Influence Of Slits Research Articles

Closed-Double-Magnetic Circuit for a Long-Stroke Horizontal Electromagnetic Vibration Exciter

A novel closed-double-magnetic circuit (CDMC) was presented to achieve high and uniform magnetic flux density (MFD) in the long air gap (LAG) of a long-stroke horizontal electromagnetic vibration exciter. First, the normal single-magnetic circuit (SMC) and the proposed CDMC were modeled by lumped element circuit using equivalent circuit principle, analyzed theoretically by the Kirchhoff's law and the superposition theorem. The comparison between the two circuits shows that the CDMC can have more intensive and more uniform MFD in the LAG. To strengthen the uniformity of the MFD in the LAG, the improved CDMC with uneven air gap and its design method were proposed theoretically. Thereafter, the uneven air gap structure expressed as a three-line-segment form was presented and its optimization was also conducted based on a finite element model referring to a prototype of a one-meter-stroke horizontal electromagnetic vibration excite. Then, the magnetic flux leakage of the magnetic circuits and the influence of slits in the outer magnetic yoke for practical application was also analyzed with the finite element method (FEM). The simulation demonstrates that the CDMC with optimal air gap can further improve the uniformity of the MFD in the LAG. In addition, it is also indicated that the CDMC has less flux leakage than the SMC and the influence of slits can be negligible. Finally, the experiment on the prototype also verifies the effectiveness of proposed CDMC with optimal air gap.

Experimental sound insulation performance of double frame partitions with slits

In this paper the influence of slits on sound reduction index of double steel frame partitions with and without mineral wool in the cavity was examined. It was shown that the sound insulation of the partition is strongly dependent on the relative position of the slits on each steel frame. As could be expected, the reduction in sound insulation due to slits is lower in partitions without mineral wool in the cavity, since the effect of slits is more important in the case of partitions with high sound insulation.

The influence of slits on sound transmission through a lightweight partition

In this paper the influence on sound reduction index of the length and the depth of sound leaks at the perimeter of lightweight partitions was examined. It was shown that the most important decrease on sound reduction index is caused by the first slit between lightweight partition and one of the structural members. When the length of the slit is increased, the decrease on sound reduction index is less significative. Calculated results show the same effects as measured ones.

Influence of slits on squeal in electromagnetic friction clutches and brakes.

This paper describes an investigation into influence of the lengths of the slits and the number of those on squeal. In a disk with four slits at regular intervals there are two 2-0 modes which have two nodal diameters. One has a node in the center of a slit (sine mode), and the other has a node between two adjacent slits (cosine mode). The difference Δf1 between the natural frequency of the sine mode and that of the cosine mode becomes greater as the slits grow longer. On the other hand, there is only one natural frequency of the 3-0 mode in the disk. Our squeal theory predicts that the second mode squal is reduced as theΔf1 of 2-0 modes grows greater. Experimental results show that the second mode squeal disappears and the third one is generated when the slits are long. In conclusion, four slits are effective on the second mode squeal, but not on the third one. And also the n-th mode squeal is not generated when theΔf1 of n-0 modes is large.

Influence of transverse slits on the hydrodynamic coefficients of a wing of finite span in stationary and nonstationary motion near a wall

The method of matched asymptotic expansions is used to construct an approximate solution to the problem of the influence of narrow transverse slits on the hydrodynamic coefficients of a thin rectangular wing moving near a wall. The flow in the neighborhood of a slit is described by a local asymptotic solution satisfying the condition of continuity of the pressure on the leading edge of the slit and matched to the main solution. Results of the calculations illustrate the influence of the slits on the hydrodynamic characteristics of the wing at different Strouhal numbers and aspect ratios.

Elastic scattering phenomena in mass analyzers with tandem fields

The elastic scattering in the tandem field mass analyzing systems is considered. The analysis includes deflecting electrostatic and magnetic converging, dispersing, diverging fields, and also the fields of quadrupoles. The influence of slits located on the ion beam path is indicated. An example illustrates the effect of slits on the elastically scattered current distribution in a double focusing mass spectrometer. Another example gives an idea about the influence of the diverging field on the peak tails in mass spectra.