Study on barrel vibration characteristics of typical sniper rifle

The firing accuracy of sniper rifle is significantly affected by the barrel vibration induced by shooting load. The barrel vibration is an important parameter needing to be precisely controlled, whose measurement is less studied before. The vertical vibration characteristics of sniper rifle barrel is obtained for the duration of 500 ms with high speed photography system. Both the averaged vibration frequency and maximum amplitude of the measured muzzle are gained. It is found from the test that after the appearance of the maximum value, the vibration amplitude of the muzzle reduces with nearly fixed vibration frequency. In addition, the finite element model is conducted for the barrel vibration regarding sniper rifle. And then the natural frequency as well as the vibration reflection of the barrel under the effort of shooting load is calculated with the model. The model accuracy is well validated for the numerical results are substantially in line with the measurements

Exactly solvable configuration mixing scheme in the vibrational limit of the interacting boson model

An intruder configuration mixing scheme with 2n-particle and 2n-hole configurations from n=0 up to n→ in the U(5) (vibrational) limit of the interacting boson model is proposed. A simple Hamiltonian suitable to describe the intruder and normal configuration mixing is found to be exactly solvable, and its eigenstates can be expressed as the SU(1,1) coherent states built on the U(5) basis vectors of the interacting boson model. It is shown that the configuration mixing scheme keeps lower part of the vibrational spectrum unchanged and generates the intruder states due to the mixing. Some low-lying level energies and experimentally known B(E2) ratios of Cd108,110 are fitted and compared with the experimental results

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

Algebraic Number Precoded OFDM Transmission for Asynchronous Cooperative Multirelay Networks

This paper proposes a space-time block coding (STBC) transmission scheme for asynchronous cooperative systems. By combination of rotated complex constellations and Hadamard transform, these constructed codes are capable of achieving full cooperative diversity with the analysis of the pairwise error probability (PEP). Due to the asynchronous characteristic of cooperative systems, orthogonal frequency division multiplexing (OFDM) technique with cyclic prefix (CP) is adopted for combating timing delays from relay nodes. The total transmit power across the entire network is fixed and appropriate power allocation can be implemented to optimize the network performance. The relay nodes do not require decoding and demodulation operation, resulting in a low complexity. Besides, there is no delay for forwarding the OFDM symbols to the destination node. At the destination node the received signals have the corresponding STBC structure on each subcarrier. In order to reduce the decoding complexity, the sphere decoder is implemented for fast data decoding. Bit error rate (BER) performance demonstrates the effectiveness of the proposed scheme

Discovery of novel dsRNA viral sequences by in silico cloning and implications for viral diversity, host range and evolution

Genome sequence of viruses can contribute greatly to the study of viral evolution, diversity and the interaction between viruses and hosts. Traditional molecular cloning methods for obtaining RNA viral genomes are time-consuming and often difficult because many viruses occur in extremely low titers. DsRNA viruses in the families, Partitiviridae, Totiviridae, Endornaviridae, Chrysoviridae, and other related unclassified dsRNA viruses are generally associated with symptomless or persistent infections of their hosts. These characteristics indicate that samples or materials derived from eukaryotic organisms used to construct cDNA libraries and EST sequencing might carry these viruses, which were not easily detected by the researchers. Therefore, the EST databases may include numerous unknown viral sequences. In this study, we performed in silico cloning, a procedure for obtaining full or partial cDNA sequence of a gene by bioinformatics analysis, using known dsRNA viral sequences as queries to search against NCBI Expressed Sequence Tag (EST) database. From this analysis, we obtained 119 novel virus-like sequences related to members of the families, Endornaviridae, Chrysoviridae, Partitiviridae, and Totiviridae. Many of them were identified in cDNA libraries of eukaryotic lineages, which were not known to be hosts for these viruses. Furthermore, comprehensive phylogenetic analysis of these newly discovered virus-like sequences with known dsRNA viruses revealed that these dsRNA viruses may have co-evolved with respective host supergroups over a long evolutionary time while potential horizontal transmissions of viruses between different host supergroups also is possible. We also found that some of the plant partitiviruses may have originated from fungal viruses by horizontal transmissions. These findings extend our knowledge of the diversity and possible host range of dsRNA viruses and offer insight into the origin and evolution of relevant viruses with their hosts