Development of a Filament Extruder Using Flow Theory with the Newtonian Fluid Assumption

This article presents an investigation of the flow characteristics of the polymer melt in a single-screw extruder and the design of a filament extruder to verify the above theory. The flow characteristics of the polymer melt in a single-screw extruder are likable to that of a viscous liquid between two infinitely parallel sheets, one moving and the other stationary. An integrated flow equation was then found for a case when the viscosity of a liquid remains constant in an isothermal extrusion. These flow behavior theories were then verified via the design and fabrication of a filament extruder for 3D printers

Development of a Filament Extruder Using Flow Theory with the Newtonian Fluid Assumption

This article presents an investigation of the flow characteristics of the polymer melt in a single-screw extruder and the design of a filament extruder to verify the above theory. The flow characteristics of the polymer melt in a single-screw extruder are likable to that of a viscous liquid between two infinitely parallel sheets, one moving and the other stationary. An integrated flow equation was then found for a case when the viscosity of a liquid remains constant in an isothermal extrusion. These flow behavior theories were then verified via the design and fabrication of a filament extruder for 3D printers

An Efficient Design of the Piezoresistive Pressure Sensor Applied for Micro Aerial Vehicle

In this research, the developing process of a piezoresistive pressure sensor working in the atmosphere environment applied in micro aerial vehicle using the MEMS fabrication method is introduced. The sensor consists of four Au/Cr piezoresistors in a Wheatstone bridge configuration on a wet oxidized silicon diaphragm. To fabricate the sensor, three lithographic steps were conducted: the first one is to define the resistors and Au/Cr lines/pads, the second and the third ones are to determine the width and the thickness of the square SiO2/Si diaphragm, respectively. The sensor diaphragm shape and thickness were defined by the anisotropic etching of Si in tetramethylammonium hydroxide (TMAH) solution, and the resistors array are formed by sputtering and wet etching method. The sensor size is ~6000 µm by 6000 µm. The sensor output voltage was measured for various applied pressure levels from 0 to 1.2 bar with 5V voltage supply. The fabricated sensor also exhibits a sensitivity of 50.01 mV/bar

An Efficient Design of the Piezoresistive Pressure Sensor Applied for Micro Aerial Vehicle

In this research, the developing process of a piezoresistive pressure sensor working in the atmosphere environment applied in micro aerial vehicle using the MEMS fabrication method is introduced. The sensor consists of four Au/Cr piezoresistors in a Wheatstone bridge configuration on a wet oxidized silicon diaphragm. To fabricate the sensor, three lithographic steps were conducted: the first one is to define the resistors and Au/Cr lines/pads, the second and the third ones are to determine the width and the thickness of the square SiO2/Si diaphragm, respectively. The sensor diaphragm shape and thickness were defined by the anisotropic etching of Si in tetramethylammonium hydroxide (TMAH) solution, and the resistors array are formed by sputtering and wet etching method. The sensor size is ~6000 µm by 6000 µm. The sensor output voltage was measured for various applied pressure levels from 0 to 1.2 bar with 5V voltage supply. The fabricated sensor also exhibits a sensitivity of 50.01 mV/bar

Encouraging Dialogue around Social Issues with Latinx Students Through Literature Discussion and Culturally Relevant Literature

This teacher research study examines literature discussions with fourth and fifth grade Latinx students about books that reflect Latinx experiences. For this study, the following questions are explored (1) What social issues do students discuss in literature groups? (2) How do literary response strategies influence student dialogue? And (3) How does my theoretical frame influence my decision making as a teacher? Theories that informed the construction of the literature discussions and the decision making occurring throughout the study are examined closely. The theories intertwine and bridge education and students’ experiences as a resource in learning more about the educational setting. In this study, the discussions of students and the literature response strategies are explored as the data is analyzed to examine the student discussions around issues of immigration, family separation, borders, and so much more. The findings in this study indicate that the experiences of Latinx students are integral to the educational setting and an education that invites who they are enhances their learning experiences. Latinx students are eager for learning opportunities that invite their voices and stories. It is through the construction and assessment of the educational setting that educators can promote culturally responsive, relevant, and sustaining teaching experiences that go beyond the classroom setting. Latinx students build relationships with each other and their teachers as they engage in discussions that allow them to share and learn with each other. This study is a reminder of the crucial role teachers play in creating such powerful spaces and the value that Latinx students bring into the classroom when invited to discuss, engage, and create powerful learning experiences

The global response: How cities and provinces around the globe tackled Covid-19 outbreaks in 2021

Background: Tackling the spread of COVID-19 remains a crucial part of ending the pandemic. Its highly contagious nature and constant evolution coupled with a relative lack of immunity make the virus difficult to control. For this, various strategies have been proposed and adopted including limiting contact, social isolation, vaccination, contact tracing, etc. However, given the heterogeneity in the enforcement of these strategies and constant fluctuations in the strictness levels of these strategies, it becomes challenging to assess the true impact of these strategies in controlling the spread of COVID-19.Methods: In the present study, we evaluated various transmission control measures that were imposed in 10 global urban cities and provinces in 2021 Bangkok, Gauteng, Ho Chi Minh City, Jakarta, London, Manila City, New Delhi, New York City, Singapore, and Tokyo.Findings: Based on our analysis, we herein propose the population-level Swiss cheese model for the failures and pit-falls in various strategies that each of these cities and provinces had. Furthermore, whilst all the evaluated cities and provinces took a different personalized approach to managing the pandemic, what remained common was dynamic enforcement and monitoring of breaches of each barrier of protection. The measures taken to reinforce the barriers were adjusted continuously based on the evolving epidemiological situation.Interpretation: How an individual city or province handled the pandemic profoundly affected and determined how the entire country handled the pandemic since the chain of transmission needs to be broken at the very grassroot level to achieve nationwide control

Review: Facial Anthropometric, Landmark Extraction, and Nasal Reconstruction Technology

Facial anthropometrics are measurements of human faces and are important figures that are used in many different fields, such as cosmetic surgery, protective gear design, reconstruction, etc. Therefore, the first procedure is to extract facial landmarks, then measurements are carried out by professional devices or based on experience. The aim of this review is to provide an update and review of 3D facial measurements, facial landmarks, and nasal reconstruction literature. The novel methods to detect facial landmarks including non-deep and deep learning are also introduced in this paper. Moreover, the nose is the most attractive part of the face, so nasal reconstruction or rhinoplasty is a matter of concern, and this is a significant challenge. The documents on the use of 3D printing technology as an aid in clinical diagnosis and during rhinoplasty surgery are also surveyed. Although scientific technology development with many algorithms for facial landmarks extraction have been proposed, their application in the medical field is still scarce. Connectivity between studies in different fields is a major challenge today; it opens up opportunities for the development of technology in healthcare. This review consists of the recent literature on 3D measurements, identification of landmarks, particularly in the medical field, and finally, nasal reconstruction technology. It is a helpful reference for researchers in these fields

Characterization of geometrical parameters of plastic bottle shredder blade utilizing a two-step optimization method

In this paper, a numerical and experimental investigation of geometrical parameters of the blade for plastic bottle shredder was performed based on the Taguchi method in combination with a response surface method (RSM). Nowadays, plastic waste has become a major threat to the environment. Shredding, in which plastic waste is shredded into small bits, ready for transportation and further processing, is a crucial step in plastic recycling. Although many studies on plastic shredders were performed, there was still a need for more researches on the optimization of shredder blades. Hence, a numerical analysis was carried out to study the influences of the relevant geometrical parameters. Next, a two-step optimization process combining the Taguchi method and the RSM was utilized to define optimal parameters. The simulation results clearly confirmed that the current technique can triumph over the limitation of the Taguchi method, originated from a discrete optimization nature. The optimal blade was then fabricated and experimented, showing lower wear via measurement by an ICamScope® microscope. Hence, it can be clearly inferred from this investigation that the current optimization method is a simple, sufficient tool to be applied in such a traditional process without using any complicated algorithms or expensive software

Застосування методів topsis, mairca та EAMR для багатокритеріального прийняття рішень при шліфуванні кругами з кубічного нітриду бору

Determining the best cutting mode is a common problem for machining processes as well as for CBN (Cubic Boron Nitride) grinding on Computer Numerical Control (CNC) machines. It is even more important when it is necessary to choose a solution that meets many goals, which are in conflict. This paper presents the results of a multi-criteria decision-making (MCDM) study on CBN grinding of cylindrical-shaped parts on CNC milling machines. Three MCDM methods,  including TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution), MAIRCA (Multi-Attributive Ideal-Real Comparative Analysis), and EAMR (Evaluation by an Area-based Method of Ranking) were applied in this work. Besides, MEREC (Method based on the Removal Effects of Criteria) and Entropy methods were used to determine the weights of the criteria. In addition, the Taguchi method with L18 orthogonal array (6^1+3^3) design was used for the design of an experiment, which has four input factors including the depth of dressing cut, the spindle speed, the feed rate, and the wheel diameter. Two criteria, including the surface roughness (SR) and the material removal speed (MRS) were selected as the response outputs. The reason for choosing these two criteria is because SR and MRS are two very important output factors of a mechanical machining process as well as of the CBN grinding process on a CNC milling machine. In particular, these two criteria are always in conflict with each other. Small SR requirements will require small values of the feed speed and the depth of cut. This will lead to the reduction of MRS. From the results of this study, the use of different methods for MCDM was evaluated. In addition, rankings of alternatives have been given according to MCDM methods. Furthermore, the best alternative to guarantee both the minimum SR and the maximum MRS has been foundВизначення найкращого режиму різання є поширеною задачею у процесах механічної обробки, а також шліфування кругами з КНБ (кубічного нітриду бору) на верстатах з числовим програмним управлінням (ЧПУ). Тим більше, коли необхідно вибрати рішення, що відповідає багатьом цілям, які суперечать одна одній. У статті представлені результати дослідження багатокритеріального прийняття рішень (БКПР) щодо шліфування кругами з КНБ деталей циліндричної форми на фрезерних верстатах з ЧПУ. У роботі застосовувалися три методи БКПР, включаючи TOPSIS (метод упорядкованої переваги через подібність до ідеального рішення), MAIRCA (мультиаттрибутний порівняльний аналіз реального та ідеального) і EAMR (оцінка методом зонального ранжування). Крім того, для визначення вагових коефіцієнтів критеріїв використовувалися методи MEREC (метод, заснований на ефектах видалення критеріїв) та Entropy (ентропії). Також для планування експерименту, що має чотири вхідних фактори, включаючи глибину різання, швидкість обертання шпинделя, швидкість подачі та діаметр круга був використаний метод Тагучі з ортогональною матрицею L18 (6^1+3^3). В якості відповідних даних були обрані два критерії, включаючи шорсткість поверхні (ШП) і швидкість знімання матеріалу (ШЗМ). Вибір даних критеріїв обумовлений тим, що ШП та ШЗМ є двома дуже важливими вихідними факторами у процесі механічної обробки, а також шліфування кругами з КНБ на верстаті з ЧПУ. Зокрема, ці два критерії завжди суперечать один одному. Малі вимоги до ШП вимагатимуть невеликих значень швидкості подачі та глибини різання, що призведе до скорочення ШЗМ. За результатами дослідження було оцінено застосування різних методів для БКПР. Крім того, були дані рейтинги альтернативних рішень відповідно до методів БКПР. Також було знайдено найкраще альтернативне рішення, що гарантує як мінімальну ШП, так і максимальну ШЗ