Power Sharing Method Based on Droop Control for Three-Phase UPS Systems

The main objective of this paper is to improve the power sharing capability and to achieve synchronization between three-phase Uninterruptible power supply (UPS) units in the presence of load interruption. This paper presents a droop-controlled scheme in such a way that the computation of the instantaneous value of the active power and the reactive power are taken as feedback signals to the frequency and voltage restoration control system. The restored frequency and voltage are introduced to voltage controller circuit, which produces a suitable control signal to sinusoidal pulse width modulation circuit (SPWM). Thus producing a suitable trigger pulses to the inverter gate in order to guarantee synchronization between three-phase UPS units. Simulation of two UPS units with the same ratings (4 KW) are carried out using MATLAB. The results show the effectiveness of the proposed control system in achieving synchronization and improving the power sharing capability in the presence of load interruption. Keywords: Uninterruptible power supply; power sharing; parallel operation; droop control. DOI: 10.7176/JETP/9-4-02 Publication date: April 30th 201

INVESTIGATION OF THE EFFECT OF TEMPERATURE AND TIME OF CASE HARDENING ON THE MECHANICAL PROPERTIES AND MICROSTRUCTURE OF LOW CARBON STEEL (AISI 1020)

The main objective of this paper is experimental study of pack carburizing of carbon steels (AISI 1020) by using two parameters (holding time and carburizing temperature). This study was conducted by using electrical furnace. This process is carried out at temperatures of 950°C for durations time 90 minutes. From the experiment, the surface hardness and thickness of carbon layer was different according to the parameters used. The quenching medium that uses in this experiment is water, oil, sea water and air. For carburizing temperature at 950°C, the highest of surface hardness value for air is 128 HV that carburized for 90 minutes, the highest of surface hardness value for water is 224 HV that carburized for 90 minutes. For carburizing temperature of 950°C, the highest of surface hardness value for sea water is 166.9 HV that carburized for 90 minutes and for carburizing temperature at 950°C which is the highest of surface hardness value for oil is 126 HV. The thickness of carbon layer was between 40μm to 120μm. The result indicates the carburizing process accelerates the diffusion of carbon atoms into the surface, thus increasing the thickness of carburized layer as well as the surface hardness

In vitro Anti-Leishmania Activity and Safety of Newly Synthesized Thiazolo Pyrimidine Derivatives Augmented with Interleukine-12 (IL-12) in BALB/c Mice Experimentally- Infected with Cutaneous Leishmaniasis

Purpose: To synthesize a series of novel thiazolo pyrimidine derivatives and evaluate them in vitro and in vivo for their safety and anti-leishmanial activity using BALB/c mice.Methods: Substituted pyrazolopyrimidine and pyrazolopyrazole were synthesized by reacting amino group of 2-amino-4-cyano-pyrazol]naphthalino[1,2-d]thiazole with a variety of formamide or hydrazine hydrate. The synthesized compounds were characterized by nuclear magnetic resonance spectroscopy (1H-NMR) and mass spectroscopy (MS). The purity of the compounds was determined by elemental analysis. Safety and anti-leishmanial activity of the compounds were determined in vitro by i) viability assessment of leishmania-infected macrophages, relative abundance of IL-12p40 mRNA gene expression and levels of IL10 /IL-12 determination in supernatants of cultured macrophages treated with 2.5 and 10 μM of the compounds, using microscope cell counting, reverse transcriptase polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assay (ELISA), respectively. ii) cytotoxicity of the compounds evaluated by determination the safety index as IC50 of the compound in macrophages/IC50 of the compound in amastigotes. iii) bioassay at 16 weeks post-infection of mice treated with the reference drug, the tested compound alone and both the compound with IL-12. Disease progression and footpad thickness were evaluated regularly during treatment.Results: Compound 4 emerged as the most active anti-protozoal compound of the series against Leishmania viability (activity 60 %) compared with the reference drug (activity 65 %). When it was combined with IL-12, the activity reached 90 %.Conclusion: Compound 4 can serve as a lead molecule for further development to a clinically useful novel class of agents.Keywords: Thiazolopyrimidine, Synthesis, Leishmaniasis, Mice, Immunotherap

The effect of albumin administration on renal dysfunction after experimental surgical obstructive jaundice in male rats

AbstractThe aim was to study the influence of albumin supplementation on the changes of the kidney function and structure in cirrhotic rats induced by common bile duct ligation (BDL). Twenty-four male albino rats weighing 200–250g were divided into Group I: 6 rats underwent laparotomy alone, and the bile duct was only dissected from the surrounding tissue; Group II: 6 rats underwent a sham operation and received 2% albumin in their drinking water; Group III: 6 rats were subjected to bile duct ligation only; and Group IV: 6 rats were subjected to bile duct ligation and received a daily albumin 2% in drinking water. All rats were sacrificed after 4 weeks. We measured the liver and kidney functions and oxidative stress markers in the renal tissue and conducted a histological evaluation of the liver and kidney. The liver enzymes were decreased, but there was no significant difference in the bilirubin levels in group IV compared to group III. There was a significant elevation of serum creatinine in group III compared to group II, and serum creatinine was attenuated in group IV. The renal tissue catalase activity and reduced glutathione, as well as the nitric oxide levels, were significantly increased in group IV and were elevated in group III. Histologically, the livers of group IV showed degeneration and inflammatory cell infiltration with regeneration areas in which normal hepatocytes appeared. The kidneys of group IV showed recovery as well as areas of inflammatory cell infiltration. Some tubules appeared with normal epithelial lining. In conclusion, the results suggest that albumin partially improves the renal functions and structures after their disturbances as a result of BDL

Effect of FSW Parameters on The Microstructure and Mechanical Properties of T-joints between Dissimilar Al-Alloys

The main purpose of this research is to develop T-joints between the aluminum AA 2024-T4 and AA 7075-T6 using friction stir welding.  The effect of tool geometries, tool traveling speed, and rotational rate in the welded T-joints were investigated and discussed. Three different tools were used with different shoulder to pin ratios 3.28, 3.36, and 4.31. After optimization, the best tool dimension has used with the different rotational and welding speeds. Three tool traverse speeds of 50, 75, and 100 mm/min were used. Two rotation rates of 800 rpm and 1000 rpm were applied. After FSW, at a number of the above FSW parameters' combinations, macrostructure and microstructure analyses were done using optical microscopy. In order to have an insight into the mechanical properties, hardness measurements and tensile testing were carried out. Using small shoulder to pin ratio produced visually unacceptable T-joint. Opposite happened by using the tool with 4.31 of shoulder to pin ratio. Furthermore, the results showed sound T-welds with no obvious defects at high rotational rate of 1000 rpm with the two used traveling speeds. Asymmetric temperature distribution was observed between the two sides, advance side (AS) and retreating side (RS

The Shigella ProU system is required for osmotic tolerance and virulence : Shigella ProU in osmotic tolerance and virulence

To cope with hyperosmotic stress encountered in the environments and in the host, the pathogenic as well as non-pathogenic microbes use diverse transport systems to obtain osmoprotectants. To study the role of Shigella sonnei ProU system in response to hyperosmotic stress and virulence, we constructed deletion and complementation strains of proV and used an RNAi approach to silence the whole ProU operon. We compared the response between wild type and the mutants to the hyperosmotic pressure in vitro, and assessed virulence properties of the mutants using gentamicin protection assay as well as Galleria mellonella moth larvae model. In response to osmotic stress by either NaCl or KCl, S. sonnei highly up-regulates transcription of proVWX genes. Supplementation of betaine greatly elevates the growth of the wild type S. sonnei but not the proV mutants in M9 medium containing 0.2 M NaCl or 0.2 M KCl. The proV mutants are also defective in intracellular growth compared with the wild type. The moth larvae model of G. mellonella shows that either deletion of proV gene or knockdown of proVWX transcripts by RNAi significantly attenuates virulence. ProU system in S. sonnei is required to cope with osmotic stress for survival and multiplication in vitro and ex vivo, and for infection

MISA (Minimally Invasive Surfactant Administration) Versus Insure (Intubation, Surfactant, Extubation) In Preterms Less Than 34 Weeks With RDS

Background: Newborn Respiratory Distress Syndrome (RDS) or what is known as surfactant deficiency disorder is a syndrome that affects premature infants who are born prematurely and is caused by a developmental deficiency in the production of pulmonary surfactant or as it is called immature formation of the lungs, or as a result of a defect in the protein gene that forms pulmonary surfactant. Non-invasive positive pressure ventilation (NIPPV) is the first technique for respiratory therapy while MISA and InSurE are both the most commonly used in RDS. Objective: To compare the use of the MISA method and the InSurE method in the treatment of premature infants less than 34 weeks of gestational age with respiratory distress syndrome (RDS). Patients and methods: The sample size was 70 infants with gestational age less than 34 weeks with RDS. 35 newborn were enrolled in each group. First group received surfactant via MIST technique and the other 35 newborn received it via InSurE technique. Infants in the InSurE group required intubation, according to previous collected data from the neonatal intensive care unit (NICU) center. Results: After the injection of surfactant, the 13 (37%) infants needed another dose in the MIST group, while only 3 (8.57%) infants in the InSurE group needed a second dose of the same substance. Accordingly, the response of the MIST group was shown to be a less improvement than the InSurE group in the child's breathing methods. Conclusion: The MIST method was the most successful with a rate of 96.5% in terms of time and the child's response to treatment, and the researcher recommended that the reasons for the effectiveness of MISA in treating RDS should be studied. However duration of invasive mechanical ventilation were higher in MIST group than InSurE group

Comparison between physical properties of ring-spun yarn and compact yarns spun from different pneumatic compacting systems

A comparative study pertaining to physical and mechanical properties of ring-spun yarn vis-à-vis compact yarns spun using three different compacting systems has been reported. Rieter (K-44), Toyota (RX-240) and Suessen (Fiomax) spinning machines have been used and the condensing process of the fibres in the yarn cross-section as per these compact spinning systems is accomplished pneumatically. Thus, a yarn of linear density 5.9 tex (100 Ne) is spun on the spinning systems using Egyptian cotton of the type Giza 86. One way Anova together with least significant difference are employed to feature the means of the properties of spun yarns and a significant difference among them is observed. According to the performed statistical analysis, there is a significant difference between ring - spun yarn properties and each of the pnuematic compact spun yarns. These compact-spun yarns are also found to differ significantly in terms of their physical and mechanical properties; however, they are all found superior to the ring-spun yarn

A Multiple-Objective Environmental Rationalization and Optimization for Material Substitution in the Production of Stone-Washed Jeans- Garments

As the Textile Industry is the second largest industry in Egypt and as small and medium-sized enterprises (SMEs) make up a great portion of this industry therein it is essential to apply the concept of Cleaner Production for the purpose of reducing pollution. In order to achieve this goal, a case study concerned with ecofriendly stone-washing of jeans-garments was investigated. A raw material-substitution option was adopted whereby the toxic potassium permanganate and sodium sulfide were replaced by the environmentally compatible hydrogen peroxide and glucose respectively where the concentrations of both replaced chemicals together with the operating time were optimized. In addition, a process-rationalization option involving four additional processes was investigated. By means of criteria such as product quality, effluent analysis, mass and heat balance; and cost analysis with the aid of a statistical model, a process optimization treatment revealed that the superior process optima were 50%, 0.15% and 50min for H2O2 concentration, glucose concentration and time, respectively. With these values the superior process ought to reduce the annual cost by about EGP 105 relative to the currently used conventional method