The use of vector-valued martingales in risk theory

A completely dependent risk process with perturbation and phase-type distributed claim sizes is analyzed. Claim arrivals are modeled by a Markovian arrival process. Using a vector-valued martingale, the Laplace transform of the time to ruin is derived algorithmically. The conditional memoryless property of the phase-type distribution yields the distribution of the deficit at ruin as a corollary.     

Effect of SIMS ionization probability on depth resolution for organic/inorganic interfaces

Secondary ion mass spectrometry (SIMS) relies on the fact that surface particles ejected from a solid surface are ionized under ion bombardment. By comparing the signal of molecular secondary ions desorbed from an organic film with that of the corresponding sputtered neutral precursor molecules, we investigate the variation of the molecular ionization probability when depth profiling through the film to the substrate interface. As a result, we find notable variations of the ionization probability both at the original surface and in the interface region, leading to a strong distortion of the measured SIMS depth profile. The experiments show that the effect can act in two ways, leading either to an apparent broadening or to an artificial sharpening of the observed film‐substrate transition. As a consequence, we conclude that care must be taken when assessing interface location, width, or depth resolution from a molecular SIMS depth profile.     

Stochastic calibration of sensors in turbulent flow fields

The calibration of high-bandwidth sensors is typically carried out in an steady environment or at least a well-controlled unsteady flow. A simple technique for calibration of sensors in flow fields with arbitrary unsteadiness (such as a turbulent field) is described. Although the method requires a DC reference measurement at each calibration point, the resulting calibration is accurate for both average and unsteady measurements up to the full bandwidth of the sensor. Applications and limitations of the technique are also discussed.This work is supported by AFOSR grant F49620-93-1-0194, monitored by Dr. J. McMichael and ONR grant N00014-92-J-1918, monitored by Dr. L.P. Purtel. The author gratefully acknowledges helpful discussions with Olivier Piepsz, Ruben Rathnasingham and Bill George.     

Computing possible class fusions from character tables

An algorithm is described to compute all those maps between the character tables of two groups that have certain properties of class fusions.     

Recovery of shear modification of polypropylene melts

Long-chain branched polypropylenes (LCB-PP) of different degrees of branching (up to 1 branch/10⁴ carbon atoms) and a linear polypropylene (L-PP) are deformed at different shear conditions (rate, time and deformation) leading to reversible modifications of the entanglement structure. These modifications recover with time. Because of it the intensity of the modification and the rate of recovery are studied. At shear rates between 1?s^?1 and 10?s^?1 lower rates modify stronger. The intensity increases with shear time to a maximum at times of about 1 h where the final deformation does not control the intensity. Obviously, the disentanglement created by shearing competes with the Brownian motion coupling entanglements. Also, the intensity increases with the degree of LCB where the increase is stronger at low degrees. The rate of recovery not influenced noticeably by the initial modification strongly depends on the degree of LCB. The pertinent recovery functions grow exponentially to the limiting value of the unmodified state. Three different recovery processes are found. The fastest one with a recovery time shorter than 10³?s is assigned to linear chains. The process with a time of about 5·10³?s independent of the degree of LCB is assumed to describe the recovery of the backbones. The times for the very slow recovery of the side chains increase with the degree of LCB (between 10⁴ and 10⁵?s for the investigated samples). The recovery strength reflects the initial modification and depends on the degree of LCB. By that, the recovery behaviour provides information on the molecular structure.     

Mass spectroscopic fragmentation reactions. XXXI—the fragmentation behaviour of o-halobenzoic acids substituted in the 5-position: A novel ortho effect

A fragmentation sequence typical for o-halobenzoic acids carrying a heteroatom substituent in the 5-position is described.     

Depth profile analysis of thin film solar cells using SNMS and SIMS

SNMS (sputtered neutrals mass spectrometry) and SIMS (secondary ion mass spectrometry) are used for the depth profile analysis of thin film solar cells based on amorphous silicon. In order to enhance depth resolution, model systems are analyzed only representing parts of the layered system. Results concerning the TCO (transparent conducting oxide)/p interface and the n/i interface are presented. To minimize matrix effects, SNMS is used when the sample consists of layers with different matrices. Examples are the TCO/p interface (where the transition lengths of the depth profiles are found to be sharper when ZnO is used as TCO compared to SnO₂) and SnO₂/ZnO interfaces in coated TCO layers (where a Sn contamination inside the ZnO layer is found depending on the plasma pressure during the ZnO deposition). SIMS is used when the limits of detection reached by SNMS are not sufficient. Examples are H depth profiles in ZnO layers or P depth profiles near the n/i-interface.     

Beiträge Zur Chemie des Brompentafluorids. 3 [5]. Die Reaktionen von Brompentafluorid und Arylbromtetrafluoriden mit N-Basen,von Arylbromtetrafluoriden mit Fluoridionen und die Fluor-Aryl-Monosubstitution am Hexafluorobromat (V)-Anion

Contributions on the Chemistry of Brominepentafluoride. 3. Reactions of Brominepentafluoride and Arylbrominetetrafluoride with N-Bases, of Arylbrominetetrafluoride with Fluoride Ions, and the Fluorine-Aryl Monosubstitution Reactions on the Hexafluorobromate (V) Anion BrF₅ forms 1 : 1 adducts with pyridines in organic solvents. In BrF₅? N-base adducts the axial Br? F bond is activated for fluorine-aryl substitution reactions. Arylbrominetetrafluorides resulting from fluorine-aryl monosubstitutions also yield 1 : 1 adducts with pyridines; in contrast to BrF₅ they react with fluoride ions under reductive elimination. Fluorine-aryl substitutions on [BrF₆]^? are presented and the influence of the Lewis-acidity of the aryltransfer reagent and its coproduct is discussed.