Design, analysis, and modeling of giant magnetostrictuve transducers

The increased use of giant magnetostrictive, Terfenol-D transducers in a wide variety of applications has led to a need for greater understanding of the materials performance. This dissertation attempts to add to the Terfenol-D transducer body of knowledge by providing an in-depth analysis and modeling of an experimental transducer. A description of the magnetostriction process related to Terfenol-D includes a discussion of material properties, production methods, and the effect of mechanical stress, magnetization, and temperature on the material performance. The understanding of the Terfenol-D material performance provides the basis for an analysis of the performance of a Terfenol-D transducer. Issues related to the design and utilization of the Terfenol-D material in the transducers are considered, including the magnetic circuit, application of mechanical prestress, and tuning of the mechanical resonance. Experimental results from two broadband, Tonpilz design transducers show the effects of operating conditions (prestress, magnetic bias, AC magnetization amplitude, and frequency) on performance. In an effort to understand and utlilize the rich performance space described by the experimental results a variety of models are considered. An overview of models applicable to Terfenol-D and Terfenol-D transducers is provided, including a discussion of modeling criteria. The Jiles-Atherton model of ferromagnetic hysteresis is employed to describe the quasi-static transducer performance. This model requires the estimation of only six physically-based parameters to accurately simulate performance. The model is shown to be robust with respect to model parameters over a range of mechanical prestress, magnetic biases, and AC magnetic field amplitudes, allowing predictive capability within these ranges. An additional model, based on electroacoustics theory, explains trends in the frequency domain and facilitates an analysis of efficiency based on impedance and admittance analysis. Results and discussion explain the importance of the resonance of the electromechanical system, as distinct from the mechanical resonance. Conclusions are drawn based on the experimental work, transducer analysis, and modeling approaches

Advances in saccular aneurysm biomechanics : enlargement via rate-sensitive inelastic growth, bio-mathematical stages of aneurysm disease, and initiation profiles.

I have created the first simulation of saccular aneurysm initiation and development from a healthy artery geometry. It is capable of growing saccular aneurysm geometries from patient-specific data. My model describes aneurysm behavior in a way that bridges fields. I assume arteries are made of a rate-sensitive inelastic material which produces irreversible deformation when it is overstressed. The material is assumed to consist of a 3D hyperelastic background material embedded with 1D transversely-isotropic fibers. I optionally use a Winkler foundation term to model support of external organs and distinguish healthy tissue from diseased tissue. Lesions are defined as a local degradation of artery wall structure. My work suggests passive mechanisms of growth are insufficient for predicting saccular aneurysms. Furthermore, I identify a new concept of stages of aneurysm disease. The stages connect mathematical descriptions of the simulation with clinically-relevant changes in the modeled aneurysm. They provide an evocative framework through which clinical descriptions of arteries can be neatly matched with mathematical features of the model. The framework gives a common language of concepts---e.g., collagen fiber, pseudoelastic limit, inelastic strain, and subclinical lesion---through which researchers in different fields, with different terminologies, can engage in an ongoing dialog: under the model, questions in medicine can be translated into equivalent questions in mathematics. A new stage of “subclinical lesion” has been identified, with a suggested direction for future biomechanics research into early detection and treatment of aneurysms. This stage defines a preclinical aneurysm-producing lesion which occurs before any artery dilatation. It is a stage of aneurysm development involving microstructural changes in artery wall makeup. Under the model, this stage can be identified by its reduced strength: its structural support is still within normal limits, but presumably would perform more poorly in ex vivo failure testing than healthy tissue from the same individual. I encourage clinicians and biomechanicians to measure elastin degradation, and to build detailed multiscale models of elastin degradation profiles as functions of aging and tortuosity; and similarly for basal tone. I hope such measurements will to lead to early detection and treatment of aneurysms. I give specific suggestions of biological tissue experiments to be performed for improving and reinforming constitutive modeling techniques.Mechanical Engineerin

Electrical Activity of the Invertebrate Eye in Response to Illumination

Definite electrical changes can be detected in the eyes of many animals in response to illumination of the eyes. In the vertebrate eye these changes take the form of characteristic electrical variations known successively as the a-, b-, c-, and d-waves. Similar waves can be elicited from the compound eyes of a number of invertebrates. The simplest method of studying these electrical changes in invertebrates is to lead off by silver-silver chloride electrodes from fluid-filled chambers built around each eye. One eye is illuminated while the second eye is kept in darkness. The electrical potentials are amplified by means of a vacuum tube amplifier and are then recorded by means of a cathode ray oscillograph and moving film camera

Electrical Activity of the Invertebrate Eye in Response to Illumination

Definite electrical changes can be detected in the eyes of many animals in response to illumination of the eyes. In the vertebrate eye these changes take the form of characteristic electrical variations known successively as the a-, b-, c-, and d-waves. Similar waves can be elicited from the compound eyes of a number of invertebrates. The simplest method of studying these electrical changes in invertebrates is to lead off by silver-silver chloride electrodes from fluid-filled chambers built around each eye. One eye is illuminated while the second eye is kept in darkness. The electrical potentials are amplified by means of a vacuum tube amplifier and are then recorded by means of a cathode ray oscillograph and moving film camera

Electrical Activity of the Invertebrate Eye in Response to Illumination

Definite electrical changes can be detected in the eyes of many animals in response to illumination of the eyes. In the vertebrate eye these changes take the form of characteristic electrical variations known successively as the a-, b-, c-, and d-waves. Similar waves can be elicited from the compound eyes of a number of invertebrates. The simplest method of studying these electrical changes in invertebrates is to lead off by silver-silver chloride electrodes from fluid-filled chambers built around each eye. One eye is illuminated while the second eye is kept in darkness. The electrical potentials are amplified by means of a vacuum tube amplifier and are then recorded by means of a cathode ray oscillograph and moving film camera

Electrical Activity of the Invertebrate Eye in Response to Illumination

Definite electrical changes can be detected in the eyes of many animals in response to illumination of the eyes. In the vertebrate eye these changes take the form of characteristic electrical variations known successively as the a-, b-, c-, and d-waves. Similar waves can be elicited from the compound eyes of a number of invertebrates. The simplest method of studying these electrical changes in invertebrates is to lead off by silver-silver chloride electrodes from fluid-filled chambers built around each eye. One eye is illuminated while the second eye is kept in darkness. The electrical potentials are amplified by means of a vacuum tube amplifier and are then recorded by means of a cathode ray oscillograph and moving film camera

Sputum biomarkers and the prediction of clinical outcomes in patients with cystic fibrosis

pre-printLung function, acute pulmonary exacerbations (APE), and weight are the best clinical predictors of survival in cystic fibrosis (CF); however, underlying mechanisms are incompletely understood. Biomarkers of current disease state predictive of future outcomes might identify mechanisms and provide treatment targets, trial endpoints and objective clinical monitoring tools. Such CF-specific biomarkers have previously been elusive. Using observational and validation cohorts comprising 97 nontransplanted consecutively-recruited adult CF patients at the Intermountain Adult CF Center, University of Utah, we identified biomarkers informative of current disease and predictive of future clinical outcomes. Patients represented the majority of sputum producers. They were recruited March 2004-April 2007 and followed through May 2011. Sputum biomarker concentrations were measured and clinical outcomes meticulously recorded for a median 5.9 (interquartile range 5.0 to 6.6) years to study associations between biomarkers and future APE and time-to-lung transplantation or death. After multivariate modeling, only high mobility group box-1 protein (HMGB-1, mean = 5.84 [log ng/ml], standard deviation [SD] = 1.75) predicted time-to-first APE (hazard ratio [HR] per log-unit HMGB-1 = 1.56, p-value = 0.005), number of future APE within 5 years (0.338 APE per log-unit HMGB-1, p,0.001 by quasi-Poisson regression) and time-to-lung transplantation or death (HR = 1.59, p = 0.02). At APE onset, sputum granulocyte macrophage colony stimulating factor (GM-CSF, mean 4.8 [log pg/ml], SD = 1.26) was significantly associated with APE-associated declines in lung function (210.8 FEV1% points per logunit GM-CSF, p,0.001 by linear regression). Evaluation of validation cohorts produced similar results that passed tests of mutual consistency. In CF sputum, high HMGB-1 predicts incidence and recurrence of APE and survival, plausibly because it mediates long-term airway inflammation. High APE-associated GM-CSF identifies patients with large acute declines in FEV1%, possibly providing a laboratory-based objective decision-support tool for determination of an APE diagnosis. These biomarkers are potential CF reporting tools and treatment targets for slowing long-term progression and reducing short-term severity

Vitreous Humour Extrusion after Suxamethonium Induction of Anaesthesia in a Polytraumatized Patient: A Case Report

Introduction. Suxamethonium, a deepolarizing muscle relaxant, increases intraocular pressure. It is therefore advised to be avoided in open globe surgery, for fear of extruding ocular contents. Several anecdotal reports support this fear. Some workers however, dispute this claim. There is as yet no formal case report in the literature on the subject. Case Presentation. A 34-year old Nigerian male, was involved in a road traffic accident. He presented at the Accident & Emergency Unit of our hospital about 2 hours after the accident. Clinical examination revealed right corneal laceration (with intact ocular contents) and intra-abdominal visceral injury. Emergency laparotomy was scheduled, to be followed with corneal repair. Anaesthesia was induced with 10 mg midazolam, 100 mg ketamine, and 100 mg suxamethonium given intravenously in sequence. After laparotomy, the ophthalmologists reported for the corneal repair, only to find that the vitreous humour has been extruded. Conclusion. The fear about the use of suxamethonium in open globe situations is real. It will be good clinical judgment to use alternative drugs and techniques to effect rapid muscle relaxation, in the anaesthetic management of the open globe patient. This would be of interest to anaesthetists, ophthalmologists and clinical pharmacologists among others

Web-Based Employee Performance Assessment Application with SMART Method: An Agile Approach in the Context of the Smartphone Market

Employee performance is essential in determining the company's sustainability, so company leaders must pay attention to employee performance. Many subjective factors determine employee performance, so performance evaluations are sometimes unfair. One of the companies developing in Indonesia is a smartphone sales company, CV Jala Kencana. As the company develops and the number of employees increases, problems arise in assessing employee performance that have yet to be measurable. So that employee performance assessments can be more objective, a decision support system application is needed that can help assess employee performance. The Agile SDLC method is used in designing website-based employee performance assessment applications. Then, for the employee performance assessment feature, the Simple Multi-Attribute Rating Technique (SMART) method is used, and SHA512 encryption is applied to the employee performance assessment database, which cannot be manipulated. This research produces a web-based employee performance assessment application with features to assess employee performance objectively based on predetermined criteria.Employee performance plays a significant role in determining the company's sustainability, so company leaders must pay attention to employee performance. To determine an employee's performance more objectively, many subjective factors influence it, so performance appraisals only sometimes end up being fair. One of the companies developing in Indonesia is a smartphone sales company, CV Jala Kencana. As the CV Jala Kencana company continues to develop and the number of employees increases, problems arise in assessing employee performance, which still needs to be done objectively. So that employee performance assessments can be more objective, a decision support systems application is needed that can help assess employee performance. The Agile SDLC method is used in designing a website-based employee performance assessment application. Then, for the employee performance assessment feature, the Simple Multi-Attribute Rating Technique (SMART) method is used, and SHA512 encryption is implemented in the Database Management Systems for better database security. This research produces a web-based employee performance assessment application with features for assessing employee performance based on predetermined criteria