17 research outputs found
Design of a fully integrated CMOS highly temperature stable frequency reference
No full textA new fully integrated frequency reference has been designed, fabricated and measured. The goal of the design procedure has been high stability of the frequency over temperature variations. This should be achieved using a CMOS technology without MEMS and crystals, while being restricted by a very low power budget. The frequency is designed based on an RC time constant, where both R and C are integrated on chip. The novel topology is minimizing the sources of error that affect the frequency being produced (minimum offsets and delays that spread over temperature). According to the simulations, the fabricated oscillator is a competitive one among the RC-time-constant based ones, but the measurements showed that the tradeoff between performance and integration (accompanied with power minimization) is worse than its counterparts (MEMs based or LC based all-silicon choices), or its quartz crystal based ancestor. Ways to increase the quality even further are proposed.MicroelectronicsElectrical EngineeringElectrical Engineering, Mathematics and Computer Scienc
Design, Development and Orchestration of 5G-Ready Applications over Sliced Programmable Infrastructure
No full text5G networks design and evolution is considered as a key to support the introduction of digital technologies in economic and societal processes. Towards this direction, vertical industries' needs should be considered as drivers of 5G networks design and development with high priority. In the current manuscript, MATILDA is presented, as a holistic 5G end-to-end services operational framework tackling the overall lifecycle of design, development and orchestration of 5G-ready applications and 5G network services over programmable infrastructure, following a unified programmability model and a set of control abstractions
Las restricciones de la producción tegularia en la Lex Ursonensis
No full textRESUMEN: Sobre las cuestiones de índole semántico que plantea la primera parte del capítulo LXXVl de la Lex, que regula la producción de tejas in oppido, se efectúan aquí algunas reflexiones críticas en torno a aspectos técnicos de las instalaciones tejeras que podrían contribuir a esclarecer parte de las aparentes incongruencias filológicas, tradicionalmente detectadas en el apartado de las sanciones.Así mismo, se debate el carácter extremadamente riguroso de estas sanciones, hecho que induce a la sospecha de que el legislador fuese movido por imperativos políticos más que por razones urbanísticas, ecológicas o financieras.ABSTRACT: In this paper some critical reflexions are expressed, concerning tecnical aspectcs of tile-produccion instalations, which could contribute to elucidate partly some of the apparent philological incongruities, traditional detected in the second part of the same chapter where the sanctions are established. In the same manner, the carácter, extremely severe, of such sanctions is discussed, a fact inducing to suspect that legislator was moving from political rather than urbanistic, ecological or financial imperatives
Chaos and gene expression:A theoretical approach
No full textIntoduction: The aim of the study was to investigate whether chaotic phenomena (chaos theory) affects the process of Gene Expression. Methods: Modeling the genes X, Y and Z-which encode a certain protein P-a set of three first order differential equations has been developed and studied in phase-space (x,y,z). Results: The elementary equilibrium points in three dimensional phase portrait analysis, include attractors, saddles and repellors. Conclusions: Attractors indicate a stable equilibrium point which attenuates the production of the protein P, while the saddles and particularly the repellors correspond to an unstable dynamic system, which promotes either the production of a P-flaw protein or totally inhibits gene expression. Among other mechanisms-e.g. patents for gene treatment (US2007000515344) and modulation(US20040014083A1)-chaotic phenomena also seem to regulate in a particular way the DNA encoding, that calls for further theoretical and experimental research(e.g. cardiovascular disease, oncology). © 2011 Bentham Science Publishers Ltd
Compositional Design, Microstructure, and Thermal Processing of Aluminum-Based Complex Concentrated Alloys
No full textThree lightweight aluminum-based complex concentrated alloys with chemical compositions that have not been previously studied were manufactured and studied: Al52Mg9.6Zn16Cu15.5Si6.9 w.t.% or Al63Mg13Zn8Cu8Si8 a.t.% (alloy A), Al44Mg18Zn19Cu19 w.t.% or Al55Mg25Zn10Cu10 a.t.% (alloy B), and Al47Mg21.4Zn12Cu9.7Si9.7 w.t.% or Al52.7Mg26.6Zn5.6Cu4.6Si10.4 a.t.% (alloy AM), with low densities of 3.15 g/cm3, 3.18 g/cm3 and 2.73 g/cm3, respectively. During alloy design, the CALPHAD method was used to calculate a variety of phase diagrams for the various chemical compositions and to predict possible phases that may form in the alloy. The CALPHAD methodology results showed good agreement with the experimental results. The potential of the designed alloys to be used in some industrial applications was examined by manufacturing them using standard industrial techniques, something that is a rarity in this field. The alloys were produced using an induction furnace and pour mold casting process, while industrial-grade raw materials were utilized. Heat treatments with different soaking times were performed in order to evaluate the possibility of improving the mechanical properties of the alloys. Alloys A and AM were characterized by a multiphase microstructure with a dendritic FCC-Al matrix phase and various secondary phases (Q-AlCuMgSi, Al2Cu and Mg2Si), while alloy B consisted of a parent phase T-Mg32(Al,Zn)49 and the secondary phases α-Al and Mg2Si. The microstructure of the cast alloys did not appear to be affected by the heat treatments compared to the corresponding as-cast specimens. However, alterations were observed in terms of the elemental composition of the phases in alloy A. In order to investigate and evaluate the mechanical properties of the as-cast and heat-treated alloys, hardness testing along with electrical conductivity measurements were conducted at room temperature. Among the as-cast samples, alloy AM had the highest hardness (246 HV4), while among the heat-treated ones, alloy A showed the highest value (256 HV4). The electrical conductivity of all the alloys increased after the heat treatment, with the highest increase occurring during the first 4 h of the heat treatment
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The importance of soil and vegetation characteristics for establishing ground-nesting bee aggregations
No full textMost bee species are ground-nesters, yet knowledge on the nesting behaviour of this diverse group remains sparse. Evidence on the effectiveness of ground-nesting bee species as crop pollinators is growing, but there is limited information on their nesting habits and preferences and how to manage habitats to enhance populations on farms. In this study, artificially prepared plots of bare soil were constructed with the aim to attract ground-nesting bees to nest in a commercial orchard in Kent, UK. Nine soil parameters were measured to determine their preferred soil properties: hydraulic conductivity, soil compaction, soil moisture, soil temperature, soil stoniness, soil organic matter, soil root biomass, soil texture and vegetation cover. Eighteen non-parasitic ground-nesting bee species (7 Andrena, 9 Lasioglossum, 1 Halictus and 1 Colletes spp.) were recorded in the study plots. Soil stoniness and soil temperature at 10cm depth were positively correlated, and vegetation cover and hydraulic conductivity were negatively correlated with the number of ground-nesting bees on the plots. We show that artificially created habitats can be exploited for nesting by several ground-nesting bee species. This study’s findings can inform management practices to enhance ground-nesting bee populations in agricultural and urban areas
Location and creation of nest sites for ground-nesting bees in apple orchards
No full textWild ground-nesting bees are key pollinators of apple (Malus domestica). We explored, (1) where they choose to nest, (2) what influences site selection and (3) species richness in orchards. Twenty-three orchards were studied over three years; twelve were treated with additional herbicide to increase bare ground with the remainder as untreated controls. Vegetation cover, soil type, soil compaction, nest number and location, and species were recorded. Fourteen species of ground-nesting solitary/eusocial bee were identified. Most nests were in areas free of vegetation and areas treated with additional herbicide were utilised by ground nesting bees within three years of application. Nests were also evenly distributed along the vegetation-free strips underneath the apple trees. This area was an important ground-nesting bee habitat with mean numbers of nests at peak nest activity of 873 per ha (range 44–5705), and 1153 per ha (range 0–4082) in 2018 and 2019, respectively. Increasing and maintaining areas of bare ground in apple orchards during peak nesting events could improve nesting opportunities for some species of ground-nesting bee and, combined with flowers strips, be part of a more sustainable pollinator management approach. The area under the tree row is an important contributor to the ground-nesting bee habitat and should be kept bare during peak nesting
The Place of Young People in the Spaces of Collective Identity: Case Studies From the Millennium Green Scheme
No full textChange associated with late modernity is argued to have diminished collective identification, particularly in relation to locality, as an approach to and resource for, navigating life paths. Young peoples‟ creation of a life course has been understood as particularly responsive, or alternatively vulnerable, to such influences. Contrasting research asserts, however, that collective identification with and through particular appreciations and understandings of locality continue to provide ontological security within the circumstances of modern change. Local collective identification can be carried out via its participants‟ shared investment in symbolic interpretations of culture and space. This identification is asserted through claims to affinity with, or competency in, these socio-spatial systems and practices and the building of symbolic boundaries that contrast identities not possessing such claims. This perspective renews the significance of academic explorations of young peoples‟ choice of collective identification with locality as a tactic in managing their biography and its negotiation as an influential social, cultural and spatial context in their lives.
This thesis explores the ways in which young people negotiate the spaces and resources of local collective identification, in the context of late modernity. It employs a qualitative analysis of a community participation project – the Millennium Green Scheme - to access such issues. The participation of adult active citizens and inclusion/exclusion of young people within this scheme are understood to reflect some of the dimensions of collective identification with locality, at three case study sites. At each case study - two rural and one urban - the research takes an unusual intergenerational approach, exploring both adults‟ and young peoples‟ understandings of locality, collective identification and young peoples‟ relationship to these.
The findings suggest that young peoples‟ access to the spaces and resources of collective identification, with and through locality, are negotiated within adult defined social and cultural contexts. Further, adults mobilise cultural representations of young people that regulate this access, in relation to the symbolic resources and boundaries of local collective identification. This regulation is influenced by adult reactions to wider pressures upon collective identification associated with modernity. The research finds that although modernity may influence young peoples‟ recourse to local collective identification, it is also central in shaping adults‟ inclusion/exclusion of young people from accessing this means of navigating the life course.
Adults‟ geographies of locality are central symbolic material to their collective identification with locality. They are also found to dictate the logic of adult inclusions of young people within the spaces and resources of local collectivity. Adults at the case studies associated many young people within cultural affiliations and competencies they understood to belong to the late modern context, resulting in representations of „dislocated‟ childhood. At rural case studies these were perceived as inappropriate to local socio-spatial norms and rendered young people outside the symbolic boundaries of collective identification and endeavour. In the urban
research, young people were perceived to require reinstatement into local collective identification through education about and encouragement into, its spaces and resources. Both understandings reflected broader adult reactions to late modern change.
Young people took up the tactic of collective identification with locality or rejected it, in context dependent strategies. However their perceptions of opportunities to share identification with locality were significantly influenced by adult attempts to shape their inclusion/exclusion from spaces of collective identification. In addition, young people interpreted these inclusions/exclusions as broad comment upon their local socio-cultural and spatial status.
This research finds that locality and local collective social contexts continue to be of significance in young peoples‟ lives. It adds texture to understandings of the way in which the influence of modernity upon young peoples‟ biographical choices is experienced and negotiated from within local social and cultural relations and spaces
