Experimental study on nanoparticle deposition in straight pipe flow

Loss of the number of nanoparticles within pipe may lead to significant change of particle number distribution, total mass concentration and particles mean size. The experiments of multiple dispersion aerosol particles ranging from 5.6 nm to 560 nm in straight pipe are carried out using a fast mobility particle sizer. The particle size number distribution, total number concentrations, geometric mean size and volume are acquired under different pipe lengths and Reynolds numbers. The results show lengthening the pipe and strengthening the turbulence can promote the particle deposition process. The penetration efficiency of smaller particle is lower than the larger one, so the particle mean size increases in the process of deposition

The Hazards of Growing Up: A Study of the Changing Mechanisms of Bullying Among Girls in Shenzhen

Among the many contending theories of bullying, the widely accepted thesis known as frustration-aggression assumes that bullying is a form of aggressive behavior induced by external stress. Recently, researchers have discovered that the relationship between external stressors and bullying is sometimes moderated by internal frustration. The present investigation is an attempt to examine which of the above mechanisms can better explain female students’ bullying behaviors. Data analysis, using structural equation modeling, was based on 1,069 girls selected from 14 primary schools and 16 junior secondary schools in Shenzhen, China. The result of the analysis suggests that while bullying by girls in primary schools is directly related to external stress, bullying in secondary schools is moderated by internal frustration. The authors suggest that several risk factors, namely, (a) the competitiveness of the education system, (b) socialization processes within families and schools, and (c) developmental changes in females during puberty, may be contributing to the difference between bullying mechanisms in primary and secondary schools. Parmi les nombreuses théories contraires portant sur l'intimidation, la thèse largement acceptée, connue sous le nom de frustration-agression postule que l'intimidation est une forme de comportement agressif provoqué par le stress externe. Les chercheurs ont récemment découvert que le rapport entre les agents de stress externes et l'intimidation est parfois modéré par la frustration interne. La présente étude vise à déterminer lesquels de ces mécanismes expliquent le mieux les comportements d'intimidation par les élèves. L'analyse de données, suivant la modélisation par équation structurelle, était basée sur 1 069 filles sélectionnées de 14 écoles primaires et 16 écoles secondaires à Shenzhen, en Chine. Les résultats de l'analyse donnent à penser que l'intimidation par les filles à l'école primaire est directement liée au stress externe, alors que l'intimidation à l'école secondaire est modérée par la frustration interne. Les auteurs proposent qu'il est possible que plusieurs facteurs de risque, notamment (a) la compétitivité du système d'éducation, (b) les processus de socialisation en sein des familles et des écoles et (c) les changements de croissance chez les filles pendant la puberté, contribuent aux différences entre les mécanismes d'intimidation à l'école primaire et à l'école secondaire

Power Allocation and Time-Domain Artificial Noise Design for Wiretap OFDM with Discrete Inputs

Optimal power allocation for orthogonal frequency division multiplexing (OFDM) wiretap channels with Gaussian channel inputs has already been studied in some previous works from an information theoretical viewpoint. However, these results are not sufficient for practical system design. One reason is that discrete channel inputs, such as quadrature amplitude modulation (QAM) signals, instead of Gaussian channel inputs, are deployed in current practical wireless systems to maintain moderate peak transmission power and receiver complexity. In this paper, we investigate the power allocation and artificial noise design for OFDM wiretap channels with discrete channel inputs. We first prove that the secrecy rate function for discrete channel inputs is nonconcave with respect to the transmission power. To resolve the corresponding nonconvex secrecy rate maximization problem, we develop a low-complexity power allocation algorithm, which yields a duality gap diminishing in the order of O(1/\sqrt{N}), where N is the number of subcarriers of OFDM. We then show that independent frequency-domain artificial noise cannot improve the secrecy rate of single-antenna wiretap channels. Towards this end, we propose a novel time-domain artificial noise design which exploits temporal degrees of freedom provided by the cyclic prefix of OFDM systems {to jam the eavesdropper and boost the secrecy rate even with a single antenna at the transmitter}. Numerical results are provided to illustrate the performance of the proposed design schemes.Comment: 12 pages, 7 figures, accepted by IEEE Transactions on Wireless Communications, Jan. 201

The DKU-MSXF Diarization System for the VoxCeleb Speaker Recognition Challenge 2023

This paper describes the DKU-MSXF submission to track 4 of the VoxCeleb Speaker Recognition Challenge 2023 (VoxSRC-23). Our system pipeline contains voice activity detection, clustering-based diarization, overlapped speech detection, and target-speaker voice activity detection, where each procedure has a fused output from 3 sub-models. Finally, we fuse different clustering-based and TSVAD-based diarization systems using DOVER-Lap and achieve the 4.30% diarization error rate (DER), which ranks first place on track 4 of the challenge leaderboard

The DKU-MSXF Speaker Verification System for the VoxCeleb Speaker Recognition Challenge 2023

This paper is the system description of the DKU-MSXF System for the track1, track2 and track3 of the VoxCeleb Speaker Recognition Challenge 2023 (VoxSRC-23). For Track 1, we utilize a network structure based on ResNet for training. By constructing a cross-age QMF training set, we achieve a substantial improvement in system performance. For Track 2, we inherite the pre-trained model from Track 1 and conducte mixed training by incorporating the VoxBlink-clean dataset. In comparison to Track 1, the models incorporating VoxBlink-clean data exhibit a performance improvement by more than 10% relatively. For Track3, the semi-supervised domain adaptation task, a novel pseudo-labeling method based on triple thresholds and sub-center purification is adopted to make domain adaptation. The final submission achieves mDCF of 0.1243 in task1, mDCF of 0.1165 in Track 2 and EER of 4.952% in Track 3.Comment: arXiv admin note: text overlap with arXiv:2210.0509