4,334 research outputs found
Quick attach and release fluid coupling assembly is self-aligning, self-sealing
Fluid coupling assembly that is self-aligning, self-sealing and contains a bellow ball and socket coupling for quick attach and release is highly reliable and can handle cryogenic fluids where icing is encountered. The fluid coupling assembly is used in many fluid systems but is particularly applicable to cryogenic systems
The carbene/carbenoid chemistry of lithium and tin cyclopropylidenoids
In Chapter I of this dissertation, the Skattebol-type rearrangement (in THF solution at -78(DEGREES)) of anti-7-bromo-syn-7-lithiobicyclo4.1.0hept-2-ene (34-anti) and its C(\u277)-epimer (34-syn) is investigated. The following discoveries demonstrate that, in solution, this rearrangement proceeds through a carbenoid: (a) carbenoid 34-anti undergoes 1,3-rearrangement and generates the carbenoid coupling products 42-syn and 42-anti 17 times faster than does 34-syn, (b) the coupling products 42-syn and 42-anti are formed in a much different ratio from 34-anti (7.5 to 1) than from 34-syn (1.5 to 1), (c) no carbene trapping products were formed in the presence of a large excess of isobutylene, cyclohexene, or triethylsilane, and (d) the saturated analogs of 34-anti and 34-syn (i.e., 89-anti and 89-syn, respectively) do not generate the corresponding free cyclopropylidene under the same reaction conditions (or under a variety of other reaction conditions which are investigated in Chapter II);In Chapter III, the pyrolysis reactions of anti-7-bromo-syn-7-trimethylstannylbicyclo4.1.0hept-2-ene (35-anti) and its C(\u277)-epimer (35-syn) are studied, in hopes of observing the Skattebol rearrangement of the corresponding cyclopropylidene. The results of the gas-phase pyrolysis studies are not easily understood. In the solution phase, however, the pyrolysis reactions of 35-anti and 35-syn have both been discovered to involve initial C-Br bond heterolysis, with no carbene involvement. The reaction of 35-anti involves an ionic 1,3-rearrangement (through double bond participation), and that of 35-syn involves an ionic opening of the cyclopropyl ring (favored by the stereochemistry of the bromine group);Chapter IV describes the solution-phase pyrolysis reactions of the saturated analogs of 35-anti and 35-syn (205-anti and 205-syn, respectively). Both reactions again involve initial C-Br bond heterolysis. The major reaction pathway of 205-anti is C-Br bond heterolysis, leading to a cyclopropyl ion pair, which, in the absence of cation traps, loses trimethyltin bromide, to generate the corresponding cyclopropylidene. The major reaction pathway of 205-syn is ionic opening of the cyclopropyl ring (again favored by the stereochemistry of the bromine group)
Space-efficient detection of unusual words
Detecting all the strings that occur in a text more frequently or less
frequently than expected according to an IID or a Markov model is a basic
problem in string mining, yet current algorithms are based on data structures
that are either space-inefficient or incur large slowdowns, and current
implementations cannot scale to genomes or metagenomes in practice. In this
paper we engineer an algorithm based on the suffix tree of a string to use just
a small data structure built on the Burrows-Wheeler transform, and a stack of
bits, where is the length of the string and
is the size of the alphabet. The size of the stack is except for very
large values of . We further improve the algorithm by removing its time
dependency on , by reporting only a subset of the maximal repeats and
of the minimal rare words of the string, and by detecting and scoring candidate
under-represented strings that in the string. Our
algorithms are practical and work directly on the BWT, thus they can be
immediately applied to a number of existing datasets that are available in this
form, returning this string mining problem to a manageable scale.Comment: arXiv admin note: text overlap with arXiv:1502.0637
Introduction to the Plasma Issue
The study of the physics of ionized gases has had a long
and complicated history. The word "plasma" was first
coined by Langmuir and Tonks in 1929 to denote a gas in
which an important fraction of the molecules are dissociated
into ions and electrons, the gas as a whole remaining electrically neutral. The laboratory study of plasmas, of
course, had been pursued long before that, many important
discoveries in the realm of gas discharge phenomena
having been made in the 1800's. These studies, continuing
into the Twentieth Century as exemplified by the
work of Langmuir, served as the foundation for many practical electronic devices used for the generation, rectification, and control of electrical energy. The
plasmas used in these devices usually have a low-charge
density, and the fractional ionization is ordinarily less
than one per cent. This small percentage of ionization
is sufficient to provide good electrical conductivity
which can be controlled externally, but it is difficult
to study theoretically because of the numerous competing
processes involving neutral atoms, metastable atoms,
ions, electrons, and collective oscillations of
ions and electrons
Decoupling of Mechanical Structures with Piezoceramic Stacks
A review of the development and realisation of an adaptive interface for decoupling of two mechanical systems is presented. An approach is utilized to design an adaptronical system by means of rapid-prototyping on the basis of a simulation. The method includes the calculation of the dynamic behaviour of the mechanical structure with the help of FEM. The FE-model of the mechanical structure is reduced and embedded as modal state-space-model with the numerical simulation software MATLAB/ Simulink. Actuators and sensors are integrated into the mechanical structure. Based on the resulting dynamical behaviour of the mechanical structure an adaptive control algorithm for the decoupling of structural vibrations is developed. Experimental tests are performed to confirm and to update the simulations. The hardware-in-the-loop-simulation is performed with the commercial rapid-prototyping dSpace-system. This procedure allows the development and the evaluation of more complex adaptive mechanical structures
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