Study of meshing of beveled gears with normally decreasing arc teeth

The meshing of beveled gears was studied by the direct and inverse approaches. Gear wheels with teeth of equal height are studied, and wheels with normally-decreasing arc teeth. Different coordinate systems are utilized to plot the determination of the rotation of the originating gear wheel and the meshing line of the gear wheel which is cut. Matrices are used to determine the equations of the originating surfaces and the unit vectors of the normals to these originating surfaces

Improvement of conditions for meshing spiral bevel gears

The effect of axial pinion displacement on gear meshing conditions during cutting and correction of the rolling chain gear ratio are analyzed. The so-called inverse problem-solving method is used

Problems on the Border Lines between Geology and the Other Sciences

In this paper attention is called to the need of co-operative work among investigators in the different fields of science. Reference is made to several bulletins and papers which have already been published by the chemists of the United States Geological Survey, by the physicists of the geophysical laboratory, and by other scientists, throwing light on many problems in geology which heretofore were obscure. The necessity for further work upon border problems, already under investigation, and upon many other problems which need solution, is emphasized

Some Features of the Bering River Coal Field, Alaska

The Bering River coal field lies a few miles inland from the north shore of Controller Bay, an indentation of the Pacific coast about 1,200 miles from Seattle. In this field are the Cunningham claims which were given much publicity in connection with the Pinchot-Ballinger controversy. Much of the coal area is within the drainage basin of the Bering River. To the north of the field is the Martin River glacier, with the lofty, snowcapped Chugach range of mountains beyond; to the east of the field, and extending for many miles, is the Bering Pielmont glacier

Quantum Control Theory for State Transformations: Dark States and their Enlightenment

For many quantum information protocols such as state transfer, entanglement transfer and entanglement generation, standard notions of controllability for quantum systems are too strong. We introduce the weaker notion of accessible pairs, and prove an upper bound on the achievable fidelity of a transformation between a pair of states based on the symmetries of the system. A large class of spin networks is presented for which this bound can be saturated. In this context, we show how the inaccessible dark states for a given excitation-preserving evolution can be calculated, and illustrate how some of these can be accessed using extra catalytic excitations. This emphasises that it is not sufficient for analyses of state transfer in spin networks to restrict to the single excitation subspace. One class of symmetries in these spin networks is exactly characterised in terms of the underlying graph properties.Comment: 14 pages, 3 figures v3: rewritten for increased clarit

Hadamard States and Adiabatic Vacua

Reversing a slight detrimental effect of the mailer related to TeXabilityComment: 10pages, LaTeX (RevTeX-preprint style

Improved detection of small atom numbers through image processing

We demonstrate improved detection of small trapped atomic ensembles through advanced post-processing and optimal analysis of absorption images. A fringe removal algorithm reduces imaging noise to the fundamental photon-shot-noise level and proves beneficial even in the absence of fringes. A maximum-likelihood estimator is then derived for optimal atom-number estimation and is applied to real experimental data to measure the population differences and intrinsic atom shot-noise between spatially separated ensembles each comprising between 10 and 2000 atoms. The combined techniques improve our signal-to-noise by a factor of 3, to a minimum resolvable population difference of 17 atoms, close to our ultimate detection limit.Comment: 4 pages, 3 figure