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81.
A multi-objective control strategy for grid connection of DG (distributed generation) resources 总被引:2,自引:0,他引:2
Edris Pouresmaeil Daniel Montesinos-Miracle Oriol Gomis-Bellmunt Joan Bergas-Jan 《Energy》2010,35(12):5022-5030
This paper presents a flexible control technique for connection of DG (distributed generation) resources to distribution networks, especially during ride-through on faulty grid. This strategy is derived from the abc/αβ and αβ/dq transformations of the ac system variables. The active and reactive currents injected by the DG source are controlled in the synchronously rotating orthogonal dq reference frame. The transformed variables are used to control the VSI (voltage source inverter) which connects the DG to the distribution network. Using a P.L.L. (phase locked loop) in circuit of proposed control technique, the angle of positive sequence has been detected, in order to synchronize the currents to the distribution network. The proposed control technique has the capability of providing active and reactive powers and harmonic currents to nonlinear loads with a fast dynamic response. Simulation results and mathematical analysis have been completed in order to achieve a reduced THD (total harmonic distortion), increased power factor and compensated load’s active and reactive powers. The analyses show the high performance of this control strategy in DG applications in comparison with other existing strategies. 相似文献
82.
Esther Perales Francisco M. Martínez‐Verdú Valentín Viqueira Jesús Fernández‐Reche José A. Díaz Joan Uroz 《Color research and application》2009,34(4):330-336
In this work, we have studied the relationship among the colorimetric properties of different types of paper, having different finishing and grammage. Their color reproduction capability has also been analyzed by using the same printing technology (inkjet printing). On the one hand, we have plotted CIELAB data under the illuminant D50 into constant lightness and hue‐angle planes to be compared with MacAdam limits and with Pointer's real‐world surface color. On the other hand, we have calculated the volume gamut of the color solid associated to each color paper gamut. Analyzing the results, we have checked that there is not any clear relationship among the colorimetric properties of paper (for instance, CIE whiteness index, etc.) and the color gamut volume associated. However, the colorimetric parameters associated to the printed sample showed a quite good linear correlation between the minimum lightness (or the maximum blackness value) of the printed color chart and the color gamut volume. In particular, the greatest color gamut volume corresponds to the glossy papers taking into account this correlation for inkjet printing. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 330–336, 2009 相似文献
83.
84.
Perri Michael G.; McAdoo W. George; McAllister David A.; Lauer Joan B.; Jordan Randall C.; Yancey Donna Z.; Nezu Arthur M. 《Canadian Metallurgical Quarterly》1987,55(4):615
This study evaluated the effectiveness of two posttreatment programs designed to enhance the maintenance of weight loss. Eighty-five obese clients were randomly assigned to either (a) behavior therapy plus a peer-support maintenance program, (b) behavior therapy plus a therapist-contact maintenance program, or (c) behavior therapy only. At a 7-month follow-up session, the therapist-contact program resulted in significantly greater maintenance of weight loss compared with the peer support and behavior therapy only conditions. However, by the time of an 18-month follow-up assessment, overall relapse rates were equivalent across conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
E. William Barrera M. Cinta Pujol Concepción Cascales Joan J. Carvajal X. Mateos R. Solé J. Massons Magdalena Aguiló Francesc Díaz 《Optical Materials》2011,34(2):355-359
We synthesized crystalline Erbium Er3+ and Ytterbium Yb3+ codoped -Lu2O3 nanolayers on SiO2 microspheres using the modified Pechini method. Two different kinds of precursors, nitrates and chlorides, have been used leading to a layer-to-layer morphology and necklaces structures, respectively. In both cases, the size of nanocrystallites constituting the optical active layer is around 5 nm. We performed X-ray powder diffraction to confirm the cubic crystalline structure of the sesquioxides layer. High resolution transmission electron microscopy analyses corroborate the crystalline nature of the layer. The optical emission of Er3+ in the visible range has been recorded. 相似文献
86.
Phenolic composition and mouthfeel characteristics resulting from blending Chilean red wines
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87.
Dynamic Software Product Lines (DSPL) encompass systems that are capable of modifying their own behavior with respect to changes in their operating environment by using run-time reconfigurations. A failure in these reconfigurations can directly impact the user experience since the reconfigurations are performed when the system is already under the users control. In this work, we prototype a Smart Hotel DSPL to evaluate the reliability-based risk of the DSPL reconfigurations, specifically, the probability of malfunctioning (Availability) and the consequences of malfunctioning (Severity). This DSPL prototype was performed with the participation of human subjects by means of a Smart Hotel case study which was deployed with real devices. Moreover, we successfully identified and addressed two challenges associated with the involvement of human subjects in DSPL prototyping: enabling participants to (1) trigger the run-time reconfigurations and to (2) understand the effects of the reconfigurations. The evaluation of the case study reveals positive results regarding both Availability and Severity. However, the participant feedback highlights issues with recovering from a failed reconfiguration or a reconfiguration triggered by mistake. To address these issues, we discuss some guidelines learned in the case study. Finally, although the results achieved by the DSPL may be considered satisfactory for its particular domain, DSPL engineers must provide users with more control over the reconfigurations or the users will not be comfortable with DSPLs. 相似文献
88.
Joan Gregori Jos Juan García-Jareo Michel Keddam Francisco Vicente 《Electrochimica acta》2007,52(28):7903-7909
A theoretical impedance function is proposed for the active/passive transition of nickel in an acid sulphate medium. It is considered that passivating species progressively covers the electrode surface. This approximated model predicts the appearance of negative time constants in the impedance spectra when coverage coefficient θ values for passive species are greater than 0.5. 相似文献
89.
Pratt Michael W.; Norris Joan E.; Arnold Mary Louise; Filyer Rebecca 《Canadian Metallurgical Quarterly》1999,14(3):414
Little research so far has examined storytelling as a channel of value socialization. In the present study, 129 adults from 3 age groups (18–26, 28–50, 60–75) were asked to tell stories for adolescents about 2 of their past value-learning experiences. Generative concern (D. P. McAdams & E. de St. Aubin, 1992) and moral reasoning stage level were also assessed. Stronger generative concern was predictive of a greater sense of having learned important lessons from these past events, of stronger adult value socialization investment, and of more engaging narratives for adolescents as judged by a panel of uninstructed raters. Higher levels of moral reasoning were positively related to generative concern and to a stronger sense of past lessons learned. Generativity appears important to the project of value socialization across the adult life span. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
90.
Protecting Research Subjects, Employees and Researchers: Implications for Software Engineering 总被引:1,自引:1,他引:0
Joan E. Sieber 《Empirical Software Engineering》2001,6(4):329-341
Human subjects research entails risks for subjects and, to a lesser extent, for researchers. This paper introduces the common types of risks to subjects of empirical software engineering research, and how risk can be a function of the context in which the research is conducted. Risks for researchers are also discussed. Government regulation of the ethics of human subjects research is introduced using the example of the Common Rule that governs much human subjects research taking place in the United States. 相似文献