Influence of hydraulic engine mounts on engine shake based on full vehicle model

This work proposes a full vehicle model including hydraulic engine mounts (HEMs) to better describe the characteristics of the vehicle engine shake performance. The model consists of 14 degree of freedoms (DOFs), namely 6 of the powertrain, 1 of the fluid within the inertia track of the HEM, 3 of the car body and 4 of the unsprung mass. Simulation based on the model is performed to demonstrate how the powertrain mounting system including the HEM influences the frequency response of vehicle subjected to harmonic excitations from road

Experimental NVH evaluation of a pure electric vehicle in transient operation modes

Many driving schools adopt existing vehicle platform for integration with electric powertrains to reduce fuel consumptions. The special car consists of a conventional manual transmission but a driving motor for driving instruction. This modification can create unique challenges for noise, vibration and harshness (NVH) refinement. This paper presents an experimental NVH evaluation of the special electric vehicle, which lays more emphasis on transient operations. The powertrain mounting system, the driving motor and the transmission are tested and their NVH performances are analyzed at different transient modes. The results indicate that the transmission and the final drive contribute to the medium frequency range of interior noise due to the missing masking of the internal combustion engine. In addition, the vibration isolation performance of electric powertrain mounting system is assessed by calculating transmissibility characteristics of the powertrain mounts. It is pointed out that the transmissibility of 20 dB, which means ninety percent of the vibration energy has been reduced, may no longer be suitable for an electric powertrain mounting system. Furthermore, interior vibration behaviors such as the acceleration amplitude of seat track should be subordinated to the assessment of the powertrain mounting system

Role of metal-dependent regulation of ESX-3 secretion in intracellular survival of Mycobacterium tuberculosis

More people die every year from Mycobacterium tuberculosis infection than from infection by any other bacterial pathogen. Type VII secretion systems (T7SS) are used by both environmental and pathogenic mycobacteria to secrete proteins across their complex cell envelope. In the nonpathogen Mycobacterium smegmatis, the ESX-1 T7SS plays a role in conjugation, and the ESX-3 T7SS is involved in metal homeostasis. In M. tuberculosis, these secretion systems have taken on roles in virulence, and they also are targets of the host immune response. ESX-3 secretes a heterodimer composed of EsxG (TB9.8) and EsxH (TB10.4), which impairs phagosome maturation in macrophages and is essential for virulence in mice. Given the importance of EsxG and EsxH during infection, we examined their regulation. With M. tuberculosis, the secretion of EsxG and EsxH was regulated in response to iron and zinc, in accordance with the previously described transcriptional response of the esx-3 locus to these metals. While iron regulated the esx-3 expression in both M. tuberculosis and M. smegmatis, there is a significant difference in the dynamics of this regulation. In M. smegmatis, the esx-3 locus behaved like other iron-regulated genes such as mbtB. In M. tuberculosis, both iron and zinc modestly repressed esx-3 expression. Diminished secretion of EsxG and EsxH in response to these metals altered the interaction of M. tuberculosis with macrophages, leading to impaired intracellular M. tuberculosis survival. Our findings detail the regulatory differences of esx-3 in M. tuberculosis and M. smegmatis and demonstrate the importance of metal-dependent regulation of ESX-3 for virulence in M. tuberculosis

The contribution of the smartphone use to reducing depressive symptoms of Chinese older adults: The mediating effect of social participation

BackgroundDepression is a prevalent mental health disorder. Although Internet use has been associated with depression, there is limited data on the association between smartphone use and depressive symptoms. The present study aimed to investigate the relationship between smartphone use and depressive symptoms among older individuals in China.Methods5,244 Chinese older individuals over the age of 60 were selected as the sample from the China Longitudinal Aging Social Survey (CLASS) 2018 dataset. The dependent variable “depression symptoms” was measured using the 9-item Center for Epidemiologic Studies-Depression (CES-D) scale. The study employed multiple linear regression to investigate the relationship between smartphone use (independent variable) and depressive symptoms in older people. Thorough analyses of robustness, sensitivity, and heterogeneity were conducted to ensure the robustness and sensitivity of the findings. Additionally, mediating effect analysis was performed to elucidate the mechanism through which the dependent and independent variables were related.ResultsEmpirical study indicated that smartphone use had a negative impact on depressive symptoms among older adults, specifically leading to a reduction in such symptoms. The above-mentioned result was verified through endogenous and robustness tests. The heterogeneity analysis revealed that older individuals aged 70 years and above, male, and residing in urban areas exhibited a stronger association between smartphone use and depressive symptoms. Furthermore, the mediating effect model indicated that political participation, voluntary participation, and active leisure participation mediated the relationship between smartphone use and lower levels of depression symptoms among the older adults. However, passive leisure participation had a suppressing effect on the relationship between smartphone use and reduced depressive symptoms among the older adults.LimitationsThe causal relationship between variables required further investigation with a longitudinal design.ConclusionThese findings suggested that smartphone use may be considered an intervention to reduce depression symptoms among older people by increasing levels of political participation, voluntary participation, and active leisure participation

Prediction and Study of Air Thermal Parameters in Unexploited Mine Regions Based on Temperature Prediction Model in Whole Ventilation Network

AbstractMines with heat disaster danger have been increased year by year, in order to provide basic data for mine air- conditioning design, prediction of air thermal parameters in the mine unexploited region becomes particularly important. But at present, prediction of air thermal parameters is realized mainly by empirical formula and forecast method of single-line(main trunk road method), existing many disadvantages such as strong individual subjectivity, bad theoretical property and low forecasting precision. Therefore, a kind of air temperature prediction model in whole ventilation network based on wind enthalpy equation is put forward. By the model, air temperature prediction software in whole ventilation network which can make reasonable forecast of thermal parameters for different high temperature mines is programmed by determining air thermal parameters through wind energy equation and considering the influence of natural wind pressure. Through the prediction of the air thermal parameters of the wind route in the fifth mining area in east wing of Dongtan colliery, it can be seen that air temperature prediction model in whole ventilation network is scientific, reasonable and with strong operating nature, which can meet the requirements of the prediction of air thermal parameters in unexploited region of high temperature mines