High temperature compositions Patent

Method for producing refractory molybdenum disilicide

Future ep Physics: The Outlook for HERA

The luminosity of the electron-proton collider, HERA, will be increased by a factor of five during the long shutdown in the year 2000. At the same time longitudinal lepton beam polarisation will be provided for the collider experiments H1 and ZEUS. These far reaching upgrades to the machine will be matched by upgrades to the detectors. The result will be a unique facility for the study of the structure of the proton and the nature of the strong and electroweak interactions. The physics potential of the upgraded accelerator is discussed here together with a brief description of the HERA machine and collider detector upgrades.Comment: 13 pages, Late

The automatic validation tool for PDDL2.1

The 3rd International Planning Competition [1] was a great success and a cornerstone to this success was the initial definition of a semantics for the language used in the competition, PDDL2.1. This created a general understanding of the semantics of the domains defined using this language and therefore a general understanding of what constitutes a valid plan. With this consensus on what a valid plan is it was possible to implement an automatic plan validator, VAL. This tool conveys what is a valid plan in PDDL2.1 to anyone developing a planner using this language, as well as providing extra information in a L ATEX report featuring graphs of changing numerical values and a Gantt chart (see figure 2). Actions With Continuous Effects A numerical quantity that can be changed, a function in PDDL, is called a primitive numerical expression (PNE). These PNEs can have continuous change initiated with changes made to the values of their (time) derivatives by durative actions. The effect starts at the beginning of the durative action and ends at the end of the durative action. The introduction of continuous change creates two further complications to the discrete temporal model: 1) Continuous changes can interact with one another, and 2) Invariant conditions may depend on values that are continuously changing. The key extension to the discrete temporal model is that interactin

NASA Wallops Flight Facility Air-Sea Interaction Research Facility

This publication serves as an introduction to the Air-Sea Interaction Research Facility at NASA/GSFC/Wallops Flight Facility. The purpose of this publication is to provide background information on the research facility itself, including capabilities, available instrumentation, the types of experiments already done, ongoing experiments, and future plans

Thermoluminescent aerosol analysis

A method for detecting and measuring trace amounts of aerosols when reacted with ozone in a gaseous environment was examined. A sample aerosol was exposed to a fixed ozone concentration for a fixed period of time, and a fluorescer was added to the exposed sample. The sample was heated in a 30 C/minute linear temperature profile to 200 C. The trace peak was measured and recorded as a function of the test aerosol and the recorded thermoluminescence trace peak of the fluorescer is specific to the aerosol being tested

CP Violation, an experimental perspective

I present a review of current and near-future experimental investigations of CP violation. In this review, I cover limits on particle electric dipole moments (EDMs) and CP violation studies in the K and B systems. The wealth of results from the new B factories provide impressive constraints on the CKM quark mixing matrix elements. Current and future measurements are focusing on processes dominated by loop diagrams, which probe physics at high mass scales in low-energy experiments.Comment: Invited plenary talk, DPF meeting, August 200

Spectroscopic analysis of radiation-generated changes in tensile properties of a polyetherimide film

The effects of electron radiation on Ultem, a polyetherimide were studied for doses from 2 x 10 to the 9th power to 6 x 10 to the 9th power rad. Specimens were studied for tensile property testing and for electron paramagnetic resonance and infrared spectroscopic measurements of molecular structure. A Faraday cup design and a method for remote temperature measurement were developed. The spectroscopic data show that radiation caused dehydrogenation of methyl groups, rupture of main-chain ether linkage, and opening of imide rings, all to form radicals and indicate that the so-formed atomic hydrogen attached to phenyl radicals, but not to phenoxyl radicals, which would have formed hydroxyls. The observed decays of the radiation-generated phenoxyl, gem-dimethyl, and carbonyl radicals were interpreted as a combining of the radicals to form crosslinking. This crosslinking is the probable cause of the major reduction in the elongation of the tensile specimens after irradiation. Subsequent classical solubility tests indicate that the irradiation caused massive crosslinking

Spectroscopic comparison of effects of electron radiation on mechanical properties of two polyimides

The differences in the radiation durabilities of two polyimide materials, Du Pont Kapton and General Electric Ultem, are compared. An explanation of the basic mechanisms which occur during exposure to electron radiation from analyses of infrared (IR) and electron paramagnetic resonance (EPR) spectroscopic data for each material is provided. The molecular model for Kapton was, in part, established from earlier modeling for Ultem (pp. 1293-1298 of IEEE Transactions on Nuclear Science, December 1984). Techniques for understanding the durability of one complex polymer based on the understanding of a different and equally complex polymer are demonstrated. The spectroscopic data showed that the primary radiation-generated change in the tensile properties of Ultem (a large reduction in tensile elongation) was due to crosslinking, which followed the capture by phenyl radicals of hydrogen atoms removed from gem-dimethyl groups. In contrast, the tensile properties of Kapton remained unchanged because radical-radical recombination, a self-mending process, took place