An Investigation into the Stand-up Time of Stopes at the Birchtree Mine, Thompson, Manitoba

Open stoping is a common mining method employed in the Canadian mining industry. Extracting large volumes of rock can present stability issues which can affect productivity and safety. Many factors such as changing stress states, rock mass structure, and intact rock strength can contribute to instability. One factor not commonly assessed when examining stope stability is exposure time. With increased exposure time, the rock quality of the opening tends to degrade. Birchtree Mine located in Thompson, Manitoba, is the focus of this study due to the time dependent instability that has been observed. For the proposed project, an empirical method was chosen since these methods can easily be updated with future case histories to better reflect onsite conditions. Few empirical methods exist for assessing exposure time for open stope mining. The most common method of incorporating time with stability is Bieniawski’s 1989 RMR Stand-up Time Graph. As part of this project the original data used to create the RMR Stand-up Time Graph was reinterpreted so it could be plotted on the Stability Graph, which is used for open stope design. Case histories from the Birchtree mine, along with the original database for Bieniawski’s empirical method, have been examined. Comparisons were conducted to evaluate the accuracy and validity of the Bieniawski and Birchtree data. Other factors that may affect stability and exposure time were also discussed. This research has led to the development of a new empirical design method that incorporates exposure time in the prediction of open stope stability

Choisey – Les Malarchies, La Chaille

Le diagnostic archéologique, réalisé aux lieux-dits Les Malarchies et La Chaille sur la commune de Choisey (Jura), a permis la mise au jour de deux sites gallo-romains sur les 8,8 ha de terrains destinés à être aménagés. Les terrains concernés par cette opération sont localisés au sud-ouest du territoire communal, entre la RN5 et le canal du Rhône au Rhin. Du point de vue géomorphologique, ils sont situés dans deux zones bien distinctes : la première correspond à la base du versant calcaire q..

Port-sur-Saône – Route de Ferrière, La Grande Vie

Prescrits à la suite d’un projet de lotissement à usage d’habitation, les sondages de diagnostic archéologique au lieu-dit « La Grande Vie » sur la commune de Port-sur-Saône, ont révélé la présence de quelques vestiges archéologiques : deux fossés, une fondation de mur et une excavation non identifiée. Les éléments mobiliers sont uniquement composés de pierres calcaires (fragments, blocs et dallettes d’origine locale) et de quelques fragments de tuiles (tegulae et imbrex), ce qui permet de pr..

Pont-à-Mousson – Gravière GSM, La Maquinière

Identifiant de l'opération archéologique : F1354200100043 Date de l'opération : 2001 (SU) La fouille de sauvetage qui a eu lieu du 14 mai au 31 mai 2001 a mis au jour un petit nombre de structures excavées en bordure d'un ancien chenal peut-être lié à la Moselle. Le site est relativement petit, mais cette pauvreté en structures et en mobilier n'en diminue pas l'intérêt scientifique. Il y a tout d'abord la présence d'un bâtiment du premier âge du Fer (Hallstatt), dont le plan à une nef et pote..

Saint-Nabord – Au Perrey

Identifiant de l'opération archéologique : F1388200100018 Date de l'opération : 2001 (EV) Le projet d'extension de la gravière gérée par la société SAGRAM a conduit le service régional de l'Archéologie de Lorraine à prescrire la réalisation préalable d'un diagnostic archéologique sur les parcelles concernées. Effectués les 9 et10 avril 2001 par Jean-Marc Violot (AFAN), les sondages mécaniques n'ont révélé la présence d'aucun vestige de nature archéologique, qu'il s'agisse de mobilier ou de st..

Saint-Nabord

Identifiant de l'opération archéologique : F1388200100018 Date de l'opération : 2001 (EV) Le projet d'extension de la gravière gérée par la société SAGRAM a conduit le service régional de l'Archéologie de Lorraine à prescrire la réalisation préalable d'un diagnostic archéologique sur les parcelles concernées. Effectués les 9 et10 avril 2001 par Jean-Marc Violot (AFAN), les sondages mécaniques n'ont révélé la présence d'aucun vestige de nature archéologique, qu'il s'agisse de mobilier ou de st..

Arlay, Lombard – Desserte routière de la base de loisirs de Desnes

Le diagnostic archéologique réalisé à Lombard (Jura) a permis de reconnaître une occupation romaine, qui n’a pu être ni définie ni localisée précisément du fait de l’emprise limitée offerte aux sondages. L’occupation est attestée par un fossé et un horizon sédimentaire renfermant du mobilier romain essentiellement constitué de tegulae et de céramique commune. Quelques indices (fragments de céramique) signalent également la présence d’une occupation antérieure protohistorique (période laténien..

Solar X-ray Flare Hazards on the Surface of Mars

Putative organisms on the Martian surface would be exposed to potentially high doses of ionizing radiation during strong solar X-ray flares. We extrapolate the observed flare frequency-energy release scaling relation to releases much larger than seen so far for the sun, an assumption supported by observations of flares on other solar- and subsolar-mass main sequence stars. We calculate the surficial reprocessed X-ray spectra using a Monte Carlo code we have developed. Biological doses from indirect genome damage are calculated for each parameterized flare spectrum by integration over the X-ray opacity of water. We estimate the mean waiting time for solar flares producing a given biological dose of ionizing radiation on Mars and compare with lethal dose data for a wide range of terrestrial organisms. These timescales range from decades for significant human health risk to 0.5 Myr for D. radiodurans lethality. Such doses require total flare energies of 10^33--10^38 erg, the lower range of which has been observed for other stars. Flares are intermittent bursts, so acute lethality will only occur on the sunward hemisphere during a sufficiently energetic flare, unlike low-dose-rate, extended damage by cosmic rays. We estimate the soil and CO_2 ice columns required to provide 1/e shielding as 4--9 g cm^-2, depending on flare mean energy and atmospheric column density. Topographic altitude variations give a factor of two variation in dose for a given flare. Life in ice layers that may exist ~ 100 g cm^-2 below the surface would be well protected.Comment: To be published in Planetary and Space Science; 33 pages, 3 figure

Shorts vs. Regular Videos on YouTube: A Comparative Analysis of User Engagement and Content Creation Trends

YouTube introduced the Shorts video format in 2021, allowing users to upload short videos that are prominently displayed on its website and app. Despite having such a large visual footprint, there are no studies to date that have looked at the impact Shorts introduction had on the production and consumption of content on YouTube. This paper presents the first comparative analysis of YouTube Shorts versus regular videos with respect to user engagement (i.e., views, likes, and comments), content creation frequency and video categories. We collected a dataset containing information about 70k channels that posted at least one Short, and we analyzed the metadata of all the videos (9.9M Shorts and 6.9M regular videos) they uploaded between January 2021 and December 2022, spanning a two-year period including the introduction of Shorts. Our longitudinal analysis shows that content creators consistently increased the frequency of Shorts production over this period, especially for newly-created channels, which surpassed that of regular videos. We also observe that Shorts target mostly entertainment categories, while regular videos cover a wide variety of categories. In general, Shorts attract more views and likes per view than regular videos, but attract less comments per view. However, Shorts do not outperform regular videos in the education and political categories as much as they do in other categories. Our study contributes to understanding social media dynamics, to quantifying the spread of short-form content, and to motivating future research on its impact on society.Comment: 11 pages, 9 figures, to be published in the proceedings of ACM Web Science Conference 2024 (WEBSCI24

Shorts vs. Regular Videos on YouTube: A Comparative Analysis of User Engagement and Content Creation Trends

YouTube introduced the Shorts video format in 2021, allowing users to upload short videos that are prominently displayed on its website and app. Despite having such a large visual footprint, there are no studies to date that have looked at the impact Shorts introduction had on the production and consumption of content on YouTube. This paper presents the first comparative analysis of YouTube Shorts versus regular videos with respect to user engagement (i.e., views, likes, and comments), content creation frequency and video categories. We collected a dataset containing information about 70k channels that posted at least one Short, and we analyzed the metadata of all the videos (9.9M Shorts and 6.9M regular videos) they uploaded between January 2021 and December 2022, spanning a two-year period including the introduction of Shorts. Our longitudinal analysis shows that content creators consistently increased the frequency of Shorts production over this period, especially for newly-created channels, which surpassed that of regular videos. We also observe that Shorts target mostly entertainment categories, while regular videos cover a wide variety of categories. In general, Shorts attract more views and likes per view than regular videos, but attract less comments per view. However, Shorts do not outperform regular videos in the education and political categories as much as they do in other categories. Our study contributes to understanding social media dynamics, to quantifying the spread of short-form content, and to motivating future research on its impact on society