Digital Commons Network^™

Functionalized Loblolly Pine Derived Ultraporous Activated Hydrochars For Efficient Carbon Capture, Swarna Saha

Theses and Dissertations

The increasing concentration of anthropogenic carbon dioxide (CO₂) emissions has intensified the demand for efficient and sustainable carbon capture technologies. This dissertation investigates the development of functionalized ultraporous activated hydrochars derived from loblolly pine through hydrothermal carbonization (HTC) followed by chemical activation for enhanced CO₂ capture applications. Different functionalization strategies, including deep eutectic solvent (DES) modification, zeolite-assisted HTC, palladium-assisted HTC, and CO₂-assisted HTC, were systematically explored to evaluate the influence of pore structure, surface chemistry, and adsorption energetics on CO₂ capture performance. The synthesized materials were characterized using BET, FTIR, XRD, TGA, SEM, and adsorption isotherm modeling to establish the …

Five-State Seismic Damage Classification Of Steel-Girder Bridges On Soft Soil Using Directional Intensity Measures And Multi-Parameter Damage Indices, Ibrahim Alomari, Woubishet Zewdu Taffese, Mohammad Hossein Afsharmovahed, Genda Chen

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Rapid yet accurate post-earthquake damage assessment of highway bridges is essential to ensure transportation network resilience. Traditional inspection, fragility analysis, and finite element modeling are time-consuming or inaccurate for real-time decision-making. This study compares ten machine-learning classifiers for the seismic damage states of highway steel-girder bridges that incorporate directional intensity measures to represent the variance of ground motions. Based on the nonlinear time-history analyses of two Missouri bridges, one Michigan bridge, and one Wisconsin bridge, multi-parameter structural damage indices were proposed and mapped to five damage states from none to collapse. Among ten supervised algorithms studied, the artificial neural network …

Field Calibration Of Flow Over Tilting Weirs In Canals, Joseph E. Pugh, Timothy K. Gates, S. Karan Venayagamoorthy, Caner Kutlu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Tilting weirs are widely used to regulate water levels in open channel irrigation systems and can also provide flow measurement capability that helps optimize irrigation efficiency and ensure equitable water distribution. This case study demonstrates adaptation of lab-based tilting weir ratings to field settings, where flow behavior is more complex. We compile and analyze an extensive data set derived from independent studies of five structures within three canal systems, featuring both lined and unlined channels with discharge ranging from 0.35 to 15 m3/s (12 to 530 ft3/s). Results indicate that lab-based rating equations can be calibrated to account for site-specific …

Barrier-Drainage Performance Of A Wicking Geotextile In Controlling Capillary Rise In Silt: Experimental Evaluation, Dahao Zou, Yipeng Guo, Jiejin Chen, Yafeng Li, Xiong Zhang, Yongjie Zhang, Luqiang Ding

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Capillary rise in silt significantly degrades its strength and durability, yet the hydraulic mechanisms governing moisture control using wicking geotextile in silt remain insufficiently understood. This study investigates the barrier-drainage performance of a wicking geotextile in silt through one-dimensional column experiments, supported by preliminary trials. Three configurations were examined: a control specimen without geotextile (CS), an embedded configuration (ES), and a surface-exposed configuration (SES). Volumetric moisture content and matric suction were monitored, capillary responses at the soil-geotextile interface and water storage behavior were evaluated. The results show that the wicking geotextile initially acts as a temporary capillary barrier due to …

Impact Of Climate Change On Extreme Windstorms And Implications For Structural Design In The United States, Teng Wu, Reda Snaiki, Frank Lombardo, Sihan Li, Michele Barbato, Guirong Yan, Robert J. Trapp

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Climate change impacts various extreme windstorms associated with specific meteorological phenomena in different ways. Because various windstorms contribute to the design wind speeds, this study systematically reviewed the state-of-the-art understanding of climate change effects on wind events that collectively contribute to structural wind design in North America, particularly the US, including extratropical cyclones (as well as nor'easters), tropical cyclones, thunderstorms, and tornadoes. For each windstorm type, the general evidence of climate change impacts on storm activities (e.g., occurrence frequency and intensity) are summarized, followed by the introduction of existing simulation frameworks for yearly (or subyearly) maximum storm winds under changing …

A Transfer-Learning And Continuous Optimization-Based Framework For Predicting Heat Treatment-Dependent Mechanical Properties Of Ded-Processed Low-Alloy Steels, Atiqur Rahman, Sung Heng Wu, Ranjit Joy, Frank Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Directed energy deposition (DED) of low-alloy steels involves strongly coupled effects among alloy composition, solidification behavior, and post-deposition heat treatment, making mechanical property prediction difficult when target-domain data are limited. This study develops a transfer-learning and continuous optimization framework for predicting heat treatment-dependent yield strength (YS), ultimate tensile strength (UTS), hardness (HV), and as-solidified phase fractions of martensite, ferrite, and austenite in DED-processed low-alloy steels. A CALPHAD-based dataset was generated for 125 low-alloy steel compositions. A multilayer perceptron (MLP) surrogate was first trained as a baseline model, then fine-tuned through transfer learning and progressively updated as staged continuous optimization; the …

A Laboratory Investigation Of Energy Dissipators At Embankment Dams, Nathan L. Young

All Graduate Theses and Dissertations, Fall 2023 to Present

Dams play a critical role in protecting communities from flooding and providing reliable water supplies. When large amounts of water pass through a dam’s spillway during floods, the discharge can travel at high speeds and carry potentially destructive kinetic energy that can damage the dam or erode downstream channels if that energy is not properly controlled. To reduce this risk, engineers commonly use hydraulic structures called energy dissipators that slow spillway discharge and safely release it downstream.

Commonly used energy dissipators at embankment dams include stilling basins that rely on a hydraulic jump – a sudden rise in water depth …

Nanostructured Negative Electron Affinity Gallium Arsenide Photocathodes With Enhanced Quantum Efficiency And Extended Charge Lifetime For Advanced Photoinjectors, Md Aziz Ar Rahman

Physics Theses & Dissertations

This dissertation presents a comprehensive experimental and computational investigation of nanostructured negative electron affinity (NEA) gallium arsenide (GaAs) photocathodes. This work was undertaken to achieve higher quantum efficiency (QE) and longer charge lifetime than conventional flat NEA GaAs electron sources commonly used in photoinjectors. Finite-Difference Time-Domain and charge-transport simulations of three types of nanostructure geometries reveal substantial QE enhancement over flat GaAs via Mie resonance mode excitation. Consequently, the truncated nanocone array (TNCA) photocathodes with heights of 400, 700, and 1000 nm were fabricated and NEA activated via Cs-NF₃ deposition. In a low-voltage ultra-high vacuum chamber with a base pressure …

Decarbonizing The C3 Splitter: Performance Optimization And Environmental Impact Of Mvr Integration, Dalia A. Ali Associate Prof.

Chemical Engineering

Due to the relatively low volatility (α) of propane and propene components, their separation is one of the most energy-intensive processes in the petrochemical industry. This study evaluates the technical, environmental and thermodynamic performance of a mechanical vapor recompression (MVR) heat pump integrated into a C3 splitter, compared to a conventional steam-heated distillation column. A sensitivity study was conducted using Aspen Plus software at different pressures, reflux ratios (RR) and at turndown operations. According to the results, the MVR system uses a compressor to raise the overhead vapor pressure to 38.7 bar to operate the heater without the need for …

From Screening To Risk: Assessment Of Potentially Toxic Elements In Children's Toys Along The El Paso, Tx, U.S.A.-Ciudad Juarez, Chih, Mex Border Region, Jesus Rodriguez-Loya

Open Access Theses & Dissertations

Children are uniquely vulnerable to potentially toxic elements (PTEs), absorbing them more readily than adults and encountering them through the hand-to-mouth behaviors of early childhood. Exposure carries element-specific consequences: lead (Pb) impairs cognitive development with no established safe threshold; cadmium (Cd) damages the kidneys and reduces bone mineralization; arsenic (As) is a recognized carcinogen and developmental neurotoxicant; hexavalent chromium (Cr) is carcinogenic and induces allergic dermatitis; nickel (Ni) is the leading cause of allergic contact dermatitis in children; and excess zinc (Zn) disrupts copper absorption and causes gastrointestinal distress. Toys are a distinctive source of such exposure, yet none had …

Multi-Dimensional Framework For Industry 5.0: Integrating Human-Centric, Sustainability, And Operational Resilience, Tamer Adel Mohamed, Mohamed Boumalkha, Ahmed S.I. Amar

Mechanical Engineering

Industry 5.0 reframes digital transformation as a socio-technical endeavor in which automation serves human capabilities, environmental limits, and operational continuity. Yet, much of the current discourse remains either conceptual—lacking implementable metrics—or technologycentric— treating humans and sustainability as constraints instead of design objectives. This paper develops a multi-dimensional implementation framework that operationalizes the three pillars of Industry 5.0: human-centricity, sustainability, and operational resilience. We synthesize recent advances in collaborative robotics and safety-aware human–robot collaboration, digital twins (including human and supply-chain twins), and AI-driven decision support—augmented by emerging 6G ultra-reliable low-latency networking capabilities such as reconfigurable intelligent surfaces, terahertz communications, multi-access edge …

Experimental And Molecular Dynamic Simulation Assessment Of H2/Brine/Cement Interfacial Interactions During Underground Hydrogen Storage, Nurudeen Yekeen, Sikiru, Ahmed Al-Yaseri, Berihun Mamo Negash

Research outputs 2022 to 2026

Cement is widely used as a structural and sealing material to ensure hydrogen containment in geological formations. However, the influence of H2–brine–cement wettability and H2–brine interfacial tension (IFT) on the integrity and sealing efficiency of cemented caprocks remains poorly understood. Furthermore, previous studies provide limited insights into hydrogen adsorption and sorption behavior under subsurface storage conditions. In this study, wettability and IFT of H2–brine–cement systems were experimentally measured at pressures of 500–1000 psi and temperatures of 25–50 °C to evaluate hydrogen migration, trapping, and the performance of cemented seals. Molecular dynamics simulations were conducted at pressures of 500–3000 psi and …

Policy And Regulation In Virtual Power Plants Development, Hemlal Bhattarai, Aziz, Stefan Lachowicz

Research outputs 2022 to 2026

Electricity systems are changing due to the rapid deployment of distributed energy resources (DER), which also presents significant regulatory obstacles to their coordinated integration into energy markets and power grids. However, the majority of current material in publications concentrate on operational optimization and technical architectures, with little systematic synthesis of the legal and policy frameworks governing the deployment of VPP on a broad scale. To provide grid services, improve flexibility and support decarbonization objectives, virtual power plants (VPP) have become a crucial aggregation method. To close this gap, this research critically looks at the institutional roles, market structures, global policy …

Clogging Behaviour And Management In Two Full-Scale Infiltration Schemes: A Treated Wastewater Basin And A Surface-Water Weir In Australia, John Awad, Declan Page, Joanne Vanderzalm, Geoffrey J. Puzon, Jason Wylie, Falko Mathes, Debbie Reed, Michael Bartkow, Mehdi Khiadani, Karen Barry, Peter Dillon

Research outputs 2022 to 2026

Managed Aquifer Recharge (MAR) schemes are increasingly used to enhance water security, yet infiltration schemes are susceptible to clogging which consequently reduces operational efficiency. This study examines two full-scale Australian case studies: Jurien Bay (JB, Western Australia) and Lockyer Valley (LV, Queensland), representing treated wastewater (TWW) and surface water recharge, respectively. Recharge water at JB exhibited high clogging potential in relation to literature values proposed to manage clogging: total suspended solids (TSS) ranged from 100 to 176 mg/L (target ≤2 mg/L), turbidity 70–100 NTU (target ≤3 NTU), and total nitrogen (TN) 5–16 mg/L (target ≤10 mg/L). LV showed lower clogging …

Experimental Thermal-Hydraulic Performance Enhancement Of A Parabolic-Trough Solar Collector Using 3d-Printed Propeller-Shaped Turbulators, Shayan Pourhemmati, Barun Kumar Das, Majid Tolouei-Rad, Abdellah Shafieian

Research outputs 2022 to 2026

This experimental study investigates the thermal-hydraulic performance of a parabolic trough collector (PTC) equipped with propeller-shaped turbulators, which were 3D printed and installed along the absorber tube to enhance convective heat-transfer by increasing flow mixing. Nine turbulator configurations were tested by varying the blade angle (β = 22.5° and 45°, and β = 67.5°) and the number of turbulators (Nt = 6, 12, and Nt = 18) over a Reynolds number range of 1000 to 6000. To ensure a rigorous and unbiased comparison, all experiments were conducted under identical operating conditions, including a constant inlet temperature and a constant Reynolds …

Evaluating Echo2 Biochar As Sustainable Bitumen Binder Modifier In Road Pavements: High-Temperature Performance Characterisation, Adeel Iqbal, Nuha S. Mashaan, Themelina Paraskeva, Mohamed A. Shahin

Research outputs 2022 to 2026

The incorporation of bio-derived modifiers in bitumen binders presents a practical pathway toward sustainable, carbon-sequestering road pavement infrastructure. This study evaluates commercially produced ECHO2 softwood biochar as a modifier for Australian viscosity-graded C170 bitumen, combining microstructural, thermal, physical, and rheological characterization to assess its suitability as a high-temperature reinforcing modifier. In this study, biochar was incorporated at 3%, 6%, 9%, and 12% by weight, utilizing particles smaller than 75 µm to maximize interfacial interaction. Characterization via SEM-EDS, XRD, and TGA revealed a highly stable, carbon-rich, amorphous material with a rough, porous morphology, favourable for physical interlocking with the bitumen matrix. …

Morphological Determinants Of Multiple Courtyard Configurations In Contemporary Urban Housing: A Quantitative Analysis Of Plot Area And Frontage Width, Maha Khalaf Hammad, Hasan Abdulrazzaq Hasan

AUIQ Technical Engineering Science

In modern cities with small plots and narrow frontages, courtyard-based housing has come back as a flexible way to use space. This study seeks to quantitatively examine the impact of residential plot area and frontage width on the diversity and functional distribution of courtyards in modern urban housing. A quantitative morphological approach was used by looking at the shapes of 121 modern residential plans that included internal courtyards. Using AutoCAD, we got spatial data, and then we used Microsoft Excel to look at the relationships between plot morphology, courtyard number, area, and functional role. The results show that the courtyard …

Integrating Ai-Based Electricity Demand Forecasting With Solar Grid Planning To Enhance Sustainability And Reliability, Anas Thamer Mustafa, Omar Sharaf Al-Deen Al-Yozbaky

AUIQ Technical Engineering Science

Proper electricity-demand forecasting is essential for reliable power-system planning, particularly in urban networks facing rapid demand growth and transformer overloading. However, many previous studies have treated load forecasting and renewable-energy integration as separate tasks, which limits their usefulness for practical planning. This study develops an integrated forecasting–planning framework that links AI-based electricity-demand forecasting with photovoltaic (PV) system design and transformer-loading assessment. The framework is applied to real daily data from the Al-Intisar 132/33 kV substation in Mosul, Iraq, covering electrical load, temperature, population, and date-related variables for the period 2022–2024. Fourteen forecasting models from four methodological categories were evaluated: machine-learning …

A Fuzzy–Neutrosophic Suitability Index For Selecting An Appropriate Reasoning Model Under Vagueness, Incompleteness, And Conflict, Nada A. Nabeeh, Ahmed Samy

Neutrosophic Systems with Applications

Fuzzy reasoning and neutrosophic reasoning are both used to handle uncertainty, but they are not intended for the same uncertainty structure. Fuzzy reasoning is suitable when uncertainty appears mainly as gradual vagueness, where a value may belong to a concept such as ``high risk'' or ``good performance'' to a certain degree. In this case, a membership value is often sufficient. Neutrosophic reasoning is more suitable when the problem also contains incomplete information, undecided evidence, or conflict between sources. In such cases, one membership degree may be too limited because it cannot represent support, rejection, and indeterminacy separately. This study introduces …

Foundations Of Neutrosophic N-Semirings Theory And Structural Properties, Raja Muhammad Hashim, Muhammad Gulistan, Muhammad Shahzad

Neutrosophic Systems with Applications

In this paper the concept of neutrosophic n-semirings (S∪ I, ∗ ₁, ∗ _2, ∗ ₃,..., ∗ _n, ∗ _n+1) has been introduced. The substructure of n-semirings (S∪ I, ∗ ₁, ∗ _2, ∗ ₃,..., ∗ _n, ∗ _n+1) has been defined and some useful results have been proved. Moreover, in order to familiarize the readers with these concepts some worthy examples have been coined. The left, right and two sided ideals of neutrosophic n-semirings have been paid a special heed. Finally we have turned our discussion towards the compatible and congruence …

Neutrosophic Time-Truncated Acceptance Sampling Plans Based On The Exponentiated Weibull Distribution For Reliability Applications, Divya P.R., Preethi John

Neutrosophic Systems with Applications

Classical acceptance sampling plans require precisely specified parameter values, an assumption routinely violated by measurement uncertainty and gauge imprecision in practice. This article develops Neutrosophic Time-Truncated Acceptance Sampling Plans (N-TTASP) for the Exponentiated Weibull (EW) distribution by representing the scale parameter as a neutrosophic interval. The neutrosophic sample size n_N ∈ [n_L, n_U] and acceptance number c_N ∈ [c_L, c_U] are obtained by minimizing n_U subject to dual producer and consumer risk constraints on the neutrosophic Operating Characteristic interval. A new indeterminacy ratio η is introduced as a …

Evaluating Generative Ai-Based User Interfaces Using An Integrated Neutrosophic Multi-Criteria Decision-Making Framework, Nada Mohamed, Alshaimaa A. Tantawy

Neutrosophic Systems with Applications

User Interface (UI) design can be seen as an essential aspect of human-computer interaction (HCI) and makes communication easier between people and technology. In today's digital economy, interface quality has become one of the most important business concerns, since it has a direct impact on customer satisfaction and retention while affecting revenue. Although creating user-centered and accessible interfaces is crucial, doing so is a difficult and time-consuming process, which leads to burnout for many usability professionals. Although conventional artificial intelligence (AI) was utilized for design assessment and automation, the arrival of generative AI technology has created new possibilities for automated …

Systematic Review Of The Institutionalization Of Service Learning In Higher Education, Wilmer Hernan Cruz Gutierrez

ASEAN Journal of Community Engagement

An increasing number of universities are integrating service-learning (SL) to fulfill their social mission. However, sustainable institutionalization of SL remains a persistent challenge. This study identifies and analyzes the factors, actors, and strategies that drive and inhibit SL institutionalization in higher education. Using the PRISMA 2020 guidelines, a systematic literature review analyzed 52 documents from seven academic databases (including WoS, Scopus, and ERIC). The findings were grouped into three sections: cultural (integration into institutional values/missions), process (articulation within teaching, research, and outreach), and structural dimensions (dedicated support entities). The results obtained reveal a reciprocal relationship where cultural alignment enables processual …

Digraphicsoft Sets And Bidigraphicsoft Sets: Directed And Bidirected Extensions Of Graphicsoft Modeling, Takaaki Fujita, Ajoy Kanti Das, Suman Das, Sankar Prasad Mondal, Volkan Duran, Mithun Datta

Neutrosophic Systems with Applications

Uncertainty has been modeled through a wide variety of mathematical frameworks, including fuzzy sets, neutrosophic sets, rough sets, and plithogenic sets. Among these approaches, soft sets offer a parameterized representation of uncertain information and have inspired numerous extensions, such as multisoft sets, double-framed soft sets, hypersoft sets, SuperHyperSoft sets, TreeSoft sets, ForestSoft sets, IndetermSoft sets, and IndetermHyperSoft sets.
This paper focuses on GraphicSoft Sets, which extend the classical soft-set framework by assigning a subset of the universe to each subgraph of an attribute graph. In this way, relationships among attributes are incorporated directly into the parameterized model. Building on …

Thermal Degradation Analysis Of Bagasse Fibers From Sugarcane Waste, Rashmitha Suresh, Faisal Al Nasser

Journal of Mechanical Engineering Science and Technology (JMEST)

Sugarcane is one of the important commodities in the industry where bagasse fiber as waste is abundantly available.   Sugarcane bagasse fiber has high cellulose, a key element in the utilization of bagasse. Chemical pretreatment is important to prepare the natural fiber before used as composite reinforcement. The purpose of the study is to analyze the thermal degradation of bagasse fiber after being treated using NaOH and TEMPO solution. The manufacturing method was carried out by a series of washing bagasse with distilled water and NaOH solution, subsequently soaking it in 6% NaOH and 2,2,6,6-tetramethylpiperidine-l-oxyl (TEMPO) solution, and conducted oven-dried. Thermogravimetric …

Powered Parachute Vehicle For Crew Transportation On Mars, Louis J. Spier

Beyond: Undergraduate Research Journal

To support possible future human presence on Mars where bases are likely to be spread apart, aerial vehicles could be used to transport crew and cargo between them. Designing and operating such a vehicle is very challenging because of the low atmospheric density on Mars compared to Earth, the logistics involved with transporting it to Mars, and the infrastructure necessary to operate it. This study discusses the problems involved with designing, building, and operating fixed-wing and powered parachute aircraft on Mars and presents a concept involving a powered parachute vehicle utilizing an inflatable parachute wing that can be packed together …

Ascc-M Based Transformational Education Model For Enhancing Carbon Literacy And Agroecological Resilience Among Rural Farmers, Alya Dwi Arianty, Fitria Fatichatul Hidayah, Eny Winaryati, Rica Mae Badilla Guarin

Jurnal Pendidikan Geografi: Kajian, Teori, dan Praktek dalam Bidang Pendidikan dan Ilmu Geografi

Climate change has become a major ecological and social challenge affecting food security and agricultural sustainability worldwide. The agricultural sector significantly contributes to carbon emissions through fertilizer use and land conversion, particularly in developing countries. This study aims to conceptualize a place-based, technology-enhanced Transformational Education Model grounded in Agro-Smart Carbon Capture Microbiome (ASCC-M) technology, designed to strengthen rural farmers' carbon literacy and agroecological resilience while advancing geography education through deeper understanding of human–environment interactions, spatial agricultural processes, and climate-related dynamics within real rural landscapes. The research employed conceptual design through systematic literature review and model development, integrating theories of transformative …

Spatial Analysis Of The Environmental And Climatic Explanatory Relationship Of Photovoltaic Potential For Sustainable Shrimp Farming, Dyah Lestari Widaningrum, Roikhanatun Nafi'ah, Religiana Hendarti, Alexandra Catherine Djunaedi, Evaristus Didik Madyatmadja

Journal of Environmental Science and Sustainable Development

Sustainable shrimp aquaculture requires reliable and affordable energy, particularly for coastal pond aeration. However, identifying suitable locations for photovoltaic (PV) deployment remains challenging because ground-based solar-resource measurement is expensive, spatially limited, and difficult to maintain across large coastal regions. This study develops a village-level spatial framework to evaluate PV potential for shrimp aquaculture using open geospatial datasets. The analysis covered villages across Central Java, Special Region of Yogyakarta, and East Java. PV power potential (PVout), Global Horizontal Irradiation (GHI), and Direct Normal Irradiation (DNI) were obtained from the Global Solar Atlas; land surface temperature (LST) and precipitation were derived from …

Modeling Of Air-Water Filled Rubber Dam Under Hydrostatic Conditions, Qusay Khaleel, Thair Khayyun, Khudhayer Abdullah

Engineering and Technology Journal

Inflatable dams, also called rubber dams, are flexible cylindrical inflatable and deflatable structures attached to a rigid base; these dams are basically cylindrical tubes made of rubberized material and inflated by air, water, or a combination of the two. In this paper, the air/water inflatable dam was studied and analyzed numerically using ANSYS software. The 3-parameter Mooney-Rivlin Model was used to model the rubber material of the dam. At first, a physical model from literature was used to calibrate the results of the ANSYS software, and then a new model was analyzed with different dimensions and conditions. Thirty-six simulations were …

Size Effect On The Shear Strength Of Reinforced Concrete Beams, Hind Jaber, Kaiss Sarsam, Bassman Muhammad

Engineering and Technology Journal

According to research, as the depth of a beam increases, the section's shear strength can be expected to decrease. The size effect is a phrase that has been used to describe this tendency. Testing of unreinforced specimens under shear has also shown that the shear strength might be lower than what is typically anticipated in the design. As a result, it is critical to comprehend the behavior of these structures, as they may be influenced by a size impact. Sixteen reinforced concrete beams of different rectangular cross-sections without stirrups were tested. The tested beams were simply supported made of high-strength …