Disturbance-rejection control for unbalanced operation of microgrids: Invariant-set approach.

In microgrids, voltage imbalance control is crucial to preserving the required level of power quality. The article presents a tracker design that mitigates the unbalance in the microgrids. The proposed microgrid model includes positive and negative sequences, whereby the positive sequences are controlled, and the negative sequence is treated as an external disturbance (whose effect must be attenuated).

Decentralized Sensor Fault-Tolerant Control of DC Microgrids Using the Attracting Ellipsoid Method.

System stability deterioration in microgrids commonly occurs due to unpredictable faults and equipment malfunctions. Recently, robust control techniques have been used in microgrid systems to address these difficulties. In this paper, for DC-islanded microgrids that have sensors faults, a new passive fault-tolerant control strategy is developed.

Clinical Evaluation of 660 nm Diode Laser Therapy on the Pain, Size and Functional Disorders of Recurrent Aphthous Stomatitis.

Background: Minor recurrent aphthous stomatitis (MiRAS) is one of the most common, recurrent, and painful mucosal pathological condition. It is characterised by round or shallow oval ulcers, less than 10 mm in diameter, surrounded by a thin erythematous halo. It involves non-keratinized mucosa such as the labial and buccal mucosa, the ventral surface or borders of the tongue and the floor of the mouth, but it is uncommon to occur on the keratinised mucosa.

Demographics, Clinical Characteristics, Management, and Outcomes of Acute Heart Failure Patients: Observations from the Oman Acute Heart Failure Registry.

Objectives: We sought to describe the demographics, clinical characteristics, management and outcomes of patients in Oman with acute heart failure (AHF) as part of the Gulf aCute heArt failuRe rEgistry (CARE) project.

Methods: Data were analyzed from 988 consecutive patients admitted with AHF to 12 hospitals in Oman between 14 February and 14 November 2012.

Results: The mean age of our patients was 63±12 years.

Resilient guaranteed cost control of a power system.

With the development of power system interconnection, the low-frequency oscillation is becoming more and more prominent which may cause system separation and loss of energy to consumers. This paper presents an innovative robust control for power systems in which the operating conditions are changing continuously due to load changes. However, practical implementation of robust control can be fragile due to controller inaccuracies (tolerance of resistors used with operational amplifiers).

Role of descending venography and endovenous embolization in treatment of females with lower extremity varicose veins, vulvar and posterior thigh varices.

Objective: To evaluate the prevalence of refluxing pelvic veins among female patients with lower extremity varicose veins and the role of embolization treatment in these cases.

Methods: Of 158 female patients suffering from primary varicose veins of the lower extremities presented to the Venous Disease Clinic at Dhahran Health Center between January 2002 and December 2004, 25 patients (15.8%) were noted to have vulvar or postero-medial thigh varices or both.

Caustic esophageal strictures in children: 30 years' experience.

Many children in developing countries continue to sustain caustic esophageal injures. The first line of treatment is dilatation, unless contraindicated, where 60% to 80% success rate is expected. In cases of failure, esophageal replacement is the only hope for achieving normal swallowing.