scholarly journals Crystallography Under Extreme Conditions: State of the Art and Perspectives

Author(s):  
Legrand Vincent
2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Claudio Feliciani ◽  
Iker Zuriguel ◽  
Angel Garcimartín ◽  
Diego Maza ◽  
Katsuhiro Nishinari

Abstract Although some experimental evidence showed that an obstacle placed in front of a door allows making people’s evacuations faster, the efficacy of such a solution has been debated for over 15 years. Researchers are split between those who found the obstacle beneficial and those who could not find a significant difference without it. One of the reasons for the several conclusions lies in the variety of the experiments performed so far, both in terms of competitiveness among participants, geometrical configuration and number of participants. In this work, two unique datasets relative to evacuations with/without obstacle and comprising low and high competitiveness are analyzed using state-of-the-art definitions for crowd dynamics. In particular, the so-called congestion level is employed to measure the smoothness of collective motion. Results for extreme conditions show that, on the overall, the obstacle does not reduce density and congestion level and it could rather slightly increase it. From this perspective, the obstacle was found simply shifting the dangerous spots from the area in front of the exit to the regions between the obstacle and the wall. On the other side, it was however confirmed, that the obstacle can stabilize longitudinal crowd waves, thus reducing the risk of trampling, which could be as important (in terms of safety) as improving the evacuation time. However, under urgent, competitive, but non-extreme conditions, the obstacle generally had a positive effect, helping channeling the flow of pedestrians through the exit while facilitating their interactions.


Author(s):  
Bladimir Suárez ◽  
José David Vera Rodríguez ◽  
Francisco Botero ◽  
Byron Suárez Agudelo ◽  
William Giraldo Jiménez

This article presents the investigation, analysis, and results of the intake gate closure of two vertical fixed-wheel gates at the hydroelectric project Ituango in Colombia (2400 MW) under free- flow conditions. This atypical operation was considered successful notwithstanding adverse conditions, and therefore, it can be classified as a unique operation in the field of hydraulic gates. In this article, some relevant parameters, such as the hydraulic force of the servomotor during the operation of the gate, were measured before and after the operation and analyzed, and the results were presented. A new chart is proposed for the downpull coefficient based on the collected data, which could be implemented in the closure of gates against the free flow. Considering the abovementioned factors, the authors propose some recommendations and present drawn conclusions contributing to state of the art on design, manufacturing, and operation of this type of hydraulic gates and structures for large and small dams under adverse and extreme conditions.


2021 ◽  
Vol 9 ◽  
Author(s):  
Eliane Ribeiro Januario ◽  
Patrícia Ferreira Silvaino ◽  
Arthur Pignataro Machado ◽  
Jorge Moreira Vaz ◽  
Estevam Vitorio Spinace

The processes currently used in the chemical industry for methane conversion into fuels and chemicals operate under extreme conditions like high temperatures and pressures. In this sense, the search for methane conversion under mild conditions remains a great challenge. This review aims to summarize the use semiconductors and metal-semiconductors as heterogeneous photocatalysts for methane conversion under mild conditions into valuable products. First, a brief presentation of photochemical conversion of methane is provided and then the focus of this review on the use of heterogeneous photocatalysts for methane conversion are described. Finally, the main challenges and opportunities are discussed.


Author(s):  
T. A. Welton

Various authors have emphasized the spatial information resident in an electron micrograph taken with adequately coherent radiation. In view of the completion of at least one such instrument, this opportunity is taken to summarize the state of the art of processing such micrographs. We use the usual symbols for the aberration coefficients, and supplement these with £ and 6 for the transverse coherence length and the fractional energy spread respectively. He also assume a weak, biologically interesting sample, with principal interest lying in the molecular skeleton remaining after obvious hydrogen loss and other radiation damage has occurred.


Author(s):  
Carl E. Henderson

Over the past few years it has become apparent in our multi-user facility that the computer system and software supplied in 1985 with our CAMECA CAMEBAX-MICRO electron microprobe analyzer has the greatest potential for improvement and updating of any component of the instrument. While the standard CAMECA software running on a DEC PDP-11/23+ computer under the RSX-11M operating system can perform almost any task required of the instrument, the commands are not always intuitive and can be difficult to remember for the casual user (of which our laboratory has many). Given the widespread and growing use of other microcomputers (such as PC’s and Macintoshes) by users of the microprobe, the PDP has become the “oddball” and has also fallen behind the state-of-the-art in terms of processing speed and disk storage capabilities. Upgrade paths within products available from DEC are considered to be too expensive for the benefits received. After using a Macintosh for other tasks in the laboratory, such as instrument use and billing records, word processing, and graphics display, its unique and “friendly” user interface suggested an easier-to-use system for computer control of the electron microprobe automation. Specifically a Macintosh IIx was chosen for its capacity for third-party add-on cards used in instrument control.


2010 ◽  
Vol 20 (1) ◽  
pp. 9-13 ◽  
Author(s):  
Glenn Tellis ◽  
Lori Cimino ◽  
Jennifer Alberti

Abstract The purpose of this article is to provide clinical supervisors with information pertaining to state-of-the-art clinic observation technology. We use a novel video-capture technology, the Landro Play Analyzer, to supervise clinical sessions as well as to train students to improve their clinical skills. We can observe four clinical sessions simultaneously from a central observation center. In addition, speech samples can be analyzed in real-time; saved on a CD, DVD, or flash/jump drive; viewed in slow motion; paused; and analyzed with Microsoft Excel. Procedures for applying the technology for clinical training and supervision will be discussed.


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