MIST International Journal of Science and Technology

Intelligent Head-bot, towards the Development of an AI Based Cognitive Platform

Ramisha Fariha Baki — 2023-12-28

A cognitive humanoid head is an AI enabled head-bot platform that resembles human's cognitive abilities, such as perception, thinking, learning, and decisionmaking. The platform is able to interact with human through natural language processing and recognize individuals, thus allowing seamless communication between two parties. No such cognitive platform has been introduced in Bangladesh, thus creating an open field to contribute to the field of Machine Intelligence. This study aims to develop an AI based humanoid head (head-bot) capable of imitating a range of expressions, recognizing individuals, and interacts with visitors through general conversation. The head-bot skeleton is developed using a number of hexagonal blocks of PVC sheet to mimic a humanhead- like structure where LCD, camera, microphones, and speaker are mounted. Two separate Machine Learning models are designed for face detection and recognitions, and voice enabled chat-bot implementation. The head-bot platform incorporates 2-DoF neck movements for various head gestures and face tracking. The Artificial Neural Network models are tested with accuracy of , and , for face detection and recognitions, and speech recognitions and response generation, respectively. According to the overall results and system performances, it seems that the proposed system has a number of good potentials for real life applications such as entertainment, guidance, conversations, interactive receptionists, personal companion, medical assistance, and so on.

MIJST, Vol. 11, December 2023 : 01-14

DOI: https://doi.org/10.47981/j.mijst.11(02)2023.440(01-14)

Deposition of Steel over Steel by Friction Surfacing Technique and Investigation of its Physical Geometry

Hemlata Jangid — 2023-12-28

Friction surfacing (FS) is a coating technique inspired by friction stir welding. FS is a solid-state, thermo-mechanical process providing excellent wear and corrosion resistance properties. Frictional heating elevates the temperature of the consumable rotating tool (mechtrode) up to the softening of the material, the tool is traversed along the length of the plate, and the material gets deposited onto the substrate plate with good mechanical properties and excellent corrosion resistance properties, FS process may have wider application in the mining industry to provide an adequate coating on excavator's teeth, shovel teeth, and dragline teeth. This paper has an experimental approach to investigate the coating integrity during the FSed deposition of AISI4140 (consumable rod) over EN24 plate on a conventional milling machine. Various tests like wear test, XRD analysis, hardness, IR thermography, surface roughness, FESEM images have been analysed. Experiments have shown that at a low travel speed of 16mm/min, the coating is non-uniform and an excessive increase in travel speed will not give proper time for softening of the material, resulting in a discontinuous coating so the optimum travel speed must be chosen for better quality coating. Also, one more approach has been made to explore the effect of mechtrode shapes on the flash formation of the consumable tool while deposition of mild steel over mild steel on the milling machine where conical cylinder tool shape was more efficiently worked.

MIJST, Vol. 11, December 2023 : 15-25

DOI: https://doi.org/10.47981/j.mijst.11(02)2023.427(15-25)

Physical, Mechanical, and Durability Properties of Concrete with Class F Fly Ash

Md Jahidul Islam — 2023-12-28

Concrete is one of the most used manufactured materials in the world. Fly ash (FA) is a byproduct produced from pulverized coal combustion in power generation. A total of 0.08 million tons of class F fly ash is produced from a coal-based power plant yearly in Barapukuria, Bangladesh, whose disposal is of a great issue. Therefore, this study aims to explore the possibility of using class F FA in concrete construction as a supplementary cementitious material. In this study, two different water-to-cement ratios (0.4 and 0.5), each with five cement replacement levels numerically, 0%, 10%, 20%, 30%, and 40% with FA are used. Various tests are performed on cylinder and beam specimens to assess physical, mechanical, and durability properties, such as workability, density, compressive strength (CS), splitting tensile strength (STS), flexural strength (FS), chloride ion penetrability (CIP), and shrinkage. Analyzing the results, it is reported that workability increases and density decreases with the increasing FA replacement. Mechanical properties mostly decrease with increasing FA content. However, the strength gained with age is higher for concrete with FA compared to the control concrete. The CIP reduces with FA replacement, especially at 56 days of age. Shrinkage value reduces 82% at 40% replacement FA replacement and w/c ratio 0.4. However, at 10% FA replacement and concrete age of 56 days, mechanical strength loss is infinitesimal or even better compared to the control concrete. Thus, a low replacement percentage of FA with a high curing period is a suitable concrete cement alternative.

MIJST, Vol. 11, December 2023 : 27-41

DOI: https://doi.org/10.47981/j.mijst.11(02)2023.430(27-41)

Development of Space-Borne Antenna Reflector via 3D Printing

Jaya Kori — 2023-12-28

The growing necessity of large aperture-based structures for many aerospace applications emphasizes the need to deploy large antenna structures in space. The space antennas should be light in weight and have low stowage volume, with efficient membrane packaging. The concept of additive manufacturing has been introduced to reduce weight as well as cost. In this paper, a comparative study has been done to analyze the advancement made in reducing weight with adequate strength. Based on the study, the main objectives are to develop a 3D-printed spherical reflector model with high specific strength and to assess the consistency of the model's shape. For determining the specific strength, tensile testing is performed on four different infill densities (20%, 40%, 60%, and 80%) with a grid infill pattern. It was observed that the specimen with 80% infill density has the highest tensile strength, 36.56 MPa, which is 23.51% more than 20% infill. However, the specimen with 20% infill density has the highest specific strength of 19.323 GPa/kg among the four specimens, which is approximately 64.64% higher than the 100% infill density. As a result of the testing, the spherical reflector model is 3D printed with 20% infill density, and it was found that the model achieves its shape stability and shape consistency with adequate specific strength.

MIJST, Vol. 11, December 2023 : 43-51

DOI: https://doi.org/10.47981/j.mijst.11(02)2023.431(43-51)

Terracotta in Architecture: Overview on Historical and Contemporary Practice in Bangladesh

Syed Abu Salaque — 2023-12-28

Although Terracotta is one of the oldest in almost all sub-continents and was spread out across the whole world now-a-days it has been a common, traditional, and indigenous object in Bangladesh for everyday life. Inspired by the religion or rituals, terracotta art has evolved in many ways in Bengal over time. From Babylon walls to high-performance rain screens, terracotta claddings have proven repeatedly to be technologically superior and aesthetically rich. Realizing the evolution of terracotta prepares architects to add new, creative chapters to a superior history. Through an extensive inventory of recent examples, project case studies and architectural details, this study provides a foundation for understanding the nature of the material and the opportunities it offers in the urban life. The objective of the paper is to know the evolution of terracotta as a historic, artistic and cultural materials and shapes of objects with aesthetical and technical aspects that plays an important role for place making in both exterior and interior of architectural design and building practice. The paper explores the evolution of terracotta in Bangladesh and prepares architects and builders to make new, creative uses of the timeless material. Validating the examples of expressive possibilities, this precious study can be an inspiration for students and professionals alike who are interested in creating sustainable spaces by using visual and cultural components.

MIJST, Vol. 11, December 2023 : 53-60

DOI: https://doi.org/10.47981/j.mijst.11(02)2023.412(53-60)

Antibacterial/Antiviral Face Masks: Processing, Characteristics, Challenges, and Sustainability

Md Enamul Hoque — 2023-12-28

The face mask has become a part of our daily life after the emergence of SAR-CoV-2, commonly known as the novel coronavirus 2019 or, COVID-19 all over the world. On a day-to-day basis, previously the face mask has been used to filter airborne particles entering the body and affecting the respiratory system, especially by individuals in pollution-prone areas. But as the pathogens having severe acute respiratory disease-causing abilities emerge with the potential to create a pandemic, the necessity of virus/bacteria killing ability along with the filtration efficiency of the face mask has come into account. Existing ordinary face masks have filtration capacity only. Sometimes it cannot restrict particles and pathogens of nano or even micro-scale. Moreover, when it is disposed of after use, it can be a potential source of pathogen transmission. Therefore, the development of antiviral/antibacterial face masks is the need of the hour. This article focuses on the advancement of face mask processing methods, existing and promising antibacterial/antiviral agents, socio-economic sustainability, and challenges in achieving the goal of a green environment. Besides, various characteristics of the face mask like swelling and degradation properties, morphologies (SEM, FESEM), mechanical strength, antioxidant property, and antimicrobial activity are also revealed. Lastly, some future perspectives and directives are accordingly discussed with the hope that the grim of any future pandemic should not shroud us and make the world stalled again.

MIJST, Vol. 11, December 2023 : 61-79

DOI: https://doi.org/10.47981/j.mijst.11(02)2023.421(61-79)

Bit Error Rate Performance in CDMA Free Space Optical Links with SIK Receiver under Fog Conditions

A K M Nazrul Islam — 2023-12-28

This article presents a novel analytical method for evaluating fog's impact on Bit Error Rate (BER) in an Optical Code Division Multiple Access (OCDMA) Free Space Optical (FSO) connection. The investigation employs an optical encoder and direct detection receiver employing a balanced photo detector with Sequence Inverse Keying (SIK) to explore fog effects. By scrutinizing multiaccess interference (MAI) current and signal current values at the SIK receiver's output under varied fog conditions, we deduce BER expressions for diverse scenarios. These encompass different fog thickness levels, code lengths, simultaneous users, and system parameters. The results reveal substantial OCDMA degradation due to fog thickness and users. Also, the system incurs a marked power penalty at a specific BER, especially with higher fog and user density. However, we identify a potential solution: increasing code length, effectively mitigating fog-induced performance decline.

MIJST, Vol. 11, December 2023 : 81-86

DOI: https://doi.org/10.47981/j.mijst.11(02)2023.409(81-86)

Foreword Vol.11 (December 2023)

Mohammed Saidul Islam — 2023-12-28

Abstract not available

MIJST, Vol. 11, December 2023 : xi

DOI: https://doi.org/10.47981/j.mijst.11(02)2023.455(xi)

Editor's Note Vol. 11 (December 2023)

Firoz Alam — 2023-12-28

Abstract not available

MIJST, Vol. 11, December 2023 : xiii

DOI: https://doi.org/10.47981/j.mijst.11(02)2023.454(xiii)