Arc-flash energy: The impact of fuse link manufacturers

The traditional operational and hazard control paradigm of an electrical installation has several issues pertaining to the diversity of equipment. A large maintenance inventory is a reason for concern for any manager, but the arc-flash hazard is a particularly new phenomenon, and the effects of equipment diversity on this phenomenon are even newer. The class of arc hazard can be simply increased by changing the fuse link or circuit breaker manufacturer. Management pressure to operate as well as nonstandard practices and installations are also partly responsible. The aim of this article is to take a typical situation in an industrial plant and to statistically simulate, by means of a dedicated software program, the fuse arc-flash interruption performance of various manufacturers. The purpose of this article is to obtain a more objective indication of the influence of different fuse link manufacturers on arc-flash incident energy. © 1975-2012 IEEE.

Progressive recovery of a tropical deforested stream community after a flash flood

AIM: In this study, we evaluated and compared community attributes from a tropical deforested stream, located in a pasture area, in a period before (PRED I) and three times after (POSD I, II, and III) a flash flood, in order to investigate the existence of temporal modifications in community structure that suggests return to conditions previous to the flash flood. METHODS: Biota samples included algae, macrophytes, macroinvertebrates, and fish assemblages. Changes in stream physical structure we also evaluated. Similarity of the aquatic biota between pre and post-disturbance periods was examined by exploratory ordination, known as Non-Metric Multidimensional Scaling associated with Cluster Analysis, using quantitative and presence/absence Bray-Curtis similarity coefficients. Presence and absence data were used for multivariate correlation analysis (Relate Analysis) in order to investigate taxonomic composition similarity of biota between pre and post-disturbance periods. RESULTS: Our results evidenced channel simplification and an expressive decrease in richness and abundance of all taxa right after the flood, followed by subsequent increases of these parameters in the next three samples, indicating trends towards stream community recovery. Bray-Curtis similarity coefficients evidenced a greater community structure disparity among the period right after the flood and the subsequent ones. Multivariate correlation analysis evidenced a greater correlation between macroinvertebrates and algae/macrophytes, demonstrating the narrow relation between their recolonization dynamics. CONCLUSIONS: Despite overall community structure tended to return to previous conditions, recolonization after the flood was much slower than that reported in literature. Finally, the remarkably high flood impact along with the slow recolonization could be a result of the historical presence of anthropic impacts in the region, such as siltation, riparian forest complete depletion, and habitat simplification, which magnified the effects of a natural disturbance.

Laser-flash photolysis of alpha-brominated o-xylenes

The flash photolysis (lambda = 266 nm) of four alpha -brominated omicron -xylenes in apolar solvents gives two transients characterized, depending on parent compound substitution, as either monoradicals or carbenes, and quinodimethanes. alpha -Bromomethylbenzyl radical is characterized and the novel species alpha,alpha'-dibromo-omicron -xylylene and omicron-(alpha,alpha -dibromomethyl)benzyl carbene are described for the first time. (C) 2001 Elsevier Science B.V. All rights reserved.

Potencial evocado visual por flash em cães, ovinos e equinos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Flash Mob: da rede à praça

This work explores the flash mobs, which are flash mobilizations arranged by intent that involve a large number of people to do something together in a pre-arranged place. With the advent of 2.0 Internet, the sharing of information and the mobile virtual communication grown up and showed behavior of an individual person to meet for a common interest. Those affective relationships born in the social networks come to the urban space in a real-virtual space junction and the possibilities of that are unexplored yet. Studied by this work, the Y generation is the flash mob most popular public and uses those mobilizations to reinforce their fan identity and appreciation for a media product

Optical parameters and crystallization of flash evaporated amorphous gallium antimonide films

Flash-evaporated GaSb films are analysed using a combination of optical, surface and x-ray diffraction techniques. The effects of thermal annealings on nearly stoichiometric GaSb films are studied.

A Simple Method to Evaluate, Correlate and Predict Boiling and Flash Points of Alkynes

Boiling points (T-B) of acyclic alkynes are predicted from their boiling point numbers (Y-BP) with the relationship T-B(K) = -16.802Y(BP)(2/3) + 337.377Y(BP)(1/3) - 437.883. In turn, Y-BP values are calculated from structure using the equation Y-BP = 1.726 + A(i) + 2.779C + 1.716M(3) + 1.564M + 4.204E(3) + 3.905E + 5.007P - 0.329D + 0.241G + 0.479V + 0.967T + 0.574S. Here A(i) depends on the substitution pattern of the alkyne and the remainder of the equation is the same as that reported earlier for alkanes. For a data set consisting of 76 acyclic alkynes, the correlation of predicted and literature T-B values had an average absolute deviation of 1.46 K, and the R-2 of the correlation was 0.999. In addition, the calculated Y-BP values can be used to predict the flash points of alkynes.

Densification and enhancement of the grain boundary conductivity of gadolinium-doped barium cerate by ultra fast flash grain welding

Doped barium cerate is a promising solid electrolyte for intermediate temperature fuel cells as a protonic conductor. However, it is difficult to sinter it to high density at a reasonable temperature. Moreover, it presents a high grain boundary resistivity at intermediate temperatures. Flash grain welding was applied to compacted samples, starting from a temperature of 910 degrees C and applying, for a short time, an ac electric polarization of 40 V, 1000 Hz. At that frequency, the resulting current flows through the grain boundaries promoting a welding via a local Joule heating. A large decrease of the grain boundary resistivity was observed by impedance spectroscopy. Scanning electron microscopy observations of polished and etched surfaces revealed highly sintered regions. Attempts were also made to combine flash grain welding with conventional sintering. (C) 2012 Elsevier Ltd. All rights reserved.

A simple method to evaluate, correlate and predict boiling and flash points of alkynes

Boiling points (T B) of acyclic alkynes are predicted from their boiling point numbers (Y BP) with the relationship T B(K) = -16.802Y BP2/3 + 337.377Y BP1/3 - 437.883. In turn, Y BP values are calculated from structure using the equation Y BP = 1.726 + Ai + 2.779C + 1.716M3 + 1.564M + 4.204E3 + 3.905E + 5.007P - 0.329D + 0.241G + 0.479V + 0.967T + 0.574S. Here Ai depends on the substitution pattern of the alkyne and the remainder of the equation is the same as that reported earlier for alkanes. For a data set consisting of 76 acyclic alkynes, the correlation of predicted and literature T B values had an average absolute deviation of 1.46 K, and the R² of the correlation was 0.999. In addition, the calculated Y BP values can be used to predict the flash points of alkynes.

Flash Forward: Faenza 2032. Uno sviluppo urbano senza consumo di territorio

La ricerca indaga la praticabilità di uno sviluppo urbano a crescita zero quale risposta al consumo di territorio ed allo sprawl urbano. Con ciò si intende il soddisfacimento del fabbisogno abitativo di un determinato arco temporale all'interno del tessuto urbano consolidato, operando tramite la densificazione della città, costruendo all'interno dei vuoti urbani e degli spazi di risulta, ed evitando di consumare ulteriore terreno agricolo. Lo studio viene declinato prendendo ad oggetto dell'analisi la città di Faenza e come orizzonte temporale il 2032. Il tema prevalente della ricerca riguarda la destinazione residenziale che, in base al principio della mixitè, viene portata anche nelle aree produttive e artigianali nel tentativo di contrastare la monofunzionalità dei settori urbani. Calcolate le quantità edilizie necessarie a soddisfare le esigenze abitative previste, sono stati ipotizzati numerosi interventi all'interno di alcuni tra i vuoti precedentemente catalogati; i progetti sono compresi all'interno di comparti per cui sono definite le diverse destinazioni d'uso in percentuali differenti a seconda della situazione urbana in cui sono inseriti. Di tutti gli interventi proposti, ne sono stati estratti due, localizzati in aree analoghe per vocazione e caratteristiche. Su questi si è effettuato un approfondimento progettuale alla scala architettonica quale verifica delle possibilità offerte dall'approccio urbanistico che ha guidato il masterplan.

The prediction of flash evaporation in superheated fuel injections for automotive applications

In gasoline Port Fuel Injection (PFI) and Direct Injection (GDI) internal combustion engines, the liquid fuel might be injected into a gaseous ambient in a superheated state, resulting in flash boiling of the fuel. The importance to investigate and predict such a process is due to the influence it has on the liquid fuel atomization and vaporization and thus on combustion, with direct implications on engine performances and exhaust gas emissions. The topic of the present PhD research involves the numerical analysis of the behaviour of the superheated fuel during the injection process, in high pressure injection systems like the ones equipping GDI engines. Particular emphasis is on the investigation of the effects of the fuel superheating degree on atomization dynamics and spray characteristics. The present work is a look at the flash evaporation and flash boiling modeling, from an engineering point of view, addressed to keep the complex physics involved as simple as possible, however capturing the main characteristics of a superheated fuel injection.

Flash floods and their effects on the development in El-Qaá plain area in South Sinai, Egypt

The arid regions are dominated to a much larger degree than humid regions by major catastrophic events. Although most of Egypt lies within the great hot desert belt; it experiences especially in the north some torrential rainfall, which causes flash floods all over Sinai Peninsula. Flash floods in hot deserts are characterized by high velocity and low duration with a sharp discharge peak. Large sediment loads may be carried by floods threatening fields and settlements in the wadis and even people who are living there. The extreme spottiness of rare heavy rainfall, well known to desert people everywhere, precludes any efficient forecasting. Thus, although the limitation of data still reflects pre-satellite methods, chances of developing a warning system for floods in the desert seem remote. The relatively short flood-to-peak interval, a characteristic of desert floods, presents an additional impediment to the efficient use of warning systems. The present thesis contains introduction and five chapters, chapter one points out the physical settings of the study area. There are the geological settings such as outcrop lithology of the study area and the deposits. The alluvial deposits of Wadi Moreikh had been analyzed using OSL dating to know deposits and palaeoclimatic conditions. The chapter points out as well the stratigraphy and the structure geology containing main faults and folds. In addition, it manifests the pesent climate conditions such as temperature, humidity, wind and evaporation. Besides, it presents type of soils and natural vegetation cover of the study area using unsupervised classification for ETM+ images. Chapter two points out the morphometric analysis of the main basins and their drainage network in the study area. It is divided into three parts: The first part manifests the morphometric analysis of the drainage networks which had been extracted from two main sources, topographic maps and DEM images. Basins and drainage networks are considered as major influencing factors on the flash floods; Most of elements were studied which affect the network such as stream order, bifurcation ratio, stream lengths, stream frequency, drainage density, and drainage patterns. The second part of this chapter shows the morphometric analysis of basins such as area, dimensions, shape and surface. Whereas, the third part points the morphometric analysis of alluvial fans which form most of El-Qaá plain. Chapter three manifests the surface runoff through rainfall and losses analysis. The main subject in this chapter is rainfall which has been studied in detail; it is the main reason for runoff. Therefore, all rainfall characteristics are regarded here such as rainfall types, distribution, rainfall intensity, duration, frequency, and the relationship between rainfall and runoff. While the second part of this chapter concerns with water losses estimation by evaporation and infiltration which are together the main losses with direct effect on the high of runoff. Finally, chapter three points out the factors influencing desert runoff and runoff generation mechanism. Chapter four is concerned with assessment of flood hazard, it is important to estimate runoff and tocreate a map of affected areas. Therefore, the chapter consists of four main parts; first part manifests the runoff estimation, the different methods to estimate runoff and its variables such as runoff coefficient lag time, time of concentration, runoff volume, and frequency analysis of flash flood. While the second part points out the extreme event analysis. The third part shows the map of affected areas for every basin and the flash floods degrees. In this point, it has been depending on the DEM to extract the drainage networks and to determine the main streams which are normally more dangerous than others. Finally, part four presets the risk zone map of total study area which is of high inerest for planning activities. Chapter five as the last chapter concerns with flash flood Hazard mitigation. It consists of three main parts. First flood prediction and the method which can be used to predict and forecast the flood. The second part aims to determine the best methods which can be helpful to mitigate flood hazard in the arid zone and especially the study area. Whereas, the third part points out the development perspective for the study area indicating the suitable places in El-Qaá plain for using in economic activities.