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Influence of friction characteristic on the performance of chain CVT drives

100%

Srivastava N. , Haque T.

Journal of KONES

2006

tom Vol. 13, No. 2

405-419

A continuously variable transmission (CVT) is an emerging automotive transmission technology that offers a continuum of gear ratios between desired limits. A chain CVT falls under the category of friction-limited drives as its performance and torque capacity rely significantly on the friction characteristic of the contact patch between the chain and the pulley. The present research focuses on developing models to understand the influence of different friction characteristics on the dynamic performance of a chain CVT drive. Since the friction characteristic of the contact patch may vary in accordance with the loading and design configurations, it is crucial to study the influence of friction characteristic on the performance of a CVT. A detailed planar multibody model of a chain CVT is developed in order to accurately capture the dynamics characterized by the discrete structure of the chain, which causes polygonal excitations in the system. Friction between the chain link and the pulley sheaves is modeled using different mathematical models which account for different loading scenarios. The mathematical models, the computational scheme, and the results corresponding to different loading scenarios are discussed. The results discuss the influence of friction characteristics on the dynamic performance, the axial force requirements, and the torque transmitting capacity of a chain CVT drive.

Salinity and drought tolerance conferred by in planta transformation of SNAC1 transcription factor into a high-yielding rice variety of Bangladesh

61%

Parvin S. , Biswas S. , Razzaque S. , Haque T. , Elias S. M. , Tammi R. S. , Seraj Z. I.

tom 37

nr 04

Abiotic stresses such as drought and high salinity unfavorably affect the growth and productivity of crop plants. Therefore, the development of stress-tolerant crops is essential for the affected cultivable areas. It has been shown in the current study that the overexpression of stress-responsive NAC1 (SNAC1) transcription factor (TF) significantly increases salinity and drought tolerance in a farmer-popular high-yielding, transgenic rice. The indica rice variety BRRIdhan 55, which was poorly responsive to tissue culture was transformed with the SNAC1 TF from the rice landrace Pokkali by the in planta method. Addition of acetosyringone in the Agrobacterium suspension and coculture media increased previously reported transformation efficiencies by four-folds. Integration of foreign genes into the genome of transgenic plants was confirmed by genespecific PCR and Southern blot analysis. The level of transgene expression (SNAC1) was also quantified by realtime PCR. Genetic segregation ratio for T1 progenies was calculated and found to follow the law of Mendelian inheritance. Phenotypic screening was conducted at T2 and T3 seedling stages where the transgenic lines exhibited much better tolerance compared to their control nontransgenic plants at 120 mM (NaCl) salt as well as drought stress implemented by withholding water for 20 days.