133 research outputs found

    Adaptive, High-Resolution Ultrasound Phased Array Imaging for use in the Inspection of Laser Brazed Joints in the Automotive Sector

    Get PDF
    The inspection of welded and brazed joints has been performed in several industries using ultrasonic phased array. In the automotive sector, many of the current standards for brazed joint inspection do not apply due to the high variations in surface geometry and limited accessibility to the inspection region. As the automotive industry looks to integrate laser brazing into the production process, the need to determine the size and geometry of the joint, as well as the presence of any defects, is desirable to ensure product quality and reduce costs. Currently, the use of destructive techniques, such as cross-sectioning, is employed in the inspection process, with the ultimate desire being the shift to non-destructive methods. With this in mind, ultrasonic techniques have been investigated as a possible testing method. Ultrasound techniques have evolved over the decades, starting from a single element and eventually moving to phased array techniques. Recently, the investigation of the full matrix capture method has become popular in the field of ultrasound imaging. This technique, which separates the data acquisition process from the image formation process poses a viable solution to the inspection of laser brazed joints due to the ability to compensate for varying surfaces in post-processing.In this work, we make use of this technique, deriving the image formation process as an inverse problem for an arbitrary set of ultrasonic emitters and receivers. From this, the image formation process becomes equivalent to solving the inhomogeneous Helmholtz equation. By approximating the solutions to such an equation using the ray series expansion, an estimation of the solutions can be found in a time-efficient manner. When these solutions are found, the inverse process can be rewritten as a weighted, time-delayed summation of the acquired ultrasonic data. In current work, further approximations to this image formation process are often made; however, in the inspection of the laser braze process, these approximations are found to degrade image quality in a number of cases. In this work, we propose our second order corrections as a viable solution to increase the limit under which ultrasound imaging can currently occur. This is accomplished through the design of an ultrasonic array transducer and the manufacturing of a series of simulated defects, with the final assessment being performed on real joints.These techniques were found to improve imaging in a select set of samples when the radius of curvature dropped below 2 mm. In these cases, the use of the amplitude weighting was found to drastically improve system resolution, allowing for the determination of joint size, geometry and the presence of defects

    Analysis of the Effect of Thermal Gradients on the Real-time 2D Imaging of the Spot Weld Process.

    Get PDF
    Many monitoring processes have been proposed for the spot weld process, but most of these techniques involve the use of post weld verification methods. An ultrasonic phased array has been shown to be a viable method for the monitoring the spot weld in 2D, however the presence of thermal gradients generated during the welding process can result in a loss of resolution and accuracy within the image. In this report these effects were investigated and the device’s imaging ability improved. It was found that the imaging abilities of the device are not severely degraded and that a 0.9 mm resolution is attainable using a 10 MHz phased array. Additionally the maximum 0.2 mm offset of the focused wave generated by heating was found to be correctable by monitoring of the copper water boundary. These results indicate that good potential exists in the future applications of this device

    Long-Term Management Strategies for the Maintenance of Private Roads on Nantucket

    Get PDF
    Of the 270 miles of roads on Nantucket, approximately 174 miles (or 64%) of them are privately owned. These privately owned roads are often poorly maintained due to a lack of effective long-term maintenance strategies, resulting in increased risk to public safety. The goal of this project was to evaluate long-term management strategies for the maintenance of private roads and to make recommendations for improvement appropriate for Nantucket. The team interviewed a number of Nantucket officials and homeowners, as well as several officials from other towns in Massachusetts. With the knowledge gained from these interviews, the team created a list of criteria which Nantucket officials can use to prioritize future road takings and suggested long-term management strategies

    pH Dependence of Catalysis by Pseudomonas aeruginosa Isochorismate-Pyruvate Lyase: Implications for Transition State Stabilization and the Role of Lysine 42

    Get PDF
    This publication was made possible by funds from the American Lung Association of Kansas and from the Kansas Masonic Cancer Research Institute, by the Graduate Training Program in Dynamic Aspects of Chemical Biology NIH grant T32 GM08545 (J.O.) from the National Institute of General Medical Sciences, by NIH grant P20 RR016475 from the INBRE Program of the National Center for Research Resources, and by NIH grants R01 AI77725 and K02 AI093675 from the National Institute for Allergy and Infectious Disease.An isochorismate-pyruvate lyase with adventitious chorismate mutase activity from Pseudomonas aerugionsa (PchB) achieves catalysis of both pericyclic reactions in part by the stabilization of reactive conformations and in part by electrostatic transition-state stabilization. When the active site loop Lys42 is mutated to histidine, the enzyme develops a pH dependence corresponding to a loss of catalytic power upon deprotonation of the histidine. Structural data indicate that the change is not due to changes in active site architecture, but due to the difference in charge at this key site. With loss of the positive charge on the K42H sidechain at high pH, the enzyme retains lyase activity at approximately 100-fold lowered catalytic efficiency, but loses detectable mutase activity. We propose that both substrate organization and electrostatic transition state stabilization contribute to catalysis. However, the dominant reaction path for catalysis is dependent on reaction conditions, which influence the electrostatic properties of the enzyme active site amino acid sidechains

    Opening Doors to History: Improving the Self-Guided Tour Experience at the Grabser Mühlbach

    Get PDF
    The history and community of Grabs, Switzerland were largely shaped by the millstream that flows through the small town. The Grabser Mühlbach association has strived to preserve the historical and communal significance of the mills through its museum. The self-guided tour of the privately owned mills could be improved to provide more access of information for visitors. The project investigated and developed features, such as interactive maps, links to videos of the mill interiors and personal stories of the mills, and a model website with an easily usable layout, that could enhance information accessibility. These deliverables and more, recorded in the form of a manual, will help the Grabser Mühlbach association share history with future generations

    Outpatient Psychiatry Utililzation Management

    Get PDF
    Refine and implement a standard process that provides clinical evaluation at admission, review and discharge for each patient. Clinical evaluation will lend to appropriate length of stay for patients with common diagnoses allowing for easier access into care and smoother transition back to the Primary Medical Home. Target reduction in length of stay (engaging those with less than 7 appointments that need longer treatment while shifting those who exceed standard 7 sessions back to PCP when appropriate such as primary dx ADHD)

    Genetic background modifies CNS-mediated sensorimotor decline in the AD-BXD mouse model of genetic diversity in Alzheimer\u27s disease.

    Get PDF
    Many patients with Alzheimer\u27s dementia (AD) also exhibit noncognitive symptoms such as sensorimotor deficits, which can precede the hallmark cognitive deficits and significantly impact daily activities and an individual\u27s ability to live independently. However, the mechanisms underlying sensorimotor dysfunction in AD and their relationship with cognitive decline remains poorly understood, due in part to a lack of translationally relevant animal models. To address this, we recently developed a novel model of genetic diversity in Alzheimer\u27s disease, the AD-BXD genetic reference panel. In this study, we investigated sensorimotor deficits in the AD-BXDs and the relationship to cognitive decline in these mice. We found that age- and AD-related declines in coordination, balance and vestibular function vary significantly across the panel, indicating genetic background strongly influences the expressivity of the familial AD mutations used in the AD-BXD panel and their impact on motor function. Although young males and females perform comparably regardless of genotype on narrow beam and inclined screen tasks, there were significant sex differences in aging- and AD-related decline, with females exhibiting worse decline than males of the same age and transgene status. Finally, we found that AD motor decline is not correlated with cognitive decline, suggesting that sensorimotor deficits in AD may occur through distinct mechanisms. Overall, our results suggest that AD-related sensorimotor decline is strongly dependent on background genetics and is independent of dementia and cognitive deficits, suggesting that effective therapeutics for the entire spectrum of AD symptoms will likely require interventions targeting each distinct domain involved in the disease

    Academic performance of children with sickle cell disease in the United States: A meta-analysis

    Get PDF
    Background: Students with sickle cell disease are at risk for poor academic performance due to the combined and/or interactive effects of environmental, psychosocial, and disease-specific factors. Poor academic performance has significant social and health consequences. Objective: To study academic achievement and attainment in children with sickle cell disease in the United States. Design: Medline, Embase, SCOPUS, CINAHL, ERIC, and PsycINFO were searched for peer-reviewed articles. Studies of children (ages 5–18) diagnosed with sickle cell disease of any genotype reporting academic achievement (standardized tests of reading, math, and spelling) or attainment (grade retention or special education) outcomes were included. Outcomes were analyzed using a random effects model. Achievement scores were compared to within study controls or normative expectations. Prevalence of grade retention and special education services were compared to national (United States) estimates for Black students. Age at assessment and overall IQ were evaluated separately for association with reading and mathematics scores. Subgroup analyses of reading and math scores were analyzed by cerebral infarct status (no cerebrovascular accident, silent infarct, stroke). Results: There were 44 eligible studies. Students with sickle cell disease scored 0.70, 0.87, and 0.80 (p < 0.001) SD below normative expectations on measures of reading, mathematics, and spelling, respectively. Compared to unaffected sibling and/or healthy controls (k = 8, n = 508), reading and math scores were 0.40 (p = 0.017) and 0.36 (p = 0.033) SD below expectations. Grade retention was approximately 10 times higher in students with sickle cell disease than Black students nationally. Intellectual functioning explained 97.3 and 85.8% of the variance in reading and mathematics performance, respectively (p < 0.001). Subgroup analyses revealed significant differences in reading (p = 0.034) and mathematics (p < 0.001) based on infarct status, with lower performance associated with presence of a silent infarct or stroke. Conclusion: Students with sickle cell disease demonstrate notable academic difficulties and are at high risk for grade retainment. Development of academic interventions and increased access to school support services are needed for this vulnerable population. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020179062

    Quality assessment of optic nerve sheath diameter ultrasonography: Scoping literature review and Delphi protocol.

    Get PDF
    BACKGROUND AND PURPOSE: The optic nerve is surrounded by the extension of meningeal coverings of the brain. When the pressure in the cerebrospinal fluid increases, it causes a distention of the optic nerve sheath diameter (ONSD), which allows the use of this measurement by ultrasonography (US) as a noninvasive surrogate of elevated intracranial pressure. However, ONSD measurements in the literature have exhibited significant heterogeneity, suggesting a need for consensus on ONSD image acquisition and measurement. We aim to establish a consensus for an ONSD US Quality Criteria Checklist (ONSD US QCC). METHODS: A scoping systematic review of published ultrasound ONSD imaging and measurement criteria was performed to guide the development of a preliminary ONSD US QCC that will undergo a modified Delphi study to reach expert consensus on ONSD quality criteria. The protocol of this modified Delphi study is presented in this manuscript. RESULTS: A total of 357 ultrasound studies were included in the review. Quality criteria were evaluated under five categories: probe selection, safety, positioning, image acquisition, and measurement. CONCLUSIONS: This review and Delphi protocol aim to establish ONSD US QCC. A broad consensus from this process may reduce the variability of ONSD measurements in future studies, which would ultimately translate into improved ONSD clinical applications. This protocol was reviewed and endorsed by the German Society of Ultrasound in Medicine
    • …
    corecore