Effects of interval friction coefficients on the differential mechanism dynamics

The presence of a differential mechanism is fundamental in most automotive applications. Its importance stems from allowing a vehicle to take a curve. The differential should be well-lubricated to ensure its smooth operation and mitigate its vibration level. With lubrication conditions deteriorating over time, the sliding friction coefficient becomes difficult to predict its accurate value. Thus, scrutinizing the dynamic performance of the mechanism with deterministic sliding friction can be misleading. This paper aims to investigate the dynamic performance of the automotive differential with the presence of interval sliding friction. To this end, a 3D dimensional model of automotive differential with time-varying mesh stiffness (TVMS) and bearing flexibility is proposed. The influence of sliding friction on TVMS for straight bevel gear is revealed. The Newton-Euler formulation is used to derive the dynamic equations governing the motions of the automotive differential with friction. The Chebyshev inclusion function and the least square method are used to deal with the interval mathematical formulation of the model. The scanning method is used as a reference method in this paper. There are quite similarities between the results derived by the scanning method and that of the interval process method. The reliability analysis of the differential is conducted. The outcome of this research shows that any variation of the sliding friction can alter the dynamic performance of the differential significantly. The differential is more sensitive to the friction coefficient between the ring gear and the drive pinion and between the left-side gear and two planets. The findings should make an important contribution to the analysis of the differential mechanism.

Integrated Metabolomic and Transcriptomic Analysis Reveals Differential Mechanism of Flavonoid Biosynthesis in Two Cultivars of Angelica sinensis

Angelica sinensis is a traditional Chinese medicinal plant that has been primarily used as a blood tonic. It largely relies on its bioactive metabolites, which include ferulic acid, volatile oils, polysaccharides and flavonoids. In order to improve the yield and quality of A. sinensis, the two cultivars Mingui 1 (M1), with a purple stem, and Mingui 2 (M2), with a green stem, have been selected in the field. Although a higher root yield and ferulic acid content in M1 than M2 has been observed, the differences of flavonoid biosynthesis and stem-color formation are still limited. In this study, the contents of flavonoids and anthocyanins were determined by spectrophotometer, the differences of flavonoids and transcripts in M1 and M2 were conducted by metabolomic and transcriptomic analysis, and the expression level of candidate genes was validated by qRT-PCR. The results showed that the contents of flavonoids and anthocyanins were 1.5- and 2.6-fold greater in M1 than M2, respectively. A total of 26 differentially accumulated flavonoids (DAFs) with 19 up-regulated (UR) and seven down-regulated (DR) were obtained from the 131 identified flavonoids (e.g., flavonols, flavonoid, isoflavones, and anthocyanins) in M1 vs. M2. A total 2210 differentially expressed genes (DEGs) were obtained from the 34,528 full-length isoforms in M1 vs. M2, and 29 DEGs with 24 UR and 5 DR were identified to be involved in flavonoid biosynthesis, with 25 genes (e.g., CHS1, CHI3, F3H, DFR, ANS, CYPs and UGTs) mapped on the flavonoid biosynthetic pathway and four genes (e.g., RL1, RL6, MYB90 and MYB114) belonging to transcription factors. The differential accumulation level of flavonoids is coherent with the expression level of candidate genes. Finally, the network of DAFs regulated by DEGs was proposed. These findings will provide references for flavonoid production and cultivars selection of A. sinensis.

Comparative Proteomics Reveals Differential Mechanism of Root Cold-resistance between Vitis. Riparia × V. Labrusca and Cabernet Sauvignon

Grapevines, containing large amounts of bioactive metabolites that offer health benefits, are widely cultivated around the world. The cold damage of growing outside with extreme low temperature during overwintering stage limits the expansion of production. Although the levels of morphological, biochemical and molecular in different Vitis species exposure to different temperatures have been investigated, differential expression of proteins in roots is still limited. Here, the roots of cold-resistant (Vitis. riparia × V. labrusca, T1) and cold-sensitive varieties (Cabernet Sauvignon, T3) at −4°C as well as of the former at −15°C (T2) were measured by iTRAQ-based proteomic analysis, expression levels of genes encoding candidate proteins were validated by qRT-PCR. The results showed that the root activity of cold-resistant variety was stronger than that of cold-sensitive variety, and it declined with the decrease of temperature. A total of 25 proteins were differentially co-expressed at T2 versus (vs) T1 and T1 vs T3, and these proteins were involved in stress response (e.g. DHN1, SHSPCP and USPCP), bio-signaling (e.g. PKCP, S/TPP and nsS/TP), metabolism (e.g. GluP, GluBE and PE), energy (e.g. AAC, AAACP and NADCP), and translation (e.g. rpL14, rpS21 and PPI). The relative expression levels of the candidate 13 genes were consistent with their fold-change values of proteins. The signature translation pattern for the roots at spatio-temporal treatments of varieties and temperatures provides insight into the differential mechanism of cold resistance of grapevines.

Modeling The Sport Differential Mechanism

The study is devoted to the issues of mathematical modeling and simulating the sport differential mechanism (DM) with controllable torque redistribution. The issue is caused by the elaboration of ADAS systems with the automated torque vectoring for transmissions of all-wheel-drive (AWD) vehicles and the inclusion of such devices in the combined autonomous vehicle trajectory control scheme. At the article's beginning, the use of devices for redistributing traction forces is reasoned by analyzing the curvilinear vehicle motion, where they could ensure the accuracy of vehicle steerability. The literature review highlights modern developments in the field of modeling and researching such DMs. Considering the vehicle turn with a minimum radius, the conditions corresponding to passing greater torque over the outrunning rear axle are determined. All the mechanism's components and loads acting between them are described in detail. To form an original method of mathematical description of the mechanism functioning, the system of differential equations, systems of kinematic and force connections are considered separately. The article details the mathematical approach to generalize the way for automating the equation compilation for rotational mechanical systems such as vehicle transmissions. In the simulation section, a Simulink model reflecting the functional components and calculation procedures is presented. A series of testing and simulations on the DM operation with forcible torque distribution is carried out. Modeling data are presented, and the analysis of simulation results is performed. In the completion, conclusions are made regarding the scope and use of this model and the prospects for further developing the method proposed to automate the formation of equation systems.