DSpace Collection:
http://cmuir.cmu.ac.th/jspui/handle/6653943832/7574
2024-03-28T10:03:01Zการเปรียบเทียบเทคนิคการเพิ่มประสิทธิภาพของการประมวลผลแมพรีดิวซ์สำหรับข้อมูลที่มีความเบ้
http://cmuir.cmu.ac.th/jspui/handle/6653943832/79399
Title: การเปรียบเทียบเทคนิคการเพิ่มประสิทธิภาพของการประมวลผลแมพรีดิวซ์สำหรับข้อมูลที่มีความเบ้
Authors: นักปราชญ์ กันตีวงศ์
Abstract: Nowadays, data is large in terms of volume, variety of format and changes rapidly. Therefore, it is necessary to rely on processing to make data accuracy and precision. To ensure real-time utilization and maximum benefit.
MapReduce is a framework for processing big data, including 2 functions: Map function and Reduce function. Map function processes input data set as key/value pairs and generates intermediate key/value pairs with the same key as output. Reduce function merges all intermediate values in each set. In this process, the reducer must wait for all maps to finish before the reducer starts.
Due to non-uniform distribution of big data. MapReduce process will be delayed because data that split to all nodes is not same size in map stages. As a result, each node complete processing at different times. Nodes that finish earlier must wait for the final mapper node to complete before they can proceed with reducing.
The results show that all of the algorithms studied in this paper can improve the execution time of MapReduce with skewed data. However, there are some limitations to improvement, especially when data is not heavily skewed; the overhead of the algorithms might overcome their benefits.2566-11-11T00:00:00ZDiagnosing risk of Dyslexia Based on the analysis of mouse tracking data and human computer interaction measures
http://cmuir.cmu.ac.th/jspui/handle/6653943832/79396
Title: Diagnosing risk of Dyslexia Based on the analysis of mouse tracking data and human computer interaction measures
Authors: ณัฐสินี ตั้งศิริไพบูลย์
Abstract: Our study presents the 'Direction' game as a tool for assessing the risk of reading difficulties in young children. This game evaluates directional confusion in three aspects: up-down, left-right, and cardinal directions, which is advantageous for pre-literate children as it does not rely on language skills.
In this research, we conducted tests with 102 children, both boys and girls, aged between 7 and 10 years, studying at Ban Pong Sanuk School in Lampang Province. The children were divided into two groups: 59 children in the at-risk group and 43 children without identified risks.
In the experiment, the experiment was divided into 2 periods: 1) pilot study t with a sample size of 24 people by collecting a questionnaire to bring the paper-based game to children to try and ask about their satisfaction in playing the game and 2) the main study test. The game was tested on a sample size of 102 individuals and the results were analyzed using a component classification model. The performance of this proposed model will be compared with other models including Naive Bayes, Support Vector Machine (SVM), AdaBoost, and Random Trees (RT) to assess the performance of the new model.
The results of the experiment revealed that children were able to play our game without needing someone to teach them. They felt more like they were playing a game rather than being tested or evaluated and did not feel isolated from their peers. 85% of the children who were tested reported this experience. Additionally, the children enjoyed playing our game, with 90% of the tested children expressing a liking for it.
Regarding the evaluation of reading disability risk among the sample group of 102 children, the implemented framework and procedures proved to be effective in improving the accuracy of risk assessment. In particular, the combined ensemble model of Random Trees (RT) and Support Vector Machine (SVM) demonstrated a screening efficiency of up to 86% and an area under the ROC curve of 82%. These results indicate that the model is proficient in assessing the risk of reading disabilities and enhances the screening performance. Additionally, incorporating mouse movement variables, such as fixation duration and the number of duplicate points, increased the accuracy of the assessment to over 70%. These variables are crucial in detecting deficiencies in organizational skills and attention in children at risk of reading difficulties.
In analyzing the behavior of children in at-risk and normal groups while playing the 'Direction' game, it was found that children in the at-risk group were more prone to making mistakes due to hesitation and difficulties in following instructions. However, their mouse movement speed was similar to that of the normal group, indicating that their overall game-playing abilities were not significantly different. Despite this, children in the normal group generally scored better.2023-11-10T00:00:00ZEffects of friction ratio of granular material on convection in two dimensional under vertical vibration
http://cmuir.cmu.ac.th/jspui/handle/6653943832/79370
Title: Effects of friction ratio of granular material on convection in two dimensional under vertical vibration
Authors: Tanapon Yachai
Abstract: Effective mixing and precise separation of granular materials are essential for many industries that use granular materials as raw materials in production, such as pharmaceuticals, food processing, and construction [1]. These granular materials are typically subjected to internal changes due to vibration during transportation, which directly impacts the quality and uniformity of the product. One of the key mechanisms that affects the separation and mixing phenomena is convection. Friction between particles and wall friction are important factors for convection [2-5]. However, previous studies have not been clear about the effects of friction on convection under different amplitudes. Therefore, this study investigated the influence of wall friction, particle friction, and vibration amplitude on the convection phenomena in granular materials under vertical vibration. The research aimed to numerically and experimentally investigate the influence of the particle frictions on the convection in 2D granular materials composed of disk particles under vertical vibrations. These numerical and experimental results were then compared to each other.
The present study began with the implementation of 2D simulations by using the Non-smooth Contact Dynamics (NSCD) method. The granular sample used in this study consists of 4000 disk particles with an average diameter D = 10 mm. The diameters were uniformly distributed within the range of 9 mm to 11 mm, resulting in a creation of a monodisperse granular sample. The interparticle friction coefficient (μp) and wall-particle friction coefficient (μw) were systematically changed within the range of 0.1 to 1.0. The particles were contained within a container subjected to the vertical vibration, characterized by a constant dimensionless acceleration of Γ = 5. The vibration frequency was adjusted to corresponding to the different vibration amplitudes of 0.35D, 0.5D, and 1.0D.
Next, 4000 Polymethyl Methacrylate (PMMA) particles were used in the experiment to prepare the granular sample. These particles were categorized into five different sizes: 9 mm, 9.5 mm, 10 mm, 10.5 mm, and 11 mm. The wall-particle friction coefficients (μw) were specifically varied by 0.15, 0.26, 0.36, 0.46, 0.61, 0.81, and 0.95, with the selection of different wall materials, including polytetrafluoroethylene (PTFE) tape, polyethylene (PE) tape, masking tape, sandpaper No. 10000, sandpaper No.5000, and polyurethane (PU) tape. On the other hand, the interparticle friction coefficient (μp) remained constant at a value of 0.5. The granular sample was subjected to the vertical vibration with the same conditions as done in the simulations. The vibrational amplitudes were adjusted to 0.5D and 1.0D. High-speed cameras were employed to capture the particle positions at various time steps. These capture positions were then used to calculate the particle velocities. The index associated with the convection of particles in the granular material can be subsequently determined. This index, a dimensionless angular velocity W, was introduced and developed to describe the occurrence, intensity, as well as the direction of convection.
In comparison, the results obtained from both simulations and experiments showed a similar trend. It was observed that convection remained absent when the friction coefficient μw ≤ 0.2 or μp ≤ 0.1 (the value of W approached to zero or was less than 5 × 10–4) for all vibrational amplitudes. The onset of convection appeared when μw ≥ 0.4 and μp ≥ 0.2. This phenomenon is caused by the wall friction force, inducing particles to climb on nearby ones while moving downward. At the same time, the interparticle friction plays a role in preventing slippage during this climb. The intensity of convection, denoted by the value of W, increases with μp, reaching a maximum when μw = μp. Subsequently, the intensity of convection was relatively constant when μp > μw. This is due to the fact that the wall friction force cannot overcome interparticle friction force. Additional observations from the experimental and simulation results revealed that all convections observed were the normal convections (W > 0). This provides particles at the wall move downward while those in the center region of the container migrate upward.
The vibrational amplitude significantly affects the convection in the granular samples with the higher interparticle and wall-particle friction coefficients, i.e. μp and μw ≥ 0.6. In this case, the higher friction force results in a loose-packed structure, thus leading to particles moving downward freely through such voids. As a consequence, the dimensionless angular velocity increases rapidly. Additionally, the dimensionless angular velocity obtained from the experiments and the simulations yield similar results, but that obtained from the experiments were slightly higher than that obtained from the simulations. This can be explained by the front and back cover plates of the container used in the experiments provided the friction forces driving the particles downward faster.2023-10-01T00:00:00ZDesign of PCM-water storage for improving performance of Photovoltaic/Thermal module in residential building
http://cmuir.cmu.ac.th/jspui/handle/6653943832/79365
Title: Design of PCM-water storage for improving performance of Photovoltaic/Thermal module in residential building
Authors: Vat Sun
Abstract: Photovoltaic thermal (PVT) module provides a conversion of solar energy into
simultaneous electricity and heat. Unlike normal photovoltaic (PV) module, the nominal
operating cell temperature (NOCT) used to evaluate PV module temperature and
electrical power output is not given since the value for the PVT module also depends on
mass flow rate and the inlet temperature of the module working fluid. In this study, a new
method for calculating the NOCT of glazed and unglazed PVT modules having water as
working fluid were presented. Four unglazed identical PVT modules in series connection
were tested outdoor with various mass flow rates similar to solar collector testing. The
water inlet temperature of the first PVT module of the system was varied in a range of 27
- 60 °C. A correlation for NOCT of unglazed PVT module with (Tfi - Ta)/IT and water
mass flow rate, mi was developed. In case of glazed PV'I module, the evaluation of the
NOCT is more complicated since the module temperature is rather difficult to be
measured. The thermal characteristics such as F', FR, FR(𝜏𝛼), and 𝐹𝑅𝑈𝐿, and finally the
NOCT at various water flow rates and inlet temperatures inlet temperatures could be
evaluated. It could be noted that the calculated values of the module temperature, the
outlet hot water temperature and the generated electrical power from the developed
NOCT approach agreed very well with the experimental results.
Use of phase change material (PCM) to generate temperature stratification in water
storage tank coupled with unglazed photovoltaic-thermal (PVT) module for combined
heat and power generation enhancement was investigated by experimental and numerical
analyses. In this experiment. RT42 having a melting point of 38-43 °C, was filled in a
packed-bed of 40 mm diameter spherical capsules in a water storage tank (220 L)
connecting with four identical unglazed PVI modules (each of 200 Wp) in series. The
experiments were performed outdoor with water mass flow rates of 2.4 and 5.8 LPM. The
enthalpy method with the one-dimensional finite difference method was used to calculate
the temperatures of water and PCM ball in the storage tank. It could be seen that the
simulated results on the water and the PCM temperatures, including the module
temperature of PVT modules, agreed well with those of experimental data. The model
was also used to evaluate the net electrical and net overall (both thermal and electrical
including pump power) efficiencies of the PVT modules by considering the position of
the PCM ball, the PCM amount, the circulating water mass flow rate, and the PCM type.
From this model, the PCM ball packed-bed position did not give an effect on the PVT
module performances. But increase of the PCM amount at giving circulating water mass
flow rate, higher water temperature stratification could be found, and higher
performances of PVT modules, especially in the afternoon, could be obtained.
Lower melting point PCM showed better performance of the PVI modules, but if the
melting was too low, the water temperature might not be high enough for hot water
utilization. RT42-water storage with 𝐻𝑏/𝐻 = 100% was recommended since the PVT
performance could be improved compared with normal water storage, and the water
temperature in the storage tank could reach 55 °C which was high enough for domestic
hot water. The mass flow rate of 2.4 LPM was also recommended for actual production
with the optimum overall efficiency when the pump power was included. Four PVT
modules in series connection were selected since the storage tank temperature could be
obtained at 55 °C and the average net exergy efficiency could reach 14.79%.2022-02-15T00:00:00Z