An experimental investigation of the effects of boundary layer suction on the performance of an aerothermopressor

Thesis (M.S.) Massachusetts Institute of Technology. Dept. of Mechanical Engineering, 1956.Bibliography: leaf 31.by James Frederick Fenske.M.S

Prediction intervals for future BMI values of individual children - a non-parametric approach by quantile boosting

Background: The construction of prediction intervals (PIs) for future body mass index (BMI) values of individual children based on a recent German birth cohort study with n = 2007 children is problematic for standard parametric approaches, as the BMI distribution in childhood is typically skewed depending on age. Methods: We avoid distributional assumptions by directly modelling the borders of PIs by additive quantile regression, estimated by boosting. We point out the concept of conditional coverage to prove the accuracy of PIs. As conditional coverage can hardly be evaluated in practical applications, we conduct a simulation study before fitting child- and covariate-specific PIs for future BMI values and BMI patterns for the present data. Results: The results of our simulation study suggest that PIs fitted by quantile boosting cover future observations with the predefined coverage probability and outperform the benchmark approach. For the prediction of future BMI values, quantile boosting automatically selects informative covariates and adapts to the age-specific skewness of the BMI distribution. The lengths of the estimated PIs are child-specific and increase, as expected, with the age of the child. Conclusions: Quantile boosting is a promising approach to construct PIs with correct conditional coverage in a non-parametric way. It is in particular suitable for the prediction of BMI patterns depending on covariates, since it provides an interpretable predictor structure, inherent variable selection properties and can even account for longitudinal data structures

Tribological Behavior of Near-Frictionless Carbon Coatings in High- and Low- Sulfur Diesel Fuels

The sulfur content in diesel fuel has a significant effect on diesel engine emissions, which are currently subject to environmental regulations. It has been observed that engine particulate and gaseous emissions are directly proportional to fuel sulfur content. With the introduction of low-sulfur fuels, significant reductions in emissions are expected. The process of sulfur reduction in petroleum-based diesel fuels also reduces the lubricity of the fuel, resulting in premature failure of fuel injectors. Thus, another means of preventing injector failures is needed for engines operating with low-sulfur diesel fuels. In this study, the authors evaluated a near-frictionless carbon (NFC) coating (developed at Argonne National Laboratory) as a possible solution to the problems associated with fuel injector failures in low-lubricity fuels. Tribological tests were conducted with NFC-coated and uncoated H13 and 52100 steels lubricated with high- and low- sulfur diesel fuels in a high-frequency reciprocating test machine. The test results showed that the NFC coatings reduced wear rates by a factor of 10 over those of uncoated steel surfaces. In low-sulfur diesel fuel, the reduction in wear rate was even greater (i.e., by a factor of 12 compared to that of uncoated test pairs), indicating that the NFC coating holds promise as a potential solution to wear problems associated with the use of low-lubricity diesel fuels

EMIL The energy materials in situ laboratory Berlin a novel characterization facility for photovoltaic and energy materials

A knowledge based approach towards developing a new generation of solar energy conversion devices requires a fast and direct feedback between sophisticated analytics and state of the art processing test facilities for all relevant material classes. A promising approach is the coupling of synchrotron based X ray characterization techniques, providing the unique possibility to map the electronic and chemical structure of thin layers and interface regions with relevant in system in situ sample preparation or in operando analysis capabilities in one dedicated laboratory. EMIL, the Energy Materials In situ Laboratory Berlin, is a unique facility at the BESSY II synchrotron light source. EMIL will be dedicated to the in system, in situ, and in operando X ray analysis of materials and devices for energy conversion and energy storage technologies including photovoltaic applications and photo electrochemical processes. EMIL comprises up to five experimental end stations, three of them can access X rays in an energy range of 80 eV 10 keV. For example, one key setup of EMIL combines a suite of advanced spectroscopic characterization tools with industry relevant deposition facilities in one integrated ultra high vacuum system. These deposition tools allow the growth of PV devices based on silicon, compound semiconductors, hybrid heterojunctions, and organo metal halide perovskites on up to 6 sized substrates. EMIL will serve as a research platform for national and international collaboration in the field of photovoltaic photocatalytic energy conversion and beyond. In this paper, we will provide an overview of the analytic and material capabilities at EMIL

Conceivable security risks and authentication techniques for smart devices

With the rapidly escalating use of smart devices and fraudulent transaction of users’ data from their devices, efficient and reliable techniques for authentication of the smart devices have become an obligatory issue. This paper reviews the security risks for mobile devices and studies several authentication techniques available for smart devices. The results from field studies enable a comparative evaluation of user-preferred authentication mechanisms and their opinions about reliability, biometric authentication and visual authentication techniques

Race-specific genotypes of Pseudomonas syringae pv. tomato are defined by the presence of mobile DNA elements within the genome

Pseudomonas syringae pv. tomato is the causal agent of bacterial speck of tomato, an important disease that results in severe crop production losses worldwide. Currently, two races within phylogroup 01a (PG01a) are described for this pathogen. Race 0 strains have avirulence genes for the expression of type III system-associated effectors AvrPto1 and AvrPtoB, that are recognized and targeted by the effector-triggered immunity in tomato cultivars having the pto race-specific resistance gene. Race 1 strains instead lack the avrPto1 and avrPtoB genes and are therefore capable to aggressively attack all tomato cultivars. Here, we have performed the complete genome sequencing and the analysis of P. syringae pv. tomato strain DAPP-PG 215, which was described as a race 0 strain in 1996. Our analysis revealed that its genome comprises a 6.2 Mb circular chromosome and two plasmids (107 kb and 81 kb). The results indicate that the strain is phylogenetically closely related to strains Max13, K40, T1 and NYS-T1, all known race 1 strains. The chromosome of DAPP-PG 215 encodes race 1-associated genes like avrA and hopW1 and lacks race 0-associated genes like hopN1, giving it a race 1 genetic background. However, the genome harbors a complete ortholog of avrPto1, which allows the strain to display a race 0 phenotype. Comparative genomics with several PG01a genomes revealed that mobile DNA elements are rather involved in the evolution of the two different races