431 research outputs found

    Application of a ratiometric laser induced fluorescence (LIF) thermometry for micro-scale temperature measurement for natural convection flows

    Get PDF
    A ratiometric laser induced fluorescence (LIF) thermometry applied to micro-scale temperature measurement for natural convection flows. To eliminate incident light non-uniformity and imperfection of recording device, two fluorescence dyes are used: one is temperature sensitive fluorescence dye (Rhodamine B) and another is relatively temperature insensitive fluorescence dye (Rhodamine 110). Accurate and elaborate calibration for intensity ratio verses temperature obtained using an isothermal cuvette, which was controlled by two thermo-bathes. 488nm Ar-ion laser used for incident light and two filter sets used for separating each fluorescence emission. Thermally stratified filed of 10mm channel with micro-scale resolution measured within 1.3?C uncertainty of liner prediction with 23?m x 23?m spatial resolution. Natural convection flows at 10mm channel also observed. The several difficulties for applying to heated evaporating meniscus were identified and a few resolutions were suggested

    The Strategies of Korean American Churches that are Ministering to Korean Students Studying in America

    Get PDF
    In America, there are a lot of Korean Churches for Korean people. Among them, the churches of Korean students are different from the churches of Korean immigrants because they have different purposes coming to America. In Korean student churches most members are students and they are preparing to be a leader for the future and for the glory of God. Therefore, the churches of Korean students have to focus on ministry of sowing. Then, they have to do strategy of a small group meeting changing a seeker from an unbeliever, strategy of a worship changing a believer from a seeker, strategy of a discipleship training changing a disciple from a believer, and strategy of serving changing a professional missionary from a disciple

    Thermal stability of nano-structured selective emitters for thermophotovoltaic systems

    Get PDF
    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 97-103).A fundamental challenge in solar-thermal-electrical energy conversion is the thermal stability of materials and devices at high operational temperatures. This study focuses on the thermal stability of tungsten selective emitters for thermophotovoltaic (TPV) systems which are anticipated to enhance the conversion efficiency. Selective emitters, 2-D photonic crystals, are periodic micro/nano-scale structures that are designed to affect the motion of photons at certain wavelengths. The structured patterns, however, lose their structural integrity at high temperatures, which disrupt the tight tolerances required for spectral control of the thermal emitters. Through analytical studies and experimental observations, the failure modes of tungsten 2-D photonic crystal are indentified. There were four major mechanisms of thermal degradation by which micro/nano-scale structures change their geometry when heated: grain growth and recrystallization, oxidation, surface diffusion, and evaporation. A novel idea of flat surface tungsten photonic crystal (FSTPC) was proposed and was validated by theoretical modeling and by experiments. Pre-annealing or using single crystalline tungsten will prevent the grain growth. A thin layer of diffusion barrier will prevent oxidation and/or evaporation and maintain the optical performance. By filling in the micro/nano-scale cavities with a damascened IR transparent ceramic, the surface of the emitter will have negligible second derivative of the curvature, and thus eliminates the surface diffusion even at high temperatures. Accelerated tests on silicon-based 2-D photonic crystal show that the micro/nano-scale structures on the silicon surface survive for at least 100 hours at 400 °C, homologous temperature of 0.4, which is equivalent temperature of 1200 °C for tungsten. Based on a scale-accelerated failure model, the life time of the Flat Surface Tungsten Photonic Crystal (FSTPC) is estimated to be at least 40 years at 800 °C.by Heon Ju Lee.Ph.D

    Optimal path planning for autonomous underwater gliders in time-varying flow fields

    Full text link
    University of Technology Sydney. Faculty of Engineering and Information Technology.Marine robots perform various oceanic missions for commercial, scientific and military purposes. Some of these tasks include resource tracking, environmental surveying and coastal surveillance. Underwater gliders are a special class of marine robots that do not use active propulsions to move forward. This property makes the gliders more energy-efficient compared to other marine robots, and thus well-suited for long-duration missions. These missions benefit from autonomous operations that are either energy-optimal or time-optimal to maximising glider operation time and minimise human interactions. Such a level of automation is difficult to achieve, however. The underwater glider operates under a high-dimensional dynamic model with non-linear control, making it difficult to model mathematically. Optimal navigation in a flow field environment, known as Zermelo's Problem, is also a century-old open problem. This research introduces a trim-based model that reduces the glider control problem to a simpler 6D kinodynamic problem. We address this simpler problem using a state-of-the-art sampling-based algorithm to demonstrate full 3D underwater glider motion planning over various static flow fields and obstacles. For real-world applications, it is also essential to consider the dynamics of the environment. Therefore it is natural to expect planning algorithms for underwater gliders to handle variations in flow fields. As the glider's performance heavily depends on the surrounding flow field, planning involves the time-dependent shortest path (TDSP) problem, which has been open since the original work on graph search problem in the 1960s. This research introduces a new special case of the TDSP problem for vehicles in dynamic ocean currents. An optimal policy is solved for a time-dependent discrete graph over a dynamic flow field in polynomial time. Integrating both the trim-based and TDSP work addresses the path planning problem for underwater gliders by synthesising a continuous path from the optimal policy using the trim-based model. The significance of this research is that it introduces an increased level of autonomy in underwater robots. The theoretical work allows for more accurate glider navigation, and considering dynamic ocean currents allows the glider to exploit the environment for practical advantages. These results also improve autonomous operation so that it requires less manual intervention from humans. This thesis shows examples of these ideas, and we are currently planning a long-duration field deployment to demonstrate these results in practice

    A case of peripheral gangrene and osteomyelitis secondary to terlipressin therapy in advanced liver disease

    Get PDF
    Variceal bleeding and hepatorenal syndrome (HRS) are serious and life-threatening complications of advanced liver disease. Terlipressin is widely used to manage both acute variceal bleeding and HRS due to its potency and long duration of action. The most severe (though rare) adverse event is ischemia. The present report describes the case of a patient with gangrene and osteomyelitis secondary to terlipressin therapy. A 71-year-old male with alcoholic liver cirrhosis (Child-Pugh B) and chronic hepatitis C was admitted due to a drowsy mental status. The patient had several experiences of orthopedic surgery. His creatinine level had gradually elevated to 4.02 mg/dL, and his urine output decreased to 500 mL/24 hr. The patient was diagnosed as having grade III hepatic encephalopathy (HE) and type II HRS. Terlipressin and albumin were administered intravenously to treat the HRS over 11 days. Although he recovered from the HE and HRS, the patient developed peripheral gangrene and osteomyelitis in both feet. His right toes were cured with the aid of rescue therapy, but his left three toes had to be amputated. Peripheral gangrene and osteomyelitis secondary to terlipressin therapy occur only rarely, and there is no specific rescue therapy for these conditions. Thus, attention should be paid to the possibility of ischemia of the skin and bone during or after terlipressin therapy

    A study of hepatitis B virus reactivation associated with rituximab therapy in real-world clinical practice: a single-center experience

    Get PDF
    Background/AimsThe widespread use of cytotoxic chemotherapy and immunosuppressants has resulted in reactivation of hepatitis B virus (HBV) recently becoming an issue. Although rituximab (an anti-CD20 monoclonal antibody) has revolutionized the treatment of lymphoma, recent reports have suggested that rituximab therapy increases the risk of viral-mediated complications, and particularly HBV reactivation. This study analyzed real clinical practice data for rituximab-related HBV reactivation.MethodsBetween January 2005 and December 2011, 169 patients received treatment with rituximab. Screening status of the HBV infection and frequency of preemptive therapy were determined in these patients, and the clinical features of HBV reactivation were analyzed.ResultsSeventy-nine of the 169 patients with chronic or past HBV infection were selected for evaluation of HBV reactivation. Of the 90 patients who were excluded, 22 (13.0%) were not assessed for HBsAg and anti-HBc, and 14 (8.3%) were not assessed for anti-HBc due to seronegativity for HBsAg. The selected patients were divided into those with chronic HBV infection (n=12) and those with past HBV infection (n=67); six patients (7.6%) experienced HBV reactivation. Eight patients received preemptive therapy, but three patients (37.5%) underwent HBV reactivation. Although HBsAg seropositivity was an independent risk factor for HBV reactivation (P=0.038), of the six patients with HBV reactivation, two (33.3%) had past HBV infection and three (50%) died of liver failure.ConclusionsThe findings of this study demonstrate that adherence to guidelines for screening and preemptive therapy for HBV reactivation was negligent among the included cohort. Attention should be paid to HBV reactivation in patients with past as well as chronic HBV infection during and after rituximab therapy

    Illumination invariant head pose estimation using random forests classifier and binary pattern run length matrix

    Get PDF
    In this paper, a novel approach for head pose estimation in gray-level images is presented. In the proposed algorithm, two techniques were employed. In order to deal with the large set of training data, the method of Random Forests was employed; this is a state-of-the-art classification algorithm in the field of computer vision. In order to make this system robust in terms of illumination, a Binary Pattern Run Length matrix was employed; this matrix is combination of Binary Pattern and a Run Length matrix. The binary pattern was calculated by randomly selected operator. In order to extract feature of training patch, we calculate statistical texture features from the Binary Pattern Run Length matrix. Moreover we perform some techniques to real-time operation, such as control the number of binary test. Experimental results show that our algorithm is efficient and robust against illumination change. © 2014, Kim et al.; licensee Springer.1

    Efficacy and safety of hepatic arterial infusion chemotherapy for advanced hepatocellular carcinoma as first-line therapy

    Get PDF
    Background/AimsHepatic arterial infusion chemotherapy (HAIC) with 5-fluorouracil and cisplatin for intractable advanced hepatocellular carcinoma (HCC) may have survival benefits. We aimed to determine the efficacy and safety of HAIC for advanced HCC as first-line therapy.MethodsA total of 54 patients who received only HAIC with 5-fluorouracil (750 mg/m2 on days 1-4) and cisplatin (25 mg/m2 on days 1-4) for advanced HCC from Jan. 2009 to Dec. 2011 were selected. According to Child-Pugh class, the overall survival (OS), progression-free survival (PFS), and adverse events after HAIC were investigated retrospectively.ResultsMedian OS and PFS between the Child-Pugh A group (n=24) and the Child-Pugh B/C group (n=30) were 8.7 (95% confidence interval [CI]: 4.7-12.7) vs. 3.7 months (95% CI: 2.0-5.3), and 7.1 (95% CI: 3.8-10.4) vs. 3.6 months (95% CI: 2.0-5.2), respectively. Although median OS and PFS were not statistically significant between the two groups (P=0.079, P=0.196), the Child-Pugh class B/C tended to influence poor OS. Serious adverse events ≥ grade 3 occurred frequently in both groups (83.3 vs. 96.7%, P=0.159). Responders (22.2%, complete or partial response) significantly differed in median OS, compared to non-responders (13.1 vs. 4.4 months, P=0.019). Achievement of complete or partial response was an independent prognostic factor of OS (hazard ratio: 0.4, 95% CI: 0.2-0.8, P=0.011).ConclusionsAchievement of response after HAIC provide a survival benefit in patients with advanced HCC, but HAIC should be administered cautiously in patients with Child-Pugh class B/C, because of a relatively low survival and high incidence of serious adverse events

    Fabrication of flexible UV nanoimprint mold with fluorinated polymer-coated PET film

    Get PDF
    UV curing nanoimprint lithography is one of the most promising techniques for the fabrication of micro- to nano-sized patterns on various substrates with high throughput and a low production cost. The UV nanoimprint process requires a transparent template with micro- to nano-sized surface protrusions, having a low surface energy and good flexibility. Therefore, the development of low-cost, transparent, and flexible templates is essential. In this study, a flexible polyethylene terephthalate (PET) film coated with a fluorinated polymer material was used as an imprinting mold. Micro- and nano-sized surface protrusion patterns were formed on the fluorinated polymer layer by the hot embossing process from a Si master template. Then, the replicated pattern of the fluorinated polymer, coated on the flexible PET film, was used as a template for the UV nanoimprint process without any anti-stiction coating process. In this way, the micro- to nano-sized patterns of the original master Si template were replicated on various substrates, including a flat Si substrate and curved acryl substrate, with high fidelity using UV nanoimprint lithography
    corecore