469 research outputs found
A New Hybrid Root-Finding Algorithm to Solve Transcendental Equations Using Arcsine Function
The objective of this paper is to propose a new hybrid root finding algorithms for solving non-linear equations (NLEs) or transcendental equations (TEs). The proposed algorithm is based on the trigonometrical algorithm using arcsine function to find a root. Several numerical examples are presented to illustrate the proposed algorithms, and comparisons are presented with other existing methods to show efficiency and accuracy. Implementation of the proposed algorithms is presented in a mathematical software tool Maple
First Approximation of Population Distributions on the International Space Station
This paper presents an analysis of data derived from thousands of publicly available photographs showing life on the International Space Station (ISS) between 2000 and 2020. Our analysis uses crew and locational information from the photographsâ metadata to identify the distribution of different population groupsâby gender, nationality, and space agency affiliationâacross modules of the ISS, for the first time. Given the significance of the ISS as the most intensively inhabited space habitat to date, an international cooperative initiative involving 26 countries and five space agencies, and one of the most expensive building projects ever undertaken by humans, developing an understanding of which people are using different parts of the space station is critical for future usage of this and other stations. This study also sheds light on problems faced by future space station designers who are concerned with optimal usage of their habitats. The data from this investigation have been permanently deposited with Open Context. It is freely available for use under a Creative Commons license (CC BY 4.0) at https://doi.org/10.6078/M7668B9H
Automated Identification of Astronauts on Board the International Space Station: A Case Study in Space Archaeology
We develop and apply a deep learning-based computer vision pipeline to automatically identify crew members in archival photographic imagery taken on-board the International Space Station. Our approach is able to quickly tag thousands of images from public and private photo repositories without human supervision with high degrees of accuracy, including photographs where crew faces are partially obscured. Using the results of our pipeline, we carry out a large-scale network analysis of the crew, using the imagery data to provide novel insights into the social interactions among crew during their missions
Crystal structures of pure 3-(4-bromo-2-chlorophenyl)-1-(pyridin-4-yl) benzo [4, 5] imidazo [1, 2-d][1, 2, 4] triazin-4 (3H)-one and contaminated with 3-(4-bromophenyl)-1 âŠ
The side product of the cyclocondensation reaction between ethyl benzimidazole-2-carboxylate and the nitrile imine of the corresponding hydrazonyl chloride, C20H11BrClN5O, crystallized in two crystal forms. Form (1) is a co-crystal of the target compound (without any chlorine substituent) and a side product containing a Cl atom in position 2 of the bromophenyl group, C20H12BrN5O·0.143C20H11BrClN5O. (2) contains the pure side product. The slightly different conformation of the ring systems leads to a different packing of (1) and (2), but both crystal structures are dominated by ÏâÏ interactions
An Analysis of Sentence-Like Utterances of IELTS Mock Speaking Test Scripts
The present study examines non-Malaysian candidatesâ performance in an IELTS mock speaking test with regards to their use of different types of sentence structure utterances. Audio recorded data was obtained from eight students of three different levels of proficiency, namely; foundation, intermediate and advanced, in which thereafter an analysis was carried out using Radford (1990; 1997) sentence types. A semi-structured interview was also employed to gauge the candidatesâ opinions on answering the test questions as well the interlocutorâs views on the candidatesâ performance. The test was conducted by an IELTS trained interlocutor. It was found that most candidates were able to understand the questions, their responses were mainly simple sentence utterances indicated by many disjointed and choppy ideas. The semi-structured interview answers show that most candidatesâ high level of nervousness and anxiety caused them not to be able to speak fluently, and as a result, their ideas were expressed in simple sentence structures that lacked logical coordination. It is hoped that the findings of the present study would help the current IETLS course module developers to integrate lessons on the different types of sentence structures in training test candidates to express complete and complex structured responses
Color-to-Grayscale: Does the Method Matter in Image Recognition?
In image recognition it is often assumed the method used to convert color images to grayscale has little impact on recognition performance. We compare thirteen different grayscale algorithms with four types of image descriptors and demonstrate that this assumption is wrong: not all color-to-grayscale algorithms work equally well, even when using descriptors that are robust to changes in illumination. These methods are tested using a modern descriptor-based image recognition framework, on face, object, and texture datasets, with relatively few training instances. We identify a simple method that generally works best for face and object recognition, and two that work well for recognizing textures
Bifunctional non-noble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting
Developing earth-abundant, active and stable electrocatalysts which operate in the same electrolyte for water splitting, including oxygen evolution reaction and hydrogen evolution reaction, is important for many renewable energy conversion processes. Here we demonstrate the improvement of catalytic activity when transition metal oxide (iron, cobalt, nickel oxides and their mixed oxides) nanoparticles (~20 nm) are electrochemically transformed into ultra-small diameter (2–5 nm) nanoparticles through lithium-induced conversion reactions. Different from most traditional chemical syntheses, this method maintains excellent electrical interconnection among nanoparticles and results in large surface areas and many catalytically active sites. We demonstrate that lithium-induced ultra-small NiFeOx nanoparticles are active bifunctional catalysts exhibiting high activity and stability for overall water splitting in base. We achieve 10 mA cm−2 water-splitting current at only 1.51 V for over 200 h without degradation in a two-electrode configuration and 1 M KOH, better than the combination of iridium and platinum as benchmark catalysts.open10
Identification of a CpG Island Methylator Phenotype that Defines a Distinct Subgroup of Glioma
SummaryWe have profiled promoter DNA methylation alterations in 272 glioblastoma tumors in the context of The Cancer Genome Atlas (TCGA). We found that a distinct subset of samples displays concerted hypermethylation at a large number of loci, indicating the existence of a glioma-CpG island methylator phenotype (G-CIMP). We validated G-CIMP in a set of non-TCGA glioblastomas and low-grade gliomas. G-CIMP tumors belong to the proneural subgroup, are more prevalent among lower-grade gliomas, display distinct copy-number alterations, and are tightly associated with IDH1 somatic mutations. Patients with G-CIMP tumors are younger at the time of diagnosis and experience significantly improved outcome. These findings identify G-CIMP as a distinct subset of human gliomas on molecular and clinical grounds
Electrochemical and Photoelectrochemical Investigation of Water Oxidation with Hematite Electrodes
Atomic layer deposition (ALD) was utilized to deposit uniform thin films of hematite (α-Fe2O3) on transparent conductive substrates for photocatalytic water oxidation studies. Comparison of the oxidation of water to the oxidation of a fast redox shuttle allowed for new insight in determining the rate limiting processes of water oxidation at hematite electrodes. It was found that an additional overpotential is needed to initiate water oxidation compared to the fast redox shuttle. A combination of electrochemical impedance spectroscopy, photoelectrochemical and electrochemical measurements were employed to determine the cause of the additional overpotential. It was found that photogenerated holes initially oxidize the electrode surface under water oxidation conditions, which is attributed to the first step in water oxidation. A critical number of these surface intermediates need to be generated in order for the subsequent hole-transfer steps to proceed. At higher applied potentials, the behavior of the electrode is virtually identical while oxidizing either water or the fast redox shuttle; the slight discrepancy is attributed to a shift in potential associated with Fermi level pinning by the surface states in the absence of a redox shuttle. A water oxidation mechanism is proposed to interpret these results
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