Exile, return, record : exploring historical narratives and community resistance through participatory filmmaking in 'post-conflict’ Guatemala

Following previous experiences of violence and forced displacement, ‘the returnees’ from the Guatemalan campesino community ‘Copal AA la Esperanza’ are now defending their territory against the construction of a hydroelectric dam. The returnees unexpectedly mobilized me as a Belgian historian to ‘make’ their ‘shared history’ and produce a documentary about their past and present struggle. The aim of this article is to reflect on how and why I developed a participatory, filmmaking-based methodology to tackle this challenge. I focus on filmmaking, participation and knowledge production to demonstrate the epistemological and ethical benefits of a dialogue between disciplines and methodologies as much as between academic and community practices and concepts. As such, I exemplify my visual participatory approach through its engagement with post-colonial histories and the co-creation of shared knowledge at the intersection of community and research interests. Moreover, I demonstrate how filmmaking can be developed as a grounded, visual, and narrative approach connecting media activism with ‘performative ethnography’. Combining insights from participatory action research (PAR) with Johannes Fabian’s notion of ‘performance’, I argue for ‘nonextractivist methodologies’; ‘knowing with’ instead of ‘knowing-about’. From being a side project and a matter of research ethics, participatory filmmaking turned for me into an investigative tool to explore the collective production and mobilization of historical narratives. I argue that participatory research should not be limited to communities participating in research projects; researchers can equally participate in community projects without this obstructing scientific research. In sum, participatory visual methods challenge us to reconsider the role of academics in (post-conflict) settings

An efficient technique based on polynomial chaos to model the uncertainty in the resonance frequency of textile antennas due to bending

The generalized polynomial chaos theory is combined with a dedicated cavity model for curved textile antennas to statistically quantify variations in the antenna's resonance frequency under randomly varying bending conditions. The nonintrusive stochastic method solves the dispersion relation for the resonance frequencies of a set of radius of curvature realizations corresponding to the Gauss quadrature points belonging to the orthogonal polynomials having the probability density function of the random variable as a weighting function. The formalism is applied to different distributions for the radius of curvature, either using a priori known or on-the-fly constructed sets of orthogonal polynomials. Numerical and experimental validation shows that the new approach is at least as accurate as Monte Carlo simulations while being at least 100 times faster. This makes the method especially suited as a design tool to account for performance variability when textile antennas are deployed on persons with varying body morphology

Advantages of PSWF-based models for UWB systems

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Cylindrically-bent rectangular patch antennas: novel modeling techniques for resonance frequency variation and uncertainty

Wearable textile antennas are basic components in body-centric communication systems. Flexible wearable patch antennas, when integrated into a body-worn garment are subjected to bending, causing variation in the resonance frequency when compared to the flat-antenna. Bending conditions vary statistically among different human subjects. Therefore, it is very important to be able to predict performance variations due to bending. We propose novel models which allow to predict the deterministic and statistical variation in resonance frequency of rectangular wearable patch antennas. They consist of an analytical model for cylindrical-rectangular patch antennas, expressing resonance frequency as a function of the bending radius, and a novel technique based on polynomial chaos, that quantifies statistically the variations of the resonance frequency under randomly varying bending conditions. The proposed models have been experimentally and numerically verified, and proven to be much faster and computationally less expensive than traditional techniques based on EM solvers and Monte Carlo simulations, making them very advantageous tools for the design and characterization of body-worn patch antennas

Rigorous analysis of internal resonances in 3-D hybrid FE-BIE formulations by means of the Poincaré-Steklov operator

3-D hybrid finite-element (FE) boundary integral equation (BIE) formulations are widely used because of their ability to simulate large inhomogeneous structures in both open and bounded simulation domains by applying each method where it is the most efficient. However, some formulations suffer from breakdown frequencies at which the solution is not uniquely defined and errors are introduced due to internal resonances. In this paper, we investigate the occurrence of spurious solutions resulting from these resonances by using the concept of the Poincare-Steklov or Dirichlet-to-Neumann operator, which provides a relation between the tangential electric field and the electric current on the boundary of a domain. By identifying this operator in both the FE and BIE method, several new properties of internal resonances in 3-D hybrid FE-BIE formulations are easily derived. Several conformal and nonconformal formulations are studied and the theory is then applied to a scattering problem

Procesos para la producción de papel y pulpa : de la naturaleza a la mesa

Fil: Boeykens, Susana. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Química; Argentina.Existen varios procesos para la producción de papel y esto depende del tipo de producto que se\nproduzca. Desde la elección de los árboles de los cuales se obtiene la celulosa hasta la calidad del\npapel y el tratamiento de los efluentes, las metodologías varían y los productos utilizados en el proceso\nimplican consecuencias diversas. ¿Cómo se fabrica el papel, cuáles son las opciones de fabricación\nexistentes y cuánto compromete cada tipo de producción y tratamiento al medio ambiente?

A stochastic framework to model bending of textile antennas

The polynomial chaos expansion is combined with a dedicated cylindrical cavity model to quantify the statistical variations in textile antenna performance under random bending conditions

Defining New Parameters for Green Engineering Design of Treatment Reactors

This study proposes a green way to design Plug Flow Reactors (PFR) that use biodegradable polymer solutions, capable of contaminant retaining, for industrial wastewater treatment. Usually, to the design of a reactor, the reaction rate is determined by tests on a Continuous Stirred-Tank (CST), these generate toxic effluents and also increase the cost of the design. In this work, empirical expressions (called “slip functions”), in terms of the average concentration of the contaminant, were developed through the study of the transport behaviour of CrVI into solutions of xanthan gum. “In situ” XRμF was selected as a no-invasive micro-technique to determine local concentrations. Slip functions were used with laboratory experiments planned in similar conditions using Plug Flow Reactors, to obtain useful dimensionless parameters for the industrial design