An automatic scaling method for obtaining the trace and parameters from oblique ionogram based on hybrid genetic algorithm

Abstract

Scaling oblique ionogram plays an important role in obtaining ionospheric structure at the midpoint of oblique sounding path. The paper proposed an automatic scaling method to extract the trace and parameters of oblique ionogram based on hybrid genetic algorithm (HGA). The extracted 10 parameters come from F2 layer and Es layer, such as maximum observation frequency, critical frequency, and virtual height. The method adopts quasi‐parabolic (QP) model to describe F2 layer's electron density profile that is used to synthesize trace. And it utilizes secant theorem, Martyn's equivalent path theorem, image processing technology, and echoes' characteristics to determine seven parameters' best fit values, and three parameter's initial values in QP model to set up their searching spaces which are the needed input data of HGA. Then HGA searches the three parameters' best fit values from their searching spaces based on the fitness between the synthesized trace and the real trace. In order to verify the performance of the method, 240 oblique ionograms are scaled and their results are compared with manual scaling results and the inversion results of the corresponding vertical ionograms. The comparison results show that the scaling results are accurate or at least adequate 60–90% of the time.

A Robust Feature Extraction and Parameterized Fitting Algorithm for Bottom‐Side Oblique and Vertical Incidence Ionograms

“…Automatic profile inversion or true height analysis is commonly based on single or stepwise (overlapped) polynomial fitting techniques (Titheridge, ). Fuzzy segmentation has also been applied in place of skeletonization (Tsai & Berkey, ). Template‐matching techniques, which directly fit a synthesized trace or curve, drawn from a candidate set of parametric profiles, to extracted features or amplitude data in the ionogram image (e.g., Ding et al, ; Fox & Blundell, ; Jiang et al, ; Song et al, ; Wright et al, ). A prominent example is Autoscala (Pezzopane & Scotto, , , ; Scotto, ; Scotto & Pezzopane, ), developed for the AIS‐INGV ionosonde (Zuccheretti et al, ).…”

“…2. Template-matching techniques, which directly fit a synthesized trace or curve, drawn from a candidate set of parametric profiles, to extracted features or amplitude data in the ionogram image (e.g., Ding et al, 2007;Fox & Blundell, 1989;Jiang et al, 2014;Song et al, 2016;Wright et al, 1972). A prominent example is Autoscala (Pezzopane & Scotto, 2004Scotto, 2009;, developed for the AIS-INGV ionosonde (Zuccheretti et al, 2003).…”

“…Many such algorithms are restricted to vertical incidence (VI) geometry, although there are some examples that have specifically been developed or adapted for oblique incidence observations, without requiring an equivalent range transformation (e.g., Ippolito et al, 2015;Redding, 1996;Roughan, 1996;Song et al, 2016). In most cases, ordinary (o) and extraordinary (x) polarization modes remain unseparated in oblique incidence ionograms, which creates greater challenges for the scaling software and means magneto-ionic effects cannot be neglected.…”

Utilization of nature-inspired algorithms for gas condensate reservoir optimization

“…Arun field operated by Mobil lost over 50% of its initial productivity due to condensations issues (Afidick et al 1994;Barnum et al 1995). Shell reported 67% productivity loss (Smits et al 2001) because of the same aspect.…”

“…Dry gas injections were implemented in Sleipnerost Ty (Huerta Quinones et al 2010) and Margham condensate gas field in Dubai (Ernster et al 1988). In the field practice, dry gas (consisting of mostly methane) has been often used as injection gas; nevertheless, some researchers propose more widely available and cheaper substitute in the form of CO 2 , nitrogen, air, C 4 H 10 + C 5 H 12 injection, rich gas injection (Siregar et al 1992;Sanger et al 1998;Sadooni and Zonnouri 2015;Xiong et al 2007;Lewis and Couples 1993;Asar et al 1988). However, due to mixing of nitrogen, CO 2 and others with reservoir fluid, significant liquid dropout occurs, even though the pressure is maintained above the dew point value of the gas.…”