264,904 research outputs found
Elimination of rocket engine asymmetric loads during tests at sea level
Secondary injection concept eliminates asymmetric loads and may increase thrust rocket engine loads during sea level tests. The concept uses either a tubular manifold with evenly spaced injection ports or secondary fluid injected at the turbine exhaust inlet to the thrust chamber
Two generic transfers and a synonymy for some North American Elateridae (Coleoptera)
During various studies, three instances of necessary taxonomic change were found. These changes are provided here to clarify the taxonomy of these taxa for those studies
Ethical Problems in Evaluation Research
For some time, social scientists have been concerned with ethics in research. Much of what they have written has focused on research in general, but many of the points they raise are applicable to evaluation research in particular. Included among these concerns are informed consent, the right to treatment, the right to refuse treatment, implicit coercion, powerlessness of subjects, and, perhaps most important, external access to confidential data
Making It to the Major Leagues: Career Movement between Library and Archival Professions and from Small College to Large University Libraries
published or submitted for publicatio
Matchings and Hamilton Cycles with Constraints on Sets of Edges
The aim of this paper is to extend and generalise some work of Katona on the
existence of perfect matchings or Hamilton cycles in graphs subject to certain
constraints. The most general form of these constraints is that we are given a
family of sets of edges of our graph and are not allowed to use all the edges
of any member of this family. We consider two natural ways of expressing
constraints of this kind using graphs and using set systems.
For the first version we ask for conditions on regular bipartite graphs
and for there to exist a perfect matching in , no two edges of which
form a -cycle with two edges of .
In the second, we ask for conditions under which a Hamilton cycle in the
complete graph (or equivalently a cyclic permutation) exists, with the property
that it has no collection of intervals of prescribed lengths whose union is an
element of a given family of sets. For instance we prove that the smallest
family of -sets with the property that every cyclic permutation of an
-set contains two adjacent pairs of points has size between
and . We also give bounds on the general version of this problem
and on other natural special cases.
We finish by raising numerous open problems and directions for further study.Comment: 21 page
Constant-frequency, variable-duty-cycle multivibrator
Circuit provides a pulse source of constant frequency with a duty cycle that is adjustable by an external input signal. It could serve as a switching mode voltage regulator or as a switching source for control systems
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