关键词：
Density functional theory;Surface oxygen;Kinetics analysis;Sensing mechanism;SnO2(110)
摘要：
Surface oxygen species play a key role in determining the chemi-resistive gas sensing performance of SnO2. 2 . Through surface modification, the type of oxygen species at different working temperatures can be modulated, leading to changes in carrier concentration and surface activity. Single atom structures (SAS) hold enormous potential in the gas sensing domain; however, the impact of different SAS on surface oxygen species on SnO2 2 remains unclear, resulting in inconsistent improvements in sensing properties. This study conducted a theoretical investigation of different 4d noble metal SAS (Ru, Rh, and Pd) modified SnO2(1 2 (1 10) surface, encompassing both electronic and chemical sensitization. All three SAS, when substituting penta-coordinated Sn atom (Sn5c), 5 c ), can inject holes and create a thicker depletion layer to varying degrees. Ru and Rh SAS can accelerate the decomposition of adsorbed O2 2 and O3. 3 . More importantly, Ru and Rh can hinder the combination of adsorbed O* species with adjacent two-coordinated lattice oxygen (O2c), 2 c ), enhancing the chemical stability of O*, which plays a decisive role in detecting reducing gases, with Ru exhibiting a better effect. This theoretical work not only enhances methods and mechanisms for adjusting surface oxygen species and improving the sensing performance of SnO2-based 2-based gas sensors, but also provides useful guidance for screening and designing SAS in experimental procedures on different semiconductor metal oxide surfaces.
通讯机构：
[Zhang, C ] W;Wuhan Polytech Univ, Sch Elect & Elect Engn, Wuhan 430048, Peoples R China.
关键词：
personal audio system;sound field control;acoustic contrast;reconstruction error;array effort
摘要：
<jats:p>A personal audio system has a wide application prospect in people’s lives, which can be implemented by sound field control technology. However, the current sound field control technology is mainly based on sound pressure or its improvement, ignoring another physical property of sound: particle velocity, which is not conducive to the stability of the entire reconstruction system. To address the problem, a sound field method is constructed in this paper, which minimizes the reconstruction error in the bright zone, minimizes the loudspeaker array effort in the reconstruction system, and at the same time controls the particle velocity and sound pressure of the dark zone. Five unevenly placed loudspeakers were used as the initial setup for the computer simulation experiment. Simulation results suggest that the proposed method is better than the PM (pressure matching) and EDPM (eigen decomposition pseudoinverse method) methods in the bright zone in an acoustic contrast index, the ACC (acoustic contrast control) method in a reconstruction error index, and the ACC, PM, and EDPM methods in the bright zone in a loudspeaker array effort index. The average array effort of the proposed method is the smallest, which is about 9.4790, 8.0712, and 4.8176 dB less than that of the ACC method, the PM method in the bright zone, and the EDPM method in the bright zone, respectively, so the proposed method can produce the most stable reconstruction system when the loudspeaker system is not evenly placed. The results of computer experiments demonstrate the performance of the proposed method, and suggest that compared with traditional methods, the proposed method can achieve more balanced results in the three indexes of acoustic contrast, reconstruction error, and loudspeaker array effort on the whole.</jats:p>
摘要：
Urban sound event detection can automatically preload relevant information for a robot to ensure that it can be applied to various scene-activity tasks. To address the limitations of timbre similarity and scene recognition by audio collection devices, a fusion model based on the self-attention mechanism is proposed in this paper. The model consists of scattering transform and self-attention model. The scattering transform computes modulation spectrum coefficients of multiple orders through cascades of wavelet convolutions and modulus operators. It is learnable compared with Mel-scale Frequency Cepstral Coefficients (MFCC), and can be used to better restore the semantic features of some sound scenes with similar timbres. The transformer has an outstanding effect on Natural Language Processing (NLP) owing to its self-attention mechanism. In this paper, the self-attention mechanism in its encoder was used in the model, mainly to make the feature granularity consistent to refine the features. In addition, Focal Loss function was adopted in the model to curb the sample distribution imbalance. The Google Command and ESC-50 were used to supplement the scene categories of dataset UrbanSound8K. The model parameters of the learnable filters that performed well on the dataset UrbanSound8K were preserved to fine-tune the other two datasets with insufficient data volume and more target categories. The length of slice duration was further explored the in the model. The experimental results show that the model can achieve better performance in a large range of scene models.
关键词：
Energy consumption;named data networking;underwater acoustic sensor networks
摘要：
In recent years, a typical representation of the next-generation Internet architecture, named data networking (NDN), and a critical form of the underwater Internet of Things (IoT), underwater acoustic sensor networks (UASNs), have attracted widespread attention in academia. Meanwhile, since the battery energy of the sensor node is limited and the battery is difficult to replace or recharge in underwater environments, extending the networks' lifetime has become a key issue in UASNs. In this paper, we try to deploy a UASN on NDN architecture and explore the energy consumption of the NDN-based UASN under shallow water and deep water conditions based on the relay network topology. A simulation is carried out to compare the delay performance of NDN-based and IP-based UASNs and validate the result. It is believed that the study could provide a theoretical criterion for the selection of the direct or relay path to optimize energy consumption in the future deployment of NDN-based UASNs.
摘要：
This paper mainly introduces the basic principles of BCH code, which is a type of error control codes. The error control system is an important method to improve the communication transmission system. Communication system that containing BPSK modulation is built by MATLAB and through simulating and analyzing the performance of BCH communication systems, it was discovered that the BCH code transmission characteristic has significant gain. This paper provides the theory basis for the projects that contain BCH code.
期刊：
Lecture Notes in Electrical Engineering,2013年227 LNEE(VOL. 5):679-686 ISSN：1876-1100
通讯作者：
Chen, X.(xfangchen@126.com)
作者机构：
[Chen, Xiufang] College of Electrical and Electronic Engineering, Wuhan Polytechnic University, Wuhan, China;[Zhang, Chaoping] Department of Physical and Electronic Engineering, Leshan Normal University, Leshan, China
