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Articles 35881 - 35910 of 196352

Full-Text Articles in Engineering

Impact Of Stormwater Infiltration On Rainfall-Derived Inflow And Infiltration: A Physically Based Surface–Subsurface Urban Hydrologic Model, Kun Zhang, Anthony J. Parolari Jul 2022

Impact Of Stormwater Infiltration On Rainfall-Derived Inflow And Infiltration: A Physically Based Surface–Subsurface Urban Hydrologic Model, Kun Zhang, Anthony J. Parolari

Civil and Environmental Engineering Faculty Research and Publications

The subsurface fate of stormwater infiltration enhanced by green infrastructure (GI) is unknown. GI redirects stormflows from the surface into the subsurface, which can be partitioned to evapotranspiration or baseflow, or be intercepted by buried infrastructure trenches. Stormwater that infiltrates sanitary sewer pipes is referred to as rainfall-derived inflow and infiltration (RDII) and represents a rapid pathway for infiltrated stormwater to reach receiving waters. To quantify the partitioning of infiltrated stormwater between slow and fast flows, a physically-based hydrologic model was developed integrating coupled surface–subsurface processes and urban sewer systems and applied to a sewershed near Milwaukee, WI. In this …

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Dice Testing With The Running Chi-Square Distribution, Warren Campbell, Hunter Wimsatt Jul 2022

Dice Testing With The Running Chi-Square Distribution, Warren Campbell, Hunter Wimsatt

SEAS Faculty Publications

Dice are not fair. Producing a geometrically precise, uniform die is not possible. Casino dice come as close as possible to perfectly random dice because they are machined to an accuracy of a few ten-thousandths of an inch and the putty used for the pips (dots) is the same density as the plastic die body. Polyhedral dice used in games like Dungeons and Dragons are far more difficult to manufacture to high tolerances. Some dice are fairer than others. Since 20-sided dice (D20s) are very difficult to manufacture precisely, they were the focus of this study. The running chi-square distribution …

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Influence Of Rainfall-Induced Erosion On The Stability Of Sandy Slopes Treated By Micp, Shihui Liu, Kang Du, Kejun Wen, Catherine Armwood-Gordon, Lin Li Jul 2022

Influence Of Rainfall-Induced Erosion On The Stability Of Sandy Slopes Treated By Micp, Shihui Liu, Kang Du, Kejun Wen, Catherine Armwood-Gordon, Lin Li

Civil and Architectural Engineering Faculty Research

As an environmentally friendly technology, microbially induced calcite precipitation (MICP) is widely used to improve the engineering properties of soil. The goal of this study was to investigate the effect of rainfall-induced erosion on the stability of sandy slopes which were treated by MICP technology. The observation of the erosion pattern of low concentration (0.25 M Ca) and high concentration (0.5 M Ca) of MICP-treated slopes, the mechanical behaviors of MICP-treated and cement-treated samples, and the effects of rainfall-induced erosion on the roughness of 0.5 M Ca MICP-treated and 10% cement-treated slope were studied through visual observation, unconfined compressive tests, …

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Power Management Strategy Of A Pem Fuel Cell-Battery Powered Electric Vehicle, Susanta K. Das, Jinsu Kim Jul 2022

Power Management Strategy Of A Pem Fuel Cell-Battery Powered Electric Vehicle, Susanta K. Das, Jinsu Kim

Mechanical Engineering Publications

A MATLAB-Simulink based mathematical vehicle simulation model is developed in this investigation to analyze power management strategy of a proton exchange membrane (PEM) fuel cell and battery powered electric vehicle. The vehicle simulation model incorporated a real- world commercial passenger vehicle operator’s drive cycle inputs and associated vehicle dynamics to determine accurate estimation of total onboard power requirements and withdrawal of power from the fuel cell and battery sources to meet the demand. The power management strategy is designed to meet the vehicle’s onboard power demand based on the availability of hybrid combi-nation of fuel cell and battery power sources. …

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Microstructure Dependence Of The Thermal Radiative Properties In Yttria-Stabilized Zirconia Thermal Barrier Coatings, Yao Wang Jul 2022

Microstructure Dependence Of The Thermal Radiative Properties In Yttria-Stabilized Zirconia Thermal Barrier Coatings, Yao Wang

Theses and Dissertations

Thermal barrier coatings (TBCs) based on the yttria-stabilized zirconium dioxide (YSZ) are widely used in gas turbines. With increasing gas turbine combustion temperature to improve the thermal efficiency, the radiative heat transfer properties of YSZ coatings become important. Currently there is no clear understanding the relationship between the coating microstructure and the radiative properties. In this study, a hybrid computational approach is developed to invert the radiative properties form the spectral measurement. To investigate the relationship between the radiative properties and microstructure, a predictive model of the scattering coefficient is developed based on the pore size distribution obtained from SEM …

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Learning Term Weights By Overfitting Pairwise Ranking Loss, Ömer Şahi̇n, İlyas Çi̇çekli̇, Gönenç Ercan Jul 2022

Learning Term Weights By Overfitting Pairwise Ranking Loss, Ömer Şahi̇n, İlyas Çi̇çekli̇, Gönenç Ercan

Turkish Journal of Electrical Engineering and Computer Sciences

A search engine strikes a balance between effectiveness and efficiency to retrieve the best documents in a scalable way. Recent deep learning-based ranker methods are proving to be effective and improving the state-of-the-art in relevancy metrics. However, as opposed to index-based retrieval methods, neural rankers like bidirectional encoder representations from transformers (BERT) do not scale to large datasets. In this article, we propose a query term weighting method that can be used with a standard inverted index without modifying it. Query term weights are learned using relevant and irrelevant document pairs for each query, using a pairwise ranking loss. The …

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Automated Question Generation And Question Answering From Turkish Texts, Fati̇h Çağatay Akyön, Ali̇ Devri̇m Eki̇n Çavuşoğlu, Cemi̇l Cengi̇z, Si̇nan Onur Altinuç, Alpteki̇n Temi̇zel Jul 2022

Automated Question Generation And Question Answering From Turkish Texts, Fati̇h Çağatay Akyön, Ali̇ Devri̇m Eki̇n Çavuşoğlu, Cemi̇l Cengi̇z, Si̇nan Onur Altinuç, Alpteki̇n Temi̇zel

Turkish Journal of Electrical Engineering and Computer Sciences

While exam-style questions are a fundamental educational tool serving a variety of purposes, manual construction of questions is a complex process that requires training, experience and resources. Automatic question generation (QG) techniques can be utilized to satisfy the need for a continuous supply of new questions by streamlining their generation. However, compared to automatic question answering (QA), QG is a more challenging task. In this work, we fine-tune a multilingual T5 (mT5) transformer in a multitask setting for QA, QG and answer extraction tasks using Turkish QA datasets. To the best of our knowledge, this is the first academic work …

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Design And Implementation Of A Bioinspired Leaf Shaped Hybrid Rectenna As A Green Energy Manufacturing Concept, Kayhan Çeli̇k, Erol Kurt Jul 2022

Design And Implementation Of A Bioinspired Leaf Shaped Hybrid Rectenna As A Green Energy Manufacturing Concept, Kayhan Çeli̇k, Erol Kurt

Turkish Journal of Electrical Engineering and Computer Sciences

In this communication, the novel low cost hybrid energy harvester combining rectifying antenna with the solar cell for feeding the low power energy systems are reported. The bioinspired leaf shaped monopole antenna is designed to work in the most used communication frequency bands such as GSM-1800, UMTS-2100, WIFI-2.45 and LTE-2.65 GHz for the energy harvesting purposes and microstrip low pass filter is also added on the feeding line for the second harmonic rejection for increasing the efficiency of the harvester. The solar cell is placed on the ground plane of the designed leaf shaped antenna for using volumetric space efficiently …

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Preserving Users’ Privacy In Iot Systems Through Network-Based Access Control, Ahmed Khalid A Alhazmi Jul 2022

Preserving Users’ Privacy In Iot Systems Through Network-Based Access Control, Ahmed Khalid A Alhazmi

Theses and Dissertations

Privacy issues have plagued the rapid proliferation of the Internet of Things (IoT) devices. Resource-constrained IoT devices often obscure transparency for end-users. A lack of transparency and control complicates user trust in IoT. Additionally, a growing history of misuse and abuse exists in IoT. Notably, a smart TV has periodically scanned and collected users’ private information without consent, while power companies have adjusted the temperature of smart thermostats during heat waves. Due to a hybrid of distributed ecosystems within IoT, users cannot easily implement traditional access control over their devices as data flows within different nodes for storage and processing. …

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Breast Cancer-Caps: A Breast Cancer Screening System Based On Capsule Network Utilizing The Multiview Breast Thermal Infrared Images, Devanshu Tiwari, Manish Dixit, Kamlesh Gupta Jul 2022

Breast Cancer-Caps: A Breast Cancer Screening System Based On Capsule Network Utilizing The Multiview Breast Thermal Infrared Images, Devanshu Tiwari, Manish Dixit, Kamlesh Gupta

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposed an accurate and fully automated breast cancer early screening system called the "Breast Cancer-Caps". The capsule network is used in this approach for the cancer detection in breast utilizing the thermal infrared images for the first time. This capsule network is trained with the help of Dynamic as well as Static breast thermal images dataset consisting of left, right, frontal views along with a new multiview thermal images. These multiview breast thermal images are fabricated by concatenating the conventional left, frontal and right view breast thermal images. The other current and popular deep transfer learning models such …

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Oblique Packing And Tunable Excitonic Coupling In Dna-Templated Squaraine Rotaxane Dimer Aggregates, Matthew S. Barclay, Christopher K. Wilson, Simon K. Roy, Olga A. Mass, Azhad U. Chowdhury, Jonathan S. Huff, Daniel B. Turner, Paul H. Davis, Bernard Yurke, William B. Knowlton, Jeunghoon Lee, Ryan D. Pensack Jul 2022

Oblique Packing And Tunable Excitonic Coupling In Dna-Templated Squaraine Rotaxane Dimer Aggregates, Matthew S. Barclay, Christopher K. Wilson, Simon K. Roy, Olga A. Mass, Azhad U. Chowdhury, Jonathan S. Huff, Daniel B. Turner, Paul H. Davis, Bernard Yurke, William B. Knowlton, Jeunghoon Lee, Ryan D. Pensack

Materials Science and Engineering Faculty Publications and Presentations

When molecules are aggregated such that their excited states form delocalized excitons, their spatial arrangement, or packing, can be coarsely controlled by templating and finely controlled by chemical substitution; however, challenges remain in controlling their packing on intermediate length scales. Here, we use an approach based on mechanically interlocked molecules to promote an elusive oblique packing arrangement in a series of three squaraine rotaxane dimers. We template the squaraine rotaxane dimers using DNA and observe two excitonically split bands of near-equal intensity in their absorption spectra – a distinct signature of oblique packing, validated by theoretical modeling of the experimental …

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Stability And Interaction Analysis Of Inverter-Based Resources In Power Grids, Li Bao Jul 2022

Stability And Interaction Analysis Of Inverter-Based Resources In Power Grids, Li Bao

USF Tampa Graduate Theses and Dissertations

The increasing penetration of inverter-based resources (IBRs) introduces some unexpected dynamic issues, including low-frequency oscillations. To investigate these phenomenon, a laboratory-scale grid-following voltage-source converter (VSC) system is implemented to demonstrate weak grid oscillations. Grid-following control is applied in VSC to provide active power, reactive power or ac voltage control. The test bed is also replicated in electromagnetic transient (EMT) simulation environment (MATLAB/SimPowerSystems) for benchmark purpose. Case studies are carried out to demonstrate low-frequency oscillations under real power/ac voltage or real power/reactive power control. An analytical model is carried out to examine the stability condition and compared with EMT or hardware …

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Internal Energy Balance And Aerodynamic Heating Predictions For Hypersonic Turbulent Boundary Layers, Matthew Barone, Gary L. Nicholson, Lian Duan Jul 2022

Internal Energy Balance And Aerodynamic Heating Predictions For Hypersonic Turbulent Boundary Layers, Matthew Barone, Gary L. Nicholson, Lian Duan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The elemental equation governing heat transfer in aerodynamic flows is the internal energy equation. For a boundary layer flow, a double integration of the Reynolds-averaged form of this equation provides an expression of the wall heat flux in terms of the integrated effects, over the boundary layer, of various physical processes: turbulent dissipation, mean dissipation, turbulent heat flux, etc. Recently available direct numerical simulation data for a Mach 11 cold-wall turbulent boundary layer allows a comparison of the exact contributions of these terms in the energy equation to the wall heat flux with their counterparts modeled in the Reynolds-averaged Navier-Stokes …

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Biofeedback Technologies As Extended Cognition: A Philosophical Analysis, Haesoo Park Jul 2022

Biofeedback Technologies As Extended Cognition: A Philosophical Analysis, Haesoo Park

Student Publications

Every year technologies become more sophisticated and more accessible. Some have become a seamless extension of mind, so much so that they are better understood no longer as tools, but as integral parts of how our mind works. Biofeedback devices are examples of such technologies that are increasingly used in institutional contexts and for personal use. They offer a presumed scientific and objective basis for life decisions and behavioral health interventions, as well as a promise of new forms of self-knowledge. Yet in the very design of biofeedback technologies are cultural and institutional values that are rarely critically appraised. This …

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Contracting Strategies: A Different Approach To Address Long-Term Performance, Maria Calahorra-Jimenez Jul 2022

Contracting Strategies: A Different Approach To Address Long-Term Performance, Maria Calahorra-Jimenez

Mineta Transportation Institute

For cost-efficiency, public safety, and sustainability, improving long-term performance in highway projects is imperative for public administrations. Project delivery and procurement methods provide an opportunity to align design and construction processes with this goal. While previous studies have explored whether project delivery methods impact the long-term performance of highway projects, these studies did not focus on how core elements within project procurement relate to long-term performance. Thus, to fill this gap, this research explores how and to what extent long-term evaluation criteria are considered in design-build best-value procurement of highway projects. To this end, the team conducted content analysis on …

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Measuring The Rol Of Digital Engineering: It's A Journey, Not A Number, Tom Mcdermott, Kaitlin Henderson, Eileen Van Aken, Alejandro Salado, Joseph Bradley Jul 2022

Measuring The Rol Of Digital Engineering: It's A Journey, Not A Number, Tom Mcdermott, Kaitlin Henderson, Eileen Van Aken, Alejandro Salado, Joseph Bradley

Engineering Management & Systems Engineering Faculty Publications

Systems engineering as a discipline has long had difficulty providing quantifiable evidence of its value (Honour 2004); DE transformation provides an opportunity to better measure its value. Transitioning from a document-based to a model-based approach is expensive, and organizations want to know if the effort and cost to adopt MBSE is worth it.

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Snow Parameters Inversion From Passive Microwave Remote Sensing Measurements By Deep Convolutional Neural Networks, Heming Yao, Yanming Zhang, Lijun Jiang, Hong Tat Ewe, Michael Ng Jul 2022

Snow Parameters Inversion From Passive Microwave Remote Sensing Measurements By Deep Convolutional Neural Networks, Heming Yao, Yanming Zhang, Lijun Jiang, Hong Tat Ewe, Michael Ng

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a novel inverse method based on the deep convolutional neural network (ConvNet) to extract snow's layer thickness and temperature via passive microwave remote sensing (PMRS). The proposed ConvNet is trained using simulated data obtained through conventional computational electromagnetic methods. Compared with the traditional inverse method, the trained ConvNet can predict the result with higher accuracy. Besides, the proposed method has a strong tolerance for noise. The proposed ConvNet composes three pairs of convolutional and activation layers with one additional fully connected layer to realize regression, i.e., the inversion of snow parameters. The feasibility of the proposed method …

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Improved Current Shunt Characterization Method For Core Loss Measurement, Anfeng Huang, Xu Wang, Hanyu Zhang, Chulsoon Hwang, David Pommerenke, Jun Fan Jul 2022

Improved Current Shunt Characterization Method For Core Loss Measurement, Anfeng Huang, Xu Wang, Hanyu Zhang, Chulsoon Hwang, David Pommerenke, Jun Fan

Electrical and Computer Engineering Faculty Research & Creative Works

With the increasing switching frequencies and power densities in modern power converters, magnetic core losses are becoming more essential for efficiency and thermal optimization. Traditionally, the two-winding method suffers from sensitivity to phase error in practical measurements; this is mainly created by the unknown phase shift of a current-sensing resistor. Several methods have been developed to characterize the phase shift of a current shunt resistor; however, the load effects of oscilloscopes are ignored. As a result, the corresponding phase shift can be significantly underestimated. This article proposes an improved method for phase shift extraction of a current shunt to solve …

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A 3d Non-Stationary Mimo Channel Model For Reconfigurable Intelligent Surface Auxiliary Uav-To-Ground Mmwave Communications, Baiping Xiong, Zaichen Zhang, Hao Jiang, Jiangfan Zhang, Liang Wu, Jian Dang Jul 2022

A 3d Non-Stationary Mimo Channel Model For Reconfigurable Intelligent Surface Auxiliary Uav-To-Ground Mmwave Communications, Baiping Xiong, Zaichen Zhang, Hao Jiang, Jiangfan Zhang, Liang Wu, Jian Dang

Electrical and Computer Engineering Faculty Research & Creative Works

Unmanned aerial vehicle (UAV) communications exploiting millimeter wave (mmWave) can satisfy the increasing data rate demands for future wireless networks owing to the line-of-sight (LoS) dominated transmission and flexibility. In reality, the LoS link can be easily and severely blocked due to poor propagation environments such as tall buildings or trees. To this end, we introduce a reconfigurable intelligent surface (RIS), which passively reflects signals with programmable reflection coefficients, between the transceivers to enhance the communication quality. Specifically, in this paper we generalize a three-dimensional (3D) non-stationary wideband end-to-end channel model for RIS auxiliary UAV-to-ground mmWave multiple-input multiple-output (MIMO) communication …

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Advanced In Vitro Models For Studying Bone Physiology, Kairui Zhang Jul 2022

Advanced In Vitro Models For Studying Bone Physiology, Kairui Zhang

Dissertations - ALL

Bone is a highly calcified organic-inorganic composite tissue with complicated hierarchical structure. The presence of complex multi-cellular organization within opaque mineralized matrix makes it challenging to use conventional methods to study in vivo bone physiology even using model animals. To address this challenge, numerous in vitro models have been developed to study bone physiology under well-defined and repeatable experimental conditions although proving their physiological relevance remains a key challenge. This work aims to design and develop new in vitro models that better represent in vivo bone physiology with defined control over chemical and physical microenvironments, at low costs and high …

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Technology Roadmap For Standards Of Healthcare Data Cyber Security: Influence Of Public Policy On Consumer Healthcare Cyber Security Protections, Alison Nalven, Courtney Wright, Jennifer Lynn Zeitouni, Nolan Thompson, Sara Ferdousi, Saumya Saxena Jul 2022

Technology Roadmap For Standards Of Healthcare Data Cyber Security: Influence Of Public Policy On Consumer Healthcare Cyber Security Protections, Alison Nalven, Courtney Wright, Jennifer Lynn Zeitouni, Nolan Thompson, Sara Ferdousi, Saumya Saxena

Engineering and Technology Management Student Projects

From the dot com boom to now the Internet of Things (IoT) and Machine Learning era, the evolving digital world that people live in has brought new challenges for protecting personal data and information. IoT devices, smart phones, numerous apps, and more, constantly collect personal health data with many positive intentions. However, the recent overturning of Roe vs. Wade by the United States Supreme Court has generated concerns in particular on who and how personal health data can be used by both governments and private companies with unintended consequences for users. Cyber security and regulations for protecting personal health data …

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Non-Gaussian Analysis Of Herbarium Specimen Damageto Optimize Specimen Collection Management, Aris Yaman, Yulia Aris Kartika, Ariani Indrawati, Zaenal Akbar, Lindung P. Manik, Wita Wardani, Tutie Djarwaningsih, Taufik Mahendra, Dadan R. Saleh Jul 2022

Non-Gaussian Analysis Of Herbarium Specimen Damageto Optimize Specimen Collection Management, Aris Yaman, Yulia Aris Kartika, Ariani Indrawati, Zaenal Akbar, Lindung P. Manik, Wita Wardani, Tutie Djarwaningsih, Taufik Mahendra, Dadan R. Saleh

Knowledge Engineering and Data Science

Damage to specimen collections occurs in practically every herbarium across the world. Hence, some precautions must be taken, such as investigating the factors that cause specimen damage in their collections and evaluating their herbarium collection handling and usage policy. However, manual investigation of the causes of herbarium collection damage requires a lot of effort and time. Only a few studies have attempted to investigate the causes of herbarium collection damage. So far, the non-gaussian approach to detecting the causes of damage to herbarium specimens has not been studied before. This study attempted to explore the effect of species type, time, …

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Social Distancing Monitoring System Using Deep Learning, Amelia Ritahani Ismail, Nur Shairah Muhd Affendy, Asmarani Ahmad Puzi Jul 2022

Social Distancing Monitoring System Using Deep Learning, Amelia Ritahani Ismail, Nur Shairah Muhd Affendy, Asmarani Ahmad Puzi

Knowledge Engineering and Data Science

COVID-19 has been declared a pandemic in the world by 2020. One way to prevent COVID-19 disease, as the World Health Organization (WHO) suggests, is to keep a distance from other people. It is advised to stay at least 1 meter away from others, even if they do not appear to be sick. The reason is that people can also be the virus carrier without having any symptoms. Thus, many countries have enforced the rules of social distancing in their Standard Operating Procedure (SOP) to prevent the virus spread. Monitoring the social distance is challenging as this requires authorities to …

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Automatic 3d Cranial Landmark Positioning Based Onsurface Curvature Feature Using Machine Learning, Putu Hendra Suputra, Anggraini Dwi Sensusiati, Myrtati Dyah Artaria, Gijsbertus Jacob Verkerke, Eko Mulyanto Yuniarno, I Ketut Eddy Purnama Jul 2022

Automatic 3d Cranial Landmark Positioning Based Onsurface Curvature Feature Using Machine Learning, Putu Hendra Suputra, Anggraini Dwi Sensusiati, Myrtati Dyah Artaria, Gijsbertus Jacob Verkerke, Eko Mulyanto Yuniarno, I Ketut Eddy Purnama

Knowledge Engineering and Data Science

Cranial anthropometric reference points (landmarks) play an important role in craniofacial reconstruction and identification. Knowledge to detect the position of landmarks is critical. This work aims to locate landmarks automatically. Landmarks positioning using Surface Curvature Feature (SCF) is inspired by conventional methods of finding landmarks based on morphometrical features. Each cranial landmark has a unique shape. With the appropriate 3D descriptors, the computer can draw associations between shapes and landmarks using machine learning. The challenge in classification and detection in three-dimensional space is to determine the model and data representation. Using three-dimensional raw data in machine learning is a serious …

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The Effect Of Resampling On Classifier Performance: Anempirical Study, Utomo Pujianto, Muhammad Iqbal Akbar, Niendhitta Tamia Lassela, Deni Sutaji Jul 2022

The Effect Of Resampling On Classifier Performance: Anempirical Study, Utomo Pujianto, Muhammad Iqbal Akbar, Niendhitta Tamia Lassela, Deni Sutaji

Knowledge Engineering and Data Science

An imbalanced class on a dataset is a common classification problem. The effect of using imbalanced class datasets can cause a decrease in the performance of the classifier. Resampling is one of the solutions to this problem. This study used 100 datasets from 3 websites: UCI Machine Learning, Kaggle, and OpenML. Each dataset will go through 3 processing stages: the resampling process, the classification process, and the significance testing process between performance evaluation values of the combination of classifier and the resampling using paired t-test. The resampling used in the process is Random Undersampling, Random Oversampling, and SMOTE. The classifier …

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Commercial Short-Haul Flight Or Autonomous Mobility-On-Demand: Modeling Air Passengers’ Modal Choice, Agatha Kessler Fentress Jul 2022

Commercial Short-Haul Flight Or Autonomous Mobility-On-Demand: Modeling Air Passengers’ Modal Choice, Agatha Kessler Fentress

Doctoral Dissertations and Master's Theses

Commercial short-haul flights (SF) are vital to airports and airlines because they account for one-third of hub traffic and have higher profit margins than the long-haul market. While U.S. commercial air passenger travel has increased steadily over the past decades, SF has been declining and was doing so before the unprecedented decrease in air travel caused by restrictions related to the COVID-19 global pandemic. Once autonomous mobility-on-demand (aMoD) is more viable than the human-driven car, demand for SF could be negatively impacted. Although there is published research on SF and aMoD, studies on factors influencing the choice between SF and …

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Experimental Characterization Of Additively Manufactured Multi-Feather Wingtip Devices, Patricio Garzon Jul 2022

Experimental Characterization Of Additively Manufactured Multi-Feather Wingtip Devices, Patricio Garzon

Doctoral Dissertations and Master's Theses

Soaring birds have evolved to fly for long periods of time without flapping their wings. Inspired by the flight of these birds, the proposed thesis presents an experimental investigation focused on wingtip devices designed based on biomimicry. The overarching engineering objective was to reduce the induced drag as a means to improve the fuel efficiency via these experimental wingtips. An associated secondary objective was to establish a method for manufacturing complex structures suitable for wing tunnel testing. A manufacturing technique that involved using composite weaves to reinforce additively manufactured structures was developed. This technique has the potential to reduce manufacturing …

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Effect Of Spray Rails On Takeoff Performance Of Amphibian Aircraft, Soham Bahulekar Jul 2022

Effect Of Spray Rails On Takeoff Performance Of Amphibian Aircraft, Soham Bahulekar

Doctoral Dissertations and Master's Theses

Amphibian aircraft have seen a rise in popularity in the recreational and utility sectors due to their ability to take off and land on both land and water, thus serving a myriad of purposes such as aerobatics, surveillance, and firefighting. The design of such seaplanes requires to be both aerodynamically and hydrodynamically efficient, especially during the takeoff phase. In the past, naval architects have implemented ways to make boats, yachts, and large ships more efficient; one of them being the addition of chine strips and spray rails on the hull. This thesis study explores the possibility of implementing spray rails …

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Synthetic Gecko Inspired Dry Adhesive Through Two-Photon Polymerization For Space Applications, Zefu Ren Jul 2022

Synthetic Gecko Inspired Dry Adhesive Through Two-Photon Polymerization For Space Applications, Zefu Ren

Doctoral Dissertations and Master's Theses

This work aims to develop an advanced and cost-effective fabrication process to produce a simplified gecko-inspired microstructure with two-photon polymerization and polymer molding, aimed to improve the adhesive properties of microstructures. Such adhesive microstructures can be implemented for multi-purpose adhesive grasping devices, which have recently gained significant interest in the space exploration sector. Previous gecko-inspired microstructures were reviewed, and the new gecko-inspired microstructures have been developed with the adaptation of additive manufacturing methods for facile fabrication. The examined microstructures in this thesis were the tilted mushroom-shaped and wedge-shaped designs, which could both maximize adhesion by shearing the micropillars toward the …

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Optimization Of Rover Wheel Geometries For Planetary Missions, Nikita Amberkar Jul 2022

Optimization Of Rover Wheel Geometries For Planetary Missions, Nikita Amberkar

Doctoral Dissertations and Master's Theses

Rovers have been launched into space for exploration of the Moon and Mars to collect samples of rock and soil. To continue the explorations, the rovers need to have reliable wheels to drive around. However, due to the soil being soft, the wheels on the rover start to lose traction and the wheels sink while driving to various locations. Previous work in this field has been done experimentally or with the use of simulations. Only a few references report the effect of uncertainties in grouser simulation on the traction efficiency. The objective of this work was to (a) Understand the …

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