Fuzzy pre-compensated PI control of active filters

This paper deals with a new and improved control technique for shunt active filters (AF) used for compensating unwanted harmonic currents injected in the mains due to nonlinear varying loads. This work is motivated by the need to find a permanent solution to the rigorous hit and trial method for evaluating system parameters in an indirect control of AF. A fuzzy pre-compensated PI (Proportional-Integral) controller is used to fuzzify the reference DC voltage of AF to the controller input so that the overshoots and undershoots in its DC link voltage are minimized and the settling time is improved. A three-phase diode rectifier with R-L (Resistive-Inductive) load is used as a non-linear load to study the effectiveness of the proposed controller of the AF. Robustness to filter parameter variations, insensitivity to controller parameter variations, and transient response has been taken as performance evaluation parameters. The results are shown through simulations in Matlab using power system block sets to demonstrate the capability of the proposed controller of the AF

Improved control of three phase active filters using genetic algorithms

This paper deals with a new control technique of system parameter evaluation for a parallel three phase active filters (AF) to eliminate harmonics and to compensate reactive power of non-linear loads. The work is motivated by the need to minimize the burden on the DC-link capacitor voltage under dynamic load conditions. Genetic algorithm is used to obtain an optimized control of DC-link voltage. A three phase diode rectifier with R-L loading is used as a non-linear load. The system dynamic performance is analyzed based on its transient response to load change and load unbalancing. Moreover, the robustness of the system to filter parameter variation is also studied. The AF is found effective to meet IEEE-519 standard recommendations on harmonics level

Neuromyelitis optica-IgG testing in an Indian cohort with neuromyelitis optica and related demyelinating disorders: Our experience

Background: Neuromyelitis optica (NMO) is an immune-mediated inflammatory demyelinating disorder of the central nervous system with a predilection for the optic nerves and the spinal cord. Immunopathological evidence suggests that the target antigen of the disease is aquaporin-4. An IgG antibody against this protein has been explored as a molecular marker for the disease and as a diagnostic tool due to its high sensitivity and specificity in various populations. Objective: To assess the value of NMO-IgG testing in Indian patients with clinical and magnetic resonance imaging features consistent with NMO and longitudinally extensive transverse myelitis (LETM). Materials and Methods: Forty-five patients with clinical and magnetic resonance imaging features consistent with NMO, LETM, and MS were tested for serum NMO-IgG. Of these patients, 22 patients satisfied revised (2006) Wingerchuk criteria for NMO (excluding NMO-IgG status) and 11 patients had LETM. Twelve patients satisfied the revised (2010) McDonald criteria for multiple sclerosis (MS). Results: Of the 21 patients, satisfying the criteria for NMO and for whom the test results were available, 17 were positive for NMO-IgG (80.9%), and of the 11 patients having LETM, 6 (54.5%) were positive for NMO-IgG. In one patient with NMO, the test result was not available. None of the 12 patients satisfying McDonald criteria for MS showed NMO-IgG seropositivity. Conclusion: Our study suggests that it is worthwhile to pursue NMO-IgG testing as a diagnostic tool for patients with clinical and Magnetic Resonance Imaging (MRI) features consistent with NMO and LETM in the Indian population

Power quality enhancement of grid integrated solar PV system based on adaptive noise reduction control

This paper presents implementation of a two stage three phase PV-grid interfaced system with a three phase VSC which has been utilized as a multifunctional device. Adaptive noise reduction technique is used to control multifunctional VSC which transfers the active power from PV system to the grid and also works as an active power filter (APF) to improve power quality at AC mains. The control algorithm presented here has a fast and accurate dynamic response. The proposed SPV energy system has been implemented with linear and non-linear load to show harmonic elimination, load balancing and power factor correction

Generalized electronic controller for multi-pulse battery charging systems

This paper presents a generalized electronic controller suitable for multi-pulse battery charging for high power applications. The proposed controller is a generalized control scheme which can be used to develop a battery charging system for any pulse number such that two-pulse, six-pulse, twelve-pulse, eighteen-pulse and twenty four-pulse battery charging system. The two-pulse, six-pulse and twelve-pulse battery charging system has been implemented in the laboratory using the proposed generalized electronic controller. The test results of all these developed system are presented in this paper for validating the proposed scheme

Phylogenetic subtypes of human T-lymphotropic virus type I and their relations to the anthropological background

Isolates of human T-lymphotropic virus type I(HTLV-I) were phylogenetically analyzed from native inhabitants in India and South America (Colombia and Chile) and from Ainu (regarded as pure Japanese descendants from the preagricultural 'Jomon' period). Their genomes were partially sequenced together with isolates from Gabon in central Africa and from Ghana in West Africa. The phylogenetic tree was constructed from the sequence data obtained and those of previously reported HTLV-I isolates and simian T- lymphotropic virus type I (STLV-I) isolates. The heterogeneity of HTLV-I was recently recognized, and one major type, generally called the 'cosmopolitan' type, contained Japanese, Caribbean, and West African isolates. The phylogenetic tree constructed in the present study has shown that this cosmopolitan type can be further grouped into three lineages (subtypes A, B, and C). Subtype A consists of some Caribbean, two South American, and some Japanese isolates, including that from the Ainu

Progressive cavitating leukoencephalopathy: a novel childhood disease.

We report 19 patients with a previously undelineated neurodegenerative syndrome characterized by episodic acute onset of irritability or neurological deficits between 2 months and 3.5 years of age, followed by steady or intermittent clinical deterioration. Seven children died between 11 months and 14 years of age. Cranial magnetic resonance imaging (MRI) shows patchy leukoencephalopathy with cavities, and vascular permeability, in actively affected regions. Early lesions affect corpus callosum and centrum semiovale, with or without cerebellar or cord involvement. After repeated episodes, areas of tissue loss coalesce with older lesions to become larger cystic regions in brain or spinal cord. Diffuse spasticity, dementia, vegetative state, or death ensues. Gray matter is spared until late in the course. In some, incomplete clinical or MRI recovery occurs after episodes. The clinical course varies from rapid deterioration to prolonged periods of stability that are unpredictable by clinical or MRI changes. Elevated levels of lactate in brain, blood, and cerebrospinal fluid, abnormal urine organic acids, and changes in muscle respiratory chain enzymes are present but inconsistent, without identifiable mitochondrial DNA mutations or deletions. Pathological studies show severe loss of myelin sparing U-fibers, axonal disruption, and cavitary lesions without inflammation. Familial occurrence and consanguinity suggest autosomal recessive inheritance of this distinct entity

Higher latitude is significantly associated with an earlier age of disease onset in multiple sclerosis

Background Age at onset (AAO) in multiple sclerosis (MS) is an important marker of disease severity and may have prognostic significance. Understanding what factors can influence AAO may shed light on the aetiology of this complex disease, and have applications in the diagnostic process