Title2Event: Benchmarking Open Event Extraction with a Large-scale Chinese Title Dataset

Event extraction (EE) is crucial to downstream tasks such as new aggregation and event knowledge graph construction. Most existing EE datasets manually define fixed event types and design specific schema for each of them, failing to cover diverse events emerging from the online text. Moreover, news titles, an important source of event mentions, have not gained enough attention in current EE research. In this paper, We present Title2Event, a large-scale sentence-level dataset benchmarking Open Event Extraction without restricting event types. Title2Event contains more than 42,000 news titles in 34 topics collected from Chinese web pages. To the best of our knowledge, it is currently the largest manually-annotated Chinese dataset for open event extraction. We further conduct experiments on Title2Event with different models and show that the characteristics of titles make it challenging for event extraction, addressing the significance of advanced study on this problem. The dataset and baseline codes are available at https://open-event-hub.github.io/title2event.Comment: EMNLP 202

Pervasive hybridization during evolutionary radiation of Rhododendron subgenus Hymenanthes in mountains of southwest China

Radiations are especially important for generating species biodiversity in mountainous ecosystems. The contribution of hybridization to such radiations has rarely been examined. Here, we use extensive genomic data to test whether hybridization was involved in evolutionary radiation within Rhododendron subgenus Hymenanthes, whose members show strong geographic isolation in the mountains of southwest China. We sequenced genomes for 143 species of this subgenus and 93 species of four other subgenera, and found that Hymenanthes was monophyletic and radiated during the late Oligocene to middle Miocene. Widespread hybridization events were inferred within and between the identified clades and subclades. This suggests that hybridization occurred both early and late during diversification of subgenus Hymenanthes, although the extent to which hybridization, speciation through mixing-isolation-mixing or hybrid speciation, accelerated the diversification needs further exploration. Cycles of isolation and contact in such and other montane ecosystems may have together promoted species radiation through hybridization between diverging populations and species. Similar radiation processes may apply to other montane floras in this region and elsewhere

Periodic Motions and Bifurcation Trees in a Parametric Duffing Oscillator

This thesis is a study of bifurcation trees of periodic motions in a parametric Duffing oscillator. The bifurcation trees from period-1 to period-4 motions are investigated by a semi-analytic method. For the semi-analytic method, the discretization of differential equations of nonlinear dynamical systems is obtained to attain the implicit mapping structure. Following the development of implicit mapping structure, the periodic nodes of periodic motions are computed. The stability and bifurcation conditions are carried out by the eigenvalue analysis. For a better understanding of nonlinear behaviors of periodic motions, the harmonic frequency-amplitude characteristics are presented by the finite Fourier series. Numerical simulations are illustrated to verify the analytical predictions. Based on the comparison of numerical and analytical result, the trajectory, time history, harmonic amplitude and harmonic phase plots of period-1 to period-4 motions are completed

MODELLING METHODOLOGY AND PRACTICES FOR PERFORMANCE EVALUATION OF AN ELECTRICAL THSA

International audienceWith the development of power-by-wire technology, conventional hydraulically powered trimmable horizontal stabilizer actuators (THSA) are being replaced by-all electric types in the latest generation of more electric aircraft (MEA). However, the performance evaluation of an electrical THSA in terms of control dynamics, power sizing, backdrivability, load rejection, thermal management, response to fault, etc. still lacks of well-established preliminary model-based methods and practices. This work deals with the multi-level modelling and simulation of complex multidisciplinary effects, with special considerations to the mechanical transmission of the THSA. Real experiments are used to identify the uncertain model parameters and to validate the proposed models

Simulations and Experiments of the Soil Temperature Distribution after 2.45-GHz Short-Time Term Microwave Treatment

Microwave treatment is a green and pollution-free soil disinfection method. The application of microwaves to disinfect soil before cultivation is highly important to increase crop yields and protect the ecological environment. The electromagnetic field is an important parameter influencing the soil temperature field in the process of microwave soil treatment, and the change in soil temperature directly affects soil disinfection. Therefore, this article carried out research on the heating pattern in North China loess due to microwave treatment. First, COMSOL software was employed to simulate the microwave soil treatment process to analyze microwave penetration into soil. Second, with the application of microwaves at the designed frequency produced with a 2.45-GHz tunable microwave generating microdevice, soil with water contents of 0%, 10%, 20%, and 30% was treated for 10~60 s (at 10-s time intervals), and experiments on the influence of the microwave output power, treatment time, and soil moisture content on the soil temperature were performed via the controlled variable method. The simulation results indicate that with increasing soil moisture content, the microwave frequency inside the soil model increases, and the electric field intensity value decreases in the model at the same depth. After microwaves traverse through the 20-cm soil model, the incident field strength is three orders of magnitude lower than the outgoing field strength. The results of the microwave soil treatment experiment reveal that: (1) Compared to microwave output power levels of 1.8 and 1.6 kW, a level of 2 kW is more suitable for microwave soil disinfection. (2) After treatment, the highest temperature occurs on the soil surface, not within the soil. (3) The location of the highest soil internal temperature after microwave treatment increasingly approaches the soil surface with increasing soil moisture content, and the microwave output power does not affect the location of the highest soil internal temperature. Combining the electromagnetic field simulation and microwave soil treatment experiment results, it was found that the higher the field strength is, the higher the temperature value, and the highest soil internal temperature after microwave treatment often occurs at the first electromagnetic wave peak

Simulations and Experiments of Soil Temperature Distribution after 2.45 GHz Long-Term Microwave Treatment

Soil disinfection is an important agronomic measure to prevent soil-borne diseases, insects, weeds and other hazards. Based on the premise of being environmentally friendly, microwave soil disinfection can improve crop yield and quality in a pollution-free, residue-free and green way. The law of microwave soil heating is the theoretical basis of microwave soil disinfection. Therefore, in this paper, loess soil of North China and black soil of Northeast China are used as test materials to explore the law of soil heating under the action of microwaves. First, COMSOL Multiphysics software was used to simulate the temperature field change in the microwave-irradiated soil, and a simulation model of the temperature field of the microwave-irradiated soil was constructed to analyze the effective working range and temperature distribution characteristics of the microwave-irradiated soil. Second, using the 2.45 GHz microwave treatment, the following conditions were tested: soil moisture conditions of 10%, 15%, 20% and 23% (within the natural moisture content range). The loess and black soil were treated by microwave irradiation for 1~12 min, respectively (1 min/time increment). A single-factor experiment was designed to explore the influence of these factors on the soil heating law. The results show that the two soil surface temperatures are positively correlated with the soil moisture content, both of which satisfy Tsurface23% > Tsurface20% > Tsurface15% > Tsurface10%, and the surface temperature of black soil is higher than that of loess. According to the experimental results of the internal temperature distribution of loess and black soil irradiated by microwaves, the surface equations of “irradiation time–soil depth-soil temperature” and “irradiation time–soil moisture content–soil temperature” were constructed by surface fitting. When the irradiation time and moisture conditions are the same, the average temperature inside the irradiation area satisfies T¯α black soil > T¯α loess. The results of long-term microwave soil heating preliminarily confirmed the feasibility of microwave soil disinfection and the optimal conditions of microwave irradiation in loess of North China and Northeast black soil, which provides a certain reference for the study of soil-borne diseases inactivation at high temperature

Adaptive Robust Fault-Tolerant Regulation of Mechatronic Systems with Prescribed-Time Convergence

In this paper, we propose a synchronized prescribed-time control strategy for a class of nonlinear mechatronic systems with external disturbance, actuation saturation, and actuator faults, which features simultaneous translational and rotational motion tracking in the same prescribed time. Dual quaternion is employed to model the coupling effect between translational and rotational motions, which provides a unified representation for describing multiple degree-of-freedom motions. In addition, online adaptive technology is incorporated for real-time monitoring and separation of actuator failure information. The adaptive capability of the controller to parameter perturbation, disturbance, and fault deviation is therefore enhanced. Furthermore, the closed-loop system is featured by L2 gain stability/robustness against thrust output deviation, while the system trajectory is guaranteed to converge with user-defined settling time. Finally, numerical simulations on a microsatellite platform with redundant thrusters are performed to verify the effectiveness of the proposed fault-tolerant control approach