Journal Issue: Journal of Advances in Engineering and Technology (JAET)
Volume
Volume 03
Number
Issue ii
Issue Date
2025-02
Journal Title
Journal ISSN
2950-7138
Journal Volume
Articles
Intelligent Reflecting Surface for 6G Wireless Communication
(SLIIT, Faculty of Engineering, 2025-02) Malshan, K. A. T. I.; Iddamalgoda, G. D. D.; Rajendran, H.; Aashiq, M. N. A.; Haleem, M. A. L. A.
In the context of future 6G wireless communication, addressing challenges related to non-line-ofsight
communication is paramount. This paper presents the design and prototyping of Intelligent
Reflecting Surfaces (IRS) as a solution to provide wireless connectivity in the absence of Line-of-Sight
(LoS) propagation paths for effective wireless communication. We simulated phase-shifter unit cell
structures of IRS utilizing CST Studio software suite. A prototype IRS consisting of a two-dimensional
array of unit cells was designed and built. Our tests on the prototype revealed the effectiveness of the
design exhibiting a remarkable 315o of dynamic range in phase shift performance at 2.4 GHz. The losses
introduced by the IRS in reflecting an incident signal were brought down to an acceptable limit via an
iterative design and simulation process. Measurements on phase shifting properties were performed using
a low-cost Vector Network Analyzer (VNA). A comparative study was carried out on the simulation and
experimental outcomes and good agreement was found confirming the effectiveness of the prototype IRS.
Material Wastage on Cost Overrun in Construction Projects: An Impact Study Carried Out in Sri Lanka
(SLIIT, Faculty of Engineering, 2025-02) Kothalawala, N.T.B.; Malkanthi, S.N.; Dharmaratne, P.D.
Cost overruns are a prevalent issue in construction industry, and material wastage is recognized as
one of the key contributory factors of it. Against that background, this research investigates the impact of
material wastage on cost overruns in construction projects experienced in Sri Lanka. It strives to achieve
the objective of providing insights into the relationship between material wastage and cost overruns and
identifying potential strategies to mitigate its impact. The research methodology developed in this concern
involves a comprehensive literature review to establish a theoretical premise of material wastage and cost
overruns in construction projects. The data about the issue was collected through surveys, interviews, and
site inspections of a series of ongoing and completed construction projects in Sri Lanka. Later, the data
was analyzed statistically to determine the extent of material wastage and its impact on cost overruns.
The findings achieved thereby reveal a significant correlation between material wastage and cost overruns
in construction projects in Sri Lanka, highlighting that inefficient project planning, inadequate
supervision, lack of skilled labour, and ineffective procurement practices contribute to material wastage,
which ultimately leads to cost overruns. The financial implications of this situation are substantial and
affect project budgets and profitability. Based on the research findings, the paper strives to make
recommendations for strategies to mitigate material wastage and reduce cost overruns in construction
projects. These include improved project planning and scheduling, enhanced supervision and training,
effective procurement and inventory management, and adoption of sustainable construction practices.
Linearization of Nonlinear Components in Instruments
(SLIIT, Faculty of Engineering, 2025-02) de Silva, Clarence W.
Real instruments, devices, and components are found to be nonlinear and are represented by
nonlinear analytical models. Accordingly, linear systems (or models) have idealized representations.
However, it is realized far more convenient to analyze, simulate, design, and implement nonlinear
devices through the use of linear models. Also, regarding some devices, the degree of nonlinearity may
not be significant. In such cases, nonlinear devices are often “approximated” by linear models. Against
that background, this paper explores several important methods of linearization of nonlinear physical
devices with practical examples.
Rice Husk Derived Biomass Briquettes for Boilers: Ingredient-Based Product Quality Study
(SLIIT, Faculty of Engineering, 2025-02) Lakshika, H.N.M.; Arachchige, U. S.P.R; Koliyabandara, P.A
This research investigates the feasibility of repurposing rice husk waste into sustainable biomass
briquettes, addressing environmental and economic challenges associated with conventional biomass
sources in Sri Lanka. The study involves a comprehensive analysis of rice husk utilization, focusing on
three size fractions: original size, particles less than 5mm, and powder form. Rice husks less than 5mm
was observed to have a composition of optimal fixed carbon content (11.63% ± 0.215), moisture content
(10.53% ± 0.013), volatile matter (80.72% ± 0.005), and ash content (7.65% ± 0.004). The binding
agents, namely starch, dummala tree resin, and wastepaper pulp, were used for briquette production. The
optimal compositions for briquettes made with rice husk particles less than 5mm were determined as
follows: rice husk with starch (1:6), rice husk with tree resin (1:7), and rice husk with wastepaper pulp
(1:5). The calorific values of these optimum briquettes were found to be 15.446 MJ/kg for starch-based
briquettes, 15.278 MJ/kg for paper pulp-based briquettes, and 15.323 MJ/kg for tree resin-based
briquettes. In addition, briquettes made with an equal ratio (1:1) of binders showed calorific values of
14.175 MJ/kg for starch, 14.227 MJ/kg for paper pulp, and 15.275 MJ/kg for tree resin, with tree resinbased
briquettes exhibiting the highest calorific value. In the product quality evaluation study carried
out with these results, the proximate and ultimate analyses were conducted to characterize the briquettes
and the thermogravimetric analysis (TGA) was conducted to characterize the rice husk and to examine
the physical properties of the produced briquettes. The findings indicate that repurposing rice husk waste
with various binding agents offers a sustainable solution for biomass fuel production. Accordingly,
natural tree resin briquettes exhibited the highest density, compression ratio, and shatter resistance.
These results suggest that utilizing natural tree resin can effectively address waste management
challenges and create an environmentally friendly and economically viable industrial sector in Sri Lanka.
Correlation of tensile strength of blended cement concrete with specimen dimensions and aggregate size: A practical test review
(SLIIT, Faculty of Engineering, 2025-02) Amarasinghe, N; Somaratna, N
Test specimen dimensions affect most strength properties of concrete. The existing empirical
relationships in this regard are predominantly based on concrete samples made by using Ordinary
Portland cement (OPC). An important recent trend in Sri Lanka has been the increasing use of blended
cements. This makes it necessary to examine whether the relationships hold for blended cements as well.
In this study, split cylinder tensile strength tests were conducted to determine whether the specimen size
and the tensile strength of concrete prepared using a blended cement (Portland Composite Cement
(PCC)) display relationships similar to OPC. Tests were conducted on specimens using two cement types
– OPC and PCC - and three concrete mix ratios and a range of specimen dimensions to study the effect
of the specimen length (L), diameter (D), and aggregate size (a) on the split cylinder tensile strength (T).
The data was examined using dimensional analysis based on Buckingham's π theorem. A slight
increasing trend was observed in the ratio of split cylinder tensile strength to mean a compressive
strength (T/fc,mean) with an increasing L/D ratio. As for the ratio of the aggregate size to the specimen
diameter (a/D), the analysis showed an increasing trend in T/fc,mean values with an increasing a/D ratio,
indicating a significant correlation between T/fc,mean and a/D. A nonlinear regression analysis was
used in an attempt to determine a functional relationship among the non-dimensional parameters
T/fc,mean, L/D, and a/D. But the differences in the derived relationships for different concrete mixes
were too large for reaching a common relationship. Perhaps this was due to the small number of data
points available. It was seen that relationships established for OPC may hold true for PCC too. However,
the data used was limited in range and more comprehensive further tests should be conducted to confirm
these findings.
Description
Editor-in-Chief
Professor Rahula Attalage
Editorial Committee
Dr. Nandika Miguntenna
Dr. Lakmini Malasinghe
Dr. Priyantha Bandara
Dr. Mudith Karunarathna
Ms. Priyanwada De Silva
Advisory Board
Prof. Dilanthi Amarathunga University of Huddersfield, UK
Prof. Janaka Ekanayake University of Peradeniya, Sri Lanka
Prof. Kyaw Thu Kyushu University, Japan
Prof. Jagath Manatunge, University of Moratuwa, Sri Lanka
Prof. George Mann Memorial University of Newfoundland, Canada
Prof. Srinath Perera, Western Sydney University, Australia
Prof. Ahmed Abu–Siada Curtin University, Australia
Prof. R. Thevamaran, University of Wisconsin, Madison, USA
Prof. S. C. Wirasinghe University of Calgary, Canada
Editorial Assistant / Secretary of the Journal
Ms. Priyanwada De Silva
Keywords
Load Frequency Control, Interconnected Power Systems, Fuzzy Controllers, Zone-Specific Control, Pine Needles, Bio-Briquettes, Biomass Boiler, Tensile Strength, Blended Cement Concrete, Specimen Dimensions, Aggregate Size, Rice Husk, Biomass Briquettes, Product Quality, Linearization, Nonlinear Components, Instruments, Material Wastage, Cost Overrun, Construction Projects, Sri Lanka, Intelligent Reflecting Surface, 6G Wireless Communication