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71.
This contribution presents a methodology to efficiently obtain the numerical and computer solution of dynamic power systems with high penetration of wind turbines. Due to the excessive computational load required to solve the abc models that represent the behavior of the wind turbines, a parallel processing scheme is proposed to enhance the solution of the overall system. Case studies are presented which demonstrate the effectiveness and applications of the proposed methodology. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
72.
Gnanasambandapillai Ramtharan Nicholas Jenkins Olimpo Anaya‐Lara Ervin Bossanyi 《风能》2007,10(4):293-301
An assessment of the impact that the representation of rotor structural dynamics has on the electrical transient performance of fixed‐speed induction generators (FSIGs) and doubly fed induction generators (DFIGs) wind turbines is presented. A three‐mass model that takes into account not only the shaft flexibility but also the blade flexibility in the structural dynamics is developed and used to derive an effective two‐mass model of the drive train dynamics, which represents the dominant natural frequency of vibration of the rotor structure. For the purposes of this investigation, the dynamic performance of both FSIG and DFIG wind turbines is evaluated during electrical transients such as a three‐phase fault in the network. The studies are conducted in the software code Bladed, where a detailed representation of the structural dynamics is used to derive the three‐mass model and the effective two‐mass model. Simulation results which illustrate how these representations of the rotor dynamics affect the response of the wind turbine during the fault are presented and discussed. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
73.
This work is devoted to the experimental investigation and theoretical modeling of biological products with high initial moisture content which implies significant volume contraction. Firstly, experimental equipment which was designed to continuously determine variations in the global moisture content and in the temperature of the sample is introduced. Furthermore, the equipment is controlled by a PC which records experimental information in real time. In particular, measurement of the radial and temporal distributions of moisture content and temperature during the drying process of the homogeneous porous media potato are given. The mean moisture content and temperature curves are also given. 相似文献
74.
Lara Naurath Christoph Weidner Thomas R. Rüde Andre Banning 《Mine Water and the Environment》2011,30(3):231-236
Sodium fluorescein (uranine) is one of the most popular fluorescent dyes for tracer experiments due to its chemical properties,
low detection limits and low costs. As a limiting factor, it is generally assumed that Na-fluorescein cannot be properly detected
under acid conditions because of weak fluorescence intensities at the standard excitation wavelength (490 nm). This laboratory
study introduces a method to quantify Na-fluorescein in low pH waters without having to raise pH to alkaline conditions, which
spares the time- and cost-intensive filtration of hydroxide precipitates prior to analysis. It was applied for recovery tests
in water samples from five mining sites in Germany. These were buffered to pH 1.5 where Na-fluorescein shows a second fluorescence
intensity maximum at an excitation wavelength of 438 nm. The method had satisfying recovery rates although, as expected, a
higher detection limit compared to standard wavelength and pH. High Fe contents in the waters are a limiting factor—the impact
of increasing Fe concentrations at a constant dye spike was evaluated and yielded a distinct negative trend between Fe and
detected Na-fluorescein, probably due to Fe-fluorescein complexation. However, good recovery can be expected in mine waters
with up to ≈100 mg L−1 Fe. The method of standard addition offers a potential calculative solution for higher Fe concentrations, resulting in significantly
better Na-fluorescein recovery rates, compared to direct measurements. The method introduced here represents a promising approach
for improving Na-fluorescein applicability in acid environments. 相似文献
75.
River fragmentation is a process highly detrimental for fish survival by impeding their migrations. Although fragmentation by big dams has been studied, there is still a big deficiency of data related to small barriers. This study was designed as a detailed, local-scale analysis of several chosen river stretches in the Sandomierz Basin, Poland. It aimed to: (1) map all natural and artificial barriers in the study area, (2) assess the impacts of these barriers on fish migration, (3) compare findings to existing databases, and (4) make recommendations for improved barrier management. Ten lowland rivers covering a total 424 km length were surveyed by river walkovers and kayak surveys, with all the barriers mapped and all the artificial structures assessed for fish migration using the ICE protocol protocol for ecological continuity. There were 67 beaver dams and 89 artificial barriers recorded, with only 24% of the latter being included in national databases. The average artificial barrier density in all the surveyed rivers was 0.2 barriers/km and varied from 0.75 barriers/km in first order streams to 0.01 barriers/km in sixth order river. The findings revealed that 18% of the barriers were passable for all fish species, with 35% totally impassable. The analysis of specific barrier parameters indicated that water depth at the barrier had a greater influence on fish passability than the barrier height. Several barriers were proposed for removal to specifically improve the potential for fish migration. 相似文献
76.
Nuno Vale Mariana Pereira Joana Santos Catarina Moura Lara Marques Diana Duarte 《International journal of molecular sciences》2023,24(1)
Chemotherapy is the main treatment for most early-stage cancers; nevertheless, its efficacy is usually limited by drug resistance, toxicity, and tumor heterogeneity. Cell-penetrating peptides (CPPs) are small peptide sequences that can be used to increase the delivery rate of chemotherapeutic drugs to the tumor site, therefore contributing to overcoming these problems and enhancing the efficacy of chemotherapy. The drug combination is another promising strategy to overcome the aforementioned problems since the combined drugs can synergize through interconnected biological processes and target different pathways simultaneously. Here, we hypothesized that different peptides (P1–P4) could be used to enhance the delivery of chemotherapeutic agents into three different cancer cells (HT-29, MCF-7, and PC-3). In silico studies were performed to simulate the pharmacokinetic (PK) parameters of each peptide and antineoplastic agent to help predict synergistic interactions in vitro. These simulations predicted peptides P2–P4 to have higher bioavailability and lower Tmax, as well as the chemotherapeutic agent 5-fluorouracil (5-FU) to have enhanced permeability properties over other antineoplastic agents, with P3 having prominent accumulation in the colon. In vitro studies were then performed to evaluate the combination of each peptide with the chemotherapeutic agents as well as to assess the nature of drug interactions through the quantification of the Combination Index (CI). Our findings in MCF-7 and PC-3 cancer cells demonstrated that the combination of these peptides with paclitaxel (PTX) and doxorubicin (DOXO), respectively, is not advantageous over a single treatment with the chemotherapeutic agent. In the case of HT-29 colorectal cancer cells, the combination of P2–P4 with 5-FU resulted in synergistic cytotoxic effects, as predicted by the in silico simulations. Taken together, these findings demonstrate that these CPP6-conjugates can be used as adjuvant agents to increase the delivery of 5-FU into HT-29 colorectal cancer cells. Moreover, these results support the use of in silico approaches for the prediction of the interaction between drugs in combination therapy for cancer. 相似文献
77.
Petra Buri&#x; Ivana arapar Dijana Pavi
i&#x;-Hamer Ines Kova
i&#x; Lara Jurkovi&#x; Maja Dutour Sikiri&#x; Darija Domazet Jura&#x;in Nevenka Mikac Niko Ba
i&#x; Daniel Mark Lyons 《International journal of molecular sciences》2023,24(1)
Silver nanoparticles represent a threat to biota and have been shown to cause harm through a number of mechanisms, using a wide range of bioassay endpoints. While nanoparticle concentration has been primarily considered, comparison of studies that have used differently sized nanoparticles indicate that nanoparticle diameter may be an important factor that impacts negative outcomes. In considering this, the aim of the present study was to determine if different sizes of silver nanoparticles (AgNPs; 10, 20, 40, 60 and 100 nm) give rise to similar effects during embryogenesis of Mediterranean sea urchins Arbacia lixula and Paracentrotus lividus, or if nanoparticle size is a parameter that can modulate embryotoxicity and spermiotoxicity in these species. Fertilised embryos were exposed to a range of AgNP concentrations (1–1000 µg L−1) and after 48 h larvae were scored. Embryos exposed to 1 and 10 µg L−1 AgNPs (for all tested sizes) showed no negative effect in both sea urchins. The smaller AgNPs (size 10 and 20 nm) caused a decrease in the percentage of normally developed A. lixula larvae at concentrations ≥50 µg L−1 (EC50: 49 and 75 μg L−1, respectively) and at ≥100 µg L−1 (EC50: 67 and 91 μg L−1, respectively) for P. lividus. AgNPs of 40 nm diameter was less harmful in both species ((EC50: 322 and 486 μg L−1, for P. lividus and A. lixula, respectively)). The largest AgNPs (60 and 100 nm) showed a dose-dependent response, with little effect at lower concentrations, while more than 50% of larvae were developmentally delayed at the highest tested concentrations of 500 and 1000 µg L−1 (EC50(100 nm); 662 and 529 μg L−1, for P. lividus and A. lixula, respectively. While AgNPs showed no effect on the fertilisation success of treated sperm, an increase in offspring developmental defects and arrested development was observed in A. lixula larvae for 10 nm AgNPs at concentrations ≥50 μg L−1, and for 20 and 40 nm AgNPs at concentrations >100 μg L−1. Overall, toxicity was mostly ascribed to more rapid oxidative dissolution of smaller nanoparticles, although, in cases, Ag+ ion concentrations alone could not explain high toxicity, indicating a nanoparticle-size effect. 相似文献
78.
Lara Qasim Andreas Makoto Hein Sorin Olaru Jean-Luc Garnier Marija Jankovic 《Systems Engineering》2023,26(4):347-364
System reconfiguration is essential in complex systems management, as it is an enabler of system flexibility and adaptability. It ensures system operation and increases reliability, availability, maintainability, testability, safety, and reuse of system entities and technologies. For the reconfiguration of a system in use, it is necessary to assess, in continuity, the system's state with regard to its context. Identifying data supporting system reconfiguration represents a major industrial challenge and is linked directly to the development of industrial reconfiguration tools. Reconfiguration tools are based on a data model, also called ontology, which represents key concepts of system reconfiguration and their relationships. A particular difficulty of developing the data model is the multi-domain nature of reconfiguration. Furthermore, it needs to address a considerable diversity of system types. Few publications propose an ontology supporting data identification and tool development for the entire process. Hence, in this paper we propose to formalize the system reconfiguration process and propose an overarching ontology, which we call OSysRec. This ontology considers data at the management, dynamics, and structure level. The proposed ontology has been developed based upon expert knowledge and several industrial uses cases. The OSysRec ontology allowed a better understanding of the reconfiguration process, and hence it can be deployed for developing efficient and effective reconfiguration tools at the industrial scale. The ontology has been tested on an industrial case study to validate the proposed approach. 相似文献
79.
80.