3,348 research outputs found
Hawking radiation-quasinormal modes correspondence for large AdS black holes
It is well-known that the non-strictly thermal character of the Hawking
radiation spectrum generates a natural correspondence between Hawking radiation
and black hole quasinormal modes. This main issue has been analyzed in the
framework of Schwarzschild black holes, Kerr black holes and nonextremal
Reissner-Nordstrom black holes. In this paper, by introducing the effective
temperature, we reanalysis the non-strictly thermal character of large AdS
black holes. The results show that the effective mass corresponding to the
effective temperature is approximatively the average one in any dimension. And
the other effective quantities can also be obtained. Based on the known forms
of frequency in quasinormal modes, we reanalysis the asymptotic frequencies of
the large AdS black hole in three and five dimensions. Then we get the formulas
of the Bekenstein-Hawking entropy and the horizon's area quantization with
functions of the quantum "overtone" number .Comment: 6 page
MM-PCQA: Multi-Modal Learning for No-reference Point Cloud Quality Assessment
The visual quality of point clouds has been greatly emphasized since the
ever-increasing 3D vision applications are expected to provide cost-effective
and high-quality experiences for users. Looking back on the development of
point cloud quality assessment (PCQA) methods, the visual quality is usually
evaluated by utilizing single-modal information, i.e., either extracted from
the 2D projections or 3D point cloud. The 2D projections contain rich texture
and semantic information but are highly dependent on viewpoints, while the 3D
point clouds are more sensitive to geometry distortions and invariant to
viewpoints. Therefore, to leverage the advantages of both point cloud and
projected image modalities, we propose a novel no-reference point cloud quality
assessment (NR-PCQA) metric in a multi-modal fashion. In specific, we split the
point clouds into sub-models to represent local geometry distortions such as
point shift and down-sampling. Then we render the point clouds into 2D image
projections for texture feature extraction. To achieve the goals, the
sub-models and projected images are encoded with point-based and image-based
neural networks. Finally, symmetric cross-modal attention is employed to fuse
multi-modal quality-aware information. Experimental results show that our
approach outperforms all compared state-of-the-art methods and is far ahead of
previous NR-PCQA methods, which highlights the effectiveness of the proposed
method. The code is available at https://github.com/zzc-1998/MM-PCQA
Sliding-Mode-Observer-Based Position Estimation for Sensorless Control of the Planar Switched Reluctance Motor
This paper proposes a position estimation method for a planar switched reluctance motor (PSRM). In the method, a second-order sliding mode observer (SMO) is used to achieve sensorless control of a PSRM for the first time. A sensorless closed-loop control strategy based on the SMO without a position sensor for the PSRM is constructed. The SMO mainly consists of a flux linkage estimation, an adaptive current estimation, an observing error calculation, and a position estimation section. An adaptive current observer is applied in the current estimation section to minimize the error between the measured and estimated currents and to increase the accuracy of the position estimation. The flux linkage is estimated by the voltage equation of the PSRM, and the estimated flux linkage is then used to estimate the phase current in the adaptive current observer. To calculate the observing error of the SMO using the measured and estimated phase currents, the observing error of the thrust force is introduced to replace the immeasurable state error of the position and speed of the mover. The sliding surface is designed based on the error of the thrust force, and stability analysis is given. Once the sliding surface is reached, the mover position is then estimated accurately. Finally, the effectiveness of the proposed method for the PSRM is verified experimentally
1β,10α:4β,5α-Diepoxy-7αH-germacran-6β-ol monohydrate
In the title compound, C15H26O3·H2O, a sesquiterpenoid molecule with a germacrene backbone that contains two epoxide groups and one hydroxyl group. Intermolecular O—H⋯O hydrogen bonds between the epoxy groups and solvent water molecules give rise to an infinite three-dimensional supramolecular structure
Subjective and Objective Quality Assessment for in-the-Wild Computer Graphics Images
Computer graphics images (CGIs) are artificially generated by means of
computer programs and are widely perceived under various scenarios, such as
games, streaming media, etc. In practical, the quality of CGIs consistently
suffers from poor rendering during the production and inevitable compression
artifacts during the transmission of multimedia applications. However, few
works have been dedicated to dealing with the challenge of computer graphics
images quality assessment (CGIQA). Most image quality assessment (IQA) metrics
are developed for natural scene images (NSIs) and validated on the databases
consisting of NSIs with synthetic distortions, which are not suitable for
in-the-wild CGIs. To bridge the gap between evaluating the quality of NSIs and
CGIs, we construct a large-scale in-the-wild CGIQA database consisting of 6,000
CGIs (CGIQA-6k) and carry out the subjective experiment in a well-controlled
laboratory environment to obtain the accurate perceptual ratings of the CGIs.
Then, we propose an effective deep learning-based no-reference (NR) IQA model
by utilizing multi-stage feature fusion strategy and multi-stage channel
attention mechanism. The major motivation of the proposed model is to make full
use of inter-channel information from low-level to high-level since CGIs have
apparent patterns as well as rich interactive semantic content. Experimental
results show that the proposed method outperforms all other state-of-the-art NR
IQA methods on the constructed CGIQA-6k database and other CGIQA-related
databases. The database along with the code will be released to facilitate
further research
Fasciolopsis buski (Digenea: Fasciolidae) from China and India may represent distinct taxa based on mitochondrial and nuclear ribosomal DNA sequences
Sequences of primers used to amplify fragments of Fasciolopsis buski mitochondrial genome. (DOCX 17 kb
Organic carbon amendments affect the chemodiversity of soil dissolved organic matter and its associations with soil microbial communities
The “4 per mil” initiative recognizes the pivotal role of soil in carbon re-sequestration. The need for evidence to substantiate the influence of agricultural practices on chemical nature of soil carbon and microbial biodiversity has become a priority. However, owing to the molecular complexity of soil dissolved organic matter (DOM), specific linkages to microbial biodiversity have eluded researchers. Here, we characterized the chemodiversity of soil DOM, assessed the variation of soil bacterial community composition (BCC) and identified specific linkages between DOM traits and BCC. Sustained organic carbon amendment significantly (P < 0.05) increased total organic matter reservoirs, resulted in higher chemodiversity of DOM and emergence of recalcitrant moieties (H/C < 1.5). In the meantime, sustained organic carbon amendment shaped the BCC to a more eutrophic state while long-term chemical fertilization directed the BCC towards an oligotrophic state. Meanwhile, higher connectivity and complexity were observed in organic carbon amendment by DOM-BCC network analysis, indicating that soil microbes tended to have more interaction with DOM molecules after organic matter inputs. These results highlight the potential for organic carbon amendments to not only build soil carbon stocks and increase their resilience but also mediate the functional state of soil bacterial communities
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