Digital Commons Network^™

Multi-Commodity Flow Models For Logistic Operations Within A Contested Environment, Isabel Strinsky

All Theses

Today's military logistics officers face a difficult challenge, generating route plans for mass deployments within contested environments. The current method of generating route plans is inefficient and does not assess the vulnerability within supply networks and chains. There are few models within the current literature that provide risk-averse solutions for multi-commodity flow models. In this thesis, we discuss two models that have the potential to aid military planners in creating route plans that account for risk and uncertainty. The first model we introduce is a continuous time model with chance constraints. The second model is a two-stage discrete time model …

Comparative Design Space For Bistable Composites: An Integrated Framework Of Optimization, Finite Element Analysis, And Experimental Testing, Jonathan Bolanos

All Theses

Bistable composites are a class of advanced materials that can actuate between two stable shapes, making them attractive for a wide range of engineering applications. However, designing these composites to achieve optimal performance remains a challenging task. To address the challenge, this research develops an integrated framework that combines a genetic algorithm optimization technique, finite element analysis in Abaqus, and experimental testing to explore the design comparative space for square bistable composites composed of DA 409 carbon fibers. This leads to the study of generating an optimization algorithm to account for the relationship between the chances of a successful maximum …

Multiple Objective Function Optimization And Trade Space Analysis, Yifan Xu

All Theses

Optimization can assist in obtaining the best possible solution to a design problem by varying related variables under given constraints. It can be applied in many practical applications, including engineering, during the design process. The design time can be further reduced by the application of automated optimization methods. Since the required resource and desired benefit can be translated to a function of variables, optimization can be viewed as the process of finding the variable values to reach the function maxima or minima. A Multiple Objective Optimization (MOO) problem is when there is more than one desired function that needs to …

An Application Of Optimized Bistable Laminates As A Low Velocity, Low Impact Mechanical Deterrent, Graham Lancaster

All Theses

This research considers the problem of using bistable laminates as a mechanical deterrent to the impending impact of a particle. The structure will be controlled through an algorithm that will utilize piezoelectric devices to activate them in unison with the bistable laminate to successfully deter. A novel experimental setup will be constructed to ensure that the bistable laminate stays fixed when acting as a mechanical deterrent. Piezoelectricity is the main driving force of the bistable laminate to morph and this study will use a Macro Fiber Composite (MFC) actuator that contains piezoelectric ceramic rods in a patch to transfer electrical …

Interdiction Models To Disrupt The Operations Of Sex Trafficking And Other Forced Illicit Labor Networks, Michael T. Clark

All Theses

Sex traffickers often force their victims to work in both commercial sex markets and perform other illicit activities (e.g., drug dealing, theft, and fraud). Current literature has failed to address interdiction models that aim to disrupt all components of a sex traffickers’ operation, including these other illicit activities. In this thesis, we present a interdiction problem, and its single-level linear optimization reformulation, to reduce the profit of a human trafficking network concurrently operating in the commercial sex market and other illicit activity markets. Our novel formulation aims to investigate the practical implications of interdiction decisions made to disrupt a human …

Investigations Of External Resources And The Impact Of Imaging On Patient Flow In The Emergency Department, Marisa Shehan

All Theses

The problems associated with Emergency Department (ED) crowding are numerous, varied, and complex. Though overcrowded Emergency Departments are frequently attributed to overcrowded hospitals, crowding is also impacted by bottlenecks in patient flow. While discrete-event simulation (DES) is commonly used to model ED flow, external resources are typically excluded from these models due to their complexity and the limited amount of known information for these processes. Instead, external resources such as consults, labs, and imaging are modeled using estimation and/or educated guesswork. In this study, the impact of imaging on patient flow was assessed through data analysis of specific imaging factors, …

Automating The Design Optimization Of Vehicle Structures, William Bruce Mccormack

All Theses

structures, parametric design and finite element analysis are common tools for simulating structural behavior of systems under static and quasi-static loading. While these tools provide significant benefits over physical experimentation, cumbersome to set up and this time-consuming setup may need to be repeated many times while iterating on a design. The designers would therefore benefit from automating this design and analysis process so that they can explore the design space more efficiently or obtain higher performance design alternatives. To take full advantage of the benefits of this automation, it important to make the process as quick and easy as possible. …

Optimizing The Restoration Of Fire Dependent Forests Of The Southern Blue Ridge Escarpment With Gis Modeling Approaches, Keith Phelps

All Theses

Prescribed fire and overstory manipulation through mechanized timber harvesting are important tools for the ecological restoration of fire-dependent forests/woodlands, which have been altered extensively by twentieth century fire suppression policies. However, there are many challenges in using these tools due to terrain, logistic, and social constraints; issues exacerbated in rugged mountainous terrain. This thesis creates a series of ArcGIS models which are used as decision support tools for ecological restoration, using prescribed fire and mechanized timber harvesting equipment operation, in mountainous terrain. My GIS modeling approaches use 13,118 ha of forest area within the Jocassee Gorges Natural Resource Area (situated …

Design Of A Single Layer Metamaterial For Pressure Offloading In Transtibial Amputees, Nathan Kenneth Brown

All Theses

While using a prosthesis, transtibial amputees can experience pain and discomfort brought on by significant changes in pressure across a finite area of skin, known as pressure gradients, at the interface between the residual limb and prosthetic socket. These pressure gradients can lead to dermatological issues, deep tissue damage, and prolonged joint and muscle pain. Current prosthetic interface solutions attempt to alleviate these pressure gradients by using highly compliant homogenous liners to distribute and therefore reduce pressures. This research investigates an approach to reduce peak pressure gradients around the limb through the design of a new inlay made from artificially …

Modeling And Optimization Of Self-Healing Polymers, Amy Murdaugh

All Theses

Continuous interests in developing self-healable polymers are driven by the desire to extend life spans of existing functional materials. Combining mathematical modeling and optimization approaches with experimental studies, an ultimate aim is to predict the flow and macroscopic wound closures in polymeric materials. Corresponding numerical simulations to experimental results are presented, utilizing two mathematical models that describe bulk or layer flow. An optimization routine for this self-healing process is described and implemented using two different approaches, competitive with each other with respect to accuracy. Finally a multi-layer model is simulated to show the flow profile of multiple layers rather than …

Using Origami Folding Techniques To Study The Effect Of Non-Linear Stiffness On The Performance Of Jumping Mechanism, Blake Betsill

All Theses

This research uses Origami patterns and folding techniques to generate non-linear force displacement profiles and study their effect on jumping mechanisms. In this case, the jumping mechanism is comprised of two masses connected by a Tachi-Miura Polyhedron (TMP) with non-linear stiffness characteristics under tensile and compressive loads. The strain-softening behavior exhibited by the TMP enables us to optimize the design of the structure for improved jumping performance. I derive the equations of motion of the jumping process for the given mechanism and combine them with the kinematics of the TMP structure to obtain numerical solutions for the optimum design. The …

Improvements To Mle Algorithm For Localizing Radiation Sources With A Distributed Detector Network, Guthrie Cordone

All Theses

Maximum Likelihood Estimation (MLE) is a widely used method for the localization of radiation sources using distributed detector networks. While robust, MLE is computationally intensive, requiring an exhaustive search over parameter space. To mitigate the computational load of MLE, many techniques have been presented, including iterative and multi-resolution methods.

In this work, we present two ways to improve the MLE localization of radiation sources. First, we present a method to mitigate the pitfalls of a standard multi-resolution algorithm. Our method expands the search region of each layer before performing the MLE search. Doing so allows the multi-resolution algorithm to correct …

Behavior And Energy Loss Optimization Of An Elastic Material Metastructure, Andrew S. Montalbano

All Theses

Advances in additive manufacturing expand the possibilities of what can be designed and produced. One such example is producing structures that possess designed properties. Because the structure itself has the designed property, it does not require the structure's base material to have it. This allows the use of materials that lack a property to gain that property through geometry. Most elastic materials such as steel do not possess any form of energy loss under loading in their elastic regime. This research asks if a structure made from an elastic material could be designed in such a way to provide energy …

Developing Optimization System For Improving Highway Network Performance Under Seismic Hazards: A Case Study Of Charleston, Sc, Nixon Wonoto

All Theses

A significant number of bridges in the Central and Southeastern United States (CSUS) are known to have a design that is lacking or no seismic consideration. In an article by Wong et al., Charleston is considered an active seismic zone, and the economic loss from the Charleston region could reach over $14 billion if 1886 Charleston’s earthquake would happen again in the near future. Due to lack of present consideration in seismic design for bridges in CSUS, there has been emerging research that studies retrofit strategies for CSUS region such as in Charleston. However, most of the retrofit program, including …

Design Of Meta-Material Tank Track System With Experimental Testing And Sensitivity Analysis Of Additively Manufactured Meta-Material Backer Pads, Samuel J. Franklin

All Theses

Operational wear and hysteretic heat loss frequently affect the rubber components of the M1 Abrams main battle tank, leading to deterioration of the material and laborious replace and repair efforts in tactical situations. In previous work at Clemson University, meta-material backer pads had been designed and optimized using the Unit Cell Synthesis method and the Modified Unit Cell Synthesis method to match the characteristic deformation behavior of current elastomer backer pads on the M1 Abrams battle tank. In this case, a meta-material is a periodic, unit cell based, material that exhibits global mechanical properties that differ from the mechanical properties …

Optimization Techniques For The Developing Distribution System, Shane Kimble

All Theses

The most rapidly changing part of today’s power grid is the distribution system. Many new technologies have emerged that revolutionize the way utilities provide, and now sometimes receive, power to and from their customers. To an extent, the push for de-regulation of utilities has also led to an increased focus on reliability and efficiency. These changes make design and operation of power systems more complex causing utilities to question if they are operating optimally.

Operations Research (OR) is an area of mathematics where quantitative analysis is used to provide a basis for complex decision making. The changing landscape in electric …

Multilevel Methods For Sparsification And Linear Arrangement Problems On Networks, Emmanuel John

All Theses

The computation of network properties such as diameter, centrality indices, and paths on networks may become a major bottleneck in the analysis of network if the network is large. Scalable approximation algorithms, heuristics and structure preserving network sparsification methods play an important role in modern network analysis. In the first part of this thesis, we develop a robust network sparsification method that enables filtering of either, so called, long- and short-range edges or both. Edges are first ranked by their algebraic distances and then sampled. Furthermore, we also combine this method with a multilevel framework to provide a multilevel sparsification …

Design Optimization Of Tank Track Pad Meta-Material Using The Cell Synthesis Method, Neehar Milind Kulkarni

All Theses

The elastomeric backer pad on the M1 Abrams tank track experiences highly cyclic and dynamic loads during normal operating conditions. As a result, extensive heat is generated within the pad due to its viscoelastic hysteretic nature which leads to its early failure. Research has been carried out in the past at Clemson University to design a meta-material that will mimic the deformation behavior of the elastomeric backer pad but will be made out of a linearly elastic constitutive material to eliminate hysteresis. A meta-material in this context is an artificial material in the form of a periodic structure that exhibits …

Identifying Target Properties For The Design Of Meta-Material Tank Track Pads, Venkata Sampath Dangeti

All Theses

On track vehicle systems, track pads are designed to provide traction and support the weight of the vehicle, they have limited service life due to common failure by blowout. According to the literature, blowout is a failure mode caused by overheating due to hysteresis in elastomeric materials during high speed operations. Elastomers are used primarily for their high compliance, which is essential to protect the suspension components and maintain structural integrity of the track pad. The objective of the work is to explore the use of linear elastic meta-materials with optimized topology to replace elastomers and reduce or eliminate the …

Cost And Embodied Energy Optimization Of Rectangular Reinforced Concrete Beams, Alexander Kosloski

All Theses

Concrete has a large environmental footprint so it is desirable to find ways to efficiently design structural members. Engineers can exercise their abilities early on in the design phase of construction projects to reduce the environmental footprint by minimizing the amount of materials required. One way to achieve these results is to optimize the design of structural concrete. In this study, simple-span rectangular reinforced concrete (RC) beams with a range of different bending moments were analyzed. The primary goal was to combine life cycle analysis (LCA), numerical optimization, and reinforced concrete mechanics to create a framework for designing efficient RC …

Connecting Architecture, Fitness, Optimizations And Performance Using An Anisotropic Diffusion Filter, Sumedh Naik

All Theses

Over the past decade, computing architectures have continued to exploit multiple levels of parallelism in applications. This increased interest in parallel computing has not only fueled the growth of multi-core processors but has also lead to an emergence of several non-traditional computing architectures like General Purpose Graphical Processing Units (GP-GPUs), Cell Processors, and Field Programmable Gate Arrays (FPGAs). Of these non-traditional computing architectures, GP-GPUs have gained widespread popularity due to their massively parallel computational abilities and relative ease of programmability.
Several software development ecosystems have emerged to harness the power of these parallel architectures. Although several threading libraries like POSIX …

A New Metaheuristic Algorithm Motivated By The Rooting Phenomena In Plants, Behzad Nemati

All Theses

In this thesis, we present a new metaheuristic algorithm for analyzing challenging optimization problems. Initial testing reveals the potential for the algorithm, which is based on the rooting phenomena found in plants in nature, to quickly produce effective solutions to challenging combinatorial optimization problems in the class NP. We present computational results describing the proposed metaheuristic's efficacy for an important class of scheduling problems and discuss areas of future work and application.

Modeling, Finite Element Analysis, And Optimization Of Non-Pneumatic Tire (Npt) For The Minimization Of Rolling Resistance, Mallikarjun Veeramurthy

All Theses

Recently, the development of non-pneumatic tires (NPT) such as the Michelin Tweel is receiving increased attention due to potential advantages over pneumatic tires such as low mass, no run flat, good contact pressure distribution, and low rolling resistance (RR). This study focuses on the design of a NPT based on properties of vertical stiffness, contact pressure, and rolling energy loss. Using a finite element (FE) model, a parametric study is conducted to study the effect on vertical stiffness, contact pressure, and rolling resistance (RR) response considering three design variables: (1) thickness of the spokes, (2) the shear band thickness, and …

Simultaneous Optimization Of Macronutrient Factors In Plant Tissue Culture Using Turmeric (Curcuma Longa L.) As A Model, Sean Halloran

All Theses

Murashige and Skoog 1962 performed one-factor-at-a-time (OFAT) experimentation in order to regenerate tobacco callus on semi-solid agar medium. This work became an established medium for tissue culture micropropagation and experimentation. Micropropagation is done in niche markets with herbaceous perennials, among other crops, and the optimization of various inputs to produce maximal responses is a necessary step towards process development. This current study of macronutrient factors simultaneously altered media volume, amount of tissue (plants per vessel), sucrose, nitrogen (as NO3- and NH4+ ions), and K+ in a d-optimal design space with only 55 experimental units (including 5 true replicates). The first …

Requirements Determination Of A Novel Non-Pneumatic Wheel Shear Beam For Low Rolling Resistance, Niranjan Thyagaraja

All Theses

The hysteretic loss associated with cyclic shear in the elastomeric shear layer is one of the prevailing concerns for the development of a low rolling loss non-pneumatic wheel. We propose to eliminate the hysteretic losses associated with the elastomeric shear layer and thus, reduce the corresponding rolling resistance by using linear elastic materials which are inherently non-hysteretic. Since the shear modulus of a viscoelastic shear layer is less than that of an elastic material by several orders of magnitude, the challenge to achieve a low effective shear modulus shear layer with linear elastic materials directs towards the development of a …

Agent-Based Under Hood Packing, Karthik Ravindranath

All Theses

Improving vehicle performance and passenger comfort has been a prime engineering concern and focus of research for many years in automotive design. Turning to high-performance components in an effort to improve vehicle performance alone is often not enough and their placement and interactions with other components should also be an integral part of the improvement process. With the advancement in hybrid electric vehicle technology, the packing of components under the hood is ever more essential and challenging. Under hood packing is a multi-objective optimization problem with many, and mostly conflicting objectives. A non-deterministic multi-objective evolutionary algorithm needs to be integrated …

Determining The Global Maximum Biofuel Production Potential Without Conflicting With Food And Feed Consumption, Watcharapol Pumkaew

All Theses

This study tries to resolve the competition between food and biofuel by balancing the allocation between food and feed areas and biofuel areas for the entire world. The maximum energy production is calculated by determining the theoretical amount of energy that can be grown, once food and feed consumption is taken into account, based on the assumption that unprotected grass and woody lands and forest lands can be converted into cultivated lands. The total optimum land area for biofuel energy, 4,926.49 Mha, consists of corn, rapeseed, sugar beet, sugar cane, and grasses. When considering energy conversion efficiency, the maximum energy …

Synthesis Of Optimal Usage Of Available Aggregates In Highway Construction And Maintenance, Benjamin Skidmore

All Theses

The optimization of the available aggregates for highway construction and maintenance is vital both from an economic and environmental perspective. By not optimizing the aggregate supply project costs escalate as a simple response to supply and demand, and just as important the fact that aggregate is a natural resource and a limited one, it is crucial that is used as efficiently as possible. This paper examines specifically the use of aggregates by the South Carolina Department of Transportation, but can easily be adapted to any state. Through DOT and quarry surveys and an examination of aggregate gradation specifications it was …

Optimization And Characterization Of Biodiesel Production From Cottonseed And Canola Oil, Hem Joshi

All Theses

Transesterification of cottonseed oil and canola oil was carried out using low molecular weight alcohols and potassium hydroxide. For cottonseed oil, a central composite design with eight factorial, six center and six axial points was used to study the effect of catalyst concentration, molar ratio of ethanol to cottonseed oil and reaction temperature on percentage yield and percentage initial absorbance (%A385nm) of the biodiesel. Catalyst concentration and molar ratio of ethanol to cottonseed oil were the most influential variables affecting percentage conversion and percentage initial absorbance. Maximum percentage yield of 98 % is predicted at a catalyst concentration of 1.07 …

Optimal Placement Of Metal Foils In Ultrasonic Consolidation Process, Raji Rexavier

All Theses

Ultrasonic Consolidation is a combination of additive and subtractive
manufacturing processes resulting in considerable material waste. This waste is a
function of the geometry of the part being manufactured and of the relative
placement of the layer with respect to the metal bands. Thus the waste may be
minimized by careful choice of the layer angle and offset from the original
position.
Previous work done in this field had developed an automated algorithm which
optimally places and orients the individual slices of the STL file of the artifact
being manufactured. However, the problem was solved on a 2-D scale and …