Desenvolvida maioritariamente a partir da Revolucao Industrial, a automatizacao dos sisternas e equipamentos que nos rodeiam é re- sponsdvel por um progresso tecnoldgico e crescimento econdédmico sem ...precedentes, mas também por uma incessante dependéncia energética. Atualmente, combustiveis fésseis ainda tendem a surgir com principal fonte de energia, mesmo em paises desenvolvidos, devido a facilidade ha sua extragao e dominio da tecnologia necessdria 4 sua utilizacao. No entanto, a percecdo quer da sua finddvel disponibilidade, quer do impacto ambiental desta pratica, tem levado a uma crescente producao de energia proveniente de fontes renovaveis.A sua facil manuten¢ao, aliada ao facto de serem praticamente ines- gotdveis, faz das energias solar e edlica uma solucdo muito promissora. Neste contexto, esta dissertacao propée facilitar a produg3o de energia proveniente destas fontes.Assim, neste trabalho sao estudados os inversores de poténcia, equipa- mentos responsdveis por converter energia MIC disponibilizada por uma fonte solar ou edlica em energia AC tradicional. Seguidamente é discu- tida e projetada uma nova arquitetura que, para além de conseguir um alto rendimento energético, tem também a capacidade de se adaptar face ao tipo de conversdo pretendida pelo utilizador, caso este queira vender energia & rede elétrica, ser independente desta ou apostar num sistema de auto consumo.Para alcangar 0 alto rendimento energético prometido, o inversor pro- jetado faz uso de um conversor DC-DC ressonante, cuja arquite- tura diminui consideravelmente a energia dissipada na conversao, per- mitindo assim uma maior densidade de poténcia.A versatilidade do equipamento é disponibilizada por um algoritmo de controlo adaptativo, responsdvel por avaliar o comportamento deste a cada iteragao e fazer as alteragdes necessdrias para alcancar a maxima estabilidade ao longo de todo o processo.Para uma avaliacdo do funcionamento da arquitetura proposta, apresenta-se a simulacdo da mesma utilizando o software de simulacao PLECS.
Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope ...with an aperture of at least \(4m\). With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the \(6.5m\) James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.
This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the ...spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.
Is it launch time yet? Breda, David; Chinn, Robert
Telephony,
02/1999, Letnik:
236, Številka:
7
Journal Article
The greatest start-up challenge facing a prospective local multipoint distribution service (LMDS) operator, or any wireless local loop provider, is to balance the need for a rapid and timely service ...launch with the need for fully customer-ready operations at the time of launch. Not only must the network installation bye error-free, but all the supporting business operations must be ready to support and manage customers better than the competition. A common thread running through success stories is the application of new techniques for deploying and launching services - specifically, launch-readiness testing and assessment programs. At the foundation of a launch-readiness program is a clear picture of what the final product is and how it should perform from a customer's point of view. Launch-readiness assessment techniques depart form traditional deployment and test approaches in that they focus on assessing the commercial readiness of systems, business processes and customer-facing employees from a customer perspective before the first subscriber is installed on the network.
Patients presenting to the healthcare system with rotator cuff pathology do not always receive high quality care. High quality care occurs when a patient receives care that is accessible, ...appropriate, acceptable, effective, efficient, and safe. The aim of this study was twofold: 1) to develop a clinical pathway algorithm that sets forth a stepwise process for making decisions about the diagnosis and treatment of rotator cuff pathology presenting to primary, secondary, and tertiary healthcare settings; and 2) to establish clinical practice guidelines for the diagnosis and treatment of rotator cuff pathology to inform decision-making processes within the algorithm.
A three-step modified Delphi method was used to establish consensus. Fourteen experts representing athletic therapy, physiotherapy, sport medicine, and orthopaedic surgery were invited to participate as the expert panel. In round 1, 123 best practice statements were distributed to the panel. Panel members were asked to mark "agree" or "disagree" beside each statement, and provide comments. The same voting method was again used for round 2. Round 3 consisted of a final face-to-face meeting.
In round 1, statements were grouped and reduced to 44 statements that met consensus. In round 2, five statements reached consensus. In round 3, ten statements reached consensus. Consensus was reached for 59 statements representing five domains: screening, diagnosis, physical examination, investigations, and treatment. The final face-to-face meeting was also used to develop clinical pathway algorithms (i.e., clinical care pathways) for three types of rotator cuff pathology: acute, chronic, and acute-on-chronic.
This consensus guideline will help to standardize care, provide guidance on the diagnosis and treatment of rotator cuff pathology, and assist in clinical decision-making for all healthcare professionals.
Excessive consumption of sugar has a well-established link with obesity. Preliminary results show that a tax levied on sugar-sweetened beverages (SSBs) by the Portuguese government in 2017 led to a ...drop in sales and reformulation of these products. This study models the impact the market changes triggered by the tax levied on SSBs had on obesity incidence across various age groups in Portugal.
We performed a national market analysis and population-wide modelling study using market data for the years 2014-2018 from the Portuguese Association of Non-Alcoholic Drinks (GlobalData and Nielsen Consumer Panel), dietary data from a national survey (IAN-AF 2015-2016), and obesity incidence data from several cohort studies. Dietary energy density from SSBs was calculated by dividing the energy content (kcal/gram) of all SSBs by the total food consumption (in grams). We used the potential impact fraction (PIF) equation to model the projected impact of the tax-triggered change in sugar consumption on obesity incidence, through both volume reduction and reformulation. Results showed a reduction of 6.6 million litres of SSBs sold per year. Product reformulation led to a decrease in the average energy density of SSBs by 3.1 kcal/100 ml. This is estimated to have prevented around 40-78 cases of obesity per year between 2016 and 2018, with the biggest projected impact observed in adolescents 10 to <18 years old. The model shows that the implementation of this tax allowed for a 4 to 8 times larger projected impact against obesity than would be achieved though reformulation alone. The main limitation of this study is that the model we used includes data from various sources, which can result in biases-despite our efforts to mitigate them-related to the methodological differences between these sources.
The tax triggered both a reduction in demand and product reformulation. These, together, can reduce obesity levels among frequent consumers of SSBs. Such taxation is an effective population-wide intervention. Reformulation alone, without the decrease in sales, would have had a far smaller effect on obesity incidence in the Portuguese population.
This study explores the decision-facilitating role of performance measurement systems (PMSs) in firms attempting to translate competence ambidexterity (i.e., the simultaneous pursuit of exploration ...and exploitation) into innovation ambidexterity outcomes (i.e., the achievement of both radical and incremental innovations). Drawing on paradox and organisational conflict literature, this study emphasises the role of cognitive conflict, generated by PMSs, in shaping the relationships between competence ambidexterity and innovation ambidexterity. Based on survey data from a sample of 90 Irish firms, our findings indicate that competence ambidexterity is associated with (a) the choice to have a balanced set of performance measures, and (b) the use of PMSs for frequent and intensive debate between top managers. Furthermore, the study reveals that these choices are interdependent, as they function as complements in generating cognitive conflict, which in turn drives the realisation of innovation ambidexterity outcomes. The results also show that cognitive conflict is not directly associated with the development of competence ambidexterity, but is instead generated through the conjoint action of a balanced PMS design and the use of PMSs for intensive debate. Overall, this study demonstrates the interdependent nature of choices concerning the design and use of PMSs, and the significant role of PMSs as generators of cognitive conflict in firms attempting to achieve ambidexterity.
PDF
