Pairs Of Rays Research Articles

Seismic Reprocessing Overcomes Uncertainty in Offshore Egyptian Field

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 214066, “Seismic Reprocessing Leads to New Breakthroughs—A Successful Case in the ASH Field, AG Basin in Egypt,” by Mohamed Elokr and Ahmed Lotfy, Kuwait Energy Egypt, and Wei Xing, United Energy Group, et al. The paper has not been peer reviewed. _ The ASH oil field is in the eastern portion of the AG Basin in Egypt. The Lower Cretaceous Alam El Bueib is the main oil-producing formation. Because of the high heterogeneity of the Abu Roash succession, in addition to the influence of thick limestone of the Upper Cretaceous and the influence of multiple complex faults, the quality of seismic data is very poor, requiring seismic reprocessing. Two key techniques were used to achieve the goal: New vertical seismic profile (VSP) well data were acquired to adjust the velocity model, and common reflection angle migration (CRAM) prestack depth migration (PSDM) was used for reprocessing. Introduction The ASH field produces oil from the Aptian Lower Cretaceous reservoir. The ASH structure is interpreted as an elongated east-northeast/west-southwest anticline with intensive breaching on the downthrown side of northwest/southeast to west-northwest/east-southeast-oriented normal faults with obvious signature of synsedimentary activities. The entire area was subject to a series of tectonic events affecting the Western Desert, which led to a complex fault regime clearly recognized in the ASH structure by a series of horizontal displacement across the northwest/southeast faults. Strike/slip to oblique-slip faults also are observed from thicknesses of the cretaceous formations, creating significant difficulty in fault definition. The 3D seismic data acquired in 2007 suffered from losing amplitude of the Lower Cretaceous and deep Jurassic reflectors because of the complex structure. The strong carbonate markers disappear north of the field, where high, dense fault intersection is present closing from the main bounding fault. Loss of seismic amplitude could have severe effects on of the future economics of the field. The seismic survey was reprocessed two times without significant enhancement of the fault imaging. PSDM was run without velocity control, resulting in an uncertain velocity model with inaccurate fault imaging and a mismatching between actual and prognosed depths of the drilled wells of greater than 50 m. This contradiction in reservoir mapping meant that the northern portion of the field remained unexplored. Acquiring VSP in the recently drilled well encouraged reprocessing of the 3D seismic survey using well velocity as a control point in adjusting the seismic velocity model, and application of CRAM technology to improve fault imaging and appraise the uncertain area of the ASH field. CRAM Methodology CRAM was developed as a type of beam migration. Asymptotic ray tracing is performed, assuming that one-way diffraction rays from the subsurface image point to the surface sources and receivers. The takeoff angles from the image point are measured around a given local normal to a background reflection surface for each source ray and receiver ray. A system of source and receiver ray pairs is formed, and the recorded seismic data can be mapped into a local angle domain based on the reflection angles at the subsurface image points.​​​​

Correlation among crystal and local structure, phase transition, and Li–ion conduction of solid electrolyte Li7La3Zr2O12

The correlation among the crystal and local structure, phase transition, and Li–ion conduction of the solid electrolyte Li7La3Zr2O12 (LLZ) was investigated by quantum beam technique. According to the results of Rietveld refinement using Neutron diffraction data, the Li (8a) and Li (16f) sites have the deficiency of approximately 3∼5% in LLZ. These results of Li site occupancies were adopted to the Rietveld refinements with in situ Synchrotron X–ray Diffraction's (SR–XRD) from 300 K to 1000 K. The phase transition from the tetragonal to cubic phase was observed in in situ SR–XRD. The results of Rietveld refinements with in situ SR–XRD showed the coexistence of the tetragonal and cubic phase from 860 K to 880 K. The Li–ion conduction was discussed with respect to the atomic displacement parameters, electric density estimated by Rietveld refinements and Maximum Entropy Method (MEM) analysis, and local structure estimated by X–ray Absorption Spectra (XAS) and Pair Distribution Function (PDF) analysis. The Li–ion diffusion mechanism was discussed with crystal and local structures at high temperatures of LLZ. In particular, the coexistence of tetragonal phase at the phase transition, the bond of the Li and oxide at tetragonal phase, and the low symmetry of ZrO6 up to about 930 K are thought to inhibit Li diffusion.

Investigation of the Hydrodynamic Characteristics of Two Manta Rays Tandem Gliding

Collective motion is a unique biological habit of manta rays. As the most basic unit, the hydrodynamic mechanism of tandem gliding deserves further study. In this paper, a numerical simulation method was used to explore the influence of the front-to-back distance and the angle of attack on the overall and individual hydrodynamic performance of a pair of manta rays gliding. Specifically, a numerical simulation of the hydrodynamic parameters and the distribution of pressure and velocity fields was carried out when the pair of manta rays were arranged at a distance of 0.25–1 times the body length and the angle of attack was −8° to 8°. The simulation results show that, when a pair of manta rays glide at close range, compared to a single manta ray gliding, the resistance of the leader is greatly reduced, and the lift changes little, while the resistance of the follower is greatly increased, and the lift is significantly reduced. For the average resistance of the system, in the specific scenario of a close range and a small negative degree angle of attack, the two manta rays’ tandem gliding system can significantly reduce the resistance and play a role in reducing resistance and saving energy. The research content of this paper provides a theoretical basis for understanding the biological habits of manta rays and designing an underwater bionic robot group system.

The laser matter interaction in the QED regime

Contemporarily, with the rapid development of the laser techniques, the peak intensity of the laser reaches 1023 W/cm2. In this case, the laser plasma interaction enters the QED regime. With this in mind, this research demonstrates the state-of-art simulations results in the frame. Specifically, a brief introduction to the QED effect is introduced primarily. Subsequent, the progress of ultra-intensity laser, and the state-of-art facilities are discussed. Afterwards, the theoretical description of Compton scattering and Electron-Positron pairs generation are discussed. Eventually, application of high intensity gamma ray and EP pairs are presented. These results shed light on guiding further exploration of the QED physics.

A new perleidid neopterygian fish from the Early Triassic (Dienerian, Induan) of South China, with a reassessment of the relationships of Perleidiformes.

Neopterygii is the largest clade of ray-finned fishes, including Teleostei, Holostei, and their closely related fossil taxa. This clade was first documented in the Early Carboniferous and underwent rapid evolutionary radiation during the Early to Middle Triassic. This article describes a new perleidid neopterygian species, Teffichthys elegans sp. nov., based on 13 well-preserved specimens from the lower Daye Formation (Dienerian, Induan) in Guizhou, China. The new species documents one of the oldest perleidids, providing insights into the early diversification of this family. The results of a phylogenetic analysis recover Teffichthys elegans sp. nov. as the sister taxon to Teffichthys madagascariensis within the Perleididae. T. elegans sp. nov. shares three derived features of Perleididae: the length of the anteroventral margin of the dermohyal nearly half the length of the anterodorsal margin of the preopercle; the anteroventral margin of the preopercle nearly equal to the anterior margin of the subopercle in length; and the anteroventral margin of the preopercle one to two times as long as the anterodorsal margin of the preopercle. It possesses diagnostic features of Teffichthys but differs from T. madagascariensis by the following features: presence of three supraorbitals; six pairs of branchiostegal rays; relatively deep anterodorsal process of subopercle; absence of spine on the posterior margin of the jugal; and pterygial formula of D26/P14, A22, C36/T39-41. The Perleidiformes are restricted to include only the Perleididae, and other previously alleged ‘perleidiform’ families (e.g., Hydropessidae and Gabanellidae) are excluded to maintain the monophyly of the order. Similar to many other perleidids, T. elegans sp. nov. was likely a durophagous predator with dentition combining grasping and crushing morphologies. The new finding also may indicate a relatively complex trophic structure of the Early Triassic marine ecosystem in South China.

No Longer Ballistic, Not Yet Diffusive—the Formation of Cosmic-Ray Small-scale Anisotropies

Abstract The arrival directions of TeV-PeV cosmic rays are remarkably uniform due to the isotropization of their directions by scattering on turbulent magnetic fields. Small anisotropies can exist in standard diffusion models, however, only on the largest angular scales. Yet, high-statistics observatories like IceCube and High-Altitude Water Cherenkov Observatory have found significant deviations from isotropy down to small angular scales. Here, we explain the formation of small-scale anisotropies by considering pairs of cosmic rays that get correlated by their transport through the same realization of the turbulent magnetic field. We argue that the formation of small-scale anisotropies is the reflection of the particular realization of the turbulent magnetic field experienced by cosmic rays on timescales intermediate between the early, ballistic regime and the late, diffusive regime. We approach this problem in two different ways: First, we run test particle simulations in synthetic turbulence, covering for the first time the TV rigidities of observations with realistic turbulence parameters. Second, we extend the recently introduced mixing matrix approach and determine the steady-state angular power spectrum. Throughout, we adopt magneto-static, slab-like turbulence. We find excellent agreement between the predicted angular power spectra in both approaches over a large range of rigidities. In the future, measurements of small-scale anisotropies will be valuable in constraining the nature of the turbulent magnetic field in our Galactic neighborhood.

Comparison of First and Second Pectoral Fin Rays for Use in Aging Shortnose Sturgeon (Acipenser brevirostrum LeSueur, 1818)

Acipenser brevirostrum (Shortnose Sturgeon) is an endangered fish found in eastern North American rivers. Age data are largely lacking for the species, particularly in southern rivers. Such data can be acquired by examining the annuli of the pectoral fin rays. This study's objective was to compare ages derived from the first versus second pectoral fin rays. In 2020, we obtained paired pectoral ray samples from 59 Shortnose Sturgeon from 2 Georgia rivers. After processing, 35 ray pairs were examined by 3 independent readers. Only 21% of ray pairs were assigned the exact same age; 56% of pairs were assigned ages within 1 year. There was considerable overlap in length at assigned age for both first and second pectoral rays.

A 3D Point-of-Intention Estimation Method Using Multimodal Fusion of Hand Pointing, Eye Gaze and Depth Sensing for Collaborative Robots

Hand pointing psychologically expressing intention has been fused with eye gaze to assist in detecting the point of intention (POI). Ideally, a POI detection approach using a pair of hand-pointing and eye-gaze rays may achieve precise POI positioning in 3-dimensional (3D) space; however, an object sometimes occludes the detection process in real applications. This paper proposes a method of 3D POI estimation using multimodal fusion of hand pointing, eye gaze and depth sensing for collaborative robots. In this method, depth sensors are used to assist in the fusion of the original hand-pointing and eye-gaze rays to determine the POI based on a volume of interest (VOI) to find 3D POI. At real production sites where humans work with collaborative robots, workpieces may sometimes occlude the depth sensors, resulting in blind views. This problem is solved by increasing the number of depth sensors and arranging them with overlapping view ranges to cover otherwise blind views due to occlusion. The number of depth sensors is determined based on the largest possible obstacle size determined by users in advance. Experiments performed by 10 participants confirm the effectiveness of POI estimation in the presence of obstacles; specifically, with our proposed method, we measured 3D POIs at 50 cm, 70 cm, 75 cm, 80 cm, 85 cm, 90 cm, and 95 cm with average distance errors of 0.82%, 0.68%, 0.68%, 0.72%, 0.76%, 0.87%, and 0.81%, respectively, compared with the conventional POI estimation method based on the fusion of hand pointing and eye gaze.

The Determinant Inner Product and the Heisenberg Product of $Sym(2)$

The aim of this work is to introduce and study the nondegenerate inner product $<\cdot , \cdot >_{det}$ induced by the determinant map on the space $Sym(2)$ of symmetric $2\times 2$ real matrices. This symmetric bilinear form of index $2$ defines a rational symmetric function on the pairs of rays in the plane and an associated function on the $2$-torus can be expressed with the usual Hopf bundle projection $S^3\rightarrow S^2(\frac{1}{2})$. Also, the product $<\cdot , \cdot >_{det}$ is treated with complex numbers by using the Hopf invariant map of $Sym(2)$ and this complex approach yields a Heisenberg product on $Sym(2)$. Moreover, the quadratic equation of critical points for a rational Morse function of height type generates a cosymplectic structure on $Sym(2)$ with the unitary matrix as associated Reeb vector and with the Reeb $1$-form being half of the trace map.

Molecular structure of amorphous slags: An experimental and numerical approach

This study presents a description of the structure of amorphous slags, with particular attention to the Ca local environment and the medium range arrangement of Ca-sites. Using Ca K-edge X -ray absorption spectroscopy (XANES and EXAFS) and pair distribution function (PDF) as well as numerical modeling combining Molecular Dynamics and Reverse Monte-Carlo, we demonstrate that Ca occurs in a complex environment with a distribution between 6- and 7-coordinated sites. Ca atoms are not distributed randomly within the glass structure: the Ca sites are linked by edges and form a complex percolating sub-network of network-modifying cations. The aluminosilicate network in slags is highly depolymerized with, on average, Q2.06 arrangements for Si, indicating the predominance of chain-like structural units and Q2.67 arrangements for Al in more polymerized units cross-linking the Ca-domains. The Ca percolating sub-network forms clusters that may enhance the early dissolution rate of slags in water.

A new stem-neopterygian fish from the Middle Triassic (Anisian) of Yunnan, China, with a reassessment of the relationships of early neopterygian clades

AbstractNeopterygii is a taxonomically diverse group of ray-finned fishes, including Teleostei, Holostei and their closely related fossil taxa. Here, a new small-sized stem-neopterygian with extraordinarily long teeth, Louwoichthys pusillus gen. et sp. nov., is described based on 14 well-preserved specimens from the Middle Triassic (Anisian) marine deposits of Yunnan, China. Louwoichthys is closely related to Luopingichthys from the same fossil beds and Ctenognathichthys from the Middle Triassic of the Monte San Giorgio area in Europe; the three genera are grouped into the family Louwoichthyidae fam. nov., which is recovered as sister to the ‘perleidiform’ Pseudobeaconiidae. Given that ‘Perleidiformes’ is notoriously paraphyletic, a new order, Louwoichthyiformes ord. nov., is introduced to group both families. The louwoichthyiform monophyly is strongly supported by a series of derived features, such as a relatively short maxilla, an anteriorly inclined preopercle, a subopercle with a prominent anteroventral extension, and two or three pairs of branchiostegal rays. Louwoichthys is one of the smallest louwoichthyiforms, having a largest standard length of 39 mm. It is deduced to be a scavenger that might use its long and sharp teeth to grasp and tear the prey from the substrate or to bite a piece from a larger prey item.

Effects of temperature inversion in the lower atmosphere on dispersion and angle of arrival of highly directional beams

The performance of free-space optical applications can be improved using beams of different wavelengths for the auxiliary actions of pointing/tracking or turbulence correction. Chromatic dispersion owing to the atmosphere is an issue for multiwavelength systems, and the dispersion of electromagnetic signals is typically predicted based on refractive conditions from standard atmospheric models. However, for long near-horizontal paths near the Earth’s surface, substantial refractive index gradients that are associated with features such as inverse temperature layers and ducts can be encountered. These features can significantly alter the ray trajectory, the chromatic divergence, and the angle of arrival of directional beams relative to standard atmosphere predictions. A ray tracing approach was implemented to examine the chromatic divergence and angle of arrival of the rays through various practical and extreme atmospheric conditions involving a temperature inversion layer. Over a distance of 150 km along the ground, a brief encounter with the layer can cause pairs of rays with wavelengths 532 and 1550 nm to diverge up to 4.5 times greater than their standard atmosphere predictions. For a single wavelength, a linear increase of angle of arrival with initial launch angle was found for the standard atmosphere, but this trend was significantly altered in the presence of an inversion layer. Extreme refractive conditions with a large inversion layer were simulated to produce optical ducting over long distances. Chromatic separation of rays as large as 280 m was observed when only one of the two wavelengths remained in the duct.

Диамагнитные структуры — основа квазистационарного медленного солнечного ветра

The results presented in this review reflect the fundamentals of the modern understanding of the nature of the structure of the slow solar wind (SW) along the entire length from the Sun to the Earth's orbit. It is known that the source of the slow quasi-stationary SW on the Sun is the belt and the chains of coronal streamers The streamer belt encircles the entire Sun as a wave-like surface (skirt), representing a sequence of pairs of rays with increased brightness (plasma density) or two lines of rays located close to each other. Neutral line of the radial component of the solar global magnetic field goes along the belt between the rays of each of these pairs. The streamer belt extends in the heliosphere is as the heliospheric plasma sheet (HPS). Detailed analysis of data from Wind and IMP-8 satellites showed that HPS sections on the Earth orbit are registered as a sequence of diamagnetic tubes with high density plasma and low interplanetary magnetic field. They represent an extension of rays with increased brightness of the streamer belt near the Sun. Their angular size remains the same over the entire way from the Sun to the Earth's orbit. Each HPS diamagnetic tube has a fine internal structure on several scales, or fractality. In other words, diamagnetic tube is a set of nested diamagnetic tubes, whose angular size can vary by almost two orders of magnitude. These sequences of diamagnetic tubes that form the base of slow SW on the Earth's orbit has a more general name — diamagnetic structures (DS). In the final part of this article, a comparative analysis of several events was made, based on the results of this review. He made it possible to find out the morphology and nature of the origin of the new term “diamagnetic plasmoids” SW (local amplifications of plasma density), which appeared in several articles published during 2012–2018. The analysis carried out at the end of this article, for the first time, showed that the diamagnetic plasmoids SW are the small-scale component of the fractal diamagnetic structures of the slow SW, considered in this review.

Diamagnetic structures as a basis of quasi-stationary slow solar wind

The results presented in this review reflect the fundamentals of the modern understanding of the nature of the structure of the slow solar wind (SW) along the entire length from the Sun to the Earth's orbit. It is known that the source of the slow quasi-stationary SW on the Sun is the belt and the chains of coronal streamers The streamer belt encircles the entire Sun as a wave-like surface (skirt), representing a sequence of pairs of rays with increased brightness (plasma density) or two lines of rays located close to each other. Neutral line of the radial component of the solar global magnetic field goes along the belt between the rays of each of these pairs. The streamer belt extends in the heliosphere is as the heliospheric plasma sheet (HPS). Detailed analysis of data from Wind and IMP-8 satellites showed that HPS sections on the Earth orbit are registered as a sequence of diamagnetic tubes with high density plasma and low interplanetary magnetic field. They represent an extension of rays with increased brightness of the streamer belt near the Sun. Their angular size remains the same over the entire way from the Sun to the Earth's orbit. Each HPS diamagnetic tube has a fine internal structure on several scales, or fractality. In other words, diamagnetic tube is a set of nested diamagnetic tubes, whose angular size can vary by almost two orders of magnitude. These sequences of diamagnetic tubes that form the base of slow SW on the Earth's orbit has a more general name — diamagnetic structures (DS). In the final part of this article, a comparative analysis of several events was made, based on the results of this review. He made it possible to find out the morphology and nature of the origin of the new term “diamagnetic plasmoids” SW (local amplifications of plasma density), which appeared in several articles published during 2012–2018. The analysis carried out at the end of this article, for the first time, showed that the diamagnetic plasmoids SW are the small-scale component of the fractal diamagnetic structures of the slow SW, considered in this review.

Zygocaulus nagoensis N. Gen. and N. Sp. (Trichostrongyloidea: Dictyocaulidae), a Peculiar Bursate Nematode Collected from an Alien Frog, Polypedates leucomystax, in Nago, Okinawa Island, Japan

A peculiar bursate nematode, Zygocaulus nagoensis n. gen. and n. sp. (Trichostrongyloidea: Dictyocaulidae: Mertensinematinae), was described from an alien frog, Polypedates leucomystax (Anura: Rhacophoridae), collected on Okinawa Island, Japan. It is related to Mertensinema and Borrellostrongylus, the only hitherto known genera of Mertensinematinae, but is readily distinguished from them by having only 2 pairs of lateral rays and simple distal ends of the dorsal ray branches.

Quasilinear convexity and quasilinear stars in the ray space of a supertropical quadratic form

Relying on rays, we search for submodules of a module V over a supertropical semiring on which a given anisotropic quadratic form is quasilinear. Rays are classes of a certain equivalence relation on V, that carry a notion of convexity, which is consistent with quasilinearity. A criterion for quasilinearity is specified by a Cauchy-Schwartz ratio which paves the way to a convex geometry on , supported by a ‘supertropical trigonometry’. Employing a (partial) quasiordering on , this approach allows for producing convex quasilinear sets of rays, as well as paths, which contain a given quasilinear set in a systematic way. Minimal paths are endowed with a surprisingly rich combinatorial structure, delivered to the graph determined by pairs of quasilinear rays – apparently a fundamental object in the theory of supertropical quadratic forms.

Parsimonious slope tomography based on eikonal solvers and the adjoint-state method

Velocity macromodel building is an essential step of the seismic imaging workflow. Indeed, obtaining acceptable results through migration or full waveform inversion is highly dependent on the kinematic accuracy of the background/initial velocity model. Two decades ago, stereotomography was proposed as an alternative to reflection traveltime tomography, the first relying on semi-automatic picking of locally coherent events associated with small reflection or diffraction segments tied to scatterers in depth by a pair of rays, while the latter on interpretive picking of laterally continuous reflections. The flexibility of stereotomography paved the way for many developments that have shown the efficiency of the method whilst emphasizing on the complementary information carried out by traveltimes and slopes of locally coherent events. A recent formulation recast stereotomography under a matrix-free formulation based on eikonal solvers and the adjoint-state method. In the latter, like in the previous works, the scatterer positions and the velocity field are updated jointly to tackle the ill-famed velocity–position coupling in reflection tomography. Following on from this adjoint-state formulation, we propose a new parsimonious formulation of slope tomography that offers the chance to restrain the problem to minimizing the residuals of a single data class being a slope, in search of a sole parameter class being the subsurface velocity field. This parsimonious formulation results from a variable projection, which is implemented by enforcing a consistency between the scatterer coordinates and the velocity macromodel through migration of kinematic attributes. We explain why the resulting reduced-parametrization inversion is more suitable for tomographic problems than the most common joint inversion strategy. We benchmark our method against the complex Marmousi model along with a validation through time domain full waveform inversion and then present the results of a field data case study.

Droplet sizing with a wavelength modulated laser.

The light scattered by spherical droplets much larger than the wavelength may be modeled with rays associated with scattering orders that follow the laws of geometrical optics. These rays travel different paths as they are reflected and refracted by the droplet. Therefore, there is an optical pathlength difference (OPD) between these rays as they arrive on the detector. By illuminating the droplet with a frequency or wavelength modulated laser, the OPD of any pair of rays can be measured from the beat frequency that results when the rays interfere on the detector. Sweep wavelength lasers are well suited for this application given their rapid sweep rate and broad sweep wavelength band.

Description of Loffienema dhanoriensis gen. n., sp. n. (Nematoda: Rhabditidae) from Jammu and Kashmir State, India.

A new genus, Loffienema dhanoriensis gen. n., sp. n. is described and illustrated from soil mixed with mature compost of Biodiversity Park, Baba Ghulam Shah Badshah (BGSB) University, Rajouri, Jammu and Kashmir, India. It is characterized by medium-sized body, slightly offset labial region, weakly developed, isoglottoid stegostom, amphidelphic reproductive system, slender and separate spicules, spathulate gubernaculum and reduced bursa with eight pairs of bursal rays. Its relationship and distinguishing features with other closely related genera are discussed.

USE OF DIAGRAMS AS INSTRUCTIONAL AIDS IN TEACHING OF GEOMETRICAL CONCEPTS AT SECONDARY SCHOOL LEVEL

Angle is a complex topic defined in a variety of contexts; some define angle to be as a pair of rays coming from a single point, as a rotation about a single point, or in a curve. Due to the multiple definitions of angle students get confused as to what an angle truly consists of. This study paid close attention to the misconceptions high school geometry students ’ hold about the concept of angle and how to help them gain a more conceptual understanding of this essential concept with the use of different Diagrams. The main idea behind the conduction of this study is to investigate the effect of use of diagrams as instructional aids on the conceptual understanding of angles. The study hypothesizes that angle can be learned using interactive Diagrams. The results of this study showed that diagrams which based on different A.V aids was shown to be more beneficial for the students who used to clear the concept of angles.