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To computer-simulate solar-concentrating facilities, an accurate knowledge of the Sun’s position as a function of latitude, longitude, time and date is required. In this work, it is reported first a simplified description of a general algorithm, developed by the astronomy community to accomplish that. Our implementation of this algorithm (included in our Light Analysis Modelling package) has been successfully validated against well trusted astronomy data. The software was then used to produce a wide range of results for 2024, for two well-known research facilities, the most northern (Jülich, Germany) and the most southern (Protaras, Cyprus) heliostat fields listed in the official SFERA-III EU project. This includes altitude and azimuth data, sunrise and sunset data, analemma curves, angular speed data and geocentric Sun trajectories around the observer’s position. Other ray-tracing techniques are also reported to help simulate the Sun vectors reaching the solar devices. The truly inspiring results obtained show how important this type of software is, from the scientific and industrial point of view, to better understand our relationship with our neighbor star, the Sun.

This work demonstrates that the quasi-homogeneous distribution of concentrated solar flux is achievable by using double paraboloid reflection, with a primary reflector to concentrate the sunlight, and a secondary reflector to homogenise the radiation flux. For that, three slightly different secondary reflectors were designed and manufactured, matching the specifications of the paraboloid concentrator of the SF60 solar furnace located in PSA—Plataforma Solar de Almería, which was used as primary reflector. Starting from preliminary simulations of the optical apparatus, the secondary geometries were selected and then the reflectors were manufactured from 7075-T6 aluminium alloy, using conventional and CNC machining technologies, with further processing to achieve a mirror-like finish. The results obtained from solar irradiation tests corroborate that the “double paraboloid reflection” methodology proposed in previous theoretical works seems to be technically feasible and can be a solution for obtaining homogeneously distributed fluxes of highly concentrated solar radiation.

The ornamental stone industry has always played an important role in the world economy. Polishing the slabs to increase their gloss is important to enhance the beauty and richness of these natural materials. Many industrial polishing machines rely on a rotating head’s movement along zigzag trajectories (controlled by belt, transverse and rotational speeds), to erode the surface as stochastically as possible (to avoid scratches and other visual defects caused by paths that are too symmetrical). Optimizing (and automatizing) these three speeds together therefore represents a significant gain for the industry, in time, energy, and quality of product. In this work we show that this optimization can be accomplished by fulfilling these conditions: (1) the displacement of the polishing head after a single zigzag movement should be smaller than its diameter; and (2) the displacement of the polishing head after a single rotation should be smaller than its radius. To assess the validity of these two conditions, we studied the polishing activity using experiments based on gloss measurements of the polished stone and computer simulations based on the geometric contacts between the tool and the stone. We concluded that: (i) a clear correlation can be established between experimental and simulation data; (ii) the two displacement parameters represent an effective way to control the quality and efficiency of the polishing process; and (iii) there is a limit to the gloss acquired through polishing processes, thus polishing above a given threshold decreases the efficiency without increasing the quality. The correspondence between experimental and modelling results opens the door to further optimizations of these polishing processes in the future.

This article explores Bernard Stiegler’s philosophical approach to culture in dialogue with Oliver Marchart’s postfoundational framework and conflictual aesthetics. Through the exposition of two different cases of gestural devices, it exposes Stiegler’s potential postfoundational aesthetics as an attempt to establish the necessary conditions for re-thinking the grounded-ungrounded existing relationship between humans, technical objects, and the composition of potential realities to grasp from an autopoietic relationship. These artistic and cultural examples are considered critical concepts that enhance and interrupt the philosophical discourse. The article argues that Stiegler’s aesthetics is committed to the capacity that art, as a technology of the spirit, can contribute as agency in shaping public power, even when these agents are not directly in conflict and develop lesser and fragile performative technics through which a memory becomes present again.

Este artículo explora la obra y el pensamiento del pedagogo francés Fernand Deligny (1913-1996), centrándose en su último proyecto comúnmente denominado la Tentative des Cévennes, desarrollado entre 1967-1996. A partir de esta experiencia que Deligny forjó junto a sus colaboradores, el artículo expone la generación de una particular forma de conocimiento, una filosofía subordinada a una red solidaria formada por cuerpos humanos y no humanos, entornos y situaciones, gestos mínimos, acciones cotidianas y acontecimientos contingentes, visibles sólo a través de una serie de dispositivos estéticos que se desarrollaron durante este periodo: escritos, trazas, mapas, películas, entrevistas y vagabundeos. Esta filosofía gestual estaría ligada a una serie de acciones que constituirían un sistema orgánico en su aparente dispersión material. El artículo está organizado a partir de una contextualización biográfica e histórica, para posteriormente desplegar el marco teórico de la investigación y una conclusión.

Abstract Background Access to prevention options, including HIV pre-exposure prophylaxis (PrEP), remains a public health priority for gay, bisexual, and other men who have sex with men (MSM), especially in London. We describe PrEP use in a London community sample of MSM before the introduction of a national PrEP programme in October 2020. Methods From June–August 2019, MSM aged ≥ 18 recruited from London commercial venues were asked to self-complete a sexual health questionnaire and provide an oral fluid sample for anonymous HIV antibody testing. Descriptive analyses of demographic characteristics, service engagement and outcomes, as well as sexual risk and prevention behaviours were examined in the survey population and in those reporting current PrEP use. We performed sequential, multivariate analyses examining current PrEP use in MSM of self-perceived HIV-negative/unknown status with identified PrEP-need defined as the report of condomless anal sex (CAS) in the last three months, or the report of CAS (in the last year) with an HIV-positive/unknown status partner not known to be on HIV treatment, in reflection of UK PrEP guidelines. Results One thousand five hundred and thirty-fifth questionnaires were completed across 34 venues, where 1408 were analysed. One in five MSM of self-perceived HIV-negative/unknown status reported current PrEP use (19.7%, 242/1230). In men with PrEP-need, 68.2% (431/632) did not report current use. Current PrEP use was associated with age (aOR: 3.52, 95% CI: 1.76–7.02 in men aged 40–44 vs men aged 18–25) and education (aOR: 1.72, 95% CI: 1.01–2.92 in men with ≥ 2 years/still full-time vs no/

Este número de Inmaterial, diseño, arte y sociedad se fija en las responsabilidades y compromisos ante la gran variedad de residuos y deshechos que generamos, así como en las posibilidades materiales, estratégicas, conceptuales y creativas que estos suponen para la investigación en arte y en diseño. El número reúne también tres artículos de la sección Miscelánea.

El diseño, como campo multidisciplinar, se enfrenta a un reto cada vez mayor dado su papel en la producción de sobras, residuos, restos y vestigios. Tanto la industrialización como la fabricación en la industria del diseño implican una hiperproductividad que choca con las limitaciones de nuestro mundo. ¿Cómo está, o debería estar, el diseño abordando estas cuestiones, desde sus diferentes superficies de práctica e investigación? ¿De qué manera los investigadores del diseño están desarrollando, o deberían desarrollar, enfoques críticos sobre una agencia sensible, social, política y económica que está tocando diferentes aspectos de nuestras sociedades en desarrollo? ¿Cómo el diseño como práctica y la investigación a través de la práctica deberían componer los espacios para permitir una respuesta consciente a un entorno sociopolítico y empresarial múltiple y a veces confuso y complejo? ¿Qué tipo de herramientas están explorando y desarrollando los diseñadores investigadores, tanto conceptual como materialmente, para afrontar y participar en estos debates más amplios? ¿Cómo podemos empezar a pensar e impulsar las prácticas de diseño postsostenible?