... the theta angle as the arccosine of the ratio of the horizontal gradient amplitude (HGA) to the analytical signal amplitude (ASA), and contrast the cosine of theta with the HGA and ASA in edge detection. A combined use of the HGA and ASA for interpretation of contacts (or edges) has been well investigated...

... the relationships between the local wavenumber ( Thurston and Smith, 1997 ; Smith et al., 1998 ; Thurston et al., 2002 ; Salem et al., 2005 ; Smith and Salem, 2005 ) and the analytic signal amplitude ( Hsu et al., 1996 ; Bastani and Pedersen, 2001 ; Salem and Ravat, 2003 ; Salem et al., 2004 ; Salem, 2005...

... and then write transformed (or enhanced) data to a commercial database. In addition to RTPVD, the other enhancements GAMS can generate are the zeroth-order analytic-signal amplitude ( ASA 0 ), tilt, spatial derivatives of ASA 0 , the zeroth-order local wavenumber, the first-order analytic-signal amplitude...

... of bodies, so the anomalies are very broad and the precise location of the edges is difficult to interpret. A third alternative is to use the first- or second-order local wavenumbers ( Thurston and Smith, 1997 ; Smith et al., 1998 ), but like ASA 1 , these also highlight edges and the local...

... the industry “best practice” of using at least two methods of depth estimation, we have used three methods: the tilt-depth (TD) method ( Salem et al., 2007 ), the source parameter imaging (SPI) method ( Thurston and Smith, 1997 ; Thurston et al., 2002 ), and the finite SPI (FSPI) method ( Salem et al., 2014...

... A-7 and A-8, obtain the p-derivative for the ASA of a thin dike by taking the inverse of | k | F { ASA } . The same procedure can be applied to the ASA 2 p-vertical derivative ( ASA 2 − PVD ): ASA 2 − PVD = F − 1 { | k | F { ASA...

... + Y 2 + Z 2 ASA = ( ∂ f ∂ x ) 2 + ( ∂ f ∂ y ) 2 + ( ∂ f ∂ z ) 2 Instantaneous (local) amplitude A = r x 2 + r y 2 + f 2 Phase of 3D vector Magnetic inclination I = tan − 1...

... the derivative-based filters, the total-gradient filter proposed by Roest et al. (1992) is one of the most popular filters. This filter is commonly referred to as the 3D analytical signal amplitude (ASA), and is defined as the square root of the square sum of the x , y , and z...

...Figure 1b. Christian missionary Asa Thurston. 4 ...

...). Hawai‘i’s earliest Christian missionaries were among the first Westerners to explore Kīlauea Volcano and witnessed native Hawaiians using volcanic heat. In June 1823, missionaries William Ellis, Asa Thurston, Artemas Bishop, and Joseph Goodrich witnessed native Hawaiians cooking their food in the hot earth...

... ). Perhaps one of the greatest proponents of a national park at Kīlauea was American businessman Lorrin A. Thurston whose grandfather, Asa Thurston, explored Kīlauea with William Ellis in 1823. Thurston practiced law in Hawai‘i and entered politics where he supported numerous projects opening the Hawaiian...

... of the posttrip reporting and analysis was carried on by renowned scientists not on the expedition, including John Cassin of the Academy of Natural Sciences, Asa Gray of Harvard, Spencer Baird of the Smithsonian, and Louis Agassiz, then at Harvard (his immense volume on fish, completed in the last years of his...

... . . . . . . . . . . . . . . 49 Kelmscott Road, Itarborne, Birmingham, England. 1920. Pregnoff, M. V. . . . . . . . . . . . . . . 350 California St., San Francisco, Calif. 1939. Proctor, Asa G. . . . . . . . . . . . . . . Box 327, Woodland, Calif. 1942. ?Public Service Dept., City of Glendale . . . . . . . . . . . . . . 119 N...

... ). Acheson (1985) reported that Asa Gray (1810–1888) and Charles Lyell (1797–1875) also lectured to the Institute, but we have not found a record of Lyell’s lecture during his 1852 visit to Saint John ( Miller and Buhay 2007b ). The playwright, poet and author Oscar Wilde (1854–1900) made an appearance...

... St., San Francisco 8, Calif., 1939. Proctor, Asa G . . . . . . . . . . . . . . . Box 327, Woodland, Calif., 1943. Rabbit, Mary Collins . . . . . . . . U. S. Coast and Geodetic Survey, Washington 25, D.C., 1937. Ramirez, J. Emilio, S.J . . . . . . :Instituto Geofisico de los Andes Colombianos...

... , 200 – 212 . Nikitenko BL and Shurygin BN ( 1994 ) Lower Toarcian black shales and Pliensbachian-Toarcian crisis of the biota of Siberian paleoseas . In Proceedings 1992 International Conference on Arctic Margins, Anchorage, Alaska (eds DK Thurston and K Fujita ), pp...

... . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lamont Geological Observatory, Palisades, N.Y., 1948. Proctor, Asa G. . . . . . . . . . . . . . . . . . . . . . . . . . . Box 327, Woodland, Calif., 1943. Rabbitt, Mrs. Mary C. . . . . . . . . . . . . . . . . . . . U. S. Geological Survey, Washington 25, D.C., 1937. Raitt, R. W...