Energetic and Dynamic Effects of Operating Fluid on Fluidic Artificial Muscle Actuators

Pneumatic artificial muscles (PAMs) are a relatively common type of lightweight, fluid power actuation. Some disadvantages of PAMs include the compressibility of the working fluid and low damping. These characteristics result in low efficiencies, poor dynamic response, as well as undesired oscillations of the actuators. This paper presents utilizing hydraulic liquid as the working fluid instead of compressed air. Hydraulic operation resulted in almost triple the efficiency of pneumatic operation. The artificial muscles are experimentally characterized both quasi-statically and dynamically. The quasi-static experiments include the tension-strain relationship as a function of pressure, and an actuator net work efficiency analysis. The dynamic tests consist of a free vibration experiment to determine the change in effective spring constant and damping terms. These experiments are conducted for both PAMs and HAMs (hydraulic artificial muscles), and the results are presented herein.

A fly ash particles media filter for decentralized wastewater treatment systems

The contribution of this work is twofold: (i) estimation of the hydraulic operation of a coal combustion byproduct (CCBs) through its physical filtration by developing a physical model, and in broader terms, (ii) promoting the transformation of native disposal materials into beneficial materials. We developed an experiment which examines fly ash as a CCBs for its hydraulic performance, and runs in four main stages: First, fly ash in its natural state is tested in the laboratory to check if its effective size and uniformity coefficient match with recommendations in the literature; Then, fly ash of effective grain size as recommended in the literature is derived; Further, a physical model comprised of such a derived fly ash media filter and which supports horizontal flow of the effluent is developed; Finally, the hydraulic performance of the physical model comprised of derived fly ash in presence of effluent is evaluated and proved that fly ash is an appropriate media filter for hydraulic performance. The work clearly highlights the potential of the easy to reach and costless native fly ash as a media filter for treatment of wastewater which we consider a viable future work.