124 research outputs found

    Evaluation of Fuzzy Logic Subsets Effects on Maximum Power Point Tracking for Photovoltaic System

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    Photovoltaic system (PV) has nonlinear characteristics which are affected by changing the climate conditions and, in these characteristics, there is an operating point in which the maximum available power of PV is obtained. Fuzzy logic controller (FLC) is the artificial intelligent based maximum power point tracking (MPPT) method for obtaining the maximum power point (MPP). In this method, defining the logical rule and specific range of membership function has the significant effect on achieving the best and desirable results. This paper presents a detailed comparative survey of five general and main fuzzy logic subsets used for FLC technique in DC-DC boost converter. These rules and specific range of membership functions are implemented in the same system and the best fuzzy subset is obtained from the simulation results carried out in MATLAB. The proposed subset is able to track the maximum power point in minimum time with small oscillations and the highest system efficiency (95.7%). This investigation provides valuable results for all users who want to implement the reliable fuzzy logic subset for their works

    A strategy to characterize the LISA-Pathfinder cold gas thruster system

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    The cold gas micro-propulsion system that will be used during the LISA-Pathfinder mission will be one of the most important component used to ensure the "free-fall" of the enclosed test masses. In this paper we present a possible strategy to characterize the effective direction and amplitude gain of each of the 6 thrusters of this system

    Diagnostic accuracy of FET-PET/CT, FDG-PET/CT and diffusion-weighted MRI in detection of nodal metastases in surgically treated endometrial and cervical carcinoma

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    PURPOSE:Pre-operative nodal staging is important for planning treatment in cervical cancer (CC) and endometrial cancer (EC) but remains challenging. We compare nodal staging accuracy of {18}^F-ethyl-choline-(FEC)-PET/CT, {18}^F-Fluoro-deoxy-glucose-(FDG)-PET/CT and diffusion-weighted-MRI (DW-MRI) with conventional morphological MRI. Experimental Design: A prospective, multicentre observational study of diagnostic accuracy for nodal metastases was undertaken in 5 gyne-oncology centres. FEC-PET/CT, FDG-PET/CT and DW-MRI were compared to nodal size and morphology on MRI. Reference standard was strictly correlated nodal histology. Eligibility included operable CC stage=>1B1 or EC (grade 3 any stage with myometrial invasion or grade 1-2 stage=>II). RESULTS: Among 162 consenting participants, 136 underwent study DW-MRI and FDG-PET/CT, and 60 underwent FEC-PET/CT. 267 nodal regions in 118 women were strictly correlated at histology (nodal positivity rate 25%). Sensitivity per-patient (n=118) for nodal size, morphology, DW-MRI, FDG- and FEC-PET/CT were 40%*, 53%, 53%, 63%* and 67% for all cases (*p=0.016); 10%, 10%, 20%, 30% and 25% in CC (n=40); 65%, 75%, 70%, 80% and 88% in EC (n=78). FDG-PET/CT outperformed nodal size (p=0.006) and size ratio (p=0.04) for per-region sensitivity. False positive rates were all <10%. CONCLUSIONS: All imaging techniques had low sensitivity for detection of nodal metastases and cannot replace surgical nodal staging. The performance of FEC-PET/CT was not statistically different to other techniques that are more widely available. FDG-PET/CT had higher sensitivity than size in detecting nodal metastases. False positive rates were low across all methods. The low false positive rate demonstrated by FDG-PET/CT may be helpful in arbitration of challenging surgical planning decisions

    Free-flight experiments in LISA Pathfinder

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    The LISA Pathfinder mission will demonstrate the technology of drag-free test masses for use as inertial references in future space-based gravitational wave detectors. To accomplish this, the Pathfinder spacecraft will perform drag-free flight about a test mass while measuring the acceleration of this primary test mass relative to a second reference test mass. Because the reference test mass is contained within the same spacecraft, it is necessary to apply forces on it to maintain its position and attitude relative to the spacecraft. These forces are a potential source of acceleration noise in the LISA Pathfinder system that are not present in the full LISA configuration. While LISA Pathfinder has been designed to meet it's primary mission requirements in the presence of this noise, recent estimates suggest that the on-orbit performance may be limited by this `suspension noise'. The drift-mode or free-flight experiments provide an opportunity to mitigate this noise source and further characterize the underlying disturbances that are of interest to the designers of LISA-like instruments. This article provides a high-level overview of these experiments and the methods under development to analyze the resulting data.Comment: 13 pages, 5 figures. Accepted to Journal Of Physics, Conference Series. Presented at 10th International LISA Symposium, May 2014, Gainesville, FL, US

    In-flight thermal experiments for LISA pathfinder: simulating temperature noise at the inertial sensors

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    Thermal Diagnostics experiments to be carried out on board LISA Pathfinder (LPF) will yield a detailed characterisation of how temperature fluctuations affect the LTP (LISA Technology Package) instrument performance, a crucial information for future space based gravitational wave detectors as the proposed eLISA. Amongst them, the study of temperature gradient fluctuations around the test masses of the Inertial Sensors will provide as well information regarding the contribution of the Brownian noise, which is expected to limit the LTP sensitivity at frequencies close to 1 mHz during some LTP experiments. In this paper we report on how these kind of Thermal Diagnostics experiments were simulated in the last LPF Simulation Campaign (November, 2013) involving all the LPF Data Analysis team and using an end-to-end simulator of the whole spacecraft. Such simulation campaign was conducted under the framework of the preparation for LPF operations

    Micrometeoroid Events in LISA Pathfinder

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    The zodiacal dust complex, a population of dust and small particles that pervades the Solar System, provides important insight into the formation and dynamics of planets, comets, asteroids, and other bodies. Here we present a new set of data obtained using a novel technique: direct measurements of momentum transfer to a spacecraft from individual particle impacts. This technique is made possible by the extreme precision of the instruments flown on the LISA Pathfinder spacecraft, a technology demonstrator for a future space-based gravitational wave observatory that operated near the first Sun-Earth Lagrange point from early 2016 through Summer of 2017. Using a simple model of the impacts and knowledge of the control system, we show that it is possible to detect impacts and measure properties such as the transferred momentum (related to the particle's mass and velocity), direction of travel, and location of impact on the spacecraft. In this paper, we present the results of a systematic search for impacts during 4348 hours of Pathfinder data. We report a total of 54 candidates with momenta ranging from 0.2μNs\,\mu\textrm{Ns} to 230μNs\,\mu\textrm{Ns}. We furthermore make a comparison of these candidates with models of micrometeoroid populations in the inner solar system including those resulting from Jupiter-family comets, Oort-cloud comets, Hailey-type comets, and Asteroids. We find that our measured population is consistent with a population dominated by Jupiter-family comets with some evidence for a smaller contribution from Hailey-type comets. This is in agreement with consensus models of the zodiacal dust complex in the momentum range sampled by LISA Pathfinder.Comment: 22 pages, 14 figures, accepted in Ap

    Is gynaecological surgical training a cause for concern? A questionnaire survey of trainees and trainers

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    <p>Astract</p> <p>Background</p> <p>Concerns have been raised as to whether the current postgraduate training programme for gynaecological surgery is being detrimentally affected by changes in working practices, in particular the European Working Time Directive (EWTD). The purpose of this study was to investigate the surgical activity of obstetrics and gynaecology trainees and to explore trainees' and trainers' opinions on the current barriers and potential solutions to surgical training.</p> <p>Methods</p> <p>Two questionnaire surveys were conducted, one to obstetrics and gynaecology trainees working within the West Midlands Deanery and a second to consultant gynaecologists in the West Midlands region.</p> <p>Results</p> <p>One hundred and four trainees (64.3%) and 66 consultant gynaecologists (55.0%) responded. Sixty-six trainees (66.7%) reported attending up to one operating list per week. However, 28.1% reported attending up to one list every two weeks or less and 5 trainees stated that they had not attended a list at all over the preceding 8 weeks. Trainees working in a unit with less than 3999 deliveries attended significantly more theatre sessions compared to trainees in units with over 4000 deliveries (p = 0.007), as did senior trainees (p = 0.032) and trainees attached to consultants performing major gynaecological surgery (p = 0.022). In the previous 8 weeks, only 6 trainees reported performing a total abdominal hysterectomy independently, all were senior trainees (ST6 and above). In the trainers' survey, only two respondents (3.0%) agreed that the current program produces doctors competent in general gynaecological surgery by the end of training, compared to 48 (73.8%) respondents who disagreed.</p> <p>Conclusions</p> <p>Trainees' concerns over a lack of surgical training appear to be justified. The main barriers to training are perceived to be a lack of team structure and a lack of theatre time.</p

    Craniofacial surgery for nonmelanoma skin malignancy: Report of an international collaborative study

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    AbstractBackground.This study examined the efficacy of craniofacial surgery (CFS) in treating locally advanced nonmelanoma skin cancer (NMSC).Methods.One hundred twenty patients who underwent CFS for NMSC were identified from 17 participating institutions. Patient, tumor, and treatment information was analyzed for prognostic impact on survival.Results.Surgical margins were negative in 74%, close in 3%, and involved in 23% of patients. Complications occurred in 35% of patients, half of which were local wound problems. Operative mortality was 4%. Median follow‐up interval after CFS was 27 months. The 5‐year overall survival (OS), disease‐specific survival (DSS), and recurrence‐free survival (RFS) rates were 64%, 75%, and 60%, respectively. Squamous cell histology, brain invasion, and positive resection margins independently predicted worse OS, DSS, and RFS.Conclusion.CFS is an effective treatment for patients with NMSC invading the skull base. Histology, extent of disease, and resection margins are the most significant predictors of outcome. © 2007 Wiley Periodicals, Inc. Head Neck, 200

    CT694 and pgp3 as Serological Tools for Monitoring Trachoma Programs.

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    Defining endpoints for trachoma programs can be a challenge as clinical signs of infection may persist in the absence of detectable bacteria. Antibody-based tests may provide an alternative testing strategy for surveillance during terminal phases of the program. Antibody-based assays, in particular ELISAs, have been shown to be useful to document C. trachomatis genital infections, but have not been explored extensively for ocular C. trachomatis infections. An antibody-based multiplex assay was used to test two C. trachomatis antigens, pgp3 and CT694, for detection of trachoma antibodies in bloodspots from Tanzanian children (n = 160) collected after multiple rounds of mass azithromycin treatment. Using samples from C. trachomatis-positive (by PCR) children from Tanzania (n = 11) and control sera from a non-endemic group of U.S. children (n = 122), IgG responses to both pgp3 and CT694 were determined to be 91% sensitive and 98% specific. Antibody responses of Tanzanian children were analyzed with regard to clinical trachoma, PCR positivity, and age. In general, children with more intense ocular pathology (TF/TI = 2 or most severe) had a higher median antibody response to pgp3 (p = 0.0041) and CT694 (p = 0.0282) than those with normal exams (TF/TI = 0). However, 44% of children with no ocular pathology tested positive for antibody, suggesting prior infection. The median titer of antibody responses for children less than three years of age was significantly lower than those of older children. (p<0.0001 for both antigens). The antibody-based multiplex assay is a sensitive and specific additional tool for evaluating trachoma transmission. The assay can also be expanded to include antigens representing different diseases, allowing for a robust assay for monitoring across NTD programs

    Enteric Infection with Citrobacter rodentium Induces Coagulative Liver Necrosis and Hepatic Inflammation Prior to Peak Infection and Colonic Disease

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    Acute and chronic forms of inflammation are known to affect liver responses and susceptibility to disease and injury. Furthermore, intestinal microbiota has been shown critical in mediating inflammatory host responses in various animal models. Using C. rodentium, a known enteric bacterial pathogen, we examined liver responses to gastrointestinal infection at various stages of disease pathogenesis. For the first time, to our knowledge, we show distinct liver pathology associated with enteric infection with C. rodentium in C57BL/6 mice, characterized by increased inflammation and hepatitis index scores as well as prominent periportal hepatocellular coagulative necrosis indicative of thrombotic ischemic injury in a subset of animals during the early course of C. rodentium pathogenesis. Histologic changes in the liver correlated with serum elevation of liver transaminases, systemic and liver resident cytokines, as well as signal transduction changes prior to peak bacterial colonization and colonic disease. C. rodentium infection in C57BL/6 mice provides a potentially useful model to study acute liver injury and inflammatory stress under conditions of gastrointestinal infection analogous to enteropathogenic E. coli infection in humans.United States. Army Research Office (Institute for Soldier Nanotechnology grant 6915539 (SRT))National Institutes of Health (U.S.) (Grant P01 CA026731)National Institutes of Health (U.S.) (Grant P30 ES02109)National Institutes of Health (U.S.) (Toxicology Training grant ES-070220
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