Since screw compressor rotors are of a helical shape and tool points engaged in their manufacturing pass different cutting length, the tools do not wear uniformly along the rotor profiles. The nonuniformity depends on a difference between the rotor point angle and pressure angle and on the rotor helix angle. A difference in relative movement between the tool and the rotors with and without the ...

Composite helical structures (CHSs) can store and release strain energy through elastic deformation, which have been used in automobile aerospace structures. The compressive stiffness to weight ratio is the core design of these structures, requiring an optimal geometric configuration. Seven state-of-the-art Genetic Algorithms were employed benchmarked optimise two conflicting objectives, maximi...

The self-assembly of helical ribbons is examined in a variety of multicomponent enantiomerically pure systems that contain a bile salt or a nonionic detergent, a phosphatidylcholine or a fatty acid, and a steroid analog of cholesterol. In almost all systems, two different pitch types of helical ribbons are observed: high pitch, with a pitch angle of 54 +/- 2 degrees, and low pitch, with a pitch...

The structure of a 62 base nuclease resistant fragment of E. coli 5S RNA (bases 1-11, 69-87, 89-120) has been examined by small angle x-ray scattering. The results obtained are indistinguishable from those expected if this oligonucleotide complex were a perfect RNA double helix of about 30 base pairs. These results indicate that this portion of 5S RNA is in a configuration which is approximatel...

Using an exact solution for the pair interaction potential, we show that long, rigid, chiral molecules with helical surface charge patterns have a preferential interaxial angle ~ RH L where L is the length of the molecules, R is the closest distance between their axes, and H is the helical pitch. Estimates based on this formula suggest a solution for the puzzle of small interaxial angles in α-h...

Using an exact solution for the pair interaction potential, we show that long, rigid, chiral molecules with helical surface charge patterns have a preferential interaxial angle approximately sqrt[RH]/L, where L is the length of the molecules, R is the closest distance between their axes, and H is the helical pitch. Estimates based on this formula suggest a solution for the puzzle of small inter...

The dynamics of a finite a-helix have been studied in the harmonic approximation by a vibrational analysis of the atomic motions about their equilibrium positions. The system was represented by an empirical potential energy function, and all degrees of freedom (bond lengths, bond angles, and torsional angles) were allowed to vary. The complete results were compared with a more restrictive model...

We consider a unit speed curve α in the Euclidean ndimensional space E and denote the Frenet frame of α by {V1, . . . ,Vn}. We say that α is a cylindrical helix if its tangent vector V1 makes a constant angle with a fixed direction U . In this work we give different characterizations of such curves in terms of their curvatures. AMS Mathematics Subject Classification (2000): 53C40, 53C50

BACKGROUND Acute auriculocephalic angle refers to an ear with helix that is spaced closely to the cranium. An increasing number of patients with acute auriculocephalic angle wish to undergo corrective operation for aesthetic purposes. However, there is a paucity of data regarding acute auriculocephalic angle. This paper proposes a treatment protocol for patients with acute auriculocephalic angl...