To meet demanding mission objectives, most current satellites for Earth and Universe observation are equipped with large flexible appendages. However, due to the coupling between spacecraft rigid and ...elastic dynamics, unwanted elastic vibrations of such flexible elements may compromise the achievement of pointing and stability requirements. Therefore, control solutions aiming at avoiding instabilities and, at worst, the failure of the mission, are currently needed. In this scenario, growing interest has been recently devoted to Active Vibration Control (AVC) strategies relying on the use of smart materials. Among them, piezoelectric patches are the most studied and tested devices for both actuating and sensing purposes. This paper aims to contribute to this line of research by investigating a different type of actuator, namely an Offset Piezoelectric Stack Actuator (OPSA), to assess its performance in damping out elastic vibrations of large space structures. Moreover, special attention is devoted to compare OPSA performance with standard patch actuators behaviour. In order to develop the AVC system, an equivalent electro-mechanical coupled Finite Element (FE) formulation is implemented, integrating both sensors and piezo-stack elements on the passive hosting structure. The final structural model including both electrical inputs/outputs, as well as modified mass and stiffness due to the additional piezo devices, is then obtained. A parametric analysis is carried out to optimize the maximum control action exerted by the OPSA device. Finally, the OPSA numerical model is experimentally validated by mounting it on a cantilever plate, representative of a scaled solar panel. Experimental data are used not only to verify the device expected functioning, but also to tune the parameters in the OPSA FE model, which can be finally integrated in a planar satellite dynamics simulator to evaluate the AVC system efficiency when performing attitude manoeuvres.
•Active Vibration Control of large flexible space structures.•Use of offset piezoelectric stack actuators.•Finite Element formulation implemented, integrating both sensors and piezo-stack elements.•OPSA numerical model validation on a cantilever plate, representative of a scaled solar panel.•Finite element tuning using experimental data.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
There are large uncertainties that exist in El Niño–Southern Oscillation (ENSO) predictions. Errors in model parameters are one of the factors limiting ENSO prediction skill. In this study, we look ...for the model parameters that can induce the largest least-square changes in the sea surface temperature predictions for four El Niño events that were optimized to fit observations in the tropical Pacific: 1982 and 1987 eastern Pacific (EP) events and 1990 and 1994 central Pacific (CP) events. The ENSO model is an intermediate coupled model used at the Institute of Oceanology, Chinese Academy of Sciences (IOCAS ICM). The sensitivity of the prediction skill for each type of El Niño to the model parameters is analyzed using an optimization parameter sensitivity analysis (OPSA) method. Perturbation experiments allow us to identify three important model parameters that play a key role in ENSO dynamics from nine selected parameters. These three,
α
Tea
,
α
τ
, and
α
HF
, are related to the thermocline feedback, wind stress, and heat flux, respectively.
α
Tea
and
α
τ
are important for both types of El Niño events, while
α
HF
is another important parameter that impacts CP events. Our results show that ENSO predictions can be improved by accurate estimates of the sensitive parameters identified here. In particular, it is reasonable that accurate estimates of
α
HF
make more sense for improving CP El Niño prediction than for improving EP El Niño prediction. Increasing
α
Tea
or
α
τ
or decreasing
α
HF
tends to increase the amplitudes of these warm events. The two types of El Niño events have different sensitivities to the parameter
α
HF
, which is attributed to the role played by the vertical mixing process in the eastern equatorial Pacific. These parameter sensitivity analyses provide an improved understanding of ENSO predictability, and highlight the special importance of
α
HF
for enhancing the prediction skill for the CP El Niño.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
From a residential point of view, home energy management (HEM) is an essential requirement in order to diminish peak demand and utility tariffs. The integration of renewable energy sources (RESs) ...together with battery energy storage systems (BESSs) and central battery storage system (CBSS) may promote energy and cost minimization. However, proper home appliance scheduling along with energy storage options is essential to significantly decrease the energy consumption profile and overall expenditure in real-time operation. This paper proposes a cost-effective HEM scheme in the microgrid framework to promote curtailing of energy usage and relevant utility tariff considering both energy storage and renewable sources integration. Usually, the household appliances have different runtime preferences and duration of operation based on user demand. This work considers a simulator designed in the C++ platform to address the domestic customer’s HEM issue based on usages priorities. The positive aspects of merging RESs, BESSs, and CBSSs with the proposed optimal power sharing algorithm (OPSA) are evaluated by considering three distinct case scenarios. Comprehensive analysis of each scenario considering the real-time scheduling of home appliances is conducted to substantiate the efficacy of the outlined energy and cost mitigation schemes. The results obtained demonstrate the effectiveness of the proposed algorithm to enable energy and cost savings up to 37.5% and 45% in comparison to the prevailing methodology.
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Fungi possess diverse photosensory proteins that allow them to perceive different light wavelengths and to adapt to changing light conditions in their environment. The biological and physiological ...roles of the green light-sensing rhodopsins in fungi are not yet resolved. The rice plant pathogen
exhibits two different rhodopsins, CarO and OpsA. CarO was previously characterized as a light-driven proton pump. We further analyzed the pumping behavior of CarO by patch-clamp experiments. Our data show that CarO pumping activity is strongly augmented in the presence of the plant hormone indole-3-acetic acid and in sodium acetate, in a dose-dependent manner under slightly acidic conditions. By contrast, under these and other tested conditions, the
rhodopsin (NR)-like rhodopsin OpsA did not exhibit any pump activity. Basic local alignment search tool (BLAST) searches in the genomes of ascomycetes revealed the occurrence of rhodopsin-encoding genes mainly in phyto-associated or phytopathogenic fungi, suggesting a possible correlation of the presence of rhodopsins with fungal ecology. In accordance, rice plants infected with a CarO-deficient
strain showed more severe bakanae symptoms than the reference strain, indicating a potential role of the CarO rhodopsin in the regulation of plant infection by this fungus.
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The aim of this article is to contribute to a better definition of the overprotection construct. More specifically, it aims at establishing whether or not it can be considered just an excess of ...social support. To do this, two instruments, OPSA and UCLA-SSI, developed from different perspectives on the issue, were translated and adapted from English into Spanish. Analysis performed on a diverse sample of 436 subjects show a good reliability of scores obtained with the Spanish versions, as much on the OPSA test (α = .82 with the full format and α = .81 with the short one) as on the two selected subscales of the UCLA-SSI test (α = .88 with Need/ Want Support subscale, and α = .90 with the Support Received subscale). The relationship among the different measurements was analyzed in a typical sample of 50 recent myocardial infarction patients, as usual in this field. Results suggest that overprotection differs both in quality and quantity from given social support, but it is however related to needed social support. This new finding seems to indicate that those individuals who are more in need of social support could indeed be the more overprotected ones. Clinical and educational implications of the results are discussed.
Plants interact with microbes in many different ways and on many different levels. The most obvious interaction results in plant disease, which can be a severe threat to the global food supply. ...Therefore, research strives to uncover the mechanisms of host plant invasion, learn about the weapons used by pathogenic microbes, and understand the defense strategies of the affected plants. On the other hand, many interactions with the plant are indeed beneficial for the plant, increasing its ability to recruit limiting nutrients from the soil, preventing the growth of more detrimental microbes, or making the plant more resistant to abiotic stresses. Plants also serve as habitats for microbes that may colonize apoplastic spaces within leaves, may live on plant surfaces, or may prosper in the immediate vicinity of plant organs (e.g., in the rhizosoil). In this book, one editorial, two review articles, and twelve original research articles highlight the newest research endeavors on plants interacting with beneficial microbes, having to cope with detrimental microbes, or hosting complete microbiomes. Together, these articles contribute to the knowledge essential for the development of strategies that will prepare our plants to withstand the increasingly harsh conditions they will be exposed to in the coming years of climate change.
Priročnik za obvladovanje psihosocialnih tveganj in absentizma s pomočjo orodja OPSA ('A handbook for managing psychosocial risks and absenteeism with OPSA tool') is an integral part of the new, ...freely available tool aimed at management of psychosocial risks and health-related absenteeism (tool OPSA), which also incorporates a questionnaire and an Excel file for recording and evaluation of data from the questionnaire. Besides introducing the problem of psychosocial burdens experienced by employees at their workplace and beyond, this handbook can be used as a useful instrument for designing a various promotional and preventive arrangements which bettering employees’ health and well-being in their working settings, as suggested by recent guidelines for psychosocial risks management. A handbook is based on interactive chapters, including also numerous links to supportive health promotion websites in order to facilitate the preparation of adequate measures and related activities, commonly carried out by professionals in the field of health and safety at work. A special chapter is dedicated to instructions for working with the Excel file of OPSA tool, enabling an assessment of employees’ psychosocial burdens and risks of developing an excessive stress, absenteeism, presenteeism, turnover and experiencing of workplace violence.
Die Akademie het reeds voor die Tweede Wêreldoorlog 'n belangstelling in opera geopenbaar maar sou eers in die jare vyftig op indirekte wyse deur sy ampsbekleders en sy kantoor aktief betrokke raak ...by die bevordering van opera. Dit het tot uitdrukking gekom in die strewe om bekende operas ook in Afrikaans aan te bied, om operasangers en dirigente te bekroon en het uiteindelik gelei tot 'n bepaalde bydrae in die totstandkoming van die rade vir uitvoerende kunste in 1963. Hierdie artikel gee veral aandag aan pogings om opera in Afrikaans en onder die Afrikaanse gemeenskap te bevorder. The Akademie and opera The Akademie's interest in opera predates the Second World War. However, this interest only became more active in the 1950s when the Akademie played an indirect role, through the activities of its officials and its office, in promoting opera in South Africa. The Akademie was particularly keen on presenting Italian and German operas in Afrikaans and encouraging opera by granting rewards to opera singers and conductors. The Akademie eventually played a supporting role in establishing the four provincial councils for the performing arts in 1963. This article focuses on various efforts made to promote opera in Afrikaans and for the Afrikaans community.
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9.
UWB Channel Capacity Kaiser, Thomas; Zheng, Feng
Ultra Wideband Systems with MIMO,
2010, 2010-03-26
Book Chapter
This chapter contains sections titled: <list style="bulleted" xml:id="l1"> Introduction System Model Channel Capacity with Unknown CSI at the Transmitter Channel Capacity with Known CSI at the ...Transmitter Special Case: SISO with Two Paths Simulation Results Channel Correlation Measured Channel Capacity Summary
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