Excitation control design of local machines in a large-scale power system by using dynamic equivalencing technique

A linear optimal control design for machine excitation is developed to improve the local system stability in a large-scale power system. Dynamic equivalents for the external system are used to provide the controller with information about the original external system. The paper investigates whether external system information helps the controller to stabilize the local system and whether the dynamic equivalents are a reliable source of that information. The validity and accuracy of the proposed method is demonstrated by simulated tests on two sample power systems.     

Impact of UV radiation on activity of linear furanocoumarins andBacillus thuringiensis var.Kurstaki againstSpodoptera exigua: Implications for tritrophic interactions

Acidic fogs with a pH of 2.0 and duration of 2 hr did not reduce the efficacy ofBacillus thuringiensis var.Kurstaki (Berliner). Therefore, the impact of UV radiation was investigated on the interactions between (1) levels of the antibacterial linear furanocoumarins psoralen, bergapten, and xanthotoxin inApium graveolens (L.) occurring following a 2.0 pH acidic fog episode, (2) the noctuidSpodoptera exigua (Hübner), and (3) a sublethal dosage of the microbial pathogenB. thuringiensis var.Kurstaki. Mean time to pupation in the absence of UV radiation (survival was too low to conduct this analysis for insects exposed to UV) was significantly extended by the addition of either psoralens orB. thuringiensis. Larvae developing on diets containingB. thuringiensis plus psoralens required nearly 40% longer to pupate than controls, but their effects were additive as the interaction was not significant. Although the mean times to adult emergence were significantly different, time spent in the pupal stage did not vary significantly between treatments, indicating that increases in larval developmental time were responsible for the observed decrease in developmental rate. Mean time to mortality, a weighted average time of death, was not significantly affected by any of the treatments. In a 2 × 2 × 2 factorial analysis, all main effects (linear furanocoumarins.B. thuringiensis, UV radiation) reduced survival significantly, as did the three-way interaction. Thus, antagonistic interactions with psoralens that would reduce the effectiveness ofB. thuringiensis in the field were not observed. When pairs of main effects were nested within the two levels (presence and absence) of the third factor, several two-way interactions were found. Interestingly, the activity ofB. thuringiensis and the psoralens, individually or in combination, was enhanced by exposure to UV radiation. Implications of this research are discussed for both natural and agricultural ecosystems.Lepidoptera: Noctuidae.     

Cholera in Portugal, 1974.I. Modes of transmission

In April-November 1974, Portugal had a cholera epidemic caused by Vibrio cholerae El Tor Inaba with 2467 bacteriologically confirmed hospitalized cases and 48 deaths. Most of the country was affected, with 17 of the 18 districts reporting cases. V. cholerae was isolated from 42 per cent of shellfish tested during the epidemic, and an epidemiologic study found that a history of consumption of raw or poorly cooked cockles was significantly more common among cholera patients than among paired controls. Water from a spring and a brand of commercially bottled water were also found to be vehicles of transmission of cholera. Although night soil was sometimes used on gardens, consumption of raw fruits and vegetables was not associated with illness.     

The Canter Background Interference Procedure (BIP): effects of demographic variables on diagnosis

This paper reports a positive association between demographic variables and Canter BIP diagnostic classification. Ss are 209 middle-aged men and include psychiatric and medical patients and non-patients. To evaluate the joint effects of the demographic variables, a discriminate analysis was performed on the total sample. Race and educational level alone predicted BIP diagnosis in 67% of the cases. While none of the demographic variables was related significantly to BIP diagnosis when a discriminate analysis was performed on whites alone, age and educational level were related significantly to BIP diagnosis when a discriminate analysis was performed on blacks alone.     

The application of radionuclide infarct scintigraphy to diagnose perioperative myocardial infarction following revascularization

To evaluate the application of radionuclide infarct scintigraphy to diagnose myocardial infarction after revascularization, we obtained postoperative technetium 99m pyrophosphate myocardial scintigrams, serial electrocardiograms and CPK-MB isoenzymes in ten control and 51 revascularized patients. All control patients had negative electrocardiograms and scintigrams, but eight had positive isoenzymes. Eight revascularized patients had positive electrocardiograms, images and enzymes and two had positive scintigrams and enzymes with negative electrocardiograms. Thirty-four patients with negative electorcardiograms and scintigrams had positive isoenzymes; in only seven patients were all tests negative. Our data suggest radionuclide infarct scintigraphy is a useful adjunct to the electrocardiogram in diagnosing perioperative infarction. The frequent presence of CPK-MB in postoperative patients without other evidence of infarction suggests that further studies are required to identify all factors responsible for its release.     

Preparative polyacrylamide gel electrophoretic purification of human alpha- and beta-globin messenger RNAs

Previous studies have reported the use of globin chain-specific complementary DNAs to quantitate the amount of human globin mRNA and human globin genes in normal and abnormal cells. In order to obtain larger amounts and more purified globin mRNAs as templates for these experiments, preparative polyacrylamide gel electrophoresis in formamide has been used to separate alpha- and beta-globin mRNA from polyadenylate containing RNA of human reticulocytes. Fifty to one hundred-fifty micrograms of RNA can be applied to the preparative gel and the recovery of the globin mRNA is about 50%. The isolated alpha- and beta-globin mRNAs were assayed in a wheat germ cell-free system, and the alpha- and beta-globin synthesized quantitated by cellulose acetate electrophoresis. The purified alpha- and beta-globin mRNAs direct globin synthesis which is more than 90% either alpha- or beta-globin, respectively. The cDNAs prepared using each of the isolated mRNAs as template are also shown to be specific for alpha- or beta-mRNA sequences. The gel electrophoresis technique used permits the relatively large scale isolation of alpha- or beta-globin mRNAs from human cells.     

The structure of L-lactate oxidase from Mycobacterium smegmatis

1. An improved purification was developed for L-lactate oxidase from Mycobacterium smegmatis. 2. The mol.wt. of the native enzyme by a sedimentation-equilibrium analysis was 345 000, and other ultracentrifuge methods gave values in the range 345 000-350 000. 3. An amino acid analysis, determinations of protein and flavin, a sedimentation-velocity analysis and an approach to equilibrium analysis gave values for the subunit mol.wt. in the range 43 500-47 000. 4. It was concluded that L-lactate oxidase contains eight subunits of mol.wt. 43 500. 5. Cross-linking of the subunits with dimethyl suberimidate and electron-microscopy studies were consistent with an octameric structure.     

Effect of carbon monoxide and high oxygen modified atmosphere packaging and phosphate enhanced, case-ready pork chops

The objective of this study was to evaluate the effects of CO-MAP compared to traditional high oxygen MAP (HiOx-MAP) packaging and enhanced with different phosphate on enhanced pork quality. Pork loins were enhanced to 10.5% over initial weight to contain 0.3% salt and 0.4% phosphate (either sodium tripolyphosphate [STP] or a blend of STP and sodium hexametaphosphate) on a finished weight basis. Chops were cut, packaged in atmospheres containing 0.4% CO/30.0% CO₂/69.6% N₂ (CO-MAP) or 80% O₂/20% CO₂ (HiOx-MAP), aged in the dark, then placed in a lighted retail display case for 48 h. Chops packaged in CO-MAP were redder (higher Minolta a^* values) and darker (lower Minolta b^* values) than chops packaged in HiOx-MAP. Based on sensory scores, the CO-MAP chops were pinker than the HiOx chops after cooking. CO-MAP chops also experienced less purge loss than chops in HiOx-MAP. Results indicate that CO-MAP had no effect on flavor or consumer acceptability and only minimal effects on other characteristics.     

Using interval arithmetic for robust state feedback design

A problem of a modal P-regulator synthesis for a linear multivariable dynamical system with uncertain (interval) parameters in state space is considered. The designed regulator has to place all coefficients of the system characteristic polynomial within assigned intervals. We have developed the approach proposed earlier in Dugarova and Smagina (Avtomat. i Telemech. 11 (1990) 176) and proved a direct correlation between interval system controllability and existence of robust modal P-regulator.