Hyperbolic reflections as fundamental building blocks for multilayer optics

We reelaborate on the basic properties of lossless multilayers by using bilinear transformations. We study some interesting properties of the multilayer transfer function in the unit disk, showing that hyperbolic geometry turns out to be an essential tool for understanding multilayer action. We use a simple trace criterion to classify multilayers into three classes that represent rotations, translations, or parallel displacements. Moreover, we show that these three actions can be decomposed as a product of two reflections in hyperbolic lines. Therefore, we conclude that hyperbolic reflections can be considered as the basic pieces for a deeper understanding of multilayer optics.Comment: 7 pages, 7 figures, accepted for publication in J. Opt. Soc. Am.

Mechanisms for AAA and QoS Interaction

Proceedings of Third IEEE Workshop on Applications and Services in Wireless Networks, ASWN 2003. Bern, Switzerland, July 2-4, 2003.The interaction between Authentication, Authorization and Accounting (AAA) systems and the Quality of Service (QoS) infrastructure is to become a must in the near future. This interaction will allow rich control and management of both users and networks. DIAMETER and DiffServ are likely to turn into the future standards in AAA and QoS systems, but they are not designed to interact with each other. To face this, we propose a new Diameter-Diffserv interaction model and describe the Application Specific Module (ASM) implemented to allow this interaction. The ASM has been implemented and tested in a complete AAA-QoS IPv6 scenario

Implanted muon spin spectroscopy on 2-O-adamantane: a model system that mimics the liquid

The transition taking place between two metastable phases in 2-O-adamantane, namely the [Formula: see text] cubic, rotator phase and the lower temperature P21/c, Z  =  4 substitutionally disordered crystal is studied by means of muon spin rotation and relaxation techniques. Measurements carried out under zero, weak transverse and longitudinal fields reveal a temperature dependence of the relaxation parameters strikingly similar to those exhibited by structural glass[Formula: see text]liquid transitions (Bermejo et al 2004 Phys. Rev. B 70 214202; Cabrillo et al 2003 Phys. Rev. B 67 184201). The observed behaviour manifests itself as a square root singularity in the relaxation rates pointing towards some critical temperature which for amorphous systems is located some tens of degrees above that shown as the characteristic transition temperature if studied by thermodynamic means. The implications of such findings in the context of current theoretical approaches concerning the canonical liquid-glass transition are discussed.Postprint (author's final draft

Carbon and water footprint for the recycling process of expanded polystyrene (EPS) post-consumer waste

[Abstract] Plastic pollution of the natural environment is ubiquitous, and around 40% of all plastic waste produced globally is used in single-use products and only 9% is recycled. From this plastic waste, expandable polystyrene single-use products pose a major problem because of its great volume and low density. To abord this issue, the authors proposed a circular economy model for EPS post-consumer waste in 2019 through a case study with the help of one local plastic manufacturer. Although the idea of promoting circularity of this waste seems a priori to have a good impact on the environment, the process to reincorporate reused and/or recycled materials under the concept of CE have economic and environmental impacts on the environment that should be measured. To understand if a recycling process is truly beneficial to the environment, first we need to do a sustainability analysis, using sustainability indicators, such as Carbon Footprint (CF) and Water Footprint (WF). The objective of the present paper is to perform a sustainability analysis of the expandable polystyrene post-consumer recycling into resin pellets using CF and WF as sustainability indicators. We proposed three case scenarios considering an artisanal recycling with 2019 (A), and 2027 proposed electricity power mix (B), industrial recycling with current 2019 electricity power mix (C) and the use of virgin PS and its destination in landfill to compare. We measured the CO2 emissions and m3 of freshwater with the help of SimaPro 9.1 software. Overall, the total CO2 emissions for the case scenarios A and B are approximately 42% and 16% higher than scenario D, but scenario C exhibits a reduction of almost 50%. For the water depletion, scenarios A and B show very higher values than those of scenario D with 536% and 534%, respectively. Important to mention that scenario B presents much better values for CF than scenario A, meaning that the increase in the share of electricity production by renewable energies can improve the sustainable production of recycled PS resin

Quantification and mapping of domestic plastic waste using GIS/GPS approach at the city of Guayaquil

[Abstract] A significant contributor to the waste stream is the domestic single-use plastic used in households, being the final disposal in most cases the local landfill. There is a significant opportunity to promote resource recovery and efficiency through the introduction of circular economy strategies. However, the knowledge and management of post-consumer plastic waste in the country is poor, and there is a lack of an efficient collection and sorting system. In this context, spatial information on domestic plastic waste generation (DPWG) is essential for recycling decision-making. The integration of Geographic Information Systems (GIS) and the Global Positioning System (GPS) shows an opportunity to collect, mapping, and analyse spatial DPWG issues. Thus, this paper had a double objective. The first was to assess the evolution of eight different types of plastic waste in the city’s households and their daily per capita generation between 2019 and 2021. The second objective was to provide a complete geo-referenced information on the quantities and typologies of domestic plastic waste (DPW) produced in Guayaquil and analyse how the flows have shifted throughout the years. The results showed that PET is the most generated, recording 97.76% and 100.00 % of the households who generate this type of plastic for 2019 and 2021, respectively, with an average of 13.08 and 15.13 g/day/c. Following, we had HDPE, PP and PVC occupying the second, third and fourth place for 2019 with 5.86, 3.05, 2.54 g/day/c, respectively. On the other hand, for 2021, PP (7.43 g/day/c), HDPE (5.92 g/day/c), and LDPE (3.99 g/day/c) occupied the second, third and fourth, respectively. According to the spatial maps, the DPW increment is in most of the popular zones. These popular zones are neighborhoods with a considerable quantity of population and limited basic services. Most of these people live in extreme poverty, being a possible relation between the COVID-19 lockdown and the increasement of DPW

Introduction of the Circular Economy to Expanded Polystyrene Household Waste: A Case Study From an Ecuadorian Plastic Manufacturer

[Abstract] Transition towards a more sustainable society is a complex task. The depletion of natural resources and waste generation cannot be sustained indefinitely, i.e. as waste increases, local landfills keep growing and land availability reduces. The introduction of circular economy in effective household solid waste management practices should be considered especially for third world countries, such as Ecuador. In this context, plastic recycling is an important step, particularly the case of expanded polystyrene containers that currently are single-use only and later end up in local landfills. This paper presents a methodology for recycling Expanded Polystyrene by means of a case study from an Ecuadorian Plastic Manufacturer. First, the manufacture of resin from post-consume EPS containers was demonstrated possible by the manufacturer. Second, results show that using 30% of post-consume resin in the mix produce satisfactory laboratory results and operational recycled containers.The authors would like to thank Marco Roche, Eng.; Technical Manager of Plásticos del Litoral S.A. (PLASTLIT) for its involvement and compromise in this project. This paper is supported by the National Secretary of Superior Education, Science, Technology and Innovation (SENESCYT) – INEDITA program, project “Characterization of urban household waste in Guayaquil for the classification of plastic and organic waste and reuse in local industry

The MobyDick Project: A Mobile Heterogeneous All-IP Architecture

Proceedings of Advanced Technologies, Applications and Market Strategies for 3G (ATAMS 2001). Cracow, Poland: 17-20 June, 2001.This paper presents the current stage of an IP-based architecture for heterogeneous environments, covering UMTS-like W-CDMA wireless access technology, wireless and wired LANs, that is being developed under the aegis of the IST Moby Dick project. This architecture treats all transmission capabilities as basic physical and data-link layers, and attempts to replace all higher-level tasks by IP-based strategies. The proposed architecture incorporates aspects of mobile-IPv6, fast handover, AAA-control, and Quality of Service. The architecture allows for an optimised control on the radio link layer resources. The Moby dick architecture is currently under refinement for implementation on field trials. The services planned for trials are data transfer and voice-over-IP.Publicad

Optimization of 2-DEOXY-2-[18F] FLUORO-D-GLUCOSE positron emission tomography thorax imaging of laboratory small animals

[Abstract] AMI Annual Conference 2005, March 18-23, Orlando, FloridaThe search of oncologic lesions in thorax may be hindered by the high uptake of organs such as the heart or back muscles that prevent the proper visualization of neighbor organs. The aim of this study is to analyze to what extent glucose metabolism can be modulated to obtain an optimal thorax image in micePublicad