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Static Elastic Bending Analysis of a Three-Dimensional Clamped Thick Rectangular Plate using Energy Method
Get PDFAnalytical formulations and solutions for the thick rectangular plate static analysis with clamped support based on a three-dimensional (3-D) elasticity theory is developed using the energy method. The theoretical model, whose formulation is based on the static elastic principle as already reported in the literature, is presented herein to obviate the shear correction coefficients while considering shear deformation effect and transverse normal strain/stress in the analysis. The equilibrium equations are obtained using 3-D kinematic and constitutive relations. The deflection and rotation functions, which are the solutions of the equilibrium equation, are obtained in closed form using a general variational technique for solving the boundary value problem. The minimization energy equation yields the general equation which was used to obtain the theoretical model for the deflection and stresses of the plate. The results are compared with the available literature and the results-computed trigonometric displacement function shows that this 3-D predicts the vertical displacement and the stresses more accurately than previous studies considered in this paper. The result showed that the percentage difference between the present work and those of 2-D Mindlin FSDT, 2-D numeric analysis, and 2-D HSDT of polynomial shape functions was about 3.02%, 0.62%, and 0.33%, respectively. It is concluded that the 3-D trigonometric model gives an exact solution, unlike other 2-D theories, and can be used for clamped-supported thick plate analysis. Doi: 10.28991/HIJ-2022-03-03-03 Full Text: PD
Evaluation and Optimization of the Aerodynamic Noise Reduction of Vehicle Side View Mirrors: Experimental and Numerical Study
Get PDFAutomobile passengers are usually sensitive to the noises generated by the engine and vehicle body. One of the noise sources is the generated turbulent flow around the Vehicle Side View Mirror (VSVM) and around the A-pillar, producing fluctuating pressure. Unwanted noise is a result of fluctuating pressure around the car's body. Modification of the geometry of the vehicle body may affect the generated noise by turbulent flow. In this paper, the original side view mirror of a small sedan car named Tiba was aimed at geometry modification to decrease airborne noise. The mirror was assessed by CFD simulation and an outdoor test. Road tests were applied at three forward speeds (80, 100, and 120 km/h) to measure the sound level generated by the vehicle's side mirrors. Then, the geometry of VSVM was modified to diminish the sound pressure level of that based on decreasing turbulent flow and fluctuating pressure around the side mirror. Finally, the achieved geometry was evaluated using road tests, which showed a noise reduction of 8 to 12%. Road tests were done for the modified side car mirror. It shows that a modified mirror can reduce the sound level of airborne noise. By using this suggested modified side view mirror, the risk of annoying noise may be diminished and passenger comfortability can be increased through driving. Doi: 10.28991/HIJ-2022-03-01-08 Full Text: PD
Modifying Hidden Layer in Neural Network Models to Improve Prediction Accuracy: A Combined Model for Estimating Stock Price
Get PDFInvestment experts, who deal with stock price estimation, commonly look for the most accurate and appropriate statistical techniques to make decisions on investment. The aim of this study is to improve the accuracy of stock price prediction models through modifying the structure of a combined neural network model with time-series data, in which the main contribution is to insert the time-series analysis prediction into the hidden layer of the neural network. The proposed structure is made up of neural networks and time-series analysis, with variable reduction used to remove attributes with inter-correlations. Data has been collected over six years (72 months) from the Iranian stock market, including the number of trades, new-coin price, gold-18 price, US Dollar and Euro equivalent currencies, oil-index price, Brent-oil price, industry index, and balanced stock index, followed by developing the prediction models. Comparing the performance criteria of the proposed structure to the traditional ones in terms of the mean square and mean absolute errors revealed that inserting time-series estimated variables into hidden layers would improve the performance of neural network models to estimate stock prices for making investment decisions. Doi: 10.28991/HIJ-2022-03-01-05 Full Text: PD
Cohesive Methodology in Construction of Enclosure for 3.6m Devasthal Optical Telescope
Get PDFBuilding telescope enclosures is vital for setting up any optical observatory. An enclosure was constructed in remote hilly terrain to provide shelter to India's largest 3.6 m Devasthal Optical Telescope (DOT). Primarily, the enclosure was built to protect the telescope from tough weather conditions and provide optimum space for performing various telescope related operational and maintenance activities. Other elements that were considered in the building enclosure were low thermal mass, sustainability, seismic and acoustic considerations. A steel building designed with mostly bolted connections, suitably selected materials, and mechanical systems for facilitating construction activities on site has been built for the telescope at the Devasthal site of ARIES. The enclosure construction was quite a challenging task with various project complexities. Multidisciplinary works of civil, mechanical and electrical systems in enclosure required efforts on various fronts in parallel to achieve the targets. Limitations of resources, manpower, and site conditions were managed to keep flexibility and economics in construction. Numerous challenges faced during the making of enclosures have been discussed in the paper. Insights into the construction of enclosures will provide a basic framework and learning opportunities for managing such typical construction projects in adverse weather conditions at mountainous sites. Doi: 10.28991/HIJ-2022-03-02-05 Full Text: PD
An Integrated Approach of Multi-Criteria Decision Making to Determine the Most Habitable Planet
Get PDFEvery planet in the universe has its own characteristics. These features make the planets different among themselves. For this reason, all the different properties of the planets must be evaluated at the same time when determining habitable planets. This situation requires a multi-criteria decision making (MCDM) approach. In this study, a list of habitable planets (nine planets and the Moon) has been considered. Seventeen different criteria such as mass, gravity, diameter, density, escape velocity, rotation time, day of length, distance from the sun, perihelion, aphelion, orbital period, orbital velocity, orbital inclination, orbital eccentricity, obliquity to orbit, mean temperature, and number of satellites are taken into account. The weights of criteria are determined with DEMATEL (The Decision Making Trial and Evaluation Laboratory) by analyzing the interactions among criteria. Orbital inclination is the criterion with the highest weight, and the criterion with the lowest weight is the number of satellites. After weighting the criteria with DEMATEL, VIKOR (VIseKriterijumska Optimizacija I Kompromisno Resenje) and TOPSIS (Technique for Order Preference to Similarity to Ideal Solution) approaches are used to rank the planets. According to the TOPSIS, Earth is ranked first, Venus ranked second and Mercury ranked third in the order of the most habitable planets. According to the VIKOR method, Earth is ranked first, Mars is ranked second, and Mercury is ranked third in the order of the most habitable planets. Finally, the same calculations are considered with equal weights and the results are discussed. Doi: 10.28991/HIJ-2022-03-02-04 Full Text: PD
The Impact of Digital Marketing vs. Traditional Marketing on Consumer Buying Behavior
Get PDFObjectives: This research aims to measure the impact of digital marketing vs. traditional marketing on consumer behavior by analyzing their motives and reasons related to the orientation and purchase of products or services through social media and identifying the differences in marketing strategies used depending on the demographics of respondents. Methods: The research was realized based on primary data. For the realization of the research objectives and questions, a quantitative method was used, where 400 citizens of Kosovo were a part of the research. Findings: Based on the ordinary least squares (OLS) model, it turned out that the two marketing types impact consumer buying behavior, but digital marketing turned out to be the indicator with the greatest impact on deciding to make purchases. Also, based on the t-test and ANOVA, there was no significant difference in using traditional and digital marketing types depending on demographic variables. Novelty/improvement:Through this research, businesses receive comments on the preferences of citizens for the marketing type and the possible offers depending on the preferences, as well as the impact of traditional and digital marketing on the purchasing behavior of consumers. Doi: 10.28991/HIJ-2022-03-03-08 Full Text: PD
Multi-class SVM Classification Comparison for Health Service Satisfaction Survey Data in Bahasa
Get PDFThis study aimed to compare the Multi-class Support Vector Machine (MSVM) classification with the One-versus-One (OvO) and One-versus-Rest (OvR) approaches using unigram and bigram features. The study used the service satisfaction survey report of Denpasar public health centers by the Center for Public Health Innovation (CPHI), Medical School, Udayana University. As Bali is known as the world's main tourism destination, it is important to know about its supporting public health service through its representative capital city, Denpasar. Moreover, this study laid the foundation for the classification process using the available methods to fit in Indonesian health service satisfaction survey data, which assists in making decisions to improve health services. Since Bali is one of the provinces in Indonesia and all of those provinces refer to the same national regulation, health service satisfaction survey data that is in the Indonesian language (Bahasa) should have the same aspects, like category, priority, word-related matters (including abbreviations, acronyms, terminology), etc. that overall make it unique and need specific processing. That work was considered a contribution since there is no such study to the best of the author's knowledge and the foundation would be useful as a part of the future vision for the integrated system of Indonesian health big data. Since in reality, satisfaction survey data tends to be unbalanced, this study also compares the developed models using unigram and bigram features without and with feature selection (FS). Those features were then processed using the OvO MSVM and OvR MSVM models. k-fold cross-validation was used to divide training data and testing data and, at the same time, validate the models. Through experiments without and with FS, the OvO MSVM and OvR MSVM models with unigram features had better performance in general than the same models with bigram features. Without FS and with unigram features, comparable differences were found where the OvO MSVM model was slightly better on accuracy and precision, while the OvR MSVM model was slightly better on recall and the F1score. Without FS and with bigram features, comparable differences were also found, where the OvR MSVM model had slightly better performance than the OvO MSVM model. With FS and with unigram and bigram features, the OvR MSVM model had better performance in general than the OvO MSVM model. Doi: 10.28991/HIJ-2022-03-04-05 Full Text: PD
Constructing Calculus Concepts through Worksheet Based Problem-Based Learning Assisted by GeoGebra Software
Get PDFThis study aims to produce a valid, practical, and effective calculus learning worksheet using a problem-based learning method assisted by GeoGebra software in improving problem-solving skills. This worksheet serves as a guide to students in constructing the calculus concepts through the provided instructions according to the Problem-Based Learning syntax. Furthermore, the construction process was carried out using GeoGebra software. Students are given scaffolding to construct concepts. This research is development research. This study employs a Plomp model, which consists of three stages, namely the preliminary study, development or prototyping, and assessment phases. The subjects are 32 students in class XI.2 at the State Senior High School of 14 Padang. The results showed that the worksheet produced was valid, practical, and effective in improving students' problem-solving abilities. This implies that it would assist students in constructing calculus concepts. Furthermore, it showed that GeoGebra is capable of visualizing abstract calculus concepts, which enables students to understand higher mathematical thinking on the main concept of calculus. In conclusion, the use of GeoGebra in mathematics learning is able to help students construct mathematical concepts and improve their problem-solving abilities. Doi: 10.28991/HIJ-2022-03-03-04 Full Text: PD
Punching Shear Characterization of Steel Fiber-Reinforced Concrete Flat Slabs
Get PDFPunching shear failure in thin slabs under concentrated loads can cause shear stresses near columns. The use of steel fiber is a practical way to improve a slab-column connection's punching strength and deformation capacity. In this study, the capacity and behavior of steel fiber-reinforced concrete flat slabs are examined under punching shear force. Ten small-scale flat slabs were tested, eight of which had steel fiber and two without. Two parameters are studied in this paper, which are the fiber volume ratio (from 0% to 2%) and the stub column load shape (circle and square). The test results include the concrete compressive strength, crack patterns, punching shear, and load-defection behavior of the slabs. Based on the experimental results, it was found that the punching shear capacity of slabs with steel fiber (S5) increased by 21.8% compared to slabs without steel fiber (S1), and the slabs with steel fiber had more ductility compared to the slabs without fiber. Doi: 10.28991/HIJ-2022-03-04-08 Full Text: PD
Forensic Analysis of WhatsApp SQLite Databases on the Unrooted Android Phones
Get PDFWhatsApp is the most popular instant messaging mobile application all over the world. Originally designed for simple and fast communication, however, its privacy features, such as end-to-end encryption, eased private and unobserved communication for criminals aiming to commit illegal acts. In this paper, a forensic analysis of the artefacts left by the encrypted WhatsApp SQLite databases on unrooted Android devices is presented. In order to provide a complete interpretation of the artefacts, a set of controlled experiments to generate these artefacts were performed. Once generated, their storage location and database structure on the device were identified. Since the data is stored in an encrypted SQLite database, its decryption is first discussed. Then, the methods of analyzing the artefacts are revealed, aiming to understand how they can be correlated to cover all the possible evidence. In the results obtained, it is shown how to reconstruct the list of contacts, the history of exchanged textual and non-textual messages, as well as the details of their contents. Furthermore, this paper shows how to determine the properties of both the broadcast and the group communications in which the user has been involved, as well as how to reconstruct the logs of the voice and video calls. Doi: 10.28991/HIJ-2022-03-02-06 Full Text: PD