1,721,195 research outputs found
Technical and economical optimization of CHP systems by using gas turbine and energy recovery system
No full textExergy and Economic Analysis of Solar Chimney in Iran Climate: Tehran, Semnan, and Bandar Abbas
No full textMarkov-based performance evaluation and availability optimization of the boiler–furnace system in coal-fired thermal power plant using PSO
No full textThe appropriate maintenance strategy is essential for maintaining the thermal power plant highly reliable. The thermal power plant is a complex system that consists of various subsystems connected either in series or parallel configuration. The boiler-furnace (BF) system is one of the most critical subsystems of the thermal power plant. This paper presents availability based simulation modeling of the boiler-furnace system of thermal power plant with capacity (500MW). The Markov based simulation model of the system is developed for performance analysis. The differential equations are derived from a transition diagram representing various states with full working capacity, reduced capacity, and failed state. The normalizing condition is used for solving the differential equations. Furthermore, the performance of the system is analyzed for a possible combination of failure rate and repair rate, which revealed that failure of the boiler drum affects the system availability at most, and the failure of reheater affects the availability at least. Based on the criticality ranking, the maintenance priority has been provided for the system. The availability of the boiler-furnace system is optimized using particle swarm optimization method by varying the number of particles. The study results revealed that the maximum system availability level of 99.9845% is obtained. In addition, the optimized failure rate and repair rate parameters of the subsystem are used for suggesting an appropriate maintenance strategy for the boiler-furnace system of the plant. The finding of the study assisted the decision-makers in planning the maintenance activity as per the criticality level of subsystems for allocating the resources
Investigating eutectic behavior and material relocation in B4C-stainless steel composites using the improved MPS method
No full textIn nuclear severe accidents, eutectic reactions induce early melting of stainless steel (SS) cladding and boron carbide (B4C), leading to control rod failure and eutectic melt relocation. To accurately simulate eutectic melting, we modified the standard Moving Particle Semi-implicit (MPS) method. The conventional MPS model is inadequate due to its simplistic treatment of surface tension, and viscosity. By revising these parameters and incorporating mass diffusion and eutectic reaction criteria based on the Fe-B phase diagram, the enhanced MPS method can effectively capture the complex behaviors of eutectic melting in both 2D and 3D simulations. The study aims to measure boron concentration through the unidirectional diffusion of boron within the stainless steel (SS) layers while evaluating the updated model's ability to replicate melt relocation behavior and geometry. In the current MPS simulations, one scenario employed dummy walls as heat sources, while another scenario used SS surface particles as heat sources to avoid interference with the melt flow as it reached the bottom of the specimen. The results indicate that upon eutectic reaction, boron diffuses into the SS wall, initiating melting at the B4C-SS interface and leading to melt flow following SS cladding penetration. Also, we observed that as temperature increases, there is a proportional rise in boron concentration within the melt due to enhanced unidirectional diffusion of boron atoms into SS cladding. Additionally, the effect of gravity on boron transport has been assessed, revealing its impact on the diffusion rate. The primary focus of this study lies in assessing the eutectic reaction model in the updated MPS code, particularly examining the formation of the eutectic melt, the concentration of B4C within it, and the resemblance of the final formed melt to the experimental observations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“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
- …
