How to Staff when Customers Arrive in Batches

In settings as diverse as autonomous vehicles, cloud computing, and pandemic quarantines, requests for service can arrive in near or true simultaneity with one another. This creates batches of arrivals to the underlying queueing system. In this paper, we study the staffing problem for the batch arrival queue. We show that batches place a significant stress on services, and thus require a high amount of resources and preparation. In fact, we find that there is no economy of scale as the number of customers in each batch increases, creating a stark contrast with the square root safety staffing rules enjoyed by systems with solitary arrivals of customers. Furthermore, when customers arrive both quickly and in batches, an economy of scale can exist, but it is weaker than what is typically expected. Methodologically, these staffing results follow from novel large batch and hybrid large-batch-and-large-rate limits of the general multi-server queueing model. In the pure large batch limit, we establish the first formal connection between multi-server queues and storage processes, another family of stochastic processes. By consequence, we show that the limit of the batch scaled queue length process is not asymptotically normal, and that, in fact, the fluid and diffusion-type limits coincide. This is what drives our staffing analysis of the batch arrival queue, and what implies that the (safety) staffing of this system must be directly proportional to the batch size just to achieve a non-degenerate probability of customers waiting

Performative Strategies in the Extractive Periphery: Resisting Colonial-Capitalist Logics of Dissolution in the Anthropocene

Situated at the intersections of performance, decolonial and ecological theory, this thesis posits embodied performance strategies as a catalyst for subverting the colonial-capitalist logics of extractivism. Through close readings of the work of contemporary artists Tsēmā Igharas (Tahltan), Otobong Nkanga (Nigerian-born, Antwerp-based), Warren Cariou (Métis and European ancestry), Carolina Caycedo (Colombian mestizx, Los Angeles-based) and Rebecca Belmore (Anishinaabe), this thesis argues that the performing body translates extractive politics into the immediacy of the senses through the micro and intimate aesthetics of the corporeal to engage in a form of critical public pedagogy. Drawing on the work of scholars Leanne Betasamosake Simpson, Macarena Gómez-Barris, Laura Levin and Wanda Nanibush, this study queries what submerged perspectives are voiced and made visible in the extractive zone, and frames these perspectives within the current discourse of the Anthropocene. The artists’ land-based praxes, foregrounding Indigenous knowledges, are examined as a type of field research of specific regions’ geopolitics and temporalities—praxes which conceptualize alternative ways of representing and thinking about land through the performance of place-based relationality

A Cosmic Watershed: the WVF Void Detection Technique

On megaparsec scales the Universe is permeated by an intricate filigree of clusters, filaments, sheets and voids, the Cosmic Web. For the understanding of its dynamical and hierarchical history it is crucial to identify objectively its complex morphological components. One of the most characteristic aspects is that of the dominant underdense Voids, the product of a hierarchical process driven by the collapse of minor voids in addition to the merging of large ones. In this study we present an objective void finder technique which involves a minimum of assumptions about the scale, structure and shape of voids. Our void finding method, the Watershed Void Finder (WVF), is based upon the Watershed Transform, a well-known technique for the segmentation of images. Importantly, the technique has the potential to trace the existing manifestations of a void hierarchy. The basic watershed transform is augmented by a variety of correction procedures to remove spurious structure resulting from sampling noise. This study contains a detailed description of the WVF. We demonstrate how it is able to trace and identify, relatively parameter free, voids and their surrounding (filamentary and planar) boundaries. We test the technique on a set of Kinematic Voronoi models, heuristic spatial models for a cellular distribution of matter. Comparison of the WVF segmentations of low noise and high noise Voronoi models with the quantitatively known spatial characteristics of the intrinsic Voronoi tessellation shows that the size and shape of the voids are succesfully retrieved. WVF manages to even reproduce the full void size distribution function.Comment: 24 pages, 15 figures, MNRAS accepted, for full resolution, see http://www.astro.rug.nl/~weygaert/tim1publication/watershed.pd

Watering the St. Katherine Landscape: Exploring the Nexus between Socio-Economic and Hydro-Cultural Change

The town of St. Katherine is located in the mountainous and most water rich region of Egypt\u27s Sinai Peninsula. This relative water abundance was a critical factor to the historical and cultural landscape that emerged there over the centuries. Past human settlements have left an intricate network of catchments, conduits and wells. Much of this infrastructure is still in use today across the hundreds of orchards that dot valley floors around this growing urban center. A pipeline has recently linked this community to the Nile River hundreds of miles away restructuring water consumption patterns throughout the area and reinforcing a sedentarization process that began forty years ago. This thesis offers a critique of this development placing it squarely within the context of a fix to the overproduction inherent to capitalist based economies. It discusses the effects that increased capital flows from the tourism industry have had on St. Katherine\u27s waterscape. Drawing on a series of interviews and mental mapping exercises, it also challenges the hydro-development discourse in the area by reflecting on some of the ways that new water management schemes are being negotiated among the multiple stakeholders in and around St. Katherine

Semantic assessments of experienced biodiversity from photographs and on-site observations - a comparison

Since the 1960’s, public assessments of landscapes have often been carried out using photographic representations. How reliable and valid are these assessments compared with on-site observations? In the present study, participants have been asked to judge different areas in terms of a limited feature: the biodiversity of the area. Digitalized photos from six different study areas were made available on the Internet, along with a questionnaire consisting of a semantic form with specific words/expressions to be rated in relation to the photos (four per area). Participants were recruited via mailing lists and informal contacts. These results were compared with a study in which students and ecologists had rated the same places using the same form, but this time on-site. The Internet participants were also asked to state their profession/education to make comparisons possible. The comparisons revealed differences between on-site and photo-based ratings, but the main difference was expressed by on-site biologists regarding areas with the highest experienced biodiversity values, possibly due to their higher degree of expertise and use of more senses than can be used when judging photographs. Concerning laymen in particular, it is concluded that the comparison between on-site and photo-based ratings is not conclusive enough to allow us to determine whether it is appropriate to use one method as a substitute for the other