Engineering Commons^™

Sediment Grain Size Analysis And Characteristics Of Sedimentation Processes In The Bang Berd-Khao Tham Thong Beach, Chumphon Province, Rawadee Meeprasit, Sujaree Bureekul, Suriyan Saramul

Applied Environmental Research

This study investigated the sedimentological characteristics of the Bang Berd-Khao Tham Thong beach system, which is located along the western shore of the central Gulf of Thailand, an area that is minimally disturbed by human activity and is ideal for studying natural coastal processes. Sediment samples were collected from both coastal and marine environments across four sampling periods (July 2022, September 2022, April 2023, and June 2023). The analysis focused on the grain size distribution, sorting, skewness, kurtosis, and sediment composition, revealing a predominance of medium sand in coastal sediments and increased silt and clay contents in marine sediments. The …

The Use Of Machine Learning Algorithms For Water Quality Index Prediction In The Sai Gon River, Vietnam, Thuy Nguyen Thi Diem, Mai Nguyen Thi Huynh, Tra Tran Quang

Applied Environmental Research

Accurate prediction of the water quality index (WQI) lays the groundwork for integrated river basins and sustainable water resource management. Recent and accelerated advances in machine learning have led to various promising applications in water quality assessment. The present study leverages the predictive performance of several ML algorithms, including extreme gradient boosting (XGB), the gradient boosting model (GBM), support vector regression (SVR), and the radial basic function (RBF), to predict the WQI at three monitoring sites on the Sai Gon River from 2015–2019. In comparison, the results indicate that the XGB model outperforms the other models when eight parameters, including …

Landslide Susceptibility Mapping Via Dempster-Shafer, Statistical Index, And Certainty Factor Models In Gis And Their Comparison At Pidie Recency In Aceh, Indonesia, Septianto Aldiansyah, Amniar Ati, Fitriyani Saudi

Applied Environmental Research

Landslides are natural disasters that are active if there is an interaction of environmental factors that are considered to control them, especially in mountainous areas. This study developed a landslide susceptibility map in Pidie Regency via the Dempster-Shafer (DS), statistical index (SI), and certainty factor (CF) models. A total of 957 landslide events were mapped, 70% of which were used for modeling, whereas the remaining events were used to validate the model output. Fourteen layers of conditioning factors were used: elevation, slope, aspect, curvature, TWI, SPI, STI, NDVI, rainfall, distance from river, distance from road, distance from fault, LULC, and …

Assessment Of Landslide Susceptibility And Settlement Exposure Via Geospatial Techniques In Bulambuli Distrcit, Eastern Uganda, Andrew Mulabbi, John Calvin Esagu, Gertrude Akello, Remigio Turyahabwe

Applied Environmental Research

Landslide susceptibility is a significant concern in Elgon County, Uganda, particularly during the rainy season. This vulnerability is attributable to several factors, including steep slopes, fertile soils, and dense settlements on volcanic ridges. Landslide susceptibility maps are important in mitigating the risk particularly at the local level. The objectives of this study were 1) to model landslide susceptibility via an interpretable machine-learning model, 2) to identify the most influential factors for landslide susceptibility in the study area, and 3) to assess the exposure of settlements to landslide risk. This study employed the XGBoost model trained on nine conditioning factors via …

Exploration Of Indigeneous Biosurfactant-Producing Bacillus Sp. From Petroleum Hydrocarbon-Contaminated Soil In Indonesia, Rizky Danang Susetyo, Wahyu Wilopo, Suwarno Hadisusanto, Endah Retnaningrum

Applied Environmental Research

Hydrocarbonolastic bacteria are valuable for the remediation of petroleum-polluted environments. The production of biosurfactants by such bacteria significantly enhances hydrocarbon bioavailability and increases remediation efficiency. One genus of hydrocarbonolastic bacteria with the potential to produce biosurfactants is Bacillus, yet strain-level diversity and local adaptations remain underexplored.Tthis study aimed to isolate and characterize hydrocarbonolastic bacteria belonging to the Bacillus genus from soil samples collected at Geopetroleum Teksas Wonocolo, Kedewan District, Bojonegoro Regency, Indonesia, which is a historically underreported hydrocarbon site. Additionally, the capacity of Bacillus to synthesize biosurfactants was examined. Bacillus strains capable of biosur-factant production were identified via a polyphasic …

Influence Of Crabgrass Root Exudates On The Hydrocarbons Degrading Microorganisms In Crude Oil Contaminated Soil, Sinha Changsiriwatana, Kwang Mo Yang, Toemthip Poolpak, Prayad Pokethitiyook

Applied Environmental Research

Understanding plant‒microbial interactions in petroleum-contaminated soil is critical for enhancing phytoremediation technology. In this study, the root exudate of crabgrass (Digitaria ciliaris) was collected hydroponically, and its dominant composition was identified via GC‒MS. A soil microcosm study was subsequently conducted to evaluate the influence of crabgrass root exudates on microbial growth, dehydrogenase activity, and biodegradation of total petroleum hydrocarbons by the petroleum-degrading bacteria Micrococcus luteus WN01 and Acinetobacter lwoffii A07. The amendment of crabgrass root exudates significantly promoted microbial degradation in both A. lwoffii A07 (47.98%) and M. luteus WN01 (62.78%), which were 8.47% and 15.78% greater than …

Evaluating Anambra State's Readiness And Willingness For A Subnational Carbon Market For Climate Change Mitigation And Sustainable Development, Ojiako Godfrey Ogbo, Uchenna Cynthia Okonkwo

Applied Environmental Research

Climate change necessitates innovative strategies, with carbon markets emerging as a key tool for mitigation. This study assesses the readiness and willingness of stakeholders in Anambra State to engage in a subnational carbon market. Using a structured questionnaire distributed across government, industry, and academia, the data were analyzed through descriptive statistics, Pearson correlation, and multiple regression analysis. The findings indicate a moderate level of readiness (M = 3.47) and willingness (M = 3.48) among stakeholders. Correlation analysis revealed a significant alignment between composite willingness indicators and direct willingness to participate (r = 0.406, p = 0.004) but a weak and …

Design And Comparative Analysis Of Electric Motors With “Flux-Switching” Effect Having Reluctance Rotors And Pm Or Dc Stator Excitation, Oluwaseun A. Badewa, Ali Mohammadi, Donovin D. Lewis, Somasundaram Essakiappan, Madhav Manjrekar, Dan M. Ionel

Electrical and Computer Engineering Graduate Research

This paper introduces innovative designs for synchronous electric motors with phase coils and permanent magnets (PM) or DC-excitation coils embedded in the stator. Alongside concentrated phase coils in dedicated slots, the spoke-type PMs offer high flux intensification, while the option for DC-excitation coils eliminates demagnetization risks. Since the rotor has no active electromagnetic components, the machine can achieve high-speed operation while enabling advanced cooling systems focused solely on the stator. A special implementation with a “wave” or “serpentine” DC-excitation winding which has the potential for reduced losses depending on the motor aspect ratio is presented. The operation, control, and polarity …

Harmonic And Non-Linear Effects On The Parameters And Performance Of A Vernier Machine With Flux Concentrating Spoke Rotor, Ali Mohammadi, Yaser Chulaee, Aaron M. Cramer, Ion G. Boldea, Dan M. Ionel

Electrical and Computer Engineering Graduate Research

This paper presents a systematic study on the MAGNUS machine, which is an innovative dual-stator axial flux permanent magnet vernier machine (AFPMVM). The MAGNUS machine features a novel single-wound dual-stator design with minimal slots and an exceptionally high-polarity spoke-type permanent magnet rotor, which enables a very high flux concentration ratio. The operating principle of vernier machines is derived, showing the possible slot-pole combinations. Inductance components are introduced, and multiple methods are employed to determine the direct and quadrature axis inductances, revealing that despite its spoke-type rotor, due to a high harmonic content and a high differential leakage inductance, the MAGNUS …

Topology And Parameter Joint Identification In Imbalanced Low-Voltage Distribution Networks Based On Load Characteristic Propagation, Yanan Zhang, Gan Zhou, Huan Mao, Wei Gu, Yanjun Feng, Rui Bo

Electrical and Computer Engineering Faculty Research & Creative Works

Low-voltage distribution networks often suffer from incomplete or outdated network records, making it challenging to obtain the topology and line parameters under actual operating conditions. To address this issue, a joint identification method is proposed based on the propagation of load transient characteristics. First, the principle of load characteristic propagation is elaborated, and the concept of coupling impedance is introduced. Second, a set of linear regression equations is established based on the changes in current and voltage of the terminal measurements before and after load switching, and then these equations are solved using the least squares method to form the …

Plasmonic Nanopore Sensing For The Characterization Of Viruses And Biomolecules, Scott Renkes

Bioengineering Dissertations - Archive

The rapid advancement of nanomedicine has enabled increasingly precise nanotherapeutic platforms, including targeted nanoparticles, monoclonal antibodies, and viral gene delivery vectors. As these technologies mature, quality control and analytical characterization have emerged as critical bottlenecks, particularly in systems where functional outcomes depend on one-to-one molecular or particle–biological interactions. Conventional ensemble-averaged techniques obscure heterogeneity that is often central to therapeutic efficacy, safety, and manufacturability. A prominent example is adeno-associated virus (AAV)–based gene therapy, where production yields heterogeneous populations of empty, partially loaded, and fully loaded capsids. Genome fill percentage and integrity directly influence therapeutic efficacy and dosing accuracy, while limited understanding …

Life Cycle Assessment Approach For Trenchless Cured-In-Place Pipe Sewer Renewal Method, Shiva Mandari

Civil Engineering Theses - Archive

The advancement of underground infrastructure is vital to the development of modern society and continues to inspire technological progress. As environmental concerns grow, innovative approaches to pipeline rehabilitation are increasingly emphasizing sustainability. Assessing and contrasting the environmental effects of renewing existing pipelines versus complete replacement is key to fostering eco-conscious improvements in subsurface utility systems. Cured-in-Place Pipe (CIPP) is a commonly used trenchless method for rehabilitating pipelines. It involves inserting a flexible liner, saturated with resin, into the existing pipe. This insertion can be achieved through inversion using air or water pressure, or by mechanically pulling and inflating the liner. …

Assessment Of The Feasibility Of Utilizing Plastic Waste In Infrastructure To Promote Circular Economy In Bangladesh, Md Lutfor Rahman

Civil Engineering Dissertations - Archive

This study presents a comprehensive assessment of municipal solid waste (MSW) and plastic waste characterization across Bangladesh, with a focus on circular economy opportunities and the long-term economic viability of plastic road. Using on-site waste characterization data for 13 major cities from four geographic zones of Bangladesh —Northwest, Northeast, Southwest, and Southeast—the research identifies food waste as the dominant component of the national waste stream (67.3%), followed by plastic (12.4%), textiles (7.8%), and paper (4.7%). Among plastics, low-density polyethylene (LDPE) overwhelmingly dominates (89.7%), highlighting the continued prevalence of single-use flexible plastics.

A life cycle cost analysis (LCCA) was conducted comparing …

Characterization Of Dc Arc Flash Events Generated By Electrochemical Energy Storage, Nicolaus E. Jennings

Electrical Engineering Dissertations - Archive

The increasing rise in the use of electrochemical energy storage (ECES) like in the form of valve regulated lead acid (VRLA) batteries, lithium-ion (Li-ion) batteries, electric double layer capacitors (EDLC), and metalized film, oil filled capacitors prompt new challenges concerning electric worker safety. The primary safety hazards associated with ECES are electric shock and arc flash. The electric shock hazard is well understood to the extent where it is known what potential and exposure duration will cause levels of pain and ultimately fatality. Various personal protective equipment (PPE) like insulating gloves allow electric workers to perform maintenance with sufficient protection …

Enhanced Load Detection With Data-Driven Appliance Signatures Using Mixed Integer Linear Programming In Non-Intrusive Load Monitoring, Marina Materikina

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Despite the numerous research studies and interest in the non-intrusive load monitoring (NILM) area to improve energy efficiency, the problem of accurate and precise disaggregation of electrical devices has not been solved yet. The goal of our research is to build a method with a focus on higher accuracy on complex state-based appliances, which most approaches struggle to detect due to their power signal complexity and low consumption. Our approach is NILM with data-driven signatures (DS), with the ability to potentially predict power usage over time that would work great for suitable applications such as demand response, anomaly detection, and …

A Multi-Method Geophysical Approach For Complex Shallow Landslide Characterization, Mohammadyar Rahimi, Clinton Wood, Meersad Fathizadeh, Salman Rahimi

Civil Engineering Faculty Publications and Presentations

This case study demonstrates the value of combining multiple non-invasive geophysical methods to characterize a landslide along Highway 7 near Jasper, Arkansas, USA. Geophysical testing was conducted using Multichannel Analysis of Surface Waves (MASW), Horizontal to Vertical Spectral Ratio (HVSR), and Electrical Resistivity Tomography (ERT), supplemented by select soil borings. The geophysical investigation aimed to provide a high-resolution, near-continuous view of subsurface conditions, including bedrock depth and the location of the groundwater table or highly saturated zones within the slide area. These factors are important contributors to slope instability. The MASW results revealed a highly variable depth to weathered bedrock …

Enhancing Irs Localization Via Ml-Driven Aoa And Distance Estimation, Nikhila Kotlapara Surendran

Theses and Dissertations

Intelligent Reflecting Surfaces (IRSs) are transforming next-generation wireless networks by enabling dynamic control of the propagation environment for improved localization and security. This thesis advances Angle-of-Arrival (AoA) and distance estimation in IRS-assisted systems using a hybrid architecture with active sensing and passive reflecting elements. A modified MUSIC algorithm, optimized for near-field localization, decouples 2‑D AoA and 1‑D range estimation using a grid-and-peak pseudo-spectrum scan, achieving sub-degree AoA (0.003 rad) and sub-meter range (0.05 m) accuracy with over 100× lower complexity than classical 3D MUSIC.

The study further applies the algorithm to the DeepMIMO dataset (O1_28 scenario, 3.5 GHz) using …

A Fault-Tolerant Exchange-Coupled Spin-Ensemble Qubit At Elevated-Temperatures, Aniruddha Chakraborty

Theses and Dissertations

This thesis introduces a novel qubit architecture: the ferromagnetic exchange-coupled spin ensemble qubit (E-qubit), designed to address the noise-induced instability. In this work, the time evolution of the ensemble’s density matrix is studied using the Liouville–von Neumann equation. To benchmark against a single-spin qubit, the gate fidelity of an E-qubit is computed in the presence of thermal noise. Coherence time is also analyzed under identical thermal condition and a linear scaling is observed with qubit size . The results show that, at 6 K , the gate fidelity error (0.7 % ) of the seven- spin ensemble is an order …

Accelerated Test Method (Atm) For The Evaluation Of External Sulfate And Chloride Attack On Concrete Using Artificial Climate Environment (Ace): An Assessment Of Methodology, Eli Walker

College of Graduate Studies: Theses & Dissertations

This study seeks to investigate a testing methodology that utilizes accelerated testing methods (ATM) in conjunction with nondestructive testing methods (NDT) to assess destructive ion attacks on concrete. Through the testing of concrete samples, the impacts of chloride and sulfate ions on concrete will be tested by subjecting concrete to cyclic testing in an artificial climate environment. Electrical resistivity (ER) and ultrasonic pulse velocity (UPV) testing will evaluate the impact of the accelerated testing on the migration of destructive ions within the pore structure of the tested concrete. Based on this investigation, comparisons between accelerated, non-accelerated, and control samples will …

Enhancing The Mechanical Properties Of Sla 3d-Printed Bio-Resin From Linseed Oil Using Cellulose And Lignin Biopolymers, Chukwunonso A. Ikedionu

College of Graduate Studies: Theses & Dissertations

Abstract

This research explores the development of bio resin from linseed oil by the process of epoxidation and acrylation to produce acrylated epoxidized linseed oil (AELO). Lignin and cellulose biopolymers were added as reinforcement at varying weight fractions of 1 wt.%, 2.5 wt.%, and 5 wt.%, and their mechanical performance was compared against pure AELO. The formulations were printed using an Elegoo SLA 3D printer to create standardized test specimens like tensile bars, compression cylinders, and hardness blocks, which were all prepared according to the ASTM testing standard.

The results indicate that reinforcement effects depend on both filler type and …

Viscoelastic Property Analysis Of A Magnetorheological Elastomer Micropump For Insulin Delivery In Type 1 Diabetes, Victor Buitimea

College of Graduate Studies: Theses & Dissertations

Over two decades, there has been a significant rise in awareness regarding Type 1 Diabetes (T1D), leading to a deeper comprehension of numerous variables, including hereditary factors, patterns of occurrence, and health challenges. According to the Type 1 Diabetic Index, around 8.7 million people worldwide are affected by this chronic autoimmune illness marked by a lack of insulin and hyperglycemia. The introduction of artificial pancreas systems could save more than half a million patients by 2040. Despite the availability of various insulin delivery technologies that are offered to diabetic patients, many still are skeptical of this modern system. The issues …

Methylene Blue Adsorption On Y-Zeolite As A Nano-Porous Adsorbent: Equilibrium And Kinetic Studies, Mehdi Narimani, Maryam Gonbadi, Mohammad Mahdi Zerafat

Research outputs 2022 to 2026

The elimination of dye pollutants from industrial wastewaters, notably from sectors such as textiles and dyeing, remains a pivotal aspect of pollution mitigation endeavours. This research introduces an innovative strategy employing Y zeolite as a nano-porous adsorbent for eliminating methylene blue (MB), a prevalent cationic dye. Y zeolite was synthesised via hydrothermal technique. Through methodical experimentation, the impact of temperature, contact time, concentration, pH and adsorbent quantity on removal efficiency were examined with optimal conditions achieving 93.83% MB removal. The synthesised Y zeolite underwent characterisation utilising diverse techniques, including SEM, TEM, XRD, BET, and FTIR, which elucidated the structural and …

Corrosion Behavior Of Niti Alloys Fabricated By Laser Powder Bed Fusion In Relation To The Formed Passive Films In Hank's Solution, Yi Fan Zhang, Liang Yu Chen, Yong Liu, Hong Yu Yang, Jin Hua Peng, Chuanbo Zheng, Lina Zhang, Lai Chang Zhang

Research outputs 2022 to 2026

Laser powder bed fusion (L-PBF) produced NiTi alloys have significant potential in biomedical applications. Varying the parameters of the L-PBF process may result in the NiTi alloys with different ratios of B2 and B19′ phases, thereby, the different corrosion performance in the human body. However, a dearth of research efforts remains dedicated to resolving this issue. This work employed three different but comparable sets of parameters in the L-PBF process to produce NiTi alloys with different ratios of B2 and B19′ phases. The corrosion behavior of samples in Hank's solutions with the addition of lactic acid and their evolution of …

Sub-Bituminous Coal As A Peculiar Adsorbent For Dye Removal From Wastewater, Z. H. Rada, H. R. Abid, M. B. Ahmed, M. Zargar

Research outputs 2022 to 2026

Coal, an abundant and cost-effective adsorbent, is explored for its potential in environmentally friendly greenhouse gas storage. Herein, the adsorption of anionic (methyl orange) and cationic (methylene blue) dyes on sub-bituminous coal was intensively studied. This study is the first application of sub-bituminous coal to examine the removal of different concentrations of dyes from water. The properties of the coal were studied using advanced analytical techniques. The initial dye concentration, solution pH, and adsorbent-adsorbate contact time were investigated for their influence on the adsorption efficiency of the dyes. Adsorption kinetics were then studied by applying common kinetic models and the …

Characterization Of Load-Bearing And Failure Properties Of Fractured Rock Masses Reinforced By Negative Pressure Grouting, Juejing Fang, Kelly Yang, Farhad Aslani, Xin Lyu, Xiang He, Guiquan Li, Jiqiang Zhang

Research outputs 2022 to 2026

Grouting injection is a vital technique for addressing the challenges of high stress and significant deformation in the surrounding rock during deep mining operations, playing a crucial role in promoting green and low-carbon extraction methodologies. In this study, grouting reinforcement processes were examined by conducting grouting experiments on a fractured rock with varying negative pressures (0–100 kPa), followed by uniaxial compression testing of the grout-reinforced bodies. This investigation explored the diffusion patterns of grout under negative pressure and established a constitutive model of damage-bearing capacity for bodies reinforced by negative pressure grouting. It further studied the enhancement effect of negative …

Design Of A Robust Adaptive Cascade Fractional-Order Nonlinear-Based Controller Enhanced Using Grey Wolf Optimization For High-Power Dc/Dc Dual Active Bridge Converter In Electric Vehicles, Seyyed Morteza Ghamari, Daryoush Habibi, Mehrdad Ghahramani, Asma Aziz

Research outputs 2022 to 2026

The dual active bridge (DAB) converter is a key technology in electric vehicles (EVs), offering efficient, bidirectional DC–DC power conversion with galvanic isolation. This paper presents a novel cascade control strategy incorporating a fractional-order PID (FOPID) controller in the outer loop for precise voltage regulation and an adaptive backstepping controller (ABSC) in the inner loop for robust current control. The ABSC is designed using Lyapunov stability theory, ensuring systematic stabilization of nonlinear dynamics and robust performance under disturbances. The FOPID controller introduces superior filtering characteristics, effectively mitigating high-frequency measurement noise and transient disturbances, making it highly suitable for high-frequency power …

Investigating The Potential Of Remote Ultraviolet Sensing For Real-Time Produced Water Monitoring: A Lab-Scale Study, M. Weir, T. Robertson, D. I. Maroef, M. L. Johns, M. Zargar

Research outputs 2022 to 2026

Traditional produced water discharge monitoring techniques involve ‘end of pipe’ sample collection and analysis, offering a snapshot of discharged fluid composition and predicting the marine environmental risk through dispersion models. This study presents a proof-of-concept analysis of using ultraviolet remote sensing for real-time produced water monitoring, enabling data capture directly within the marine environment. Ultraviolet imaging was used to quantify the sheen intensity of artificially prepared produced water standards and to evaluate the relationship between image signal intensity and total petroleum hydrocarbon concentration over time. A statistically significant relationship was observed between signal intensity and total petroleum hydrocarbon concentrations, with …

A Comparative Study Of Aluminium Properties Manufactured Using Additive Friction Stir Deposition (Afsd) And Wire Arc Additive Manufacturing (Waam), Numan Habib, Ana Vafadar, Ferdinando Guzzomi

Research outputs 2022 to 2026

Wire arc additive manufacturing (WAAM) has recently gained considerable attention due to its capability to manufacture large-size metal with a length of one meter or above, with good microstructural and mechanical properties. However, the manufacture of critical components exposed to extreme environmental conditions, such as high stresses, remains the focus of most research studies. The applications of WAAM in high-tech industries, such as aerospace and marine modes, remain limited due to metallurgical challenges such as oxidation, porosity, cracking, and deformation, especially for high-strength aluminium alloys, including 6XXX and 7XXX series. The aforementioned metallurgical challenges in WAAM are minimized to some …

Assessing Techno-Economic Performance Of Synchronous Condensers And Static Synchronous Compensators In Renewable Energy-Integrated Weak-Grids Using Hedge Feedforward Feedback-Based Online Gated Recurrent Unit, Md Ohirul Qays, Iftekhar Ahmad, Daryoush Habibi, Mohammad A.S. Masoum

Research outputs 2022 to 2026

To achieve net-zero targets in many counties, renewable energy generators (REGs) are integrated with grids where less fault current is produced compared to synchronous generators. Accordingly, fault level availability, known as ‘system strength’, is reduced at point of coupling (POC) buses. A minimum system strength level is crucial for REGs to accurately detect and ride-through faults. To maintain adequate system strength in renewable energy-based weak grids, researchers and engineers have recommended supplementary devices, such as synchronous condensers (SynCons) or static synchronous compensators (STATCOMs), to provide the required fault-current. Because SynCons and STATCOMs are costly devices, their optimal sizes and placement …

Excellent Strength-Ductility Synergy Property Of Wire-Arc Additively Manufactured Mg-Gd-Y-Zr Alloy Investigated By Heat Treatment, Jiamin Li, Meng Huang, Juan Hou, Xingbin Wang, Gaopeng Xu, Yi Yang, Ning Mo, Yun Shi, Laichang Zhang, Weineng Tang

Research outputs 2022 to 2026

In this work, the GW63K (Mg-6.54Gd-3.93Y-0.41Zr, wt.%) alloy wire was utilized as the feedstock material and the thin-walled component was fabricated using wire-arc additive manufacturing technology (WAAM). The microstructural evolution during deposition and subsequent heat treatment was explained through multi-scale microstructural characterization techniques, and the impact of heat treatment on the strength-ductility synergy of the deposited alloy was systematically compared. The results showed that the microstructure of the deposited sample was mainly composed of fine equiaxed α-Mg grains and Mg24(Gd,Y)5 phase. The optimized solution heat treatment (450 °C × 2 h) had little effect on the grain size, but can …