1,724,156 research outputs found
Resume: Yang Jun 杨君
No full textThis is Yang Jun\u27s resume from the 1995 New Asian Art Show. His brief educational background and exhibition experience up until 1995 are on the left side of this paper, while one of his collage of photos is on the right. (Zhuocheng Jiang \u2726)https://digital.kenyon.edu/zhoudocs/1361/thumbnail.jp
Biosensor-mediated directed evolution of aldehyde dehydrogenase for improved production of 3-hydroxypropionic acid
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Flow Patterns Causing Saddle Instability in the Performance Curve of a Centrifugal Pump with Vaned Diffuser
Full text linkIn the present study, a reduced scale model of a low-pressure stage of a two-stage pump turbine was investigated when it operates in pump mode, which is as a centrifugal pump with vaned diffuser. An instability region was found in its Q-H curve. This instability region, centered into the flow rate interval between 0.45 to 0.7 QDes, restricts the stable operating range of the test pump.
The object of this study was to analyze the origins and development of the unsteadiness inner pump during this saddle instability region, and to find the causes of this saddle, which could guide the design, and optimization of the test pump.
Experimental and numerical approaches have been adopted to contribute the understanding on the highly complex flow interactions inside the test pump. The analyses pointed out that the instability of Q-H curve during this flow rate interval was mainly affected by the flow field unsteadiness into the diffuser. Severe flow separation occurred into the diffuser, affecting and/or affected by the unsteadiness from the impeller and return channel remarkably.
Both at full and part load, due to the U shape stay vanes in the return system, a 3-dimentional complex flow was found on the suction side of stay vane near the U turn corner. This flow caused a periodic unforced pressure disturbance with frequency St=0.6625 in the diffuser. A rotating stall with 5 cells into the diffuser was also highlighted by the experimental analyses and the numerical results validated that this disturbance was mainly due to the unsteady flow patterns in the return channel.
With the reduction of flow rate, the location of this unsteadiness in return channel move closer to the outlet of diffuser, and the unsteadiness made the flow separation near the stay vane leading edge on the suction side more severe and it impacted the flow in diffuser flow field in a more severe way.
At the same time, two types of unsteadiness were detected in the impeller in the saddle instability region. They were the flow separation with the frequency St=0.6625 at the impeller blade suction side and the wake-jet near the trailing edge of impeller blade with the frequency St=0.335, respectively. The wake-jet caused a periodic disturbance with a frequency of St=0.335 in diffuser as well. The experimental results indicated that it propagate circumferentially with 2 cells.
At the beginning of this saddle instability, in diffuser, the intensity of the fluctuations at St=0.335 and St=0.6625 both increase with the falling flow rate. With the development of these unsteady patterns, they mixed and caused a blockage in the gap between impeller and diffuser. This blockage caused the increase of the amplitude at BPF, which has been detected both by experimental and numerical results. At the same time, the further development of the blockage weakened the intensity of the two disturbances with frequency of St=0.335 and St=0.6625 in the blockage region. The blockage fully developed near the critical flow rate of 0.6 QDes. At this condition, the intensity of rotor and stator interaction increased and energy loss also increased which caused the drop of head and mean pressure at the exit of impeller. Furthermore, the disturbance in diffuser which caused by wake-jet of impeller lost the periodic character with frequency of St=0.335 at this condition. This is the reason why the non-linear component St=0.335 disappeared in diffuser around 0.6 QDes
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
Designing pores to suppress crack generation at the interface between serpentine interconnects and elastomers for highly durable stretchable electronics
No full textSerpentine interconnects enable rigid materials to have high stretchability. They are considered to be very effective architectures to enable stretchable electronics. Therefore, research has primarily focused on exploring serpentine-based designs to enhance the stretchability of the interconnect itself. However, in practical applications, the interfacial cracks caused by repetitive stretching becomes a critical issue if serpentine interconnects are encapsulated within a polymer matrix. Here, we introduce geometrically engineered pores in a polymer matrix to suppress interfacial cracks under stretching. The serpentine interconnects with optimized pores in a polymer matrix improved mechanical stability (strain at failure, fatigue life) and electrical stability compared with those without pores. Furthermore, these strategies enabled the demonstration of a stretchable light-emitting diodes (LED) array and an electrical heater.
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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