Detection of a methanol megamaser in a major-merger galaxy

We have detected emission from both the 4_{-1}-3_{0} E (36.2~GHz) class I and 7_{-2}-8_{-1} E (37.7~GHz) class II methanol transitions towards the centre of the closest ultra-luminous infrared galaxy Arp 220. The emission in both the methanol transitions show narrow spectral features and have luminosities approximately 8 orders of magnitude stronger than that observed from typical class I methanol masers observed in Galactic star formation regions. The emission is also orders of magnitude stronger than the expected intensity of thermal emission from these transitions and based on these findings we suggest that the emission from the two transitions are masers. These observations provides the first detection of a methanol megamaser in the 36.2 and 37.7 GHz transitions and represents only the second detection of a methanol megamaser, following the recent report of an 84 GHz methanol megamaser in NGC1068. We find the methanol megamasers are significantly offset from the nuclear region and arise towards regions where there is Ha emission, suggesting that it is associated with starburst activity. The high degree of correlation between the spatial distribution of the 36.2 GHz methanol and X-ray plume emission suggests that the production of strong extragalactic class I methanol masers is related to galactic outflow driven shocks and perhaps cosmic rays. In contrast to OH and H2O megamasers which originate close to the nucleus, methanol megamasers provide a new probe of feedback (e.g. outflows) processes on larger-scales and of star formation beyond the circumnuclear starburst regions of active galaxies.Comment: Accepted for publication in ApJ

Embracing Ambiguity: Improving Similarity-oriented Tasks with Contextual Synonym Knowledge

Contextual synonym knowledge is crucial for those similarity-oriented tasks whose core challenge lies in capturing semantic similarity between entities in their contexts, such as entity linking and entity matching. However, most Pre-trained Language Models (PLMs) lack synonym knowledge due to inherent limitations of their pre-training objectives such as masked language modeling (MLM). Existing works which inject synonym knowledge into PLMs often suffer from two severe problems: (i) Neglecting the ambiguity of synonyms, and (ii) Undermining semantic understanding of original PLMs, which is caused by inconsistency between the exact semantic similarity of the synonyms and the broad conceptual relevance learned from the original corpus. To address these issues, we propose PICSO, a flexible framework that supports the injection of contextual synonym knowledge from multiple domains into PLMs via a novel entity-aware Adapter which focuses on the semantics of the entities (synonyms) in the contexts. Meanwhile, PICSO stores the synonym knowledge in additional parameters of the Adapter structure, which prevents it from corrupting the semantic understanding of the original PLM. Extensive experiments demonstrate that PICSO can dramatically outperform the original PLMs and the other knowledge and synonym injection models on four different similarity-oriented tasks. In addition, experiments on GLUE prove that PICSO also benefits general natural language understanding tasks. Codes and data will be public.Comment: This work has been submitted to the Neurocomputing. Copyright may be transferred without notice, after which this version may no longer be accessibl

Vision, Deduction and Alignment: An Empirical Study on Multi-modal Knowledge Graph Alignment

Entity alignment (EA) for knowledge graphs (KGs) plays a critical role in knowledge engineering. Existing EA methods mostly focus on utilizing the graph structures and entity attributes (including literals), but ignore images that are common in modern multi-modal KGs. In this study we first constructed Multi-OpenEA -- eight large-scale, image-equipped EA benchmarks, and then evaluated some existing embedding-based methods for utilizing images. In view of the complementary nature of visual modal information and logical deduction, we further developed a new multi-modal EA method named LODEME using logical deduction and multi-modal KG embedding, with state-of-the-art performance achieved on Multi-OpenEA and other existing multi-modal EA benchmarks.Comment: Accepted by ICASSP202

Active Relation Discovery: Towards General and Label-aware Open Relation Extraction

Open Relation Extraction (OpenRE) aims to discover novel relations from open domains. Previous OpenRE methods mainly suffer from two problems: (1) Insufficient capacity to discriminate between known and novel relations. When extending conventional test settings to a more general setting where test data might also come from seen classes, existing approaches have a significant performance decline. (2) Secondary labeling must be performed before practical application. Existing methods cannot label human-readable and meaningful types for novel relations, which is urgently required by the downstream tasks. To address these issues, we propose the Active Relation Discovery (ARD) framework, which utilizes relational outlier detection for discriminating known and novel relations and involves active learning for labeling novel relations. Extensive experiments on three real-world datasets show that ARD significantly outperforms previous state-of-the-art methods on both conventional and our proposed general OpenRE settings. The source code and datasets will be available for reproducibility.Comment: This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

3,6,8-Tribromo-7-ethyl­amino-4-methyl-2H-chromen-2-one

In the title mol­ecule, C12H10Br3NO2, the 2H-chromen ring is essentially planar (r.m.s. deviation = 0.022 Å) with the ethyl­amino group oriented at 13.9 (5)° with respect to the ring. The mol­ecular structure is stabilized by intra­molecular N—H⋯Br and C—H⋯Br interactions

Applications of computer vision in measuring total cumulative pitch deviation of a gear

Kao osnovni dio mehaničkog prijenosa, zupčanici bi trebali imati visoku točnost prijenosa te se stoga mjerenje točnosti zupčanika smatra ključnom tehnologijom. Na temelju postojećeg istraživanja, u ispitivanje zupčanika uvodi se tehnologija računalnog vida. U skladu s definicijama tehničkih pokazatelja kao što su odstupanje koraka zupčanika, debljine zuba itd., analizom i istraživanjem se predlaže nova metoda mjerenja kako bi se upotpunilo određivanje modula, broja zubi i sveukupnog odstupanja koraka zupčanika. U predloženim metodama, pokazatelji kao što su korak i debljina zuba, mjere se radije dužinom luka nego tetivom luka, tako da budu u skladu s njihovim definicijama. Mjerene točke mogu se pozicionirati na referentnom opsegu zupčanika dok se ispituju odstupanja koraka i ukupna odstupanja zajedničkog koraka. Konačno, zupčanik se mjeri predloženom metodom. Glavni se test dobiva na sljedeći način. Odstupanje pojedinog koraka je 10,3 μm, ukupno zajedničko odstupanje je 44,8 μm, a odstupanje debljine zuba je 5,2 μm. Ispitivanje pokazuje da je predložena metoda izvediva i učinkovita i može zadovoljiti potrebe za točnošću u strojarstvu. Rad daje novo rješenje za mjerenje zupčanika on-line.As the basic part of the mechanical transmission, gears should have high transmission accuracy, so the gear’s precision measurement is a key technology. Based on the existing research, the computer vision technology is introduced in gear test. According to the definitions of technical indexes, such as pitch deviation, tooth thickness deviation, etc., through analysis and research, a new measurement method is proposed, so as to complete the determination of the modulus, tooth number and total accumulated pitch deviation of a gear. In the proposed methods, those indexes such as the pitch and tooth thickness, are measured in arc length, rather than in chordal length, so that they are consistent with their definitions. And the measured points can be positioned on the reference circle of a gear while the pitch and total accumulative pitch deviations are examined. Finally, a gear is measured with the proposed method. The main test is obtained as follows. The single pitch deviation is 10,3 μm, total cumulative pitch deviation is 44,8 μm, and tooth thick deviation is 5,2 μm. The experiment demonstrates that the proposed method is feasible and effective, and can meet the precision need of engineering practice. This study provides a new solution method for the gear’s on-line measurement

Research on modeling and dynamic characteristics of complex coaxial rotor system

To make up deficiency of the finite element method in predicting nonlinear dynamic characteristics of coaxial rotor systems, nonlinear dynamic model of a coaxial rotor system was established with a method combining the finite element method and the fixed interface modal synthesis method. Then an implicit time domain method was presented to solve the nonlinear equations of motion thus dynamic characteristics of the rotor system can be obtained. The computational efficiency of this method largely depends on the number of degrees of freedom with nonlinear forces acting on. With nonlinear forces of squeeze film damper and intermediate bearing considered, nonlinear dynamic response characteristics of the coaxial rotor system under multiple unbalance forces were studied in this work. The results showed that the unbalance excitation frequencies are dominant in the responses of the rotor system. Besides, due to coupling effect of the intermediate bearing some combinations of the unbalance excitation frequencies were also observed in the spectrogram. Stability and periodicity of the rotor system was investigated with bifurcation diagram, Poincare map and phase diagram. It was found that the rotor system executes multiple periods orbital motion under relatively low rotational speeds. With the increasing of rotational speed, the rotor system would execute quasi-periodic motion, chaotic motion and periodic motion again. The quasi-periodic motion and chaotic motion are closely related with the SFD. Finally, under relatively low speed, the nonlinear model was validated by comparing the simulation results with the experimental data. The proposed modeling and solving method is expected to provide theoretical and engineering basis for improving prediction of nonlinear dynamic characteristics of complex rotor systems

3,6-Dibromo-7-ethyl­amino-4-methyl-2H-chromen-2-one

In title compound, C12H11Br2NO2, the coumarin ring system is almost planar, the two rings being inclined to one another by 1.40 (15)°. There are two short intra­molecular inter­actions (N—H⋯Br and C—H⋯Br) involving the Br atoms. In the crystal, mol­ecules stack along the a-axis direction via π–π inter­actions; the centroid–centroid distances vary from 3.6484 (19) to 3.7942 (19) Å