954 resultados para Capacitor-clamped three-level inverter
Resumo:
Today, modern System-on-a-Chip (SoC) systems have grown rapidly due to the increased processing power, while maintaining the size of the hardware circuit. The number of transistors on a chip continues to increase, but current SoC designs may not be able to exploit the potential performance, especially with energy consumption and chip area becoming two major concerns. Traditional SoC designs usually separate software and hardware. Thus, the process of improving the system performance is a complicated task for both software and hardware designers. The aim of this research is to develop hardware acceleration workflow for software applications. Thus, system performance can be improved with constraints of energy consumption and on-chip resource costs. The characteristics of software applications can be identified by using profiling tools. Hardware acceleration can have significant performance improvement for highly mathematical calculations or repeated functions. The performance of SoC systems can then be improved, if the hardware acceleration method is used to accelerate the element that incurs performance overheads. The concepts mentioned in this study can be easily applied to a variety of sophisticated software applications. The contributions of SoC-based hardware acceleration in the hardware-software co-design platform include the following: (1) Software profiling methods are applied to H.264 Coder-Decoder (CODEC) core. The hotspot function of aimed application is identified by using critical attributes such as cycles per loop, loop rounds, etc. (2) Hardware acceleration method based on Field-Programmable Gate Array (FPGA) is used to resolve system bottlenecks and improve system performance. The identified hotspot function is then converted to a hardware accelerator and mapped onto the hardware platform. Two types of hardware acceleration methods – central bus design and co-processor design, are implemented for comparison in the proposed architecture. (3) System specifications, such as performance, energy consumption, and resource costs, are measured and analyzed. The trade-off of these three factors is compared and balanced. Different hardware accelerators are implemented and evaluated based on system requirements. 4) The system verification platform is designed based on Integrated Circuit (IC) workflow. Hardware optimization techniques are used for higher performance and less resource costs. Experimental results show that the proposed hardware acceleration workflow for software applications is an efficient technique. The system can reach 2.8X performance improvements and save 31.84% energy consumption by applying the Bus-IP design. The Co-processor design can have 7.9X performance and save 75.85% energy consumption.
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Liquidity is an important market characteristic for participants in every financial market. One of the three components of liquidity is market depth. Prior literature lacks a comprehensive analysis of depth in U.S. futures markets due to past limitations on the availability of data. However, recent innovations in data collection and dissemination provide new opportunities to investigate the depth dimension of liquidity. In this dissertation, the Chicago Mercantile Exchange (CME) Group proprietary database on depth is employed to study the dynamics of depth in the U.S. futures markets. This database allows for the analysis of depth along the entire limit order book rather than just at the first level. The first essay examines the characteristics of depth within the context of the five-deep limit order book. Results show that a large amount of depth is present in the book beyond the best level. Furthermore, the findings show that the characteristics of five-deep depth between day and night trading vary and that depth is unequal across levels within the limit order book. The second essay examines the link between the five-deep market depth and the bid-ask spread. The results suggest an inverse relation between the spread and the depth after adjusting for control factors. The third essay explores transitory volatility in relation to depth in the limit order book. Evidence supports the relation between an increase in volatility and a subsequent decrease in market depth. Overall, the results of this dissertation are consistent with limit order traders actively managing depth along the limit order book in electronic U.S. futures markets.
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The growing popularity of social networks, and their impact on the daily lives of consumers, contributed to news organizations marking their presence on different online platforms. In the case of Facebook, a social network that began as a personal space, it has gradually transformed into a content-sharing space (Oeldorf-Hirsch & Sundar, 2015). Nowadays, Facebook is the second most viewed website in Portugal (Alexa, 2016), and therefore, it has become crucial for Portuguese news agencies to be present on this social network. Although television continues to be the main information source in Portugal, social networks, and specifically Facebook, are increasingly important in news consumption by users (ERC, 2015). This new way of news dissemination, as well as the proliferation that these contents reach in social networks, led to news agencies exploiting these new channels, both to attract new audiences, and to redirect users to their own websites (Castillo, El-Haddad, Pfeffer, & Stempeck, 2014). Thus, it is important to understand how, and what kind of content these agencies put on their Facebook channels, as well as the strategies they use to share these same contents. This study aims to understand how the main news channels of Portuguese TV (RTP3, SIC Notícias, and TVI24) manage and use the social network Facebook to share news contents. To this end, the authors collected quantitative data of all posts placed on Facebook between February 8 and February 14 2016. Approximately 1063 posts were collected and analysed from the three Facebook pages. The results indicate that two of the three channels extensively used their Facebook pages to share and target content to their official websites. Regarding the news sources and type of media used, the three Portuguese TV news channels use similar strategies. However, in what concerns the main themes and quantity of messages per day, as well as the level of redundancy of information, the three channels manage their pages differently.
Resumo:
The growing popularity of social networks, and their impact on the daily lives of consumers, contributed to news organizations marking their presence on different online platforms. In the case of Facebook, a social network that began as a personal space, it has gradually transformed into a content-sharing space (Oeldorf-Hirsch & Sundar, 2015). Nowadays, Facebook is the second most viewed website in Portugal (Alexa, 2016), and therefore, it has become crucial for Portuguese news agencies to be present on this social network. Although television continues to be the main information source in Portugal, social networks, and specifically Facebook, are increasingly important in news consumption by users (ERC, 2015). This new way of news dissemination, as well as the proliferation that these contents reach in social networks, led to news agencies exploiting these new channels, both to attract new audiences, and to redirect users to their own websites (Castillo, El-Haddad, Pfeffer, & Stempeck, 2014). Thus, it is important to understand how, and what kind of content these agencies put on their Facebook channels, as well as the strategies they use to share these same contents. This study aims to understand how the main news channels of Portuguese TV (RTP3, SIC Notícias, and TVI24) manage and use the social network Facebook to share news contents. To this end, the authors collected quantitative data of all posts placed on Facebook between February 8 and February 14 2016. Approximately 1063 posts were collected and analysed from the three Facebook pages. The results indicate that two of the three channels extensively used their Facebook pages to share and target content to their official websites. Regarding the news sources and type of media used, the three Portuguese TV news channels use similar strategies. However, in what concerns the main thematic and quantity of messages per day, as well as the level of redundancy of information, the three channels operate their pages differently.
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This dissertation presents a comparative study of three factories in Cork Harbour area, Sunbeam Wolsey (1927-90), Irish Steel (1939-2001) and the Ford Marina Plant (1917-84). All three factories were significant industrial employers in both a domestic (Irish) and a local (Cork) context and are broadly representative of the Irish manufacturing industry that was developed under the policies of tariff protection introduced in the 1930s and gradually phased out between the late 1950s and the mid-1980s. Sunbeam Wolsey was a textile and clothing concern located on the north side of Cork City that possessed a borderline monopoly within its economic sector and was among the largest private employers of female labour in twentieth century Ireland. Irish Steel was the country’s only steel mill, located on Haulbowline island, a brief ferry-ride from the seaside town of Cobh, and was unusual in being one of the few manufacturing concerns operated as a nationalised industry under the auspices of the state. The Ford Marina plant predated the introduction of protectionism by more than a decade and began as the centre of the Ford empire’s tractor manufacturing business, before switching to the production of private motor vehicles for the Irish market in 1932. All three industries were closed or sold off when the state withdrew support, either in the form of tariff protection (Ford, Sunbeam) or direct funding (Irish Steel). While devoting much attention to the three firms, the central concern of this dissertation is not the companies themselves (though the economic history portion of the dissertation is substantial), but the workers they employed, examining the lives of these individuals both as members of the Irish working class, and, more specifically, as employees of the three factories under consideration. The project can be best described as a comparative factory study, comparing and contrasting the three workforces, focusing primarily on industrial relation and the experience of work. This dissertation utilises both documentary evidence and a significant quantity of oral testimony, breaking new ground by making the workplace the central focus of its investigation. The principal aims of the study are: 1. To document the lives of those who worked in these factories, capturing through oral testimony their subjective experiences of social class and factory life, as well as differences among narrators in terms of gender and status. In achieving this aim, the study will provide a broader social context for its detailed analysis of work and industrial relations in each firm. 2. To analyse the three workplaces and determine how and why each developed such distinct systems of industrial relations at the factory level, as well as to compare and contrast these systems. 3. To examine the nature of work in each factory and to determine how work and industrial relations in each firm developed over time, relating these changes both to internal and external factors. Additionally, the project will provide a comparative analysis of these changes.
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Background: Gatekeeper training for community facilitators, to identify and respond to those at risk of suicide, forms an important part of multi-level community-based suicide prevention programmes. Aims: This study examined the effects of gatekeeper training on attitudes, knowledge and confidence of police officers in dealing with persons at risk of suicide. Methods: A total of 828 police officers across three European regions participated in a 4-hour training programme which addressed the epidemiology of depression and suicidal behaviour, symptoms of depression, warning signs and risk factors associated with suicidal behaviour, motivating help-seeking behaviour, dealing with acute suicidal crisis and informing bereaved relatives. Participants completed internationally validated questionnaires assessing stigmatising attitudes, knowledge about depression and confidence in dealing with suicidal persons pre- and post-training. Results: There were significant differences among countries in terms of previous exposure to suicidal persons and extent of previous training. Post-training evaluation demonstrated significant improvements in stigmatising attitudes, knowledge and confidence in all three countries. Conclusion: The consistently positive effects of gatekeeper training of police officers across different regions support inclusion of this type of training as a fundamental part of multi-level community-based suicide prevention programmes and roll-out, nationally and internationally.
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Three paths of interdisciplinary work shape the future of classification research.emergence, encyclopedism, and ecology. Each of these, in method, approach, and in substantive inquiry outline both the boundaries and the intersections of the many fields that contribute to our overall understanding of classification research. This paper outlines some high level claims of this work, ties it to current research and offers some theoretical applications of these paths.
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Berry size and crop yield are widely recognized as important factors that contribute to wine quality. The final berry size indirectly affects the phenolic concentration of the wine due to skin surface-to-berry volume ratio. The effects of different irrigation levels, soil management and plant crop level on growth of ‘Trincadeira’ berries were studied. In order to test the influence of different irrigation levels (rainfed, pre-veraison and post-veraison), different soil management (tillage and natural cover crops) and different plant crop levels (8 and 16 clusters per vine), leaf water potential, skin anthocyanin, polyphenols, berry skin and seed fresh weight were measured in fruits. The segregation of berries into three different berry classes: small, medium and large, allowed to identify different levels of contribution of soil management and irrigation level into berry, skin and seeds ratios. As expected, higher water availability due to irrigation and soil tillage management during berry development induced an increase in berry flesh weight and this was more evident in larger berries; however, berry skin and seed fresh weight remained unchanged. Also, anthocyanins did not show significant differences.
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We use at microregion level from the Brazilian Census years 1975, 1985, 1995 and 2006 to assess the impact of climate change on Brazilian agriculture using a Ricardian model. We estimate the Ricardian model using repeated cross sections for each Census Year, a pooled model and a twostage model based on Hsiao 2003. Results show that a marginal increase of temperature is harmful for agriculture in all regions of Brazil, with the exception of the South. The most negative impacts are felt in the North and in the North-East. There is mixed evidence on the effect of a marginal impact of precipitation. Additional rainfall is beneficial in South, South-East and in the Center-West. It is harmful in other regions. Impact estimates with three GCM scenarios generated using the A2 SRES emission scenario show that climate change is expected to be generally harmful in 2060. In 2100 only the climate change scenario generated by the Hadley HADCM3 model predicts negative impacts; the MIMR model predicts that climate change will not significantly affect land values while the NCPCM model predicts significant beneficial effects using the Hsiao model and nonsignificant beneficial effects using the pooled model. Among Brazilian regions, only the South and some cases the South-East are expected to benefit from climate change.
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Through modelling activity, experimental campaigns, test bench and on-field validation, a complete powertrain for a BEV has been designed, assembled and used in a motorsport competition. The activity can be split in three main subjects, representing the three key components of an BEV vehicle. First of all a model of the entire powertrain has been developed in order to understand how the various design choices will influence the race lap-time. The data obtained was then used to design, build and test a first battery pack. After bench tests and track tests, it was understood that by using all the cell charac-teristics, without breaking the rules limitations, higher energy and power densities could have been achieved. An updated battery pack was then designed, produced and raced with at Motostudent 2018 re-sulting in a third place at debut. The second topic of this PhD was the design of novel inverter topologies. Three inverters have been de-signed, two of them using Gallium Nitride devices, a promising semiconductor technology that can achieve high switching speeds while maintaining low switching losses. High switching frequency is crucial to reduce the DC-Bus capacitor and then increase the power density of 3 phase inverters. The third in-verter uses classic Silicon devices but employs a ZVS (Zero Voltage Switching) topology. Despite the in-creased complexity of both the hardware and the control software, it can offer reduced switching losses by using conventional and established silicon mosfet technology. Finally, the mechanical parts of a three phase permanent magnet motor have been designed with the aim to employ it in UniBo Motorsport’s 2020 Formula Student car.
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This doctoral thesis presents a project carried out in secondary schools located in the city of Ferrara with the primary objective of demonstrating the effectiveness of an intervention based on Well-Being Therapy (Fava, 2016) in reducing alcohol use and improving lifestyles. In the first part (chapters 1-3), an introduction on risky behaviors and unhealthy lifestyle in adolescence is presented, followed by an examination of the phenomenon of binge drinking and of the concept of psychological well-being. In the second part (chapters 4-6), the experimental study is presented. A three-arm cluster randomized controlled trial including three test periods was implemented. The study involved eleven classes that were randomly assigned to receive well-being intervention (WBI), lifestyle intervention (LI) or not receive intervention (NI). Results were analyzed by linear mixed model and mixed-effects logistic regression with the aim to test the efficacy of WBI in comparison with LI and NI. AUDIT-C total score increased more in NI in comparison with WBI (p=0.008) and LI (p=0.003) at 6-month. The odds to be classified as at-risk drinker was lower in WBI (OR 0.01; 95%CI 0.01–0.14) and LI (OR 0.01; 95%CI 0.01–0.03) than NI at 6-month. The odds to use e-cigarettes at 6-month (OR 0.01; 95%CI 0.01–0.35) and cannabis at post-test (OR 0.01; 95%CI 0.01–0.18) were less in WBI than NI. Sleep hours at night decreased more in NI than in WBI (p = 0.029) and LI (p = 0.006) at 6-month. Internet addiction scores decreased more in WBI (p = 0.003) and LI (p = 0.004) at post-test in comparison with NI. Conclusions about the obtained results, limitations of the study, and future implications are discussed. In the seventh chapter, the data of the project collected during the pandemic are presented and compared with those from recent literature.
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The thesis describes three studies concerning the role of the Economic Preference set investigated in the Global Preference Survey (GPS) in the following cases: 1) the needs of women with breast cancer; 2) pain undertreament in oncology; 3) legal status of euthanasia and assisted suicide. The analyses, based on regression techniques, were always conducted on the basis of aggregate data and revealed in all cases a possible role of the Economic Preferences studied, also resisting the concomitant effect of the other covariates that were considered from time to time. Regarding individual studies, the related conclusion are: 1) Economic Preferences appear to play a role in influencing the needs of women with breast cancer, albeit of non-trivial interpretation, statistically "resisting" the concomitant effect of the other independent variables considered. However, these results should be considered preliminary and need further confirmation, possibly with prospective studies conducted at the level of the individual; 2) the results show a good degree of internal consistency with regard to pro-social GPS scores, since they are all found to be non-statistically significant and united, albeit only weakly in trend, by a negative correlation with the % of pain undertreated patients. Sharper, at least statistically, is the role of Patience and Willingness to Take Risk, although of more complex empirical interpretation. 3) the results seem to indicate an obvious role of Economic Preferences, however difficult to interpret empirically. Less evidence, at least on the inferential level, emerged, however, regarding variables that, based on common sense, should play an even more obvious role than Economic Preferences in orienting attitudes toward euthanasia and assisted suicide, namely Healthcare System, Legal Origin, and Kinship Tightness; striking, in particular, is the inability to prove a role for the dominant religious orientation even with a simple bivariate analysis.
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The abundance of visual data and the push for robust AI are driving the need for automated visual sensemaking. Computer Vision (CV) faces growing demand for models that can discern not only what images "represent," but also what they "evoke." This is a demand for tools mimicking human perception at a high semantic level, categorizing images based on concepts like freedom, danger, or safety. However, automating this process is challenging due to entropy, scarcity, subjectivity, and ethical considerations. These challenges not only impact performance but also underscore the critical need for interoperability. This dissertation focuses on abstract concept-based (AC) image classification, guided by three technical principles: situated grounding, performance enhancement, and interpretability. We introduce ART-stract, a novel dataset of cultural images annotated with ACs, serving as the foundation for a series of experiments across four key domains: assessing the effectiveness of the end-to-end DL paradigm, exploring cognitive-inspired semantic intermediaries, incorporating cultural and commonsense aspects, and neuro-symbolic integration of sensory-perceptual data with cognitive-based knowledge. Our results demonstrate that integrating CV approaches with semantic technologies yields methods that surpass the current state of the art in AC image classification, outperforming the end-to-end deep vision paradigm. The results emphasize the role semantic technologies can play in developing both effective and interpretable systems, through the capturing, situating, and reasoning over knowledge related to visual data. Furthermore, this dissertation explores the complex interplay between technical and socio-technical factors. By merging technical expertise with an understanding of human and societal aspects, we advocate for responsible labeling and training practices in visual media. These insights and techniques not only advance efforts in CV and explainable artificial intelligence but also propel us toward an era of AI development that harmonizes technical prowess with deep awareness of its human and societal implications.
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The aim of this investigation was to compare the skeletal stability of three different rigid fixation methods after mandibular advancement. Fifty-five class II malocclusion patients treated with the use of bilateral sagittal split ramus osteotomy and mandibular advancement were selected for this retrospective study. Group 1 (n = 17) had miniplates with monocortical screws, Group 2 (n = 16) had bicortical screws and Group 3 (n = 22) had the osteotomy fixed by means of the hybrid technique. Cephalograms were taken preoperatively, 1 week within the postoperative care period, and 6 months after the orthognathic surgery. Linear and angular changes of the cephalometric landmarks of the chin region were measured at each period, and the changes at each cephalometric landmark were determined for the time gaps. Postoperative changes in the mandibular shape were analyzed to determine the stability of fixation methods. There was minimum difference in the relapse of the mandibular advancement among the three groups. Statistical analysis showed no significant difference in postoperative stability. However, a positive correlation between the amount of advancement and the amount of postoperative relapse was demonstrated by the linear multiple regression test (p < 0.05). It can be concluded that all techniques can be used to obtain stable postoperative results in mandibular advancement after 6 months.
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The vast majority of maternal deaths in low-and middle-income countries are preventable. Delay in obtaining access to appropriate health care is a fairly common problem which can be improved. The objective of this study was to explore the association between delay in providing obstetric health care and severe maternal morbidity/death. This was a multicentre cross-sectional study, involving 27 referral obstetric facilities in all Brazilian regions between 2009 and 2010. All women admitted to the hospital with a pregnancy-related cause were screened, searching for potentially life-threatening conditions (PLTC), maternal death (MD) and maternal near-miss (MNM) cases, according to the WHO criteria. Data on delays were collected by medical chart review and interview with the medical staff. The prevalence of the three different types of delays was estimated according to the level of care and outcome of the complication. For factors associated with any delay, the PR and 95%CI controlled for cluster design were estimated. A total of 82,144 live births were screened, with 9,555 PLTC, MNM or MD cases prospectively identified. Overall, any type of delay was observed in 53.8% of cases; delay related to user factors was observed in 10.2%, 34.6% of delays were related to health service accessibility and 25.7% were related to quality of medical care. The occurrence of any delay was associated with increasing severity of maternal outcome: 52% in PLTC, 68.4% in MNM and 84.1% in MD. Although this was not a population-based study and the results could not be generalized, there was a very clear and significant association between frequency of delay and severity of outcome, suggesting that timely and proper management are related to survival.