High-precision hydraulic pressure control based on linear pressure-drop modulation in valve critical equilibrium state

High precision and fast response are of great significance for hydraulic pressure control in automotive braking systems. In this paper, a novel sliding mode control based high-precision hydraulic pressure feedback modulation is proposed. Dynamical models of the hydraulic brake system including valve dynamics are established. An open loop load pressure control based on the linear relationship between the pressure-drop and coil current in valve critical open equilibrium state is proposed, and also experimentally validated on a hardware-in-the-loop test rig. The control characteristics under different input pressures and varied coil currents are investigated. Moreover, the sensitivity of the proposed modulation on valve's key structure parameters and environmental temperatures are explored with some unexpected drawbacks. In order to achieve better robustness and precision, a sliding mode control based closed loop scheme is developed for the linear pressure-drop modulation. Comparative tests between this method and the existing methods are carried out. The results validate the effectiveness and superior performance of the proposed closed loop modulation method

Positive displacement compounding of a heavy duty diesel engine

A helical screw type positive displacement (PD) compressor and expander was considered as an alternative to the turbocharger and the power turbine in the Cummins advanced turbocompound engine. The Institute of Gas Technology (IGT) completed the design, layout, and performance prediction of the PD machines. The results indicate that a screw compressor-expander system is feasible up to at least 750 HP, dry operation of the rotors is feasible, cost and producibility are uncertain, and the system will yield about 4% improvement in brake specific fuel consumption (BSFC) over the advanced turbocompound engine

Volume 1 – Symposium: Tuesday, March 8

Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Components:Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Component

A study of the link between cosmic rays and clouds with a cloud chamber at the CERN PS

Recent satellite data have revealed a surprising correlation between galactic cosmic ray (GCR) intensity and the fraction of the Earth covered by clouds. If this correlation were to be established by a causal mechanism, it could provide a crucial step in understanding the long-sought mechanism connecting solar and climate variability. The Earth's climate seems to be remarkably sensitive to solar activity, but variations of the Sun's electromagnetic radiation appear to be too small to account for the observed climate variability. However, since the GCR intensity is strongly modulated by the solar wind, a GCR-cloud link may provide a sufficient amplifying mechanism. Moreover if this connection were to be confirmed, it could have profound consequences for our understanding of the solar contributions to the current global warming. The CLOUD (Cosmics Leaving OUtdoor Droplets) project proposes to test experimentally the existence a link between cosmic rays and cloud formation, and to understand the microphysical mechanism. CLOUD plans to perform detailed laboratory measurements in a particle beam at CERN, where all the parameters can be precisely controlled and measured. The beam will pass through an expansion cloud chamber and a reactor chamber where the atmosphere is to be duplicated by moist air charged with selected aerosols and trace condensable vapours. An array of external detectors and mass spectrometers is used to analyse the physical and chemical characteristics of the aerosols and trace gases during beam exposure. Where beam effects are found, the experiment will seek to evaluate their significance in the atmosphere by incorporating them into aerosol and cloud models.Recent satellite data have revealed a surprising correlation between galactic cosmic ray (GCR) intensity and the fraction of the Earth covered by clouds. If this correlation were to be established by a causal mechanism, it could provide a crucial step in understanding the long-sought mechanism connecting solar and climate variability. The Earth's climate seems to be remarkably sensitive to solar activity, but variations of the Sun's electromagnetic radiation appear to be too small to account for the observed climate variability. However, since the GCR intensity is strongly modulated by the solar wind, a GCR-cloud link may provide a sufficient amplifying mechanism. Moreover if this connection were to be confirmed, it could have profound consequences for our understanding of the solar contributions to the current global warming. The CLOUD (Cosmics Leaving OUtdoor Droplets) project proposes to test experimentally the existence a link between cosmic rays and cloud formation, and to understand the microphysical mechanism. CLOUD plans to perform detailed laboratory measurements in a particle beam at CERN, where all the parameters can be precisely controlled and measured. The beam will pass through an expansion cloud chamber and a reactor chamber where the atmosphere is to be duplicated by moist air charged with selected aerosols and trace condensable vapours. An array of external detectors and mass spectrometers is used to analyse the physical and chemical characteristics of the aerosols and trace gases during beam exposure. Where beam effects are found, the experiment will seek to evaluate their significance in the atmosphere by incorporating them into aerosol and cloud models

Closed-loop throttle control of a hybrid rocket motor.

Masters Degree. University of KwaZulu-Natal, Durban.Hybrid rocket motors produce thrust by reacting a solid fuel with a liquid oxidizer inside a combustion chamber. This approach has certain advantages over conventional solid propellant rockets including improved safety and the potential for thrust control, while also being less expensive than liquid propellant engines. Liquefying hybrid fuels, such as paraffin wax, regress at a faster rate than the conventional solid fuels like HTPB that are dominated by vaporization at the solid-gas interface. Non-classical theory is still in its infancy, however, and more work is required to validate performance models experimentally, especially where throttling of the oxidizer mass flowrate is incorporated. While hybrid motor throttlabilty remains a subject of considerable interest, there has been little investigation of throttling in motors that use high regression rate, liquefying fuels such as paraffin wax. This study proposes a closed-loop thrust control scheme for paraffin wax/nitrous oxide hybrid rocket motors using a low-cost ball valve as the controlling hardware element. There are a number of advantages to throttling hybrid rocket motors but the most important is to enforce a constant thrust curve throughout the burn. A test facility and laboratory scale hybrid rocket motor utilizing paraffin wax as fuel and nitrous oxide as oxidiser were used for experimental testing. Using a mathematical model of a laboratory-scale hybrid rocket motor, the controller constants for a PID controller were obtained and tested through experimental testing. Open-loop testing was first done in order to determine the control authority of the ball valve over the oxidiser mass flowrate, as well as characterize the oxidiser mass flowrate in relation to each valve angle value. Closed-loop testing was undertaken to verify and refine the controller constants obtained via the laboratory-scale model. The tests prompted a redesign of the injector and additions to the LabVIEW™ controller regime. Using results from the open-loop tests a feed-forward lookup table was developed to allow for the controller to move to a specified angle quickly and thereby remove nonlinearities present in flow control using ball valves. Three successful closed-loop tests were done where the controller causes the thrust of the motor to track a predetermined thrust or chamber pressure set point with a reasonable degree of accuracy. The set-point profile of the first test was a constant thrust throughout the burn while the second test had a ramp set-point profile. The final test used chamber pressure as the feedback variable and had a step-down set-point profile. This study demonstrates that thrust control can be exercised over a paraffin wax/nitrous oxide hybrid rocket motor, using a low-cost ball valve as the control element to modulate the oxidiser mass flowrate

Modular integration and on-chip sensing approaches for tunable fluid control polymer microdevices

228 p.Doktore tesi honetan mikroemariak kontrolatzeko elementuak diseinatu eta garatuko dira, mikrobalbula eta mikrosentsore bat zehazki. Ondoren, gailu horiek batera integratuko dira likido emari kontrolatzaile bat sortzeko asmotan. Helburu nagusia gailuen fabrikazio arkitektura modular bat frogatzea da, non Lab-on-a-Chip prototipoak garatzeko beharrezko fase guztiak harmonizatuz, Cyclic-Olefin-Polymer termoplastikozko mikrogailu merkeak pausu gutxi batzuetan garatuko diren, hauen kalitate industriala bermatuz. Ildo horretan, mikrogailuak prototipotik produkturako trantsizio azkar, erraz, errentagarri eta arriskurik gabeen bidez lortu daitezkeenetz frogatuko da