Biomedical Engineering and Bioengineering Commons^™

Predicting Vigilance Performance Under Transcranial Direct Current Stimulation, Nathaniel Reese Bridges

Browse all Theses and Dissertations

A brain stimulation technology called transcranial direct current stimulation (tDCS) may potentially mitigate the vigilance decrement. To practically use such technology, however, a model is necessary that indicates vigilance performance, both when stimulation is being applied and not applied. To address this issue, the author developed models capable of predicting vigilance performance in real and control stimulation conditions using previous tDCS-study data. The "all possible combinations" regression method produced over 200 models, later screened to 10. The model with the best average %error (11.49 ± 0.10) used left hemispheric cerebral blood flow velocity (CBFVL) as its sole input term-accounting for …

Influence Of Design Parameters On Cup-Stem Orientations For Impingement Free Range Of Motion In Hip Implants, Dishita Prakashbhai Patel

Browse all Theses and Dissertations

The objective of this investigation is to determine the optimum positions of the prosthesis in total hip arthroplasty that produce least amount of impingement. Theoretical ranges of six basic hip motions were determined under walking, stumbling, internal rotation at 90 flexion and external rotation at 0 extension with 15 abduction, using mathematical models and validated for impingement using finite element analysis. A generalized approach, where impingement does not occur, was developed in this study to understand influence of design parameters such as head-neck ratio, neck-shaft angle, oscillation angle, and stem offset on cup-stem orientations such as cup inclination, cup anteversion, …

A Probabilistic Assessment Of Vertebral Cortical Bone Fracture Of Intraosteonal Structures, Isaac Graham Mabe

Browse all Theses and Dissertations

Cortical bone is a porous structure. The presence of these pores creates the possibility of a local overstressed area that has the likelihood of premature failure. Some failure modes of the vertebral endplates, for example subsidence which occurs at rates as high as 77 percent, can be better predicted with further understanding of failure mechanisms and the ability to predict those mechanisms. A probabilistic assessment of the pore size and its contribution to the fracture toughness has not been investigated in the cortical shell of the vertebral endplates. This research develops a probabilistic model that has the ability to determine …

Anthropometric Analysis Of The Cervical Spine, Susan Hueston

Browse all Theses and Dissertations

An understanding of the dimensional anatomy of the cervical spine is necessary in order to help diagnose disease, deformity, injury, and device development. Previous investigation has been completed utilizing cadavers, X-rays and other imaging techniques. This research utilized computer tomography images from the trauma registry at Miami Valley Hospital in Dayton, Ohio to complete an anthropometric study of the cervical spine. Linear mathematical models were developed to investigate the relationships present in the dimensional anatomy of the cervical spine. New measurements were completed on subjects of both Caucasian and African American descent and of both genders. An approximation of the …

Investigation Of Variability In Cognitive State Assessment Based On Electroencephalogram-Derived Features, Samantha Lokelani Crossen

Browse all Theses and Dissertations

To implement adaptive aiding in modern aviation systems there is a need for accurate and reliable classification of cognitive workload. Using electroencephalogram (EEG)-derived features, it has been reported that an Artificial Neural Network (ANN) can achieve 95% or higher classification accuracy on the same day for an individual operator, but only 70% or less on a different day. To gain a further insight into this discrepancy, data from a previous study was utilized to study the classification variability. The EEG-derived features were first calculated by spectral power estimation. The variability was then analyzed by performing cognitive workload classification in which …

Selective Automatic Image Feature Detection, Aijing Wang

Browse all Theses and Dissertations

To allow automatic assessment of computed tomography (CT) images of long bones, the identification of the location of regions of interest is important. The distance between the distal and proximal styloids may act as reference points for bone length; however, the locations of the distal and proximal growth plates represent further important reference features. The current methods to locate these feature positions are manual. In this project, we attempt to find these feature positions automatically.

A CT data set was split into two subsets, a development set, and a validation set. We first extracted basic information from the stack and …

A Validation Of A Prototype Dry Electrode System For Electroencephalography, Jason Monnin

Browse all Theses and Dissertations

Current physiologically-driven operator cognitive state assessment technology relies primarily on electroencephalographic (EEG) signals. Traditionally, gel-based electrodes have been used; however, the application of gel-based electrodes on the scalp requires expertise and a considerable amount of preparation time. Additionally, discomfort can occur from the abrasion of the scalp during preparation, and the electrolyte will also begin to dry out over extended periods of time. These drawbacks have hindered the transition of operator state assessment technology into an operational environment. QUASAR, Inc., (San Diego, CA) has developed a prototype dry electrode system for electroencephalography that requires minimal preparation. A comparison of the …

Semi-Automated Dental Cast Analysis Software, Mathew Thomas

Browse all Theses and Dissertations

Dental casts have been used extensively to study almost all aspects of the human dentition. These aspects varied from the study of tooth form and morphology, inheritance and genetics, growth and development, occlusion, arch alignment and crowding to mathematical determination of dental arch form.

The aim of this project was to develop a tool to semi-automate the measurement of dental casts that would be precise, accurate and efficient. Measurements include tooth widths, arch lengths and widths, angle of rotation and crown area for each tooth.

The task was divided into two different parts: first, the development of semi-automatic software to …

Cervical Spine Biomechanical Behavior And Injury, Mbulelo T. Makola

Browse all Theses and Dissertations

A finite element model of the cervical spine including the C2 through C7 levels was developed in order to study the behavior of the cervical spine region. The model was validated in flexion extension, bending, and rotational load scenarios. The model was found to represent the biomechanical behavior of the cervical spine. The validated cervical spine finite element model was used to study spinal injury and disease processes. The model provided qualitative estimates of load carrying and stress distribution as well as range of motion.