1,721,285 research outputs found
Reachability and Controllability of Delayed Switched Boolean Control Networks
No full textIn this paper we investigate the reachability and controllability of delayed switched Boolean control networks (DSBCNs). By resorting to the algebraic state space representation method built using semi-tensor product (STP) of matrices, we provide several necessary and sufficient conditions for these properties to hold which are based on input-state incidence matrix carrying entire network dynamics information. Also, to realize the reachability of DSBCNs in shortest time, an algorithm is presented which finds switching and control sequences forcing initial state trajectory to destination state. At last, an example is given to illustrate the main results
Critical heat flux maxima during boiling crisis on textured surfaces
Full text linkEnhancing the critical heat flux (CHF) of industrial boilers by surface texturing can lead to substantial energy savings and global reduction in greenhouse gas emissions, but fundamentally this phenomenon is not well understood. Prior studies on boiling crisis indicate that CHF monotonically increases with increasing texture density. Here we report on the existence of maxima in CHF enhancement at intermediate texture density using measurements on parametrically designed plain and nano-textured micropillar surfaces. Using high-speed optical and infrared imaging, we study the dynamics of dry spot heating and rewetting phenomena and reveal that the dry spot heating timescale is of the same order as that of the gravity and liquid imbibition-induced dry spot rewetting timescale. Based on these insights, we develop a coupled thermal-hydraulic model that relates CHF enhancement to rewetting of a hot dry spot on the boiling surface, thereby revealing the mechanism governing the hitherto unknown CHF enhancement maxima.MIT Shapiro FellowshipChevron CorporationKuwait-MIT Center for Natural Resources and the Environmen
DUAL-LENS LASER HEATING FOR ARTIFICIAL BUBBLE GENERATION
Full text linkThis report investigates the transition process involved in enhancing the STEAMI laboratory laser focusing setup. Exploring the changes and new insights of going from a single-lens laser heating to a dual-lens configuration. The experimental idea was first pitched by preceding STEAM-I lab researchers [1], culminating the development and evaluation of the current configuration. The findings of this thesis are further analyzed and juxtaposed to previously collected data. Through examination of the analyzed data and parameters updated for inducing bubble nucleation using the new setup, it is established that the dual lens focusing arrangement has proven successful. However, it is noted that certain components of the overall experimental setup, such as the substrate, show signs of wear and tear, needing replacement or refurbishment
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
HIGH-SPEED OPTICAL IMAGING OF NOZZLE EXHAUST IN A LIQUID ROCKET STATIC FIRE TEST
Full text linkAt California State University of Long Beach (CSULB) the Beach Launch Team (BLT) is the rocket engineering team that is working on their current design for a liquid rocket. A static fire is a ground test that is essential in providing accurate launch data to confirm or disprove if a rocket is ready to move on to a full launch. The BLT reached the stage in their design where they were ready to perform a static fire ignition of their engine to collect force data and other internal engine data on 01/23/2023. My role in collaboration with BLT was using a high-speed camera to collect visual data from the combustion chamber and nozzle during the beginning phase of the ignition of the engine during their static fire. The visual data collected from the camera is intended to support the Launch team's data and verify that the entire system is ready for launch. It can also be used to discover errors in the static fire to better prepare the team for either their future launch or another static fire. This static fire was performed at Friends of Amateur Rocketry (FAR) alongside several independents, UCI, and MIT
LEIDENFROST EFFECT ON DROPLETS OF WATER UNDER HIGH VOLTAGE
Full text linkThis thesis explores the behavior of water droplets passing through an electric field and impacting a heated plate. The heat surface is set to a temperature of 350°C in order to demonstrate the Leidenfrost Effect. A droplet of water will be released 55 mm above the surface and be influenced by an electric field with an applied voltage range of zero to eight kilovolts. A total of nine runs with two trials each will be conducted with increments of one kilovolt. A high speed camera will be used to capture the droplet's freefall and reaction to the heat and electric field. A visual analysis will be made on the effects of electric fields and the Leidenfrost effect on droplets of water
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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