Characterization and Control of Multi-Cylinder Partially Premixed Combustion

In the last decade diesel combustion has developed in a new direction. Research has been carried out trying to prolong the ignition delay and enhance fuel/air premixing to avoid diffusion combustion as well as lowering the combustion temperature through use of EGR. One of these new combustion concepts is Partially Premixed Combustion (PPC). PPC is aimed to provide combustion with low smoke and NOx without sacrificing fuel consumption. This thesis presents the development of a multi-cylinder PPC concept. It reaches from the basic characterization of this new combustion strategy to the demands on hardware, control and fuels for a realizable PPC solution. In summary it contains a thorough PPC characterization where the results suggest that high EGR, early injection PPC strategies are to prefer over late injection approaches or smokeless rich diesel combustion. Further, a strong connection between mixing period, defined as the period between end of injection and start of combustion, and PPC has been ascertained. Based on this knowledge a combustion controller with feedback control of mixing period was derived. The operating range of multi-cylinder diesel PPC was then evaluated. The study showed that the PPC load range was limited covering only 25% of the operating region for conventional combustion. In order to reach higher loads for PPC the EGR system was rebuilt to a low pressure system. This system improves EGR/air mixing and cooling and enables high EGR and boost pressure simultaneously. Additionally, gasoline fuels were introduced to extend the ignition delay and mitigate soot formation. An extensive fuel comparison was carried out to find the most suitable fuel for PPC operation. With the improved set-up the operating range was reevaluated. By combining the use of a low pressure EGR system and standard gasoline the operating region of PPC has been extended to cover 50% of the engine nominal operating region. The final part of this thesis is dedicated to a novel method of cylinder individual efficiency estimation based on the cylinder pressure trace. With this method, control strategies aiming directly at fuel consumption optimization can be developed. An extremum seeking control algorithm was applied. The results show that the controller manages to find the maximum brake torque region both with and without external excitation. Finally, the estimation error in accumulated fuel consumption from the experiments is around 1% which shows the potential of using the absolute value of the efficiency estimation in other control concepts

Actuator Comparison and Coordination for Integrated Vehicle Dynamics Control

The purpose of this Master's Thesis was to compare and coordinate active chassis systems in a search for new ways of controlling two driving situations; side wind exposure and split friction braking. These situations were to be mastered by three active systems; active steering, brakes and suspension. Examples of how to use the systems were presented for each driving situation. The results from the investigation were then used when designing controllers for the applications. Matlab/Simulink was the key tool for evaluation of the control strategies but tests were also carried out in a real vehicle

Disordered, strongly scattering porous materials as miniature multipass gas cells

Spectroscopic gas sensing is both a commercial success and a rapidly advancing scientific field. Throughout the years, massive efforts have been directed towards improving detection limits by achieving long interaction pathlengths. Prominent examples include the use of conventional multipass gas cells, sophisticated high-finesse cavities, gas-filled holey fibers, integrating spheres, and diffusive reflectors. Despite this rich flora of approaches, there is a continuous struggle to reduce size, gas volume, cost and alignment complexity. Here, we show that extreme light scattering in porous materials can be used to realise miniature gas cells. Near-infrared transmission through a 7 mm zirconia (ZrO2) sample with a 49% porosity and subwavelength pore structure (on the order of 100 nm) gives rise to an effective gas interaction pathlength above 5 meters, an enhancement corresponding to 750 passes through a conventional multipass cell. This essentially different approach to pathlength enhancement opens a new route to compact, alignment-free and low-cost optical sensor systems

Clinical system for non-invasive in situ monitoring of gases in the human paranasal sinuses

We present a portable system for non-invasive, simultaneous sensing of molecular oxygen (O-2) and water vapor (H2O) in the human paranasal cavities. The system is based on high-resolution tunable diode laser spectroscopy (TDLAS) and digital wavelength modulation spectroscopy (dWMS). Since optical interference and non-ideal tuning of the diode lasers render signal processing complex, we focus on Fourier analysis of dWMS signals and procedures for removal of background signals. Clinical data are presented, and exhibit a significant improvement in signal-to-noise with respect to earlier work. The in situ detection limit, in terms of absorption fraction, is about 5 x 10(-5) for oxygen and 5 x 10(-4) for water vapor, but varies between patients due to differences in light attenuation. In addition, we discuss the use of water vapor as a reference in quantification of in situ oxygen concentration in detail. In particular, light propagation aspects are investigated by employing photon time-of-flight spectroscopy. (C) 2009 Optical Society of Americ

Wall-collision line broadening of molecular oxygen within nanoporous materials

Wall-collision broadening of near-infrared absorption lines of molecular oxygen confined in nanoporous zirconia is studied by employing high-resolution diode-laser spectroscopy. The broadening is studied for pores of different sizes under a range of pressures, providing new insights on how wall collisions and intermolecular collisions influence the total spectroscopic line profile. The pressure series show that wall-collision broadening is relatively more prominent under reduced pressures, enabling sensitive means to probe pore sizes of porous materials. In addition, we show that the total wall-collision-broadened profile strongly deviates from a Voigt profile and that wall-collision broadening exhibits an additive-like behavior to the pressure and Doppler broadening

Бюллетень новых поступлений за сентябрь 2015 года

I slutet av maj 2014 hölls för åttonde gången direktval till Europaparlamentet och väljare i 28 medlemsstater gick till valurnorna. Trenden med stadigt sjunkande valdeltagande stannade av och närmare 43 procent av väljarna röstade. Som Mark Franklin visade i en Sieps-publikation inför valet förklaras trenden med sjunkande valdeltagande till stor del av att EU har utvidgats och att de medlemsstater som tillkommit har haft ett lägre valdeltagande än de som har varit medlemmar en tid. Därför är den brutna trenden kanske inte så förvånande. Valkampanjen bedrevs i en kontext där den ekonomiska krisen alltjämt påverkade EU starkt. Även om eurozonen gradvis har stabiliserats, är effekterna av krisen alltjämt tydliga. Resultatet återspeglar en reaktion hos väljarna som vi känner igen från tidigare Europaparlamentsval, där större partier, i synnerhet i regeringsställning, gör sämre ifrån sig än vid nationella val. Konsekvensen den här gången blev att den politiska “mitten” tappade och flankerna i det framväxande europeiska partisystemet växte. De EU-kritiska partierna fick stor uppmärksamhet under valrörelsen och valresultaten kan delvis tolkas som en protest mot EU, även om det finns skillnader mellan medlemsstaterna och vilka uttryck kritiken tar sig. De politiska majoritetsförhållandena och utvecklingen inom partigrupperna analyseras i den här publikationen av Magnus Blomgren. I Sverige var valkampanjen intensiv och det påföljande riksdagsvalet hade sannolikt en roll i det. Två nya partier, Feministiskt initiativ och Sverigedemokraterna, lyckades vinna mandat medan Piratpartiet inte lyckades upprepa succén från 2009 och tappade sina mandat. Det svenska resultatet analyseras här av Linda Berg. Texterna i den här publikationen utgörs främst av bearbetningar av bidrag vid seminariet Valet är över – vad händer nu? som arrangerades i Stockholm den 28 maj. Det är min förhoppning att Sieps därmed ska kunna bidra till fördjupad förståelse för Europaparlamentsval och parlamentets funktionssätt. Jörgen Hettne Tillförordnad direktö

Evaluation of the U.S. EPA/OSWER Preliminary Remediation Goal for Perchlorate in Groundwater: Focus on Exposure to Nursing Infants

BACKGROUND: Perchlorate is a common contaminant of drinking water and food. It competes with iodide for uptake into the thyroid, thus interfering with thyroid hormone production. The U.S. Environmental Protection Agency’s Office of Solid Waste and Emergency Response (OSWER) set a groundwater preliminary remediation goal (PRG) of 24.5 μg/L to prevent exposure of pregnant women that would affect the fetus. This does not account for the greater exposure that is possible in nursing infants or for the relative source contribution (RSC), a factor normally used to lower the PRG due to nonwater exposures. OBJECTIVES: Our goal was to assess whether the OSWER PRG protects infants against exposures from breast-feeding, and to evaluate the perchlorate RSC. METHODS: We used Monte Carlo analysis to simulate nursing infant exposures associated with the OSWER PRG when combined with background perchlorate. RESULTS: The PRG can lead to a 7-fold increase in breast milk concentration, causing 90% of nursing infants to exceed the reference dose (RfD) (average exceedance, 2.8-fold). Drinking-water perchlorate must be < 6.9 μg/L to keep the median, and < 1.3 μg/L to keep the 90th-percentile nursing infant exposure below the RfD. This is 3.6- to 19-fold below the PRG. Analysis of biomonitoring data suggests an RSC of 0.7 for pregnant women and of 0.2 for nursing infants. Recent data from the Centers for Disease Control and Prevention (CDC) suggest that the RfD itself needs to be reevaluated because of hormonal effects in the general population. CONCLUSIONS: The OSWER PRG for perchlorate can be improved by considering infant exposures, by incorporating an RSC, and by being responsive to any changes in the RfD resulting from the new CDC data