Taiwan Association of Engineering and Technology Innovation: E-Journals
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Experimental Investigation of Impacting Flow between a Sub-Scale Twin-Rotor Configuration
Get PDFIn this paper, a series of experiments have been performed to understand the semi-quiescent and the impacting flow structure beneath the twin-rotor configuration body using a multipurpose test stand with a sub-scale model airframe in the ground effects. So, the main purpose was to perform a qualitative investigation on the recirculated impacting flow between the twin-rotors. Pressure and velocity measurements were performed by the pressure ports embedded longitudinally along the airframe. The results show that for a single rotor an impinging jet-like small region and rearward and upward flows were below the body. The presence of the second rotor in configurations causes an impacting flow formation in the longitudinal center region below the airframe and a semi-quiescent flow formed there. The positive effects of this flow includes increasing the sub-body pressure and lifting force, the pressure distribution balance, and desirable pressure gradient on sidewalls of the airframe. Tuft tests observations confirm that the location of the impacting flow formation is affected by the pressure and velocity measurements. The mentioned impacting flow aerodynamic effects must be taken into account in design of the flight controls trims and stability systems of twin-rotor configurations
Analysis of Association between Caesarean Delivery and Gestational Diabetes Mellitus Using Machine Learning
Get PDFThe study aims to analyze the association between gestational diabetes mellitus (GDM) and other risk factors of cesarean delivery using machine learning (ML). The dataset used for the analysis is from the pregnancy risk assessment survey (PRAMS), considered in two scenarios, i.e., all the data is taken, and all the data of the women who developed GDM. Further, the data is developed in two groups Data-I and Data-II by considering multiparous and primiparous women details, respectively. The correlation analysis and major classification algorithms are applied to the data. It is founded that the top risk factors for the first time cesarean delivery are the age, height, weight, race of the women, presence of hypertension and gestational diabetes mellitus. The major risk factor for repeated cesarean delivery is the previous cesarean delivery. The presence of GDM is also one of the risk factors for cesarean delivery
An Enhanced K-Nearest Neighbor Predictive Model through Metaheuristic Optimization
Get PDFThe k-nearest neighbor (KNN) algorithm is vulnerable to noise, which is rooted in the dataset and has negative effects on its accuracy. Hence, various researchers employ variable minimization techniques before predicting the KNN in the quest so as to improve its predictive capability.
The genetic algorithm (GA) is the most widely used metaheuristics for such purpose; however, the GA suffers a problem that its mating scheme is bounded on its crossover operator. Thus, the use of the novel inversed bi-segmented average crossover (IBAX) is observed. In the present work, the crossover improved genetic algorithm (CIGAL) is instrumental in the enhancement of KNN’s prediction accuracy. The use of the unmodified genetic algorithm has removed 13 variables, while the CIGAL then further removes 20 variables from the 30 total variables in the faculty evaluation dataset.
Consequently, the integration of the CIGAL to the KNN (CIGAL-KNN) prediction model improves the KNN prediction accuracy to 95.53%. In contrast to the model of having the unmodified genetic algorithm (GA-KNN), the use of the lone KNN algorithmand the prediction accuracy is only at 89.94% and 87.15%, respectively. To validate the accuracy of the models, the use of the 10-folds cross-validation technique reveals 93.13%, 89.27%, and 87.77% prediction accuracy of the CIGAL-KNN, GA-KNN, and KNN prediction models, respectively. As the result, the CIGAL carried out an optimized GA performance and increased the accuracy of the KNN algorithm as a prediction model
Genetic Based Experimental Investigation on Finishing Characteristics of AlSiCp-MMC by Abrasive Flow Machining
Get PDFImplementing non-conventional finishing methods in the aircraft industry by the abrasive flow machining (AFM) process depends on the production quality at optimal conditions. The optimal set of the process variables in metal-matrix-composite (MMC) for a varying reinforcement percentage removes the obstructions and errors in the AFM process. In order to achieve this objective, the resultant output functions of the overall process using every clustering level of variables in a model are configured by using genetic programming (GP). These functions forecast the data to vary the percent of silicon carbide particles (particles without experimentation obtaining the output functions for material removing rates and surface roughness changes of Al-MMCs machined with the AFM process by using GP. The obtained genetic optimal global models are simulated and, the results show a higher degree of accuracy up to 99.97% as compared to the other modeling techniques.
 
A Novel Investigation Method for the S21 Detection Circuit
Get PDFThis research proposes a novel method to investigate the performance of the S21 detection circuit. Aiming at low frequencies or DC, the method serves as an efficient way of verification and enjoys the benefit of low testing costs. The novel investigation method is demonstrated at 50 MHz and verified by the scattering parameters at 11.05 GHz. Based on the investigation, a model of process variations is constructed. The length of the interface paths is estimated by the model to be 63µm, which is consistent with the corresponding length of 74.6µm in the layout. For the measured phase and magnitude, the model indicates that the process variations in the device under test cause errors of 18.91% and 1.27%, whereas those in the interface paths lead to errors of 1.83% and 1%. Based on the model, practical recommendations are also proposed to further improve the measurement precision in the future
Using a Hybrid Evolutionary Algorithm for Solving Signal Transmission Station Location and Allocation Problem with Different Regional Communication Quality Restriction
Get PDFThis study aims to investigate the signal transmission station location-allocation problems with the various restricted regional constraints. In each constraint, the types of signal transmission stations and the corresponding numbers and locations are to be decided at the same time. Inappropriate set up of stations is not only causing the unnecessary cost but also making the poor service quality. In this study, we proposed a hybrid evolutionary approach integrating the immune algorithm with particle swarm optimization (IAPSO) to solve this problem where each of the regions is with different maximum failure rate restrictions. We compared the performance of the proposed method with commercial optimization software LINGO®. According to the experimental results, solutions obtained by our IAPSO are better than or as well as the best solutions obtained by LINGO®. It is expected that our research can provide the telecommunication enterprise the optimal/near-optimal strategies for the setup of signal transmission stations
Robust Adaptive Depth Control of Hybrid Underwater Glider in Vertical Plane
Get PDFHybrid underwater glider (HUG) is an advanced autonomous underwater vehicle with propellers capable of sustainable operations for many months. Under the underwater disturbances and parameter uncertainties, it is difficult that the HUG coordinates with the desired depth in a robust manner. In this study, a robust adaptive control algorithm for the HUG is proposed. In the descend and ascend periods, the pitch control is designed using backstepping technique and direct adaptive control. When the vehicle approaches the target depth, the surge speed control using adaptive control combined with the pitch control is used to keep the vehicle at the desired depth with a constant cruising speed in the presence of the disturbances. The stability of the proposed controller is verified by using the Lyapunov theorem. Finally, the computer simulation using the numerical method is conducted to show the effectiveness of the proposed controller for a hybrid underwater glider system
Densification Behavior, Microstructure, and Property of ZnO with Multi-Oxides Glass Addition at Different Sintering Temperatures
Get PDFZinc Oxide (ZnO) mixed with various amount of glasses were sintered at different temperatures. The densification behavior of zinc oxide with glass addition and its microstructure and dielectric constant sintered from 900° to 1200°C have been investigated. A unique glass composition contained GeO2, MoO3, and V2O5 (GMV) was designed to act as the sintering aid to enhance the densification and to adjust the dielectric constant of ZnO. The effect of sintering temperature on the densification behavior and dielectrics properties of ZnO was investigated by dilatometer, x-ray diffractometer, scanning electron microscopy and LCR meter. The glass additive formed a thin continuous liquid phase and rearranged ZnO particles into a dense microstructure at relatively low temperature. The dielectric constants of glass added ZnO ceramics were found to vary with the glass concentration and sintering temperature
Effect of Acceleration on Wrap Faced Reinforced Soil Retaining Wall on Soft Clay by Performing Shaking Table Test
Get PDFThis research incorporates shaking table testing of scale wrap faced soil wall models to evaluate the seismic response of embankment. Currently the seismic designs of highway or railway embankment rely on little or no empirical data for calibrating numerical simulations. This research is working towards filling that empirical data gap. The specific purpose of the study was to evaluate the seismic response of constructed embankment model regarding the different input base accelerations with fixed frequency. A series of one-dimensional (1D) shaking table tests (0.05g, 0.1g, 0.15g and 0.2g), were performed on a 0.4 meters high wrap faced reinforced-soil wall model. Additionally, it was placed over 0.3 meters high soft clayey foundation. Predominantly, the influence of the base acceleration on the seismic response was studied in this paper. The physical models were subjected to harmonic sinusoidal input motions at a fixed frequency of 1 Hz, in order to assess the seismic behavior. The effects of parameters such as acceleration amplitudes and surcharge pressures on the seismic response of the model walls were considered. The relative density of the backfill material was kept fixed at 60%. The results of this study reveal that input accelerations and surcharge load had significant influence on the model wall, pore water pressure, and changes along the elevation. Acceleration response advances with the increase in base acceleration, so the difference being more perceptible at higher elevations. The pore water pressures were found to be high for high base shaking and low surcharge pressures at higher elevations. The results obtained from this study are helpful in understanding the relative performance of reinforced soil retaining wall under different test conditions resting on soft clay
Development of Maize Stalk Cellulose Fiber Reinforced Calcined Kaolinite Clay Geopolymer Composite
Get PDFIn recent years the popularity of ecological and renewable materials has grown. Aware of the availability of local resources and economic grounds, the attention is paid to the development geopolymer composite. Geopolymers are inorganic polymers that are formed by the polymerization reaction of silico-aluminate and silico-oxide. The aim of the research was to develop single maize stalk cellulose fiber reinforced calcined kaolinte caly based geopolymer composite. Kaolinite clay was characterized for its chemical composition from two different sites located in Ethiopia to use as precursor material. In addition to that, single maize stalk fiber was extracted from the maize stalk local variety by using a retting process, sodium hydroxide purity 98 % used for chemical treatment of the fiber for 30 minutes and its tensile strength 1184 Mpa and young modulus 16 Gpa were determined based on AST M D3822 to use as reinforcement. Sodium hydroxide and sodium silicate in appropriate ratio were used as an alkaline activator. Therefore, the geopolymer composite developed from chemical treated short single maize stalk cellulose fiber and calcined kaolinite clay based geopolymer matrix activated by sodium water glass. Geopolymer composites reinforced with 0 weight%, 0.1 weight%, 0.2 weight%, 0.6 weight%, and 1 weight% maize stalk single cellulose were prepared and tested for compression strength according to AST M C 1424. Measured compression strength ranged from 16 Mpa up to 27 Mpa. The result shows that the appropriate addition of single maize stalk cellulose fibers can improve the Compression strength of a calcined kaolinite based geopolyme