86,606 research outputs found
Swirl Injection Modeling for Paraffin-Based Hybrid Rocket Engines Combustion Instabilities
No full textHybrid Rocket Engines have gained more and more attention in recent years due to their appealing safety and cost-effectiveness features, but they present some disadvantages, most notably a low regression rate. Swirl injection offers a promising solution, enhancing regression rate and stabilizing combustion by means of increased wall heat flux. This paper introduces a novel swirl model for regression rate evaluation consisting in two integrated sub-models: the first one involves a corrective factor linked to the geometric swirl number of the injector, while the other accounts for the naturally occurring swirl decay. The validity of the model was assessed across a range of different test cases, varying geometric parameters, engine scales, injection, and feeding conditions, and the results shows that the accuracy of local and mean regression rate prediction is improved. Corrections for the wall friction coefficient and the entrainment factor were introduced in an in-house code for paraffin-based fuels. A parametric analysis, carried out considering different swirl levels, revealed combustion chamber thermodynamics consistent with the expected trends observed in firing tests. Finally, an effective reduction in the delay time characteristic of the boundary layer was observed; moreover, the Rayleigh index results showed a marked decrease, indicating a decoupling of pressure fluctuations and heat release which tends to stabilize combustion as the swirl increases
Influence of Measures of Risk Prevention and Mitigation on the Frequencies of Rupture of Pipework
No full textThe paper presents a method for the quantification of the effects of measures of risk prevention or mitigation on the frequencies of rupture of pipework.
Some methodologies are given in the literature to this purpose; they however assume that each plant under analysis is characterized by the same combinations of failure causes and prevention mechanisms and this assumption is not always true.
The approach suggested in this paper is based on the methodology proposed by I.A.Papazoglou in 1999 for the quantification of the effects of the organizational and managerial factors. Taking advantage of such methodology the objective has been achieved through the definition of the ties between the failure causes that are the origin of incidents and the measures adopted from the company in order to prevent and/or to mitigate them.
After the definition of the weights that the single failure causes can have on the incident frequencies and, on the basis of a judgement on the measures of prevention and mitigation adopted, it has been possible to proceed to the modification of the frequencies.
The methodology has been applied at the most critical random events, associated to the pipework for a petrochemical plant, which have been brought back in the Safety Report of the establishment.
The influence of the measures of risk prevention and mitigation on the failure causes has been discussed and defined according with the plant managemen
An approach for the quantification of the influence of measures of risk prevention and mitigation on frequencies of rupture in piping
No full textThe paper presents a method for the quantification of the effects of measures of risk prevention or mitigation on the frequencies of rupture of pipework. Some methodologies are given in the literature to this purpose; they however assume that each plant under analysis is characterized by the same combinations of failure causes and prevention mechanisms and this assumption is not always true. The approach suggested in this paper is based on the methodology proposed by Papazoglou (1999) for the quantification of the effects of the organizational and managerial factors. Taking advantage of such methodology the objective has been achieved through the definition of the ties between the failure causes that are the origin of incidents and the measures adopted from the company in order to prevent and/or to mitigate them
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
John F. Kennedy telegram to Roosevelt
No full textJersey Homesteads (later the Borough of Roosevelt) was established in the 1930s as an agro-industrial cooperative community. It was established specifically for urban Jewish garment workers, many of whom had emigrated from Europe. President John F. Kennedy sent a telegram to the citizens of Roosevelt, New Jersey, apologizing for not being able to attend the memorial dedication in honor of former President Franklin Delano Roosevelt. (Jersey Homesteads became Roosevelt in 1945 in honor of the president.) President Kennedy expressed his gratitude to the people of Roosevelt for constructing the memorial, and commented that it will serve as a constant reminder of Roosevelt's good works
Regulation of mitotic clonal expansion and thermogenic pathway are involved in the antiadipogenic effects of cyanidin-3-O-glucoside
No full textLogarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
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