A flexible AC distribution system device for a microgrid

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Smart distribution network device for microgrid applications

This paper focuses on the design of a smart distribution network device for improving the power quality and reliability of the overall power distribution system that the microgrid is connected to. The control design employs a newly developed Model Predictive Control algorithm which optimizes the steady-state and the transient control problems separately to achieve a faster computational time for large power systems. Kalman filters are also employed as state observers to identify the required signals needed for monitoring purposes as well as to extract the harmonic spectra of the grid voltage and the load currents. The design concept is verified through different test case scenarios to demonstrate the capability of the proposed device and the results obtained are discussed. © 2012 IEEE.published_or_final_versio

Coordinated control and energy management of distributed generation inverters in a microgrid

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Is ultrasonography-guided modified coaxial core biopsy of the breast a better technique?

Objective: To compare the diagnostic rate, patient comfort, and complications of ultrasonography-guided breast biopsy using a modified coaxial technique with ultrasonography-guided fine needle aspiration and traditional core biopsy. A secondary objective was to describe the use of the coaxial technique for the biopsy of breast lesions and our initial experience. Design: Retrospective study. Setting: A regional hospital in Hong Kong. Patients: Patients, who were referred for ultrasonography-guided fine needle aspiration or biopsy from 23 November 2007 to 19 March 2008, were divided into three groups. For breast lesions of 8 mm or smaller, fine needle aspirations were performed. For breast lesions larger than 8 mm, the patients were randomly divided into groups receiving traditional core biopsies and coaxial biopsies. The pathological reports were reviewed. Main outcome measures: Diagnostic rate, patient comfort assessed in terms of pain, and any procedural complications. Results: A total of 45 ultrasonography-guided fine needle aspirations or biopsies of breast lesions were performed. All core biopsies using the traditional core technique (n=15) and coaxial technique (n=16) were diagnostic. While for fine needle aspirations, three (21%) of 14 were not diagnostic and repeat biopsies were undertaken for the corresponding patients. Except for one breast lesion biopsied with the coaxial technique that revealed invasive ductal carcinoma, all others yielded benign lesions. The average pain score for coaxial biopsies was 2.2, while for traditional core biopsies and fine needle aspirations, average scores were 3.7 and 3.8, respectively (P=0.022). No procedure-related complication was documented with either of the three techniques. Conclusion: Modified coaxial core biopsy of the breast has an optimal diagnostic rate and hence avoids the need for repeat biopsies. It is associated with better patient comfort and no increase in the risk of complications.published_or_final_versio

An economical fabrication technique for SIMOX using plasma immersion ion implantation

Buried oxide layers in Si were fabricated using non-mass analyzed plasma immersion ion implantation (PIII). The implantation was carried out by applying a large negative bias to a Si wafer immersed in an oxygen plasma and a dose of 3×1017 cm-2 of oxygen was implanted in about three minutes. Cross section transmission electron microscopy (XTEM) and Rutherford backscattering spectrometry (RES) were used to characterize the wafers. Our results indicate that a continuous buried oxide layer with a single crystal silicon overlayer was synthesizedpublished_or_final_versio

Cataract surgery in uveitis: a multicentre database study

BACKGROUND/AIMS: Cataract is an important source of visual loss in patients with uveitis. Whether or not outcomes of cataract surgery in eyes with uveitis are worse compared with non-uveitic eyes have to date been compromised by lack of reliable estimates of benefit and harm, which require data from large cohorts. METHODS: Electronic medical record data were extracted from eight independent UK clinical sites for eyes undergoing cataract extraction between January 2010 and December 2014. 1173 eyes with a recorded diagnosis of uveitis were compared with a reference group of 95 573 eyes from the same dataset. RESULTS: Uveitic eyes represented 1.2% of all eyes undergoing cataract surgery. Eyes in the uveitic group had worse preoperative visual acuity (0.87 vs 0.65 logarithm of the minimum angle of resolution (logMAR) units), were from younger patients and had shorter axial lengths and a higher incidence of ocular copathology including glaucoma. A greater number had documented small pupils, required additional surgical procedures, developed more intraoperative complications and had poorer postoperative visual acuity at all time points measured up to 6 months (0.41 vs 0.27 logMAR units at 12-24 weeks). CONCLUSIONS: This large study cohort of eyes with a diagnosis of uveitis undergoing cataract surgery highlights more precisely the complex surgical demands, copathology and worse visual outcomes in this group. These data will allow more accurate preoperative counselling and planning. Although improvement in visual acuity is achieved in most cases, prognosis should be guarded, so that patient expectations are met. Compared with the non-uveitic population, the mean postoperative visual acuity is between one and two lines worse at all time points

Development of a Bonner Sphere neutron spectrometer from a commercial neutron dosimeter

Bonner Spheres have been used widely for the measurement of neutron spectra with neutron energies ranged from thermal up to at least 20 MeV . A Bonner Sphere neutron spectrometer (BSS) was developed by extending a Berthold LB 6411 neutron-dose-rate meter. The BSS consists of a 3He thermal-neutron detector with integrated electronics, a set of eight polyethylene spherical shells and two optional lead shells of various sizes. The response matrix of the BSS was calculated with GEANT4 Monte Carlo simulation. The BSS had a calibration uncertainty of ± 8.6% and a detector background rate of (1.57 ± 0.04) × 10−3 s−1. A spectral unfolding code NSUGA was developed. The NSUGA code utilizes genetic algorithms and has been shown to perform well in the absence of a priori information.postprin

Hardness, yield strength, and plastic flow in thin film metallic-glass

2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Predictors of betel quid chewing behavior and cessation patterns in Taiwan aborigines

BACKGROUND: Betel quid, chewed by about 600 million people worldwide, is one of the most widely used addictive substances. Cessation factors in betel quid chewers are unknown. The present study explores prevalence and the quit rate of betel quid chewing in Taiwan aborigines. Our goal was to delineate potential predictors of chewing cessation. METHODS: A stratified random community-based survey was designed for the entire aborigines communities in Taiwan. A total of 7144 participants were included between June 2003 and May 2004 in this study. Information on sociodemographic characteristics, such as gender, age, obesity, education years, marital status, ethnicity, and habits of betel quid chewing, smoking and drinking was collected by trained interviewers. RESULTS: The prevalence of betel quid chewers was 46.1%. Betel quid chewing was closely associated with obesity (OR = 1.61; 95% CI: 1.40–1.85). Betel quid chewers were most likely to use alcohol and cigarettes together. Quit rate of betel quid chewers was 7.6%. Betel quid chewers who did not drink alcohol were more likely to quit (OR = 1.89; 95% CI: 1.43–2.50). Alcohol use is a significant factor related to cessation of betel quid chewing, but smoking is not. CONCLUSION: Taiwan aborigines have a high prevalence of betel quid chewers and a low quit rate. Alcohol use is strongly association with betel quid chewing. Efforts to reduce habitual alcohol consumption might be of benefit in cessation of betel quid chewing

Papillary carcinoma arising in a thyroglossal duct cyst with associated microcarcinoma of the thyroid and without cervical lymph node metastasis: a case report

<p>Abstract</p> <p>Introduction</p> <p>This is a case report of a 44-year-old woman with papillary carcinoma of a thyroglossal duct cyst.</p> <p>Case presentation</p> <p>A 44 year-old woman presented to the otolaryngology outpatient clinic with an asymptomatic anterior midline neck mass. A cervical ultrasound showed a lesion which appeared to be a thyroglossal duct cyst and surgical resection using Sistrunk's procedure was performed. The histopathologic diagnosis showed papillary carcinoma evolving from a thyroglossal duct cyst, confined to the thyroglossal cyst, with a tumor diameter of 2 cm. The patient then underwent total thyroidectomy and bilateral neck dissection. The final pathology reported an 8 mm papillary cancer in the left lobe of the thyroid without any metastasis to the cervical lymph nodes. The patient was treated with radioactive iodide and thyroid suppresion therapy was given as adjuvant treatment. The patient has been following for two years without any metastasis.</p> <p>Conclusion</p> <p>Malignancy within a thyroglossal duct cyst is very rare but should be considered in the differential diagnosis of a midline neck mass.</p