1,767 research outputs found
On the number of solutions of a transcendental equation arising in the theory of gravitational lensing
The equation in the title describes the number of bright images of a point
source under lensing by an elliptic object with isothermal density. We prove
that this equation has at most 6 solutions. Any number of solutions from 1 to 6
can actually occur.Comment: 26 pages, 12 figure
Nondestructive testing of bond integrity in foam insulation/aluminum composites
Nondestructive test methods are used for evaluating bond integrity of low-density polyurethane spray-on foam used as cryogenic insulation on aluminum alloy surfaces
The Occupation of Jacksonville, 1864 And the Battle of Olustee, Letters of Lt. C. M. Duren
Charles M. Duren of Bangor, Maine, enlisted in 1861 in the 24th Massachusetts Regiment and saw much service, including the battles of New Bern, the noteworthy attack on Fort Wagner, and others in that area. He was promoted to 2nd. Lieutenant (1863) in the 54th Massachusetts Volunteer Infantry (a Negro regiment with white officers) and commanded Company D of that regiment in the battle of Olustee, the only major engagement of the War in Florida. This brought a promotion to 1st. Lieutenant. Some time later he was shot in the knee and thrown from his horse, breaking his leg. He was honorably discharged for disabilities in 1865. He never fully recovered and died in 1869 at the age of twenty-seven
Evaluation of ultrasonics and optimized radiography for 2219-T87 aluminum weldments
Ultrasonic studies are described which are specifically directed toward the quantitative measurement of randomly located defects previously found in aluminum welds with radiography or with dye penetrants. Experimental radiographic studies were also made to optimize techniques for welds of the thickness range to be used in fabricating the External Tank of the Space Shuttle. Conventional and innovative ultrasonic techniques were applied to the flaw size measurement problem. Advantages and disadvantages of each method are discussed. Flaw size data obtained ultrasonically were compared to radiographic data and to real flaw sizes determined by destructive measurements. Considerable success was achieved with pulse echo techniques and with 'pitch and catch' techniques. The radiographic work described demonstrates that careful selection of film exposure parameters for a particular application must be made to obtain optimized flaw detectability. Thus, film exposure techniques can be improved even though radiography is an old weld inspection method
Arkansas Cotton Variety Test 2002
The primary aim of the Arkansas Cotton Variety Test is to provide unbiased data regarding the agronomic performance of cotton varieties and advanced breeding lines in the major cotton-growing areas of Arkansas. This information helps seed dealers establish marketing strategies and assists producers in choosing varieties to plant. In this way, the annual test facilitates the inclusion of new, improved genetic material into Arkansas cotton production. Variety adaptation is determined by evaluation of the varieties and lines at four University of Arkansas research stations located near Keiser, Clarkedale, Marianna, and Rohwer. Tests are duplicated in irrigated and non-irrigated culture at the Keiser and Marianna locations. In 2002, 37 entries were evaluated in the main test and 25 were evaluated in the first-year test. This report also includes the Mississippi County Cotton Variety Test (a large-plot, on-farm evaluation of 12 Round-up Ready varieties) and 12 other on-farm cotton variety tests conducted by the University of Arkansas Cooperative Extension Service
Injectivity of sections of convex harmonic mappings and convolution theorems
In the article the authors consider the class of
sense-preserving harmonic functions defined in the unit disk
and normalized so that and , where
and are analytic in the unit disk. In the first part of the article we
present two classes and of
functions from and show that if
and , then the harmonic convolution is a univalent
and close-to-convex harmonic function in the unit disk provided certain
conditions for parameters and are satisfied. In the second
part we study the harmonic sections (partial sums) where , and denote the -th partial sums of
and , respectively. We prove, among others, that if
is a univalent harmonic convex mapping,
then is univalent and close-to-convex in the disk for
, and is also convex in the disk for
and . Moreover, we show that the section of is not convex in the disk but is shown to be convex
in a smaller disk.Comment: 16 pages, 3 figures; To appear in Czechoslovak Mathematical Journa
Coefficient estimates for bi-univalent Ma-Minda starlike and convex functions
Estimates on the initial coefficients are obtained for normalized analytic
functions in the open unit disk with and its inverse
satisfying the conditions that and are both
subordinate to a starlike univalent function whose range is symmetric with
respect to the real axis. Several related classes of functions are also
considered, and connections to earlier known results are made
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