Improved Sensor Fault-Tolerant Control Technique Applied to Three-Phase Induction Motor Drive

An improved fault-tolerant control (FTC) method using mathematical functions is applied to the induction motor drive (IMD) against current sensors and speed encoder failures, which occur when the sensor is disconnected or completely damaged. The IMD with two current sensors and an encoder is speed controlled based on the field-oriented control (FOC) technique in regular operation. In this paper, an FTC unit is implemented in the FOC controller to detect and solve the sensor fault to increase the reliability of the speed control process. The measured stator currents and the feedback speed signal are integrated into the diagnosis algorithms to create a sensor fault-tolerant control function. Three diagnosis functions operating in a defined sequence are proposed for determining the health status of current and speed sensors. The FTC function performs isolation and replaces the faulty sensor signals with the proper estimated signals; then, the IMD will operate in the corresponding sensorless mode. Simulations will be performed to verify the accuracy and reliability of the proposed method under various sensor faults

Study on synthesis of some new derivatives of Malloapelta B isolated from Mallotus apelta

Six new benzopyran derivatives were synthesized by reduction reaction and Michael reaction from malloapelta B. Their structures were determined as 8-(1’-oxo-butyl)-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (2), 8-(1’-oxo-3’(R)-methyl-4’-acetyl-5’-oxo-hexyl)-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (3), 8-(1’-oxo-3’(R)-methyl-4’(S/R)-(methyl fomiate)-5’-oxo-hexyl)-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (4,4’), 8-(1’-oxo-3’(R)-methyl-4’(S/R)-(ethyl formiate)-5’-oxo-hexyl)-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (5,5’) by spectroscopic data, including two-dimensional NMR techniques and ESI spectrum.Keywords: Malloapelta B; Michael reaction; reduction reaction; 5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran

Synthesis of antiulcer drug esomeprazole.

Esomeprazole (Nexium®), the (S)-isomer of Omeprazole, is the first proton-pump inhibitor developed as a single isomer for the treatment of acid-related diseases. It is used for the treatment of peptic ulcers, gastroesophagal reflux disease, and erosive esophagitis. Herein, we report our synthetic study of esomeprazole sodium salt from the starting    2-mercapto-5-methoxybenzimidazole and 2-(chloromethyl)-4-methoxy-3,5-dimethylpyridine hydrochloride reagents. The Esomeprazole sodium salt was obtained from enantioselectivesulfoxidation reaction in moderate yield with high enantioselectivity

Eupolauridine alkaloids of Polyalthia nemoralis

Two eupolauridine alkaloids, eupolauridine (1) and 8-methoxyeupolauridine (2), together with a phenanthrene compound, 2,7-dihydroxy-3,6-dimethoxyphenanthrene (3), were isolated from the ethyl acetate extract of Polyalthia nemoralis barks. Their structures were elucidated on the basis of spectroscopic analysis and comparison with related known compounds. These compounds were evaluated the cytotoxicity on seven human cancer cell lines including KB, MCF7, LU-1, HepG2, LNCap, SW626 and SW480

A robust diagnosis method for speed sensor fault based on stator currents in the RFOC induction motor drive

A valid diagnosis method for the speed sensor failure (SSF) is an essential requirement to ensure the reliability of Fault-Tolerant Control (FTC) models in induction motor drive (IMD) systems. Most recent researches have focused on directly comparing the measured and estimated rotor speed signal to detect the speed sensor fault. However, using that such estimated value in both the fault diagnosis and the controller reconfiguration phases leads to the insufficient performance of FTC modes. In this paper, a novel diagnosis-technique based on the stator current model combined with a confusion prevention condition is proposed to detect the failure states of the speed sensor in the IMD systems. It helps the FTC mode to separate between the diagnosis and reconfiguration phases against a speed sensor fault. This proposed SSF diagnosis method can also effectively apply for IMs’ applications at the low-speed range where the speed sensor signal often suffers from noise. MATLAB/Simulink software has been used to implement the simulations in various speed ranges. The achieved results have demonstrated the capability and effectiveness of the proposed SSF method against speed sensor faults

An Improved Current-Sensorless Method for Induction Motor Drives Applying Hysteresis Current Controller

A novel strategy based on the feed-forward field-oriented control (FOC) method is proposed for the Hysteresis Current technique to control the induction motor (IM) drive without current sensors (CSs). A control scheme is proposed to estimate stator currents from reference rotor flux, rotor flux angle, and state variables as a replacement for the feedback-signal of CSs used in the hysteresis current controller (HCC). Here the rotor flux angle component is extracted from the feed-forward FOC loop. MATLAB/Simulink is applied to implement the simulations under many different operating conditions. The simulation results demonstrated the feasibility of the proposed method to obtain high performance in controlling the IM drives without the current sensors

Synthesis and biological evaluation of shikimic acid derivatives

From shikimic acid, new series of oseltamivir analogues containing either ether sulfur or ether oxygen at C-3 position were prepared and evaluated for their biological activities. This is the first report on synthesis of oseltamivir analogues with ether sulfur at C-3. Except for compounds 4d, 4f, 7c and 7d, the remaining compounds were found to be active against MCF-7, LU-1 and KB cell lines. As oseltamivir had no cytotoxicity against different cell lines such as MCF-7, LU-1, KB, MDCK, MRC-5, VERO, MK and 293, the modification of alkyl groups at C-3 of the oseltamivir ring framework could significantly increase the cytotoxicity for this class of compounds. Loss of neuraminidase inhibition activity of these synthetic oseltamivir analogues suggested that the alkyl ether groups at C-3 should be critical for their anti-neuraminidase activity

Temporal fluctuation of multidrug resistant salmonella typhi haplotypes in the mekong river delta region of Vietnam.

BACKGROUND: typhoid fever remains a public health problem in Vietnam, with a significant burden in the Mekong River delta region. Typhoid fever is caused by the bacterial pathogen Salmonella enterica serovar Typhi (S. Typhi), which is frequently multidrug resistant with reduced susceptibility to fluoroquinolone-based drugs, the first choice for the treatment of typhoid fever. We used a GoldenGate (Illumina) assay to type 1,500 single nucleotide polymorphisms (SNPs) and analyse the genetic variation of S. Typhi isolated from 267 typhoid fever patients in the Mekong delta region participating in a randomized trial conducted between 2004 and 2005. PRINCIPAL FINDINGS: the population of S. Typhi circulating during the study was highly clonal, with 91% of isolates belonging to a single clonal complex of the S. Typhi H58 haplogroup. The patterns of disease were consistent with the presence of an endemic haplotype H58-C and a localised outbreak of S. Typhi haplotype H58-E2 in 2004. H58-E2-associated typhoid fever cases exhibited evidence of significant geo-spatial clustering along the Sông H u branch of the Mekong River. Multidrug resistance was common in the established clone H58-C but not in the outbreak clone H58-E2, however all H58 S. Typhi were nalidixic acid resistant and carried a Ser83Phe amino acid substitution in the gyrA gene. SIGNIFICANCE: the H58 haplogroup dominates S. Typhi populations in other endemic areas, but the population described here was more homogeneous than previously examined populations, and the dominant clonal complex (H58-C, -E1, -E2) observed in this study has not been detected outside Vietnam. IncHI1 plasmid-bearing S. Typhi H58-C was endemic during the study period whilst H58-E2, which rarely carried the plasmid, was only transient, suggesting a selective advantage for the plasmid. These data add insight into the outbreak dynamics and local molecular epidemiology of S. Typhi in southern Vietnam

GLUCOSIDES AND UREA DERIVATIVES FROM THE SEEDS OF SCAPHIUM MACROPODUM (MIQ.) BEUMÉE

Five known compounds {carbonylbis[imino(6-methyl-3,1-phenylenel)]}bis[carbamic acid] dimethyl ester (1), (1'R,3'S,5'R,8'S,2E,4E-dihydrophaseic acid) 3'-O-beta-D-glucopyranoside (2), 3-methylbutan-1-ol beta-D-glucopyranoside (3), astragalin (4) and daucosterol (5) were isolated from the methanol extract of the seeds of Scaphium macropodum (Miq.) Beumée. The structures of the isolated compounds were elucidated by the spectroscopic methods including NMR and MS, and also by comparison with the literature data. Compounds 1-3 were isolated from this plant for the first time