An expert system for security trend analysis of a stability-limitedpower system

An expert system for dynamic security assessment (DSA) is described in which artificial intelligence techniques are applied to the transient energy function (TEF) method. The effect of contingencies on the security level and its rate of change with changing system conditions and parameters are computed using the results of the TEF sensitivity analysis program. The expert system determines the loading trend and analyzes the data obtained from TEF to compute the trend of the security index. The trend of the control parameters can then be adjusted to maintain the security index within a range of safe values. An example is given using data collected from the Northern States Power Company (NSP) where the expert system correctly computed the security index and suggested adjustments to system parameters     

Effect of some thermal and chemical pretreatments on smoked Oyster mushroom quality

The effect of different thermal and chemical pretreatments on quality and enzyme activities of smoked mushroom was investigated. Mushrooms were blanched (water and steam) and dipped in different concentrations of sulphites (SO₂), hydrogen peroxide (H₂O₂), ethylene‐di‐amine tetra‐acetic acid (EDTA) and citric acid for 10 min before smoking. Enzyme activities, colour characteristics, microbiological and sensory examinations were carried out every 2 weeks up to 8 weeks of storage in refrigerator at 4 °C. Results could be concluded that smoked mushroom pretreated with SO₂, H₂O₂ and steam blanching had the best colour values, the better score for all sensory characteristics and lower non‐enzymatic browning compared with other pretreatments. The most effective pretreatment against total aerobic bacteria and yeast & moulds were citric acid, EDTA and steam, and then smoking of mushroom can be attributed to the reduction of microbial counts. The most effective pretreatments on quality and safety of smoked mushrooms were H₂O₂ and steam. It can be concluded that thermal and chemical treatments, rather than smoking of mushroom, reduce enzyme activities and are suitable to preserve mushrooms.     

The use of spray-drying to enhance celecoxib solubility

The present research investigates the enhancement of the dissolution rate of celecoxib by using spray-drying to prepare a solid dispersion with various polymers, namely Kollicoat IR? (Kollicoat), polyvinyl alcohol (PVA) 22000, or polyethylene glycol 6000 (PEG). The investigated drug-to-polymer mass ratios were 1:1, 1:2, and 1:4 by weight. Hydroalcoholic or methylene chloride solvent systems were used. The obtained yields ranged from 65% to 78%, whereas the entrapment efficiencies were between 68% and 82%. The results revealed an increase in the dissolution rate of the prepared particles up to 200% within 20 min. The prepared particles were investigated using differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The increased dissolution rate was attributed to hydrogen bond formation between celecoxib and each polymer together with the reduced size of the formed particles offering a greater overall surface area. It was concluded that spray-drying may be considered a successful one-step technique to improve the dissolution rate of celecoxib when using Kollicoat, PVA, or PEG as the carrier polymer.     

Apparent impedance correlation of transient energy margin and timesimulation

A procedure was developed to relate the transient energy margin of a multimachine power system to the apparent impedance of a line protected by an out-of-step relay. In this procedure, only the multimachine system parameters are used, and the conventional intermediate step of forming a two-machine equivalent is eliminated. A technique for generating the swing impedance locus is described. The method is tested for a loss of generation disturbance on a 23-generator equivalent of the Florida Power & Light Co. network. The results obtained are compared with time simulation results     

Natural Uranium Heavy Water Reactors for Desalination a Comparison Bltween the Fuel Pin and Fuel Cwijster Concepts

Studies on the potential use of nuclear desalination in Egypt have been conducted. The choice of reactor type and system concept was influenced by emphasis on relaxed technological conditions so as to fit local circumstances . Natural uranium heavy water reactors were found promising. Finer details of type of fuel, cladding, coolant, and system arrangement were left for comparative studies. The question of fuel type, fuel pin versus fuel cluster, was considered. Simplified analytical and computational techniques were adopted and results verified with published criticality measurements. It was found that the pin design would have higher breeding potentials while the cluster would provide simpler core arrangement especially if a pressure vessel design is chosen. Results are given for a typical 40 MWth project study showing core features and system characteristics.     

Penicillin as a supplement in resolving the localized acute apical abscess

PROBLEM: Antibiotics are often prescribed indiscriminately to treat endodontic emergencies. OBJECTIVES: This study examined (1) the effect of penicillin supplementation on reduction of symptoms and (2) the course of recovery of localized acute apical abscess after emergency treatment. STUDY DESIGN: Patients with pulp necrosis and periapical pain and/or localized swelling were considered. Those eligible did not have any signs of spreading infections. Patients received appropriate local treatment, and a double-blind protocol was used to randomly assign them to one of three groups: penicillin VK group, placebo group, or neither medication group. All received ibuprofen 600 mg four times daily for 24 hours. Patients entered their pre- and postoperative pain and swelling experience on a visual analog scale for up to 72 hours. RESULTS: Resolution was fairly rapid in most patients. Statistical analysis of the scores of 32 respondents revealed no significant differences (at p < 0.05) between the three groups in course of recovery or symptoms at any time period. CONCLUSIONS: Patients with localized periapical pain or swelling generally recovered quickly with local treatment. The data did not show a demonstrable benefit from penicillin supplementation.     

REMOVAL OF RESIDUAL CHLORINE FROM INDIANA 5 COAL BY SUPERCRITICAL CARBON DIOXIDE EXTRACTION

The perchloroethylene coal desulfurization process has unique advantages as a precombustion coal cleaning process, that include high cleaning efficiencies, mild process conditions, minimal output of undesirable byproducts, and cost effectiveness. However, the use of perchloroethylene in the process renders an important process engineering problem of complete recovery and reuse of perchloroethylene. thus requiring a “zero discharge” condition of the solvent. Therefore, the treated coal must be stripped of any residual perchloroethylene. Carbon dioxide (CO₂) in its supercritical state has been investigated for its ability to remove chlorine from Indiana 5 coal, that has been desulfurized by the perchloroethylene (PCE) process. The reduction of CI contenttffrom a PCE treated and filtered coal has been as high as 78% The exprements have been carried out. following a statistical experimental design and the discerning characteristics of the process been identified. The solvent density and extraction conditions can be tailored in such a way as to optimally remove CI from the coal without any detrimental effects on the coal matrix. The supercritical CO₂ extraction process can be successfully implemented to the PCE coal cleaning process by replacing energy intensive steps of steam stripping and vacuum dying     

Transient Stability Program Output Analysis

The output of a conventional transient stability program is analyzed using transient energy functions for individual machines. The analyst is provided with a quantitative index of the degree of stability or instability for each generator. This index is useful for guiding the selection of subsequent case studies. The transient energy consists of two components: kinetic and potential energy. In the post-disturbance period, profiles of the kinetic energy (VKE), the potential energy (VPE), and the time derivative of the potential energy (V?PE) are obtained. These are used to develop a criterion for the degree of stress on a disturbed but stable machine, and to assess the extent of instability for an unstable machine. The method of analysis has been tested on two power networks representing the system of the state of Iowa, and validated by studies on a Philadelphia Electric Co. network.