The steady flowof an incompressible, third-grade fluid in helical screw rheometer (HSR) is studied by “unwrapping or flattening” the channel, lands, and the outside rotating barrel. The geometry is approximated as a shallow infinite channel, by assuming that the width of the channel is large as compared to the depth. The developed second-order nonlinear coupled differential equations are reduce...

In this paper, the flow of couple stress fluid is investigated in a helical screw rheometer (HSR). By unwrapping the channel, lands, and the outside rotating barrel, the geometry of HSR is approximated as a shallow infinite channel. Both oneand two-dimensional analysis of the problem is presented using rectangular coordinates. In either case an exact solution of the flow problem is presented an...

This paper presents a parameter study for optimum rotor geometrical parameter combinations of a refrigeration helical twin screw compressor with four commonly used lobe combinations and five different length/diameter ratios and wrap angles. The volumetric and indicated efficiencies of the compressor are important. So also are other factors such as rotor deflection, bearing load, bearing life an...

The title compound, C(13)H(17)NO(2), has an intra-molecular N-H⋯O hydrogen bond, forming a planar six-membered ring with a mean deviation of 0.015 (5) Å from the plane. This plane makes a dihedral angle of 7.19 (8)° with the adjacent phenyl ring. Through an inter-molecular O-H⋯O hydrogen bond, the mol-ecules with their 2(1) screw and b-translation equivalents form a helical chain running parall...

The mol-ecule of the title compound, C(13)H(21)NO(8), consists of two methyl-enedi-oxy rings and one tetra-hydro-furan ring. In the crystal, inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into helical chains running along the 6(1) screw axis. Weak inter-molecular C-H⋯O hydrogen bonds help to stabilize the crystal packing. Voids of 245 Å(3) per unit cell occur.

This article describes a case of backout of the helical blade, a rare complication of proximal femoral nail antirotation. A 31-year-old man had sustained a trochanteric fracture of his right femur. Fracture fixation using proximal femoral nail antirotation and autologous bone grafting 7 months later were performed at another hospital. However, bony union was not obtained, and the patient's pain...

Milling forces play an important role in the milling process and are generally calculated by mechanistic or numerical methods; reliable model of cutting is very for simulation process, which has big scientific significance to further improve machining quality. Ball helical technology used make holes based on principle using ball end cutter, due influence spherical surface characteristic, modeli...