The Fastest Simulation of Protein Folding Based on Torsion Angles

Backgrounds: Enormous number of possible conformations in the protein structure simulation have led molecular dynamics researchers to be frustrated until now. Some methods with defects ended their experiments into failure. This made them fail to determine the structure and function of folded protein in stable state with the lowest potential energy. This apparently exist in nature. The purpose of resolving a protein folding pathway that follows protein backbone residues torsional inertia was accomplished. Results A new method, torsion angle modeling, was adopted focused on the rotation of dihedral angles. The potential energy was calculated by rotating torsion angles of the peptide with 8 residues. It was found that when moving in the order of torsional inertia, 8 residues swivel in sequence. Six passes were repeated to find the lowest value. Conclusion The protein backbone torsion angle plays very important role in predicting protein structure. Actually it was thousand times faster or more than others to get the obvious pathway.

An Approach to Minimization of Drive Train Noise Through Redesign of Engine Mounts

Drive train noise is more annoying for passenger. For a V-hull base mine protected 4WD defence-vehicle, metallic noise was observed from drive train. To resolve this kind of NVH problem of complicated vehicle like defence required commending knowledge base and experience or say know-how. The critical constraint of subject vehicle was fixed position of engine or engine mounts and transfer case. This causes higher slope equivalent angle of first drive shaft with respect to the installation standard. Noise issue observed as consequence of aforesaid issue which has impact installation parameters of torsional, inertia and secondary coupling excitation frequencies. In this context, a structured methodology has been followed in present work for finding root causes and optimizing the design to come out with optimum solution. Engine mounts have major influence to finalize first drive line slope angle. Hence, re-designing and verification have been done for engine mounts considering its major design parameters and criteria (e.g. shape factors, shore hardness, static deflection and isolation efficiency). At the same time, effects of those changes have been verified theoretically and practically on vehicle. Pass by noise, cabin inside noise, isolation efficiency of front and rear mounts and vehicle floor vibration level were measured. The objective of the exercise is to find out a solution for minimization of drive-train noise.

Nonlinear Nonplanar Dynamics of Parametrically Excited Cantilever Beams

The nonlinear nonplanar response of cantilever inextensional metallic beams to a principal parametric excitation of two of its “exural modes, one in each plane, is investigated. The lowest torsional frequencies of the beams considered are much larger than the frequencies of the excited modes so that the torsional inertia can be neglected. Using this condition as well as the inextensionality condition, we develop a Lagrangian whose variation leads to the two integro-partial-differential equations of Crespo da Silva and Glynn. The method of time-averaged Lagrangian is used to derive four first-order nonlinear ordinary-differential equations governing the modulation of the amplitudes and phases of the two interacting modes. The modulation equations exhibit the symmetry property found by Feng and Leal by analytically manipulating the interaction coefficients in the modulation equations obtained by Nayfeh and Pai by applying the method of multiple scales to the governing integro-partial-differential equations. A pseudo arclength scheme is used to trace the branches of the equilibrium solutions and an investigation of the eigenvalues of the Jacobian matrix is used to assess their stability. The equilibrium solutions experience pitchfork, saddle-node, and Hopf bifurcations. A detailed bifurcation of the dynamic solutions of the modulation equations is presented. Five branches of dynamic (periodic and chaotic) solutions were found. Two of these branches emerge from two Hopf bifurcations and the other three are isolated. The limit cycles undergo symmetry-breaking, cyclic-fold, and period-doubling bifurcations, whereas the chaotic attractors undergo attractor-merging and boundary crises.