ABSTRACT
Sparse array design (SAD) optimizes the geometrical configuration of the loudspeaker array. It provides possibilities for further improving the performance of personal sound zone (PSZ). In this paper, the SAD problem in PSZ is formulated as a sparse multi-objective optimization problem, which takes multiple performance metrics into consideration during the sparsity promotion procedure. A swap-based group search algorithm is designed and proposed for solving the formulated non-convex and combinatorial problem to near-optimality. An approximate form is also proposed for reducing computational burden when there exist multiple target sound fields in bright zone. Simulation and experimental results suggest that the proposed method is more suitable in PSZ for controlling over trade-offs and achieving the same good or even better performances, and the proposed approximate form is effective.
ABSTRACT
The aim of multizone sound reproduction is to reproduce different sound programs to different spatial zones in a common space using a set of loudspeakers. Several multizone sound reproduction methods have been developed over the past few decades, and most of them assume that there are no listeners in the listening area. However, when listeners enter the listening area, the scattering effects will reduce the performance of the multizone sound reproduction system. In this paper, an adaptive control method of scattering effects is proposed for multizone sound reproduction. The proposed method models the scattering effects based on the equivalent source method and uses adaptive filters to estimate the scattering effect by a small number of additional microphones. To validate the proposed method, several simulations are presented. The results of the simulations indicate that the proposed adaptive method exhibits good performance when used in multizone sound reproduction with the scattering effects.
ABSTRACT
Sound projection is a method of using highly focused sources to project sound onto reflective surfaces to create the impression of surround sound, which can be realized via beamforming using loudspeaker arrays. Generally, these devices are mounted near a surface with a finite acoustic impedance, such as a TV accent wall. The beamforming performance degrades in this half-space with an impedance boundary when the filters are designed using transfer functions measured in the free field. This paper proposes a model for predicting the beamforming performance in a half-space with an impedance boundary in terms of the transfer functions in the free field. A mathematical model is presented, and the results are compared with practical measurements for a 16-driver line array in real-use environments. The results show that reflections from the boundary lead to "dark bands" in the beam, causing the beam to deviate from the designed direction. Using filters designed with transfer functions calculated by the proposed model yields improved beamforming performance.
ABSTRACT
Personal Sound Zone (PSZ) allows listeners to enjoy their individual sound without being disturbed by sound from other zones. Acoustic contrast, signal distortion, and array effort are the most frequently used metrics for measuring the performance of a PSZ system. However, usually, the three metrics cannot be optimized at the same time. A trade-off between the three metrics has to be made when designing a PSZ system. In this paper, two generalized methods based on multi-objective optimization are proposed for dealing with all possible trade-off problems between the three metrics in PSZ. Optimality analysis of the two proposed methods is taken, and the relationship between the two proposed methods is investigated. Numerical simulations are presented to validate the efficacy and flexibility of the two proposed methods.
ABSTRACT
Objective: Irritable bowel syndrome (IBS) is characterized by abdominal pain, bloating, and stool irregularity. However, its pathophysiological mechanisms, which trigger intestinal motility disorders and diarrhea leading to diarrhea-predominant IBS (D-IBS), remain largely unknown. Methods: In the present study, we established a D-IBS rat model by mother-infant separation combined with restraint stress. Then we exposed the modelled rats to suberoylanilide hydroxamic acid (SAHA) treatment, followed by determination of their visceral sensitivity. Toluidine blue staining served to reveal the effects of SAHA treatment on mast cells of D-IBS model rats. Then we measured the expression of serotonin (5-hydroxytryptamine; 5-HT) and its receptors by ELISA. Results: Construction of short hairpin RNA (sh)-serotonin transporter (SERT) lentivirus vectors verified the regulation of the 5-HT signaling pathway by phosphorylated (p)-STAT/SERT. SAHA treatment of D-IBS model rats reduced the fecal water content, electromyography integral change rate, abdominal withdrawal reflex score, and number of mast cells, as well as the expression of 5-HT type 3A (5-HT3AR), 3B receptor (5-HT3BR), and 4 receptor (5-HT4R) receptors. The treatment also elevated the expression of signal transducer and activator for transcription 3 (STAT3) and SERT. Activation of p-STAT3 may reverse the inhibitory effect of SAHA on the elevated visceral sensitivity of D-IBS model rats. Moreover, SAHA promoted the transcription of SERT through repression of the p-STAT3/5-HT signaling, thereby inhibiting the visceral sensitivity of D-IBS model rats. Conclusion: This study highlights that SAHA treatment can alleviate D-IBS through regulation of the p-STAT3/SERT/5-HT signaling pathway.
ABSTRACT
OBJECTIVE: This study was aimed to explore effect of baicalin on IKK/IKB/NF-kB signaling pathway and apoptosis-related proteins in rats with ulcerative colitis (UC). METHODS: Histopathological observation and scores of colon tissue were performed in the UC rat model. IKK/IKB/NF-kB signaling pathway and apoptosis-related proteins were measured by Western blotting. RESULTS: Baicalin significantly increased the activity of SOD, CAT and GSH-Px in colon tissue of rats with UC, but significantly decreased the content of MDA, IL-1ß, MPO, PEG2 and TNF-α in colon tissue of rats with UC. In the molecular mechanism, baicalin significantly decreased the expression of cleaved-caspase3, cleaved-caspase9, Bcl-2/Bax, cyt-c, NF-kB p-65, p-IKKß/IKKß and p-IKBα/IKBα. Baicalin could significantly inhibit p-IKBα/IKBα content change, but had no significant effect on p-IKKß/IKKß. CONCLUSION: Baicalin may have a regulating effect on IKK/IKB/NF-kB signaling pathway and apoptosis-related proteins in UC rats.
