Free-piston linear generator and the development of a solid lubrication system

The free piston linear generator is a new electromechanical generator. It converts chemical energy into electrical energy by means of a combustion process, a linear generator and a gas spring. Thereby the technology aims to have better properties than other electromechanical generators. Therefore this publication deals with the explanation of the concept, the characteristics of a free piston linear generator and one of the challenges in the development. In order to use a port scavenging the emission issue is the challenge and has to be solved. One possible solution is the use of solid lubricants to substitute motor oil. The development methodology and one aspect of the development will be explained

Eliciting density ratio classes

AbstractThe probability distributions of uncertain quantities needed for predictive modelling and decision support are frequently elicited from subject matter experts. However, experts are often uncertain about quantifying their beliefs using precise probability distributions. Therefore, it seems natural to describe their uncertain beliefs using sets of probability distributions. There are various possible structures, or classes, for defining set membership of continuous random variables. The Density Ratio Class has desirable properties, but there is no established procedure for eliciting this class. Thus, we propose a method for constructing Density Ratio Classes that builds on conventional quantile or probability elicitation, but allows the expert to state intervals for these quantities. Parametric shape functions, ideally also suggested by the expert, are then used to bound the nonparametric set of shapes of densities that belong to the class and are compatible with the stated intervals. This leads to a natural metric for the size of the class based on the ratio of the total areas under upper and lower bounding shape functions. This ratio will be determined by the characteristics of the shape functions, the scatter of the elicited values, and the explicit expert imprecision, as characterized by the width of the stated intervals. We provide some examples, both didactic and real, and conclude with recommendations for the further development and application of the Density Ratio Class

A demographic study based upon income, age and education variables as related to the willingness or unwillingness to accept foster children

The research problem in this thesis can be briefly stated as a study of a general population to test certain demographic variables, in particular those of income, age and education, which may or may not have a significant relationship to an expressed willingness to care for foster children; and to further examine whether certain special characteristics of a child, in particular those of increased age, physical handicap, minor emotional problems or mental retardation, further increase unwillingness to care for foster children. The sample was selected by a two- stage cluster sampling taken from the Southeast catchment area of metropolitan Portland, Oregon. From this sample of 787 individuals, the survey was conducted by trained interviewers, using a questionnaire and personal interview. The data used in this research project were then extracted from the larger survey, and computed to determine the relationship of age, income and education to willingness to care for foster children. The data were extracted on the basis of the chosen variables of income, age and education and five questions relating specifically to willingness to care for foster children. As had been anticipated, the findings showed that the general population is not willing to care for foster children. However, certain significant findings were related to willingness to care for foster children. A significant relationship was found between income and willingness to care for foster children in that those respondents with incomes between $4,000-$20,000 expressed the most willingness to care for foster children while there was significant underrepresentation in both the highest and lowest income groupings to express a willingness to care for foster children with an almost lineal relationship of decreasing age with increasing willingness to care for foster children. There is no significant relationship, it was found, between education of the respondent and willingness to care for foster children. There is a lineal relationship of increasing willingness to care for foster children with increasing age of the foster child. Of those individuals expressing a willingness to care for foster children, there is no significant decrease in willingness because of physical disability, minor emotional problems or mental retardation. The results of this study have certain implication for recruitment and selection of foster parents. The findings indicate the need for further research to explore why more individuals in the population do not express a willingness to care for foster children, how such an interest can be encouraged and what criteria can be used in recruitment and selection

Neutron time-of-flight measurements of charged-particle energy loss in inertial confinement fusion plasmas

Neutron spectra from secondary ^{3}H(d,n)α reactions produced by an implosion of a deuterium-gas capsule at the National Ignition Facility have been measured with order-of-magnitude improvements in statistics and resolution over past experiments. These new data and their sensitivity to the energy loss of fast tritons emitted from thermal ^{2}H(d,p)^{3}H reactions enable the first statistically significant investigation of charged-particle stopping via the emitted neutron spectrum. Radiation-hydrodynamic simulations, constrained to match a number of observables from the implosion, were used to predict the neutron spectra while employing two different energy loss models. This analysis represents the first test of stopping models under inertial confinement fusion conditions, covering plasma temperatures of k_{B}T≈1-4  keV and particle densities of n≈(12-2)×10^{24}  cm^{-3}. Under these conditions, we find significant deviations of our data from a theory employing classical collisions whereas the theory including quantum diffraction agrees with our data

Terawatt, Joule-Class Pulsed THz Sources from Microchannel Targets

Production of terawatt, joule class THz radiation sources from microchannel targets driven with 100s of joule, picosecond lasers is reported. THz sources of this magnitude are useful for non-linear pumping of matter and for charged particle acceleration and manipulation. Microchannel targets demonstrate increased conversion efficiency compared to planar foil targets, with laser energy to THz energy conversion up to 0.9 percent.Comment: 9 pages, 2 figure

Laser-Plasma Interactions Enabled by Emerging Technologies

An overview from the past and an outlook for the future of fundamental laser-plasma interactions research enabled by emerging laser systems

A mitogenomic timetree for Darwin’s enigmatic South American mammal Macrauchenia patachonica

The unusual mix of morphological traits displayed by extinct South American native ungulates (SANUs) confounded both Charles Darwin, who first discovered them, and Richard Owen, who tried to resolve their relationships. Here we report an almost complete mitochondrial genome for the litoptern Macrauchenia. Our dated phylogenetic tree places Macrauchenia as sister to Perissodactyla, but close to the radiation of major lineages within Laurasiatheria. This position is consistent with a divergence estimate of B66Ma (95% credibility interval, 56.64–77.83 Ma) obtained for the split between Macrauchenia and other Panperissodactyla. Combined with their morphological distinctiveness, this evidence supports the positioning of Litopterna (possibly in company with other SANU groups) as a separate order within Laurasiatheria. We also show that, when using strict criteria, extinct taxa marked by deep divergence times and a lack of close living relatives may still be amenable to palaeogenomic analysis through iterative mapping against more distant relatives.Facultad de Ciencias Naturales y Muse