Decoupled hydrodynamic models and their outdoor identification for an unmanned inland cargo vessel with embedded fully rotatable thrusters

Expanding the automation level of the freshly introduced fleet of self-propelled Watertruck(+) barges, which house fully-rotatable embedded thrusters, might increase their ability to compete with their less sustainable but dominating road-based alternatives. Hydrodynamic motion models, which reveal the manoeuvring capabilities of these barges, can serve as inputs for many pieces of this automation puzzle. No identified motion models or hydrodynamic data seem to be publicly available for the hull design and the novel actuation system configuration of these barges. Therefore, this study offers: (i) decoupled motion model structures for these barges for surge, sway, and yaw, with a focus on the thruster and damping models; (ii) two identification procedures to determine these motion models; (iii) all the experimental data, generated outdoors with a scale model barge to identify (i) based on (ii). In addition, the identified surge models were compared with both computational and empirical data. These comparisons offer more physical insights into the identified model structures and can aid in the model selection for which the desired complexity and accuracy evidently depend on their envisaged application. Finally, this methodology need not be limited to the vessel and actuation types utilised by us

Evaluation of patients with a recent clinical fracture and osteoporosis, a multidisciplinary approach

The aetiology of osteoporotic fractures is multifactorial, but little is known about the way to evaluate patients with a recent clinical fracture for the presence of secondary osteoporosis

Design of an active controlled muffler for internal combustion engines

status: publishe

Design of an active exhaust attenuating valve for interval combustion engines

An active silencer to attenuate internal combustion engine exhaust noise is developed. The silencer consists of an electrically controlled valve connected to a buffer volume. The pulsating flow from the engine is buffered in the volume and the valve resistance is continuously controlled such that only the mean flow passes to the atmosphere. This flow is free of fluctuations and consequently free of sound. The design of the active silencer is carried out using electrical analog circuits. First, the interaction between the active silencer and the engine will be studied using an analog circuit including the combustion engine and a linearized active silencer. Then, a detailed valve model is built in a separate electrical analog circuit. It includes the electrical, the mechanical and the flow-dynamic properties of the actuator valve. The actuator valve concept is then simulated, from which a prototype can be constructed. The active silencer has been tested on a cold engine simulator. This device generates realistic exhaust noise with the associated gas flow using compressed air. The silencer can attenuate pulsations from engines at very low revolution speed, without passive elements preconnected between the engine and the active silencer. This is not possible using loudspeaker based active silencers.status: publishe

Design of an active exhaust attenuating valve for internal combustion engines

status: publishe

Development of an active silencer for internal combustion engines

A silencer to attenuate engine exhaust noise using active control methods is developed. The device consists of an electrically driven valve, combined with a buffer volume, which is connected to the exhaust outlet. Using the mean flow through the valve and the pressure fluctuations in the volume, the valve regulates the flow in such a way that only the mean flow passes through the exhaust outlet. The fluctuations of the flow are temporally buffered in the volume. To carry out optimization and validation experiments, a cold engine simulator is developed. This device generates realistic exhaust noise and the matching gas flow using compressed air. The simulator allows quick and reliable acoustic and fluid dynamic experiments on exhaust prototypes. The active silencer is capable to reduce the exhaust noise from 91 dBA to 78 dBA after the tail pipe outlet, with a back pressure of 3 kPa to the engine.status: publishe

Development of a cold engine simulator to carry out acoustic and fluid-dynamic experiments with exhaust systems

status: publishe

Determination of the acoustical impedance of an internal combustion engine exhaust

status: publishe

Development of an active exhaust silencer for internal combustion engines using feedback control

A silencer to attenuate engine exhaust noise using active control methods has been developed. The device consists of an electrically driven valve, combined with a buffer volume, which is connected to the exhaust outlet. Using the mean flow through the valve and the pressure fluctuations in the volume, the valve regulates the flow in such a way that only the mean flow passes through the exhaust outlet. The fluctuations of the flow are temporally buffered in the volume. To carry out optimization and validation experiments, a cold engine simulator has been developed. This device generates realistic exhaust noise as well as the matching gas flow using compressed air. The simulator allows quick and reliable acoustic and fluid dynamic experiments on exhaust prototypes. The silencer is developed using electrical equivalent circuits, wherein at first instance a feedforward control is applied. The silencer has been built and the transfer function between electrical motor current of the valve and resulting acoustic pressure is measured. Based on these measurements, the feedback controller is developed and tested. The active silencer is capable to reduce the exhaust noise with 13 dBA using feedforward and 16 dBA using feedback control, with a back pressure of 10 kPa to the engine. Copyright © 2000 Society of Automotive Engineers, Inc.status: publishe