1,709 research outputs found

    Optimum Remedial Operation of Permanent Magnet Synchronous Motor

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    In critical systems, the reliability of the drive is very important. The faults are unwanted. The faults may be lead to loss of the human life and capital. This paper is addressed this problem and suggested two models to solve it. The first model doesn’t contain any special tools to improve the torque ripple and THD. The second model contains 2PI current controllers to improvement the performance at fault and remedial operation. One is for the torque and the other is for the flux. The first PI controller is feeding from the torque error between the reference and estimated torques to get new q-axis current component representing modifier current arises from uncertain things inside the machine and drive system such as temperature and parameters variations. This current will add to reference q-axis current to get robust new q-axis current to satisfy the drive requirement and solve the torque problem (ripple torque). With robust current, the total harmonic distortion is a decrease but doesn’t reach the best value so the other PI controller is used to adjust the THD. In this PI controller, the d-axis flux is compared to rotor permanent magnet flux to solve this problem arises from non-sinusoidal of the magnetic flux. The output of the PI controller is introduced to the reference d-axis current. The new d-axis current will reach the best value of THD. The simulation of the second controller is compared to the simulation of first controller to show if the second controller strong or weak. Matlab simulink is used to simulate the drive system.DOI:http://dx.doi.org/10.11591/ijece.v2i5.72

    Association of Helicobacter pylori infection and severity of coronary artery atherosclerosis in patients with suspected coronary artery disease

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    Background: There is a strong correlation between Helicobacter pylori (HP) infection and coronary artery disease (CAD). There is also a strong correlation between HP infection and the severity of coronary artery atherosclerosis in patients with CAD. Our study determined the association of HP infection and severity of coronary artery atherosclerosis in patients with suspected CAD. Methods: A prospective study of 100 individuals who had coronary angiography for coronary atherosclerosis was conducted. Body mass index (BMI), blood pressure, blood cholesterol, blood glucose, leukocyte count, hemoglobin, and urea breath test were all done on the patients. Coronary angiograms were graded based on vascular and angiographic severity scores. Results: Triglyceride, (TG), Low Density Lipoprotein (LDL), C- Reactive Protein (CRP), Erythrocyte Sedimentation Rate (ESR), vessel score, and angiographic severity score all showed high correlations with Gensini score. There was a substantial association between vessel score and TG, LDL and angiographic severity score. It was found that angiographic severity score has a substantial positive link to a person's BMI; LDL; CRP; ESR, and vessel score. Conclusion: Although HP infection has been linked to an increased risk of coronary artery disease (CAD), established risk variables outweigh their potential impact

    Garay’s Condition of Deformed Cylindrical and Translation Surfaces in E3

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    The motivation of the present work is to develop the finiteness property in our work [1, 2, 3, 4] by using Garay’s condition [5]. The mean curvature flow and the finiteness property of the cylindrical surfaces in E3 are investigated. Additionally, the linear deformation of such surfaces is studied. Finally, the translation surfaces are discussed

    Stellar parameters of Be stars observed with X-shooter

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    Aims. The X-shooter archive of several thousand telluric star spectra was skimmed for Be and Be-shell stars to derive the stellar fundamental parameters and statistical properties, in particular for the less investigated late type Be stars, and the extension of the Be phenomenon into early A stars. Methods. An adapted version of the BCD method is used, utilizing the Balmer discontinuity parameters to determine effective temperature and surface gravity. This method is optimally suited for late B stars. The projected rotational velocity was obtained by profile fitting to the Mg ii lines of the targets, and the spectra were inspected visually for the presence of peculiar features such as the infrared Ca ii triplet or the presence of a double Balmer discontinuity. The Balmer line equivalent widths were measured, but due to uncertainties in determining the photospheric contribution are useful only in a subsample of Be stars for determining the pure emission contribution. Results. A total of 78 Be stars, mostly late type ones, were identified in the X-shooter telluric standard star archive, out of which 48 had not been reported before. The general trend of late type Be stars having more tenuous disks and being less variable than early type ones is confirmed. The relatively large number (48) of relatively bright (V > 8.5) additional Be stars casts some doubt on the statistics of late type Be stars; they are more common than currently thought: The Be/B star fraction may not strongly depend on spectral subtype.Comment: Accepted for publication in A&

    MaaSim: A Liveability Simulation for Improving the Quality of Life in Cities

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    Urbanism is no longer planned on paper thanks to powerful models and 3D simulation platforms. However, current work is not open to the public and lacks an optimisation agent that could help in decision making. This paper describes the creation of an open-source simulation based on an existing Dutch liveability score with a built-in AI module. Features are selected using feature engineering and Random Forests. Then, a modified scoring function is built based on the former liveability classes. The score is predicted using Random Forest for regression and achieved a recall of 0.83 with 10-fold cross-validation. Afterwards, Exploratory Factor Analysis is applied to select the actions present in the model. The resulting indicators are divided into 5 groups, and 12 actions are generated. The performance of four optimisation algorithms is compared, namely NSGA-II, PAES, SPEA2 and eps-MOEA, on three established criteria of quality: cardinality, the spread of the solutions, spacing, and the resulting score and number of turns. Although all four algorithms show different strengths, eps-MOEA is selected to be the most suitable for this problem. Ultimately, the simulation incorporates the model and the selected AI module in a GUI written in the Kivy framework for Python. Tests performed on users show positive responses and encourage further initiatives towards joining technology and public applications.Comment: 16 page

    FABRICATION OF BIOADHESIVE OCUSERT WITH DIFFERENT POLYMERS: ONCE A DAY DOSE

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    Objective: The objective of this current study is to fabricate ocuserts to control the drug release from chosen bioadhesive polymeric matrixes to enhance patient compliance. Ciprofloxacin HCl (CFX HCl) was selected as a model drug.Methods: Different bioadhesive polymers with different film forming capabilities namely Hydroxy Propyl Methyl Cellulose (HPMC K4M), Poly Vinyl Alcohol (PVA), Sodium Carboxy Methyl Cellulose (Na CMC), Hydroxy Propyl Cellulose (HPC), Sodium Alginate (Na Alg.), pullulan and Xanthan Gum (XG) in different ratios were used in fabricating ocuserts using solvent-casting technique. Propylene Glycol (PG) was used as a plasticizer to facilitate the fabrication process. Characterization tests of the developed ocuserts were performed as well as bioadhesive tests and in vitro release studies of the incorporated drug. The obtained results were analysed using different release kinetic models. Stability of the selected ocuserts was investigated at 40±0.5 °C and 75±5% Relative Humidity (RH) for three months' storage period. In vivo ocular irritation test was performed to investigate the safety of the formula in rabbits' eyes as well as to test the release profile and thus to estimate In vitro In vivo correlation.Results: All the prepared ocuserts showed the uniformity of film characterization and bioadhesion strength ranged from 240±66 and 158±52dyne/cm2. Selected formula from the in vitro release study tested for in vivo study showed the slow release of ciprofloxacin drug up to 24 h with no signs of eye irritancy. Results for In vitro In vivo correlation showed an excellent correlation with R2 value of 0.9982.Conclusion: PVA based ocuserts proven to be a promising once-daily, effective and safe ocular delivery system of the drug

    The Effects of Midline Cerebellar rTMS on Human Pharyngeal Cortical Activity in the Intact Swallowing Motor System

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    We sought to compare the effects of 10 Hz cerebellar vermis (vs. unilateral hemispheric and sham) repetitive transcranial magnetic stimulation (rTMS) on cortical neuroelectrical activity and thereafter 10 Hz cerebellar vermis (vs. sham) rTMS on swallowing behaviour. Healthy participants (n = 25) were randomly allocated to receive vermis, unilateral hemisphere or sham 10 Hz cerebellar rTMS. Recordings were made using pharyngeal electromyography and manometry catheters, obtaining motor-evoked potentials (MEPs) and pressure recordings. The amplitudes of MEPs elicited using single-pulse TMS delivered to the pharyngeal areas of the motor cortex bilaterally were measured pre- and post-cerebellar stimulation. As in previous studies, abductor policis brevis (APB) MEPs were measured to assess post-rTMS modulation specificity. Swallowing was assessed using a swallowing accuracy task. Measurements were made at baseline and 15-min intervals for an hour post-intervention. Measurements involved TMS being used to elicit 10 MEPs bilaterally over the pharyngeal areas of the motor cortex, over the APB cortical representation adjacent to the pharyngeal area with the lowest resting motor threshold and 5 MEPs bilaterally over pharyngeal areas of the cerebellar hemispheres. Swallowing accuracy was assessed by giving participants 10 attempts to swallow and hit a digital target. Cerebellar vermis rTMS caused significant suppression of cortical pharyngeal MEP amplitudes compared with unilateral rTMS and sham (P = 0.0005, 0.002). APB and cerebellar MEP amplitudes were unaffected as were pharyngeal and APB MEP latencies. Following cerebellar vermis rTMS there was a significant reduction in swallowing accuracy compared with sham (P = 0.001). Our findings demonstrate cerebellar vermis rTMS exerts a suppressive effect on pharyngeal motor cortical activity and swallowing behaviour

    Comparative quantitative survey of patient experience in Barrett's oesophagus and other gastrointestinal disorders

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    Objective To assess health-related quality of life in patients with non-dysplastic Barrett’s oesophagus (NDBO) and endoscopically treated dysplastic Barrett’s oesophagus (DBO). Design This quantitative, self-administered questionnaire study was conducted across three National Health Service hospitals. Data were collected from three other cohorts; gastro-oesophageal reflux disease (GORD), colonic polyp surveillance and healthy individuals. Fisher’s exact and Spearman’s rank correlation tests were used for analysis. Propensity score matching adjusted for age, sex and comorbidities. Results 687 participants were eligible for analysis (NDBO n=306, DBO n=49, GORD n=132, colonic polyps n=152 and healthy n=48). 53% of NDBO participants reported similarly high cancer worry, comparable to DBO (50%, p=0.933) and colonic polyp participants (51%, p=0.355). Less cancer worry was reported in GORD participants (43.4%, p=0.01 vs NDBO). NDBO participants reported anxiety in 15.8% and depression in 8.6% of cases, which was similar to the other disease cohorts. Moderate or severe heartburn or acid regurgitation was found in 11% and 10%, respectively, in the NDBO cohort, comparable to DBO participants (heartburn 2% p=0.172, acid regurgitation 4% p=0.31) but lower (better) than GORD participants (heartburn 31% p=<0.001, acid regurgitation 25% p=0.001). NDBO participants with moderate or severe GORD symptoms were associated with higher rates of anxiety (p=<0.001), depression (p=<0.001) and cancer worry (p=<0.001). NDBO patients appropriately perceiving their cancer risk as low had lower rates of cancer worry (p=<0.001). Conclusion This study provides insight into the problems Barrett’s oesophagus patients may face. Future care pathways must be more patient focussed to address misconceptions of cancer risk, oesophageal cancer related worry and GORD symptom control
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