. It was found that implementing this device to the aircraft benefits to optimize the landing distance. This could lead to rectifying several issues occurred due to improper braking distances.

Keywords: aircraft, mechanism, optimize landing distance, runway

Procedia PDF Downloads 295

Authors: Asma A. Parlin, K. Nakamura, N. Watanabe, T. Komai

Abstract:

Understanding the effective diffusion of benzene vapor in the soil-atmosphere interface is important as an intrusion of benzene into the atmosphere from the soil is largely driven by diffusion. To analyze the vertical one dimensional effective diffusion of benzene vapor in porous medium with high water content, diffusion experiments were conducted in soil columns using Andosol soil and Toyoura silica sand with different water content; for soil water content was from 0 to 30 wt.% and for sand it was from 0.06 to 10 wt.%. In soil, a linear relation was found between water content and effective diffusion coefficient while the effective diffusion coefficient didn’t change in the sand with increasing water. A numerical transport model following unsteady-state approaches based on Fick’s second law was used to match the required time for a steady state of the gas phase concentration profile of benzene to the experimentally measured concentration profile gas phase in the column. The result highlighted that both the water content and porosity might increase vertical diffusion of benzene vapor in soil.

Keywords: benzene vapor-phase, effective diffusion, subsurface soil medium, unsteady state

Procedia PDF Downloads 122

Authors: A. Mathieu, B. Aubry, E. Chhim, M. Jobe, M. Arnaud

Abstract:

Present project consists in a study and a development of piezoelectric devices for supplying power to new generation pacemakers. They are miniaturized leadless implants without battery placed directly in right ventricle. Amongst different acceptable energy sources in cardiac environment, we choose the solution of a device based on conversion of the energy produced by pressure variation inside the heart into electrical energy. The proposed energy harvesters can meet the power requirements of pacemakers, and can be a good solution to solve the problem of regular surgical operation. With further development, proposed device should provide enough energy to allow pacemakers autonomy, and could be good candidate for next pacemaker generation.

Keywords: energy harvester, heart, leadless pacemaker, piezoelectric cells, pressure variation

Procedia PDF Downloads 430