Abstract This paper reports on the determination of the flame height of a flare system using theoretical approach based on the laws of conservation of mass, momentum and energy. The set of ordinary differential equations at steady state conditions are solved numerically by fourth order Runge-Kutta method. The extent of reaction between the fuel and the entrained air has been studied by introducing the reaction mixing efficiency parameter, as the reaction rate is fixed by local entrainment rate. The reaction mixing efficiency parameter is a key measure to determine the height of the flame and its variation with the source velocity is limited by the flame width and the maximum vertical flame velocity at the tip of the flaming region. The variation of different parameters as vertical flame velocity, flame geometry and flame temperature with flame height are shown in plots. It is found that the flame geometry undergoes an initial necking up to a certain height, followed by an increase in its spread thereafter. The flame geometry and the flame dynamics depend exclusively on the burner design and the stack exit velocity. The flame height to burner diameter ratio of the jet diffusion flame is found to vary linearly with Froude number with a constant slope in the logarithmic plot.

The present paper describes the development of an availability simulation model for Coal handling unit of a thermal plant by making the performance analysis using probabiltic approach. In the present paper, the Coal handling unit consists of five subsystems. Assuming constant failure and repair rates for all the subsystems, the mathematical formulation is based on Markov birth-death process. After drawing the transition diagram, differential equations are generated. After that, steady state probabilities are determined. One availability matrix is also developed, which provides various performance/availability levels for different combinations of failure and repair rates of all subsystems. Based upon various availability values obtained in the availability matrix and graphs of failure/repair rates of different subsystems, performance and optimum values of failure/repair rates for maximum availability of each subsystem are analyzed. Subsequently maintenance priorities are decided for all subsystems.

Die artikel beskryf die ontwikkeling van 'n beskikbaarheidsimulasiemodel vir 'n steenkoolhanteringseenheid van 'n termiese aanleg deur gebruik te maak van werkverrigtingsanalise met 'n waarskynlikheidsbenadering. In die geval bestaan die hanteringseenheid uit vyf subsisteme. Onder die aanname van konstante faling- en hersteltempo's vir al die subsisteme word die wiskundige formulering gebaseer op die Markov geboorte-sterfte-proses. Nadat die oorgangsdiagram ontwikkel is, word differensiaalvergelykings gegenereer en waarna die gestadigde toestandwaarksynlikhede vasgestel word. Een beskikbaarheidsmatriks is verder ontwikkel wat toelaat vir verskillende werkverrigting-/beskikbaarheidsvlakke teen verskillende kombinasies van faling- en hersteltempo's van alle subsisteme. Gebaseer op verskillende beskikbaarheidswaardes verkry van die beskikbaarheidsmatriks en grafieke van die falings-/hersteltempo's van die onderskeie subsisteme, word werkverrigting en optimum waardes vir faling- en hersteltempo's vir maksimum beskikbaarheid van elke subsisteem ontleed. Vervolgens word instandhoudingsprioriteite vir elke subsisteem voorgehou.

The paper aims at assessing the reliability and availability of a critical ash handling unit of a steam thermal power plant by making a performance analysis and modeling, using probability theory and the Markov Birth-Death process. After drawing a transition diagram, differential equations are generated. After that, steady state probabilities are determined. Certain decision matrices are developed, which provide various availability levels. The behaviour analysis of the reliability module reveals that the availability decreases with increasing failure rates, while operational availability improves with initial increases in repair rates for different subsystems. Based upon various availability values, the performance of each subsystem is analyzed and used to make maintenance decisions for all subsystems.

Hierdie artikel poog om die betroubaarheid en beskikbaarheid van 'n kritiese ashanteringseenheid van 'n termiese stoomkragaanleg te beoordeel deur 'n werkverrigtingsanalise en modellering te doen aan die hand van waarskynlikheidsteorie en die Markovgeboorte-sterfteproses. Nadat die oorgangsdiagram opgestel is, is differensiaalvergelykings gegenereer. Vervolgens is die gestadigde-toestandwaarskynlikhede bepaal. Sekere besluitmatrikse is ontwikkel waar verskillende beskikbaarheidsvlakke verskaf is. Die analise van die gedrag van die betroubaarheidsmodule toon dat beskikbaarheid afneem met toenemende falingstempo's, terwyl operasionele beskikbaarheid verbeter met aanvanklike toenames en hersteltempo's vir die onderskeie subsisteme. Gebaseer op die verskillende beskikbaarheidswaardes, word die werkverrigting van elke subsisteem ontleed en aangewend om instandhoudingsbesluite vir alle subsisteme te neem.

Moscas varejeiras (Diptera: Sarcophagidae) são causa conhecida de miíase e as bactérias de seus intestinos nunca foram estudadas quanto à atividade antibacteriana. Estudos antimicrobianos de Myroides spp restringem-se à cepas hospitalares. Uma bactéria Gram negativa, Myroides sp, foi isolada do intestino de moscas varejeiras adultas (Sarcophaga sp) e submetida à avaliação de parâmetros nutricionais pelo sistema BIOLOG GN, ao sequenciamento genético 16S rRNA, à sensibilidade a vários antimicrobianos pelo método de difusão de discos e à detecção dos genes de metalo beta lactamases (TUS/MUS). Os efeitos antagonistas foram testados contra bactérias Gram negativas e Gram positivas isoladas de material clínico humano, amostras ambientais e intestino do inseto. As espécies bacterianas incluíram Aeromonas hydrophila, A. culicicola, Morganella morganii subsp sibonii, Ochrobactrum anthropi, Weissella confusa, Escherichia coli, Ochrobactrum sp, Serratia sp, Kestersia sp, Ignatzschineria sp e Bacillus sp. A cepa Myroides sp foi resistente à penicilina G, eritromicina, estreptomicina, amicacina, canamicina, gentamicina, ampicilina, trimetoprim e tobramicina. Esta cepa apresentou atividade antimicrobiana contra todas as cepas exceto W.confusa, Ignatzschineria sp, A. hydrophila e M. morgani subsp sibonii. A resistência múltipla da cepa foi semelhante à de isolados clínicos, inibindo bactérias das amostras clínicas, ambientais e do intestino do inseto. Os genes de metalo beta lactamases (TUS/MUS) estavam ausentes, excluindo-se a resistência mediada por esses genes, o que indica o envolvimento de um mecanismo alternativo de secreção.

Flesh flies (Diptera: Sarcophagidae) are well known cause of myiasis and their gut bacteria have never been studied for antimicrobial activity against bacteria. Antimicrobial studies of Myroides spp. are restricted to nosocomial strains. A Gram-negative bacterium, Myroides sp., was isolated from the gut of adult flesh flies (Sarcophaga sp.) and submitted to evaluation of nutritional parameters using Biolog GN, 16S rRNA gene sequencing, susceptibility to various antimicrobials by disc diffusion method and detection of metallo β-lactamase genes (TUS/MUS). The antagonistic effects were tested on Gram-negative and Gram-positive bacteria isolated from human clinical specimens, environmental samples and insect mid gut. Bacterial species included were Aeromonas hydrophila, A. culicicola, Morganella morganii subsp. sibonii, Ochrobactrum anthropi, Weissella confusa, Escherichia coli, Ochrobactrum sp., Serratia sp., Kestersia sp., Ignatzschineria sp., Bacillus sp. The Myroides sp. strain was resistant to penicillin-G, erythromycin, streptomycin, amikacin, kanamycin, gentamycin, ampicillin, trimethoprim and tobramycin. These strain showed antibacterial action against all bacterial strains except W. confusa, Ignatzschineria sp., A. hydrophila and M. morganii subsp. sibonii. The multidrug resistance of the strain was similar to the resistance of clinical isolates, inhibiting growth of bacteria from clinical, environmental and insect gut samples. The metallo β-lactamase (TUS/MUS) genes were absent, and resistance due to these genes was ruled out, indicating involvement of other secretion machinery.

The present paper discusses the performance modeling and decision support system for a feed water unit of a thermal power plant using the concept of performance analysis and modeling. A feed water unit ensures a proper supply of water for the sound functioning of a thermal power plant. The decision support system for a feed water unit has been developed with the help of performance modeling using a probabilistic approach. After drawing a transition diagram, differential equations are generated. After that, steady state probabilities are determined. Some decision matrices are also developed, which provide various performance levels for different combinations of failure and repair rates of all subsystems. Based upon various availability values obtained in decision matrices and plots of failure rates / repair rates of various subsystems, the performance of each subsystem is analyzed, and maintenance decisions are made for all subsystems.

Vertoningsanalise en -modellering word gedoen w'r die toevoerwatersisteem van 'n termiese kragstasie. Toevoerwater is 'n belangrike factor vir die doeltreffende bedryf van 'n kragstasie. Die vertoningsanalise en -model is probalisties van aard. 'n Toestandoorgangsdiagram en bypassende differensiaalvergelykings word gebruik, gevolg deur bepaling van die bestandige sisteemtoestand. Bykomende aandag word gegee aan relevante subsisteme. Die vertoning van subsisteme word gebasseer op verskeie beskikbaarheidswaardes om sodoende instandhouding to optimiseer.

OBJECTIVE: To discover the cause of acute renal failure in 36 children aged 2 months to 6 years who were admitted to two hospitals in Delhi between 1 April and 9 June 1998. METHODS: Data were collected from hospital records, parents and doctors of the patients, and district health officials. Further information was obtained from house visits and community surveys; blood and stool samples were collected from other ill children, healthy family members and community contacts. Samples of drinking-water and water from a tube-well were tested for coliform organisms. FINDINGS: Most of the children (26/36) were from the Gurgaon district in Haryana or had visited Gurgaon town for treatment of a minor illness. Acute renal failure developed after an episode of acute febrile illness with or without watery diarrhoea or mild respiratory symptoms for which the children had been treated with unknown medicines by private medical practitioners. On admission to hospital the children were not dehydrated. Median blood urea concentration was 150 mg/dl (range 79-311 mg/dl) and median serum creatinine concentration was 5.6 mg/dl (range 2.6-10.8 mg/dl). Kidney biopsy showed acute tubular necrosis. Thirty-three children were known to have died despite being treated with peritoneal dialysis and supportive therapy. CONCLUSION: Cough expectorant manufactured by a company in Gurgaon was found to be contaminated with diethylene glycol (17.5%v/v), but a sample of acetaminophen manufactured by the same company tested negative for contamination when gas-liquid chromatography was used. Thus, poisoning with diethylene glycol seems to be the cause of acute renal failure in these children.

OBJETIVO: Descubrir la causa de la insuficiencia renal aguda padecida por 36 niños de 2 meses a 6 años de edad ingresados en dos hospitales de Delhi entre el 1 de abril y el 9 de junio de 1998. MÉTODOS: Los datos empleados proceden de historias clínicas y de la información aportada por los padres y los médicos de los pacientes y por funcionarios de salud de distrito. Se reunió también información a partir de visitas domiciliarias y encuestas comunitarias. Se obtuvieron muestras de sangre y de heces de otros niños enfermos, de familiares sanos y de contactos de la comunidad, y se analizó la presencia de microorganismos coliformes en muestras de agua de bebida y de agua de un pozo entubado. RESULTADOS: La mayoría de los niños (26/36) procedían del distrito de Gurgaon, en Haryana, o habían visitado la localidad de Gurgaon para recibir tratamiento contra una enfermedad de poca gravedad. La insuficiencia renal aguda se produjo tras un episodio febril agudo, en algunos casos acompañado de diarrea acuosa o de síntomas respiratorios leves, contra el cual médicos privados habían recetado medicamentos de naturaleza desconocida. Al ingresar en el hospital los niños no estaban deshidratados. La mediana de la concentración de nitrógeno ureico en sangre fue de 150 mg% (intervalo: 79-311 mg%), y la de la concentración sérica de creatinina, de 5,6mg% (intervalo: 2,6-10,8 mg%). La biopsia renal reveló una necrosis tubular aguda. Se sabe que 33 niños fallecieron pese a ser sometidos a diálisis peritoneal y terapia complementaria. CONCLUSIÓN: Se descubrió que un expectorante fabricado por una compañía de Gurgaon estaba contaminado por dietilenglicol (17,5% v/v); sin embargo, los resultados de un análisis por cromatografía gas-líquido de una muestra de paracetamol fabricada por la misma compañía fueron negativos. Así pues, la causa de la insuficiencia renal aguda sufrida por esos niños parece haber sido una intoxicación por dietilenglicol.

OBJECTIF: Découvrir la cause d’une insuffisance rénale aiguë chez 36 enfants âgés de 2 mois à 6 ans ayant été admis dans deux hôpitaux de Delhi entre le 1er avril et le 9 juin 1998. MÉTHODES: On a rassemblédes données en examinant les dossiers des hôpitaux et en interrogeant les parents et les médecins des enfants atteints ainsi que les responsables sanitaires du district. Des visites domiciliaires et des enquêtes en communauté ont permis d’obtenir des informations complémentaires ; on a prélevé des échantillons de sang et de selles sur d’autres enfants malades, sur des membres en bonne santé de la famille et sur des contacts communautaires. On a également fait des recherches de colibacilles dans des échantillons d’eau de boisson et d’eau provenant d’un puits tubé. RÉSULTATS: La plupart des enfants (26/36) venaient du district de Gurgaon dans l’Etat d’Haryana ou avaient séjourné à Gurgaon pour le traitement d’une affection mineure. L’insuffisance rénale aiguë est apparue après un épisode fébrile avec ou sans diarrhée aqueuse ou symptômes respiratoires bénins, traité avec des médicaments de nature inconnue par un médecin du secteur privé. A l’admission, les enfants n’étaient pas déshydratés. L’azote uréique sanguin médian était de 150 mg/100 ml (intervalle : 79-311 mg/100 ml) et la créatinine sérique médiane était de 5,6 mg/100 ml (intervalle : 2,6-10,8 mg/100 ml). Une biopsie rénale a montré une nécrose tubulaire aiguë. On sait que 33 enfants sont décédés malgré une dialyse péritonéale et un traitement de soutien. CONCLUSION: Un expectorant contre la toux fabriqué par un laboratoire de Gurgaon a été trouvé contaminé par du diéthylène glycol (17,5% v/v), mais aucune contamination n’a été décelée dans un échantillon d’acétaminophène du même fabricant lors d’une analyse par chromatographie gaz-liquide. Une intoxication par le diéthylène glycol semble donc avoir été à l’origine de l’insuffisance rénale aiguë chez ces enfants.