1,721,014 research outputs found
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Structural Design of a Geodesic-inspired Structure for Oculus: Solar Decathlon Africa 2019
No full textThe goal of this project was to create the structural design for a lightweight dome frame structure for the 2019 Solar Decathlon Africa competition in Morocco. The design consisted of developing member sizes and joint connections using both wood and steel. In order to create an innovative and competitive design we incorporated local construction materials and Moroccan architectural features. The result was a structure that would be a model for geodesic inspired homes that are adaptable and incorporate sustainable features
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The Technological Evolution of Three Office Buildings Over Time
No full textFrom the 1920s until present day, the technological evolution of the office building, or more specifically, the office building skyscraper has been eminent. From past to present, the functions of this building have changed dramatically and with this change, a component cost shift has occurred. An investigation of different technologies that have transformed over the years has been performed on three notable skyscrapers: the Empire State Building (1931 completion), the World Trade Center (1971 completion), and One World Trade Center (late 2013 projected completion). All buildings are located in New York City, New York and were constructed at relatively equal intervals throughout time, from each other. A building can be broken down into different elements and for this analysis; five specific components were investigated. They were the podium, also known as the foundation and floors, the load-bearing members of the structure, or frame, the veneer or curtain wall system, the interior finishes of the building and any machinery involved with the buildings functional usage. All three buildings incorporate all five of these components in their design, but there are distinctions as to how the percentages of importance of each changed as the evolution and knowledge of technology progressed throughout time. This study has addressed the different methods each building used to achieve a technological cutting edge of their respective periods of time of construction, within the scope of the five main building components
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Impacts of Connection Stiffness on Moment Curvature in Cold-Formed Steel Design
No full textCold-formed steel (CFS) has risen in popularity in recent years as an alternative to structural steel. In essence, CFS is hot-rolled structural steel that is further rolled and processed at room temperature; this additional processing produces more finished and accurately sized members. When design considerations are taken into account, cold-formed steel members can be utilized beyond typical automotive and storage rack applications. Initially replacing the use of wooden studs in residential construction, this material has gradually been applied to wider structural engineering projects such as primary and secondary framing in low and mid-rise buildings. This work studied the impact of connection stiffness on the moment curvature of fastened CFS elements in free-standing structures. The mechanics of structural steel and CFS elements were established through a literature review followed by parametric investigations using case study models to explore the behavior of steel members and their associated influence on the system as a whole. The impacts of varying load conditions and the removal of redundant structural members were also examined to study the system's load path distribution prior to the application of detailed connections. Bolts and screws of comparable size were utilized in connection design and applied to the CFS models to investigate the performance of both types of fasteners based on their inherent differences in connection stiffness developed as a result of a screw’s increased exterior thread area compared to that of a bolt. The resulting moment-curvature relationships were noted for each connection and compared to the moment-curvature formulations defined by the Frye-Morris model for typical structural steel connections. It was found that the use of screwed fasteners in CFS construction could provide a more resilient design compared to those employing bolted fasteners. It was also found that the constructability of CFS structures could be improved when using screwed connections because this would eliminate the need to pre-punch holes in CFS members and reduce the number of elements required to fasten members together. Additionally, a modified version of the Frye-Morris model was suggested to expand its application to CFS structures with screwed connections
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Deformation Mechanisms in Bioinspired Multilayered Materials
No full textLearning lessons from nature is the key element in the design of tough and light composites
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Design Analysis of Roller Coasters
No full textEach year 300 million people ride roller coasters at amusement parks across the United States. Although they are meant for joy and entertainment, the design is very crucial and regulated. Understanding the interaction between components and humans can help create a more thrilling and safer ride. This study researched the design of the course and the structural supports. A unique roller coaster was designed, investigating the relationship between velocity and G forces. With the profile design complete, the corresponding forces resulting from the track and train weight and train movement were calculated to determine the required dimensions of the structural support columns. This work investigated the relationship between the features of the roller coaster and the material properties of the structural supports, determining which are most impactful for the loading conditions. These results can be used to determine the required properties of a roller coaster’s structural system to maximize the material usage to minimize resources and cost
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Investigating Mechanical Behavior and Manufacturing Pathways of High Entropy Alloys: A Multiscale and Multifunctional Approach
No full textHigh Entropy Alloys (HEAs), composed of multiple principal elements in near-equiatomic ratios, have emerged as a transformative class of materials due to their exceptional mechanical properties, thermal stability, and structural versatility. This thesis provides a comprehensive investigation into the multiscale strengthening mechanisms, bulk processing techniques, and small-scale deposition approaches for HEAs, contributing both foundational understanding and technological relevance. The first segment of this work explores the intrinsic sources of strength in HEAs. Through analytical modeling and experimental validation, the role of short-range order (SRO) is quantified using chemical potential relationships and Warren-Cowley parameters. The indentation size effect (ISE) is examined via nanoindentation, highlighting scale-dependent hardness trends influenced by lattice distortion and compositional complexity. Furthermore, micropillar compression studies elucidate the microscale plastic deformation mechanisms and stress-strain responses inherent to HEA systems. The second segment addresses bulk synthesis methodologies. Arc melting and mechanical alloying are investigated in detail, with processing parameters correlated to resulting microstructures and mechanical performance. These findings form a baseline for future work in additive manufacturing, where Directed Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM) are proposed as emerging pathways for geometrically complex HEA components. The final segment shifts focus to small-scale and surface applications using cold spray technology. After establishing the fundamentals of cold spray mechanics, two peer-reviewed case studies on Al-6061 and Ti/Ti6Al4V coatings are embedded to benchmark process behavior. Building upon these, a proposed framework for cold spraying HEAs is outlined, emphasizing deposition challenges, feedstock design, and future characterization efforts. This integrated study advances the fundamental understanding of HEA strengthening and processing across scales, while laying groundwork for future functional applications in coatings and additively manufactured components. The thesis contributes to bridging the gap between theoretical insight and scalable materials engineering in the field of high entropy alloys
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Pressure-Operated Soft Robotic Snake Modeling, Control, and Motion Planning
No full textSearch and rescue mobile robots have shown great promise and have been under development by the robotics researchers for many years. They are many locomotion methods for different robotic platforms, including legged, wheeled, flying and hybrid. In general, the environment that these robots would operate in is very hazardous and complicated, where wheeled robots will have difficulty physically traversing and where legged robots would need to spend too much time planning their foot placement. Drawing inspiration from biology, we have noticed that the snake is an animal well-suited to complicated, rubble filled environments. A snake’s body has a very simple structure that nevertheless allows the snake to traverse very complex environments smoothly and flexibly using different locomotion modes. Many researchers have developed different kinds of snake robots, but there is still a big discrepancy between the capabilities of current snake robots and natural snakes. Two aspects of this discrepancy are the rigidity of current snake robots, which limit their physical flexibility, and the current techniques for control and motion planning, which are too complicated to apply to these snake robots without a tremendous amount of computation time and expensive hardware.
In order to bridge the gap in flexibility, pneumatic soft robotics is a potential good solution. A soft body can absorb the impact forces during the collisions with obstacles, making soft snake robots suitable for unpredictable environments. However, the incorporation of autonomous control in soft mobile robotics has not been achieved yet. One reason for this is the lack of the embeddable flexible soft body sensor technology and portable power sources that would allow soft robotic systems to meet the essential hardware prerequisites of autonomous systems. The infinite degree of freedom and fluid-dynamic effects inherent of soft pneumatics make these systems difficult in terms of modeling, control, and motion planning: techniques generally required for autonomous systems.
This dissertation addresses fundamental challenges of soft robotics modeling, control, and motion planning, as well as the challenge of making an effective soft pneumatic snake platform. In my 5 years of PhD work, I have developed four generations of pressure operated WPI soft robotics snakes (SRS), the fastest of which can travel about 220 mm/s, which is around one body per second. In order to make these soft robots autonomous, I first proposed a mathematical dynamical model for the WPI SRS and verified its accuracy through experimentation. Then I designed and fabricated a curvature sensor to be embedded inside each soft actuator to measure their bending angles. The latest WPI SRS is a modularized system which can be scaled up or down depending on the requirements of the task. I also developed and implemented an algorithm which allows this version of the WPI SRS to correct its own locomotion using iterative learning control. Finally, I developed and tested a motion planning and trajectory following algorithm, which allowed the latest WPI SRS to traverse an obstacle filled environment. Future research will focus on motion planning and control of the WPI SRS in outdoor environments utilizing the camera instead of the tracking system. In addition, it is important to investigate optimal control and motion planning strategies for mobile manipulation tasks where the SRS needs to move and manipulate its environment.. Finally, the future work will include the design, control, and motion planning for a soft snake robot where each segment has two degrees-of-freedom, allowing it to lift itself off the ground and traverse complex-real-world environments
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Bioinspired Approaches for Enhancing Concrete Durability and Sustainability
No full textConcrete is the backbone of modern infrastructure, yet its durability and environmental impact remain significant concerns. As the most widely used construction material, it accounts for approximately 8% of global CO2 emissions, contributing to climate change while facing inherent challenges such as cracking, permeability, and steel reinforcement corrosion. These factors significantly reduce service life, necessitate frequent repairs, and increase maintenance costs. Traditional repair methods, such as epoxy coatings and chemical corrosion inhibitors, often fail to provide long-term resilience, while conventional reinforcement techniques—primarily steel rebars and fiber additives—lack adaptability and efficiency in mitigating stress concentrations. The need for sustainable, long-lasting, and high-performance solutions for concrete durability has never been more urgent, particularly as global infrastructure demands continue to grow. This research presents a bioinspired approach to enhancing concrete performance by leveraging Carbonic Anhydrase (CA), a naturally occurring enzyme, to improve corrosion resistance and self-healing capabilities. CA acts as a catalyst, accelerating the reaction between atmospheric CO2 and calcium ions in the cementitious matrix to precipitate calcium carbonate CaCO3, which seals cracks and densifies the microstructure. Laboratory tests on CA-modified concrete demonstrate significantly reduced permeability, enhanced crack-sealing properties, and greater resistance to chloride ion ingress, a primary driver of rebar corrosion. Microstructural analysis confirms that CA-treated samples develop denser pore structures and mineralized protective layers, slowing degradation and extending structural longevity. Accelerated corrosion testing further indicates delayed crack formation and reduced corrosion rates, outperforming conventional repair materials. Computational diffusion modeling supports these findings, highlighting reduced ion transport rates and extended service life predictions for enzymatic concrete. Beyond structural benefits, Life Cycle Assessment (LCA) reveals that enzymatic concrete provides significant environmental advantages, primarily by extending infrastructure lifespan, reducing material consumption, and minimizing CO2 emissions associated with repairs and replacements. By sequestering carbon dioxide into durable mineral phases, this method contributes to carbon capture efforts, presenting a scalable, low-energy alternative for increasing concrete resilience while addressing sustainability concerns. Additionally, this research explores an innovative reinforcement strategy using 3D-printed auxetic structures with negative Poisson ratios (NPRs). Auxetic geometries, such as brick-and-mortar, bowtie, and tubular designs, are fabricated using stainless steel, aluminum, and polylactic acid (PLA) and evaluated for their impact on stress distribution and energy absorption. Experimental and numerical results indicate that stainless steel tubular auxetic reinforcements surpass conventional reinforcement strategies in load redistribution and crack propagation delay. These findings demonstrate the potential for integrating auxetic reinforcement with enzymatic concrete to further enhance resilience, toughness, and mechanical efficiency. By combining bioinspired self-healing strategies with advanced reinforcement techniques, this research provides a transformative framework for next-generation concrete materials. The findings offer a scalable solution to improving structural durability, reducing environmental impact, and increasing the sustainability of concrete infrastructure worldwide
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