234 research outputs found
Preface:LM-KBC Challenge 2024
No full textPretrained language models (LMs) have advanced a range of semantic tasks and have also shown promise for knowledge extraction from the models itself. Although several works have explored this ability in a setting called probing or prompting, the viability of knowledge base construction from LMs remains underexplored. In the 3rd edition of this challenge, participants were asked to build actual disambiguated knowledge bases from LMs, for given subjects and relations. In crucial difference to existing probing benchmarks like LAMA [1], we make no simplifying assumptions on relation cardinalities, i.e., a subject-entity can stand in relation with zero, one, or many object-entities. Furthermore, submissions need to go beyond just ranking predicted surface strings and materialize disambiguated entities in the output, which will be evaluated using established KB metrics of precision and recall. The challenge has a single track for LMs with a parameter level under 10-billion to fit into low computational requirements. The challenge received 8 submissions, of which 5 submitted a paper, and 4 were accepted for presentation. The challenge was collocated with a workshop on related topics, allowing to host extended discussions, related papers, and invited talks.</p
Agroeca coreana Namkung 1989
No full textAgroeca coreana Namkung, 1989 Fig. 13 Agroeca coreana Namkung, 1989: 24, figs 1–10; Hayashi, 1992: 136, figs 9–10. For complete bibliography see World Spider Catalog (2019). Material examined. 1♀, CHINA: Shaanxi Province, Yan’an City, Luochuan County, Han village (35°48.476′N, 109°37.938′E), 1217 m a.s.l., 26 Apr 2017, leg. Bohui Xia. 1♀, Shaanxi Province, Yan’an City, Luochuan County, Laomiao Town, Wuguangrong Village (35°36.802′N, 109°31.679′E), 975 m a.s.l., 26 Apr 2017, leg. Bohui Xia. Distribution. Russia (Far East), Korea, Japan, newly recorded from China (Fig. 17).Published as part of Mu, Yannan, Jin, Chi & Zhang, Feng, 2019, A survey of Agroeca Westring, 1861 from China (Araneae: Liocranidae), pp. 91-112 in Zootaxa 4615 (1) on page 104, DOI: 10.11646/zootaxa.4615.1.4, http://zenodo.org/record/399535
Digital-analog hybrid controlled LCL type grid connected inverter
No full textWith the continuous development of renewable energy power generation system, the research on grid-connected inverters becomes very important. This project presents a new type of control theory for LCL type grid tied inverters-the hybrid digital-analog control system. It contains digital feedback control which achieved by Hardware-in-the-loop(HIL) and analog feedforward control which achieved by OPAL-RT. The hybrid digital-analog system combines the high-speed processing performance of digital control and the real-time simulation of analog control. It also avoids the delay problem during the experiment process, and significantly improves the stability of the system and capability of suppressing harmonics.Bachelor of Engineerin
Impedance shaping method to improve grid-connected inverter under weak grid condition
No full textDue to the popularity of renewable energy, e.g., wind power and solar energy, renewable energy generation systems(REGs) have been preferred as eco-friendly power generation systems. Distributed generation resources, including renewable energy sources, are essential for the distributed generation system. Grid-connected inverters(GCIs), as indispensable parts of the distributed generation system, are endangered by the non-ideal conditions. For instance, the harmonics, high impedance in weak grid condition, and instability issues caused by impedance mismatching.
In order to address the non-ideal conditions mentioned before, there are various improving technologies being modified to enhance the performance of grid-connected inverters. Generally, the LCL filters are applied between the inverter and the power grid to suppress the harmonics. However, the resonance circuit also leads to distortion and even instability issues. Therefore, the passive damping and active damping schemes are introduced in the topology of the inverter and control block. Besides, active power filters, unlike passive damping using passive damper, utilize active components to compensate for the harmonics and therefore eliminate the negative effect of harmonics. Nonetheless, the variable grid conditions and digital delay are still serious problems for the grid-connected inverter.
Firstly, unlike traditional active power filter, especially series active power filter, the adaptive controller for the APF model is required to improve the robustness in the variable grid conditions. According to model simplification, impedance-based stability criterion and bode plot analysis, it is indicated that the proposed control method certainly increases the phase margin and stabilizes the system in the ideal case. Eventually, the proposed series adaptive stabilizer is applied in the tested single-phase grid-connected inverter with a weak grid. Moreover, the experimental results are demonstrated, which prove the correctness of it.
Despite the active power filter, the active damping methods are widely applied in the inverter side to achieve the impedance shaping. Unlike the modified active power filter, the active damping method provides virtual impedance to shape the output impedance of inverter with no power loss. However, the negative effect of digital delay in the digital controller and the potential influence of weak grid condition are challenging the performance of control design. Therefore, the hybrid controller is applied and verified to be effective in eliminating the negative effect of digital delay and weak grid.
In this thesis, impedance shaping methods, including active damping and adaptive active power filter, are proposed and the performance of inverter will be improved.
As the limitation of single-phase inverter, the feasibility of the series adaptive active power filter should be investigated with new challenges. For future works, the application of series adaptive stabilizer will be discussed in three-phase inverter and parallel-inverter system, respectively.Master of Engineerin
Information environment and corporate innovation: A survey
No full textA field of research that attracts increasing attention from scholars is the impact of the information environment on corporate innovation. In this article, I review the research from three points of view in relation to the information environment: (i) managers' voluntary disclosure, (ii) disclosure mandated by regulation, and (iii) information intermediaries (media and analysts). Research suggests that the information environment generally plays both positive and negative roles in corporate innovation by affecting effort and efficiency through different mechanisms. Finally, I put forward some suggestions on two aspects of future research directions of this field
What drives international stock return comovements?
Get PDFThis paper presents new evidence on international financial market integration using stock analyst earnings forecasts from 37 countries. By examining cash flow and discount rate news co-movements, we find that the financial and economic aspects of global market integration have diverged over time as financial integration has developed particularly more rapidly than economic integration over the past decade. However, this divergence is less severe in emerging markets when compared with developed markets, where financial integration has proceeded at a slower pace. We find that financial integration has developed relatively slowly in emerging markets due to the hampering effects of their poor information environments
Essay on international financial markets
No full text163 p.This dissertation consists of three essays. The first essay explores the underlying economic forces that drive the variation in risk premia around the world. It examines whether and how differences in the investors' information environment affect cross-country differences in the volatility of equity risk premia. We use the variance-decomposition approach and implied cost of capital method to estimate time variation in risk premia for 40 developed and developing countries worldwide. Consistent with theoretical predictions, countries with better information environments tend to experience a lower risk premium volatility, even after controlling for various country variables that are previously found to be good predictors of risk premia. Our further analysis of an exogenous event, specifically the 1997 Asian financial crisis, corroborates our finding that a country's information environment plays an important role in explaining the volatility of its market risk premium.DOCTOR OF PHILOSOPHY (NBS
Enriching Ontologies with Disjointness Axioms using Large Language Models
Get PDFOntologies often lack explicit disjointness declarations between classes, despite their usefulness for sophisticated reasoning and consistency checking in Knowledge Graphs. In this study, we explore the potential of Large Language Models (LLMs) to enrich ontologies by identifying and asserting class disjointness axioms. Our approach aims at leveraging the implicit knowledge embedded in LLMs, using prompt engineering to elicit this knowledge for classifying ontological disjointness. We validate our methodology on the DBpedia ontology, focusing on open-source LLMs. Our findings suggest that LLMs, when guided by effective prompt strategies, can reliably identify disjoint class relationships, thus streamlining the process of ontology completion without extensive manual input. For comprehensive disjointness enrichment, we propose a process that takes logical relationships between disjointness and subclass statements into account in order to maintain satisfiability and reduce the number of calls to the LLM. This work provides a foundation for future applications of LLMs in automated ontology enhancement and offers insights into optimizing LLM performance through strategic prompt design. Our code is publicly available on GitHub at https://github.com/n28div/llm-disjointness
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