Optimization of an impulse pressure generator based on the drop-weight method

Abstract

An optimized impulse dynamic pressure generator based on a drop-weight method was developed as a secondary standard. The impulse pressure generator was characterized in detail using various parameters in order to obtain a proper reference dynamic pressure, to calibrate a dynamic pressure sensor. Both a hardware filter and a software filter were successfully employed to eliminate unavoidable noise when the impulse pressure was generated. Five variables were considered to optimize the system. A larger effective area piston-cylinder assembly should be used to obtain a faster impulse pressure. To control the peak pressure using a variable drop height is easier rather than drop weight because the change is linearly proportional to the impact speed associated with the drop height. An increase in drop weight causes an increase in duration as well as an increase in peak pressure. In addition, the pressure transmission medium is very important for generating the optimized impulse pressure, so an appropriate fluid choice is required. The viscosity and bulk modulus among the fluid properties are considered as design variables. High viscosity fluids with high bulk modulus can achieve high peak pressures without jittering. The drop weight based impulse pressure generator design and implementation method is proposed based on the detailed characterizations in this study.

Financial customer classification by combined model

“…Invariant weight methods such as the minimum variance method and the minimum absolute value method, variable weight method, etc. are based on the idea of minimising the prediction error of the combined model [10][11][12][13]. However, some studies have found that if the selected single model is not appropriate, it may also lead to worse prediction performance of the final combined model [14], and thus precise analysis of data with different characteristics is required.…”

New Hydraulic High-Pressure Impulse Generator for Long-Duration Impulse Tests

“…To simplify the structure, Chen used a profiled cam to drive a single-rod hydraulic cylinder to generate the pressure impulse wave; the rotational speed of the cam indicates the frequency of the output signal [15]. Drop-weight method too has been commonly applied to develop impulse pressure generators [16,17]; however, this method can hardly provide even a rough water hammer wave. Theimer and Kolle designed a hydraulic pulse valve with a rotary spool and improved the sleeve to achieve longer wear life and better performance; these features will can help establish an open-loop system that generates the required pressure impulse signals [18].…”