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Traumatic brain injury (TBI) can be progressive and can lead to the development of a long‐term complication termed chronic traumatic encephalopathy. The mechanisms underlying the progressive changes are still unknown; however, studies have suggested that microglia‐mediated neuroinflammation in response to TBI may play a fundamental role. This study aimed to determine whether progranulin (PGRN), a major modulator of microglial activity, plays a role in the progressive damage following TBI. PGRN‐deficient and wild‐type mice were subjected to controlled cortical impact and were observed neuropathologically after 3 days, 7 days, and 5 months. Compared to sham and wild‐type mice, the PGRN‐deficient mice showed overall stronger microgliosis and astrocytosis. The astrocytosis involved broader areas than the microgliosis and was more prominent in the basal ganglia, hippocampus, and internal capsule in PGRN‐deficient mice. Ongoing neuronal death was uniquely observed in the hippocampal CA3 region of PGRN‐deficient mice at 5 months after TBI, accompanying the regional chronic microgliosis and astrocytosis involving the CA3 commissural pathway. In addition, there was M1 microglial polarization in the pericontusional area with activated TLR4/MyD88/NF‐κB signaling; however, the hippocampus showed only mild M1 polarization 7 days after TBI. Lastly, Morris water maze tests showed PGRN‐deficient mice had poorer spatial learning and memory 5 months after TBI than wild‐type or sham mice. The data indicated the PGRN deficiency caused TBI progression by promoting persistent microgliosis with microglial polarization and astrocytosis, as well as regional pathology in the hippocampus. The study suggests that PGRN should be evaluated as a potential therapy for TBI.

<div class="section abstract"><div class="htmlview paragraph">Tire cavity noise of pure electric vehicles is particularly prominent due to the absence of engine noise, which are usually eliminated by adding Helmholtz resonators with arbitrary transversal section to the wheel rims. This paper provides theoretical basis for accurately predicting and effectively improving acoustic performance of wheel resonators. A hybrid finite element method is developed to extract the transversal wavenumbers and eigenvectors, and the mode-matching scheme is employed to determine the transmission loss of the Helmholtz resonator. Based on the accuracy validation of this method, the matching design of the wheel resonators and the optimization method of tire cavity noise are studied. The identification method of the tire cavity resonance frequency is developed through the acoustic modal test. A scientific transmission loss target curve and fitness function are defined according to the noise characteristics. Combing the transmission loss prediction theory and particle swarm algorithm, the structural parameters of the wheel resonator are optimized. A remarkable attenuation of tire cavity resonance can be observed through test results.</div></div>

Since fuel cell vehicles have much higher heat dissipation requirements, 350-V high-voltage fans are adopted instead of traditional 12-V cooling fans, generating more aerodynamic noise. The installed fans are required to possess not only low sound pressure level but also good psychoacoustic performance. This paper is aimed at solving the complex correlation between subjective sound quality evaluation results and objective psychoacoustics parameters and establishing a sound quality prediction model for high-voltage fans. The noise signals of two high-voltage fans operating on a fuel cell vehicle under different running conditions are collected by an artificial head and preprocessed to acquire seven objective parameters. Then the subjective evaluation experiment on the annoyance of the noise samples is carried out based on pair-wise comparison method. A sample group of 23 adults is selected and a graphical user interface is programmed for test guiding. The subjective annoyance scores of the noise signals are obtained after data processing and effectiveness verification. By analyzing the tested results, the correlations between the subjective score and each of the single psychoacoustic parameters are summarized. Two sound quality prediction models are established by multiple linear regression and backpropagation neural network respectively, and the training results of the two methods are verified and compared, proving the reliability of neural network training results. With the established models, the sound quality of the high-voltage fans can be estimated effectively without complex subjective tests, contributing to improving the acoustic performance of fan products.

Acoustic properties of resonators installed in vehicle intake system are influenced by the high-speed airflow passing through, which causes errors between practical application and bench tests. In this paper, a test bench with airflow for measuring the resonator transmission loss is developed based on the principle of two-load method. Equipment types are selected and parameters calculation is presented. Effects of sound source protection devices on the performance of sound source are studied experimentally. A resistance resonator and several dissipative mufflers are mounted at the outlet of the vortex air pump to reduce airflow noise and verified to be effective. Finally, the transmission loss of a multi-chamber perforated resonator is measured with the developed test bench and effects of airflow on resonator acoustic properties are analyzed.