592 research outputs found

    Colonoscopy: Advanced and Emerging Techniques-A Review of Colonoscopic Approaches to Colorectal Conditions.

    Get PDF
    A complete colonoscopy is key in the diagnostic and therapeutic approaches to a variety of colorectal diseases. Major challenges are incomplete polyp removal and missed polyps, particularly in the setting of a difficult colonoscopy. There are a variety of both well-established and newer techniques that have been developed to optimize polyp detection, perform complete polypectomy, and endoscopically treat various complications and conditions such as strictures and perforations. The objective of this article is to familiarize the colorectal surgeon with techniques utilized by advanced endoscopists

    Performance of spent garnet as sand replacement in concrete at high temperature

    Get PDF
    Garnet is ideal for many commercial uses due to its potential to be recycled. The dumping millions of tons of spent garnet in landfills, quarries, oceans and waterways will cause the creating environmental concerns. In this study, spent garnet as a sand replacement is produced to innovate sustainable concrete. The research objectives are to study the effects of strength of spent garnet as sand replacement in concrete mix at high temperature and to evaluate its physical properties of spent garnet. Several laboratory experiments were conducted to determine the physical and its compressive strength before and after exposed to high temperature. Furthermore, the test for the physical properties that had been conducted were, specific gravity, bulk density and water absorption test. Other than that, the compressive strength of 30MPa at 28 days for trial mix design were prepared accordingly. The cube specimens of 100 × 100 × 100 mm were provided with substitution of 0%, 10%, 20%, 30% and 40% of spent garnet as sand replacement with 0.45 of water cement ration. All the concrete mixes containing spent garnet were produced slump of 30-60mm. Based on the test result, the cube specimen of 40 percent of spent garnet after heated started decrease in term of strength due to the present of the excessive of spent garnet particles in the concrete which can weaken the bond between aggregates and the cement paste. Thus, it reduces the concrete strength in term of less compaction of concrete has lower bonding strength

    Advances in Sensors and Sensing for Technical Condition Assessment and NDT

    Get PDF
    The adequate assessment of key apparatus conditions is a hot topic in all branches of industry. Various online and offline diagnostic methods are widely applied to provide early detections of any abnormality in exploitation. Furthermore, different sensors may also be applied to capture selected physical quantities that may be used to indicate the type of potential fault. The essential steps of the signal analysis regarding the technical condition assessment process may be listed as: signal measurement (using relevant sensors), processing, modelling, and classification. In the Special Issue entitled “Advances in Sensors and Sensing for Technical Condition Assessment and NDT”, we present the latest research in various areas of technology

    A unified multiple stress reliability model for microelectronic devices — Application to 1.55 μm DFB laser diode module for space validation

    Get PDF
    The establishment of European suppliers for DFB Laser Modules at 1.55 µm is considered to be essential in the context of future European space programs, where availability, cost and schedule are of primary concerns. Also, in order to minimize the risk, associated with such a development, the supplier will be requested to use components which have already been evaluated and/or validated and/or qualified for space applications. The Arrhenius model is an empirical equation able to model temperature acceleration failure modes and failure mechanisms. The Eyring model is a general representation of Arrhenius equation which takes into account additional stresses than temperature. The present paper suggests to take advantage of these existing theories and derives a unified multiple stress reliability model for electronic devices in order to quantify and predict their reliability figures when operating under multiple stress in harsh environment as for Aerospace, Space, Nuclear, Submarine, Transport or Ground. Application to DFB laser diode module technologies is analyzed and discussed based on evaluation test program under implementation

    Low-energy electron diffraction effects at complex interfaces

    Get PDF
    Low-energy electron scattering was used as a tool to study electron-stimulated processes at complex interfaces. The electron diffraction in each complex interface is theoretically treated by a multiple scattering formalism for quantitative analysis. Mathematical descriptions of electron-stimulated processes and a multiple scattering expansion extended from the single-scattering case are presented. This analysis method was applied in three research topics: These are 1) electron-stimulated desorption of Cl+ from Si surfaces, 2) characterization of epitaxial graphene on Si-terminated SiC(0001), and 3) low-energy electron induced DNA damage. Zone-specific desorption of Cl+ from Si(111)- 7X7:Cl surfaces was demonstrated. Graphene epitaxially grown on SiC(0001) surfaces was analyzed using Auger electron diffraction and Raman scattering spectroscopy. Finally, the roles of interfacial water and dissociative electron attachment resonances in low-energy electron-induced DNA damage were revealed. Electron scattering calculations using the "path approach" were applied in all of the above mentioned studies. The combination of theory and experiment has lead to insight regarding electron scattering with complex targets.Ph.D.Committee Chair: Thomas Orlando; Committee Member: Joseph Perry; Committee Member: Nicholas Hud; Committee Member: Phillip First; Committee Member: Rigoberto Hernande

    The Role of Recoverable and Non-Recoverable Defects in DC Electrical Aging of Highly Disordered Insulating Materials

    Get PDF
    Electrical insulation under high voltage can eventually fail, causing critical damage to electronics. Such electrostatic discharge (ESD) is the primary source of anomalies or failures on spacecraft due to charged particles from the Sun or planetary radiation belts accumulating in spacecraft insulators. Highvoltage direct current power distribution is another example of a growing industry that needs to estimate the operational lifetime of electrical insulation. My research compares laboratory tests of ESD events in common insulating materials to a physics-based model of breakdown. This model of breakdown is based on the approximation that there are two primary types of defects in structurally amorphous insulators. One of the two defect modes can switch on and off depending on the material temperature. This dual-defect model can be used to explain both ESD and less-destructive transient partial discharges. I show that the results of ESD tests agree reasonably well with the dual defect model. I also show that transient partial discharges, which are usually ignored during ESD tests, are closely related to the probability of catastrophic ESD occurring. Since many partial discharges are typically seen during one ESD test, this relationship suggests that the measurements of partial discharges could accelerate the testing needed to characterize the likelihood of ESD in insulating materials

    Therapeutic Gastrointestinal Endoscopy

    Get PDF
    Endoscopy has had a big role in the development of modern gastroenterology. Modern endoscopy will certainly be more therapeutic. It started with endoscopic hemostasis and polipectomy, than beginning of the 1970's with the advent of endoscopic sphincterotomy extended to biliopancreatic pathology and has a huge impact in this difficult pathology. Plastic stents made the first steps in endoscopic palliation of neoplastic jaundice, metallic stents, covered or uncovered are better for biliary palliation and can be used also for palliation neoplastic obstruction at different levels of the digestive tube. Resection of digestive tumors has evolved now to sub-mucosal resection, looking to have one-piece complete resection. Interventional endoscopy is now very complex and takes a lot of time for endoscopists to learn properly these techniques. This book is a very good up-to-date overview of new techniques of interventional endoscopy for those who want to learn or develop their knowledges in this field

    Model-Based Software Debugging

    Get PDF
    The complexity and size of software systems have rapidly increased in recent years, with software engineers facing ever-growing challenges in building and maintaining such systems. In particular, testing and debugging, that is, finding, isolating, and eliminating defects in software systems still constitute a major challenge in practiceMinisterio de Ciencia y Tecnología TIN2015-63502-C3-2-RFundacao para a Ciencia e a Tecnologia (FCT) UID/EEA/50014/2013European Regional Development Fund (ERDF) POCI-01-0145-FEDER-006961 (COMPETE 2020
    corecore