Development research of reflection-absorption compound type fluid pulsation attenuator
Based on the disadvantages analysis of the existing fluid pulsation attenuator, two reflection-absorption compound type of fluid pulsation attenuators which are both composed of a chamber and a mass-spring-damping system are developed: in-line reflection-absorption compound type of fluid pulsation attenuators (in-line RAFPA) and side-branch reflection-absorption compound type of fluid pulsation attenuators (side-branch RAFPA). The transfer matrix models of the two attenuators are established as well as expansion chamber attenuator and Helmholtz resonator. Based on the transfer matrix model, the transmission loss of the four attenuators is given out to evaluate their attenuation characteristic. The attenuation characteristic comparisons of in-line RAFPA with expansion chamber attenuator and side-branch RAFPA with Helmholtz resonator are carried out respectively. And the effect of the mass-spring-damping system to in-line RAFPA and side-branch RAFPA is investigated. The simulation reveals the two reflection-absorption compound type of fluid pulsation attenuators have better attenuation characteristic and are more compact than expansion chamber attenuator and Helmholtz resonator.
STUDY ON THE INSERTION LOSS CHARACTERISTICS OF SIDE BRANCH RESONATOR IN HYDRAULIC LINE
A quarter wavelength side branch resonator has been widely used as a reactive type silencer to attenuate pressure pulsation in hydraulic circuit. The structure of this conventional silencer is very simple and therefore it is a useful device in terms of cost efficiency. However, it is also known as a rather narrow frequency banded resonator that only attenuates the odd order harmonics of the pressure pulsation. In this study, the attenuation performance of side branch resonator in the hydraulic line is examined numerically by changing the parameters such as the insertion location of side branch and the length of connecting pipe between the side branch and termination load of circuits. The level of attenuation is accessed by insertion loss which is defined as the ratio of overall amplitude harmonics of pressure pulsation with and without the side branch. The paper describes the fundamental principle of side branch and the mathematical model of insertion loss characteristics. Some calculation results for the insertion loss characteristics are carried out to show the influence of even order harmonics and the interaction of pump, termination load and all pulsation propagation characteristics of the circuit including side branch.
Monte carlo simulation of events with Drell-Yan lepton pairs from antiproton-proton collisions
The complete knowledge of the nucleon spin structure at leading twist requires also addressing the transverse spin distribution of quarks, or transversity, which is yet unexplored because of its chiral-odd nature. Transversity can be best extracted from single-spin asymmetries in fully polarized Drell-Yan processes with antiprotons, where valence contributions are involved anyway. Alternatively, in single-polarized Drell-Yan the transversity happens convoluted with another chiral-odd function, which is likely to be responsible for the well known (and yet unexplained) violation of the Lam-Tung sum rule in the corresponding unpolarized cross section. We present Monte Carlo simulations for the unpolarized and single-polarized Drell-Yan pp{sup ({up_arrow}}{sup )}{yields}{mu}{sup +}{mu}{sup -}X at different center-of-mass energies in both configurations where the antiproton beam hits a fixed proton target or it collides on another proton beam. The goal is to estimate the minimum number of events needed to extract the above chiral-odd distributions from future measurements at the high energy storage ring (HESR) at GSI. It is important to study the feasibility of such experiments at HESR in order to demonstrate that interesting spin physics can be explored already using unpolarized antiprotons.