bluuebunny/crossref_metadata_2025_split huggingface dataset:
On raytracing in an elastic-anelastic medium
Authors: Krebes E. S. , Slawinski M. A. 
Published: September 2021

AbstractIn this article, we investigate seismic wave propagation in a medium consisting of a stack of anelastic layers sandwiched between two half-spaces. The upper half-space is perfectly elastic, and the lower half-space is anelastic. The source is in the upper elastic half-space. To compute a ray going from the source to the receiver (which can be anywhere in the medium), we examine two approaches. The first involves an evaluation of the Sommerfeld wavefield integral by the method of steepest descent, and we refer to the resulting ray as the stationary ray. The second involves assuming that the attenuation vector A1 of the initial ray segment emerging from the source in the elastic half-space is zero (an assumption often made in the literature), and we refer to the resulting ray as the conventional ray. We find that the stationary and conventional rays are, in general, not identical, in that the stationary ray has (a) a complex, rather than real, ray parameter; (b) a smaller travel time; (c) an initial ray segment that corresponds to an inhomogeneous elastic plane body wave (A1 ≠ 0); and (d) a substantially different value for the ray amplitude. The stationary ray actually has the smallest travel time of all possible rays, and hence it is the one that satisfies Fermat's principle of least time. Our results suggest that the stationary ray method is the correct method and that the conventional ray method is generally incorrect. The results might also find application in marine seismology, since water is practically a lossless medium.
Numerical modeling of seismic waves with a 3-D, anisotropic scalar-wave equation
Authors: Dong Zhengxin , McMechan George A. 
Published: September 2021

AbstractBy systematically defining the orientation and amount of velocity anisotropy at every point in a computational grid, and modifying the scalar-wave equation to accommodate directionally dependent velocity coefficients, scalar waves may be numerically synthesized in heterogeneous anisotropic 3-D structure by finite-differencing. The use of an intermediate, local, rotated coordinate system associated with each grid point allows the anisotropy orientation to conform spatially with 3-D structure, stress orientations, or any other correlate of the anisotropy.Both travel times and amplitudes in anisotropic media may differ significantly from those in the corresponding isotropic media. Under some conditions, the seismic response of an anisotropic flat-layered medium is nearly identical to, and may be confused with, that of a symmetrical isotropic structure. In general, these alternate interpretations can be evaluated by obtaining independent data from different recording configurations.
Seismic hazard sensitivity analysis: A multi-parameter approach
Authors: Rabinowitz Nitzan , Steinberg David M. 
Published: September 2021

Abstract
We propose a novel multi-parameter approach for conducting seismic hazard sensitivity analysis. This approach allows one to assess the importance of each input parameter at a variety of settings of the other input parameters and thus provides a much richer picture than standard analyses, which assess each input parameter only at the default settings of the other parameters. We illustrate our method with a sensitivity analysis of seismic hazard for Jerusalem. In this example, we find several input parameters whose importance depends critically on the settings of other input parameters. This phenomenon, which cannot be detected by a standard sensitivity analysis, is easily diagnosed by our method. The multi-parameter approach can also be used in the context of a probabilistic assessment of seismic hazard that incorporates subjective probability distributions for the input parameters.
High-frequency borehole seismograms recorded in the San Jacinto Fault zone, Southern California. Part 1. Polarizations
Authors: Aster Richard C. , Shearer Peter M. 
Published: September 2021

Abstract
Two borehole seismometer arrays (KNW-BH and PFO-BH) have been established in the Southern California Batholith region of the San Jacinto Fault zone by the U.S. Geological Survey. The sites are within 0.4 km of Anza network surface stations and have three-component seismometers deployed at 300 m depth, at 150 m depth, and at the surface. Downhole horizontal seismometers can be oriented to an accuracy of about 5° using regional and near-regional initial P-wave particle motions.
Shear waves recorded downhole at the KNW-BH indicate that the strong alignment of initial S-wave particle motions previously observed at the (surface) KNW Anza site (KNW-AZ) is not generated in the near-surface weathered layer. The KNW-BH surface instrument, which sits atop a highly weathered zone, displays a significantly different (≈ 20°) initial S-wave polarization direction from that observed downhole and at KNW-AZ, which is bolted to an outcrop. Although downhole initial shear-wave particle motion directions are consistent with a shear-wave splitting hypothesis, observations of orthogonally polarized slow shear waves are generally elusive, even in seismograms recorded at 300 m. A cross-correlation measure of the apparent relative velocities of Sfast and Sslow horizontally polarized S waves suggests shallow shear-wave anisotropy, consistent with the observed initial S-wave particle motion direction, of 2.3 ± 1.7 per cent between 300 and 150 m and 7.5 ± 3.5 per cent between 150 and 0 m.
Observations of Loma Prieta aftershocks from a dense array in Sunnyvale, California
Authors: Frankel Arthur , Hough Susan , Friberg Paul , Busby Robert 
Published: September 2021

AbstractA small aperture (≈300 m), four-station array was deployed in Sunnyvale, California for 5 days to record aftershocks of the Loma Prieta earthquake of October 1989. The purpose of the array was to study the seismic response of the alluvium-filled Santa Clara Valley and the role of surface waves in the seismic shaking of sedimentary basins. Strong-motion records of the Loma Prieta mainshock indicate that surface waves produced the peak velocities and displacements at some sites in the Santa Clara Valley. We use the recordings from the dense array to determine the apparent velocity and azimuth of propagation for various arrivals in the seismograms of four aftershocks with magnitudes between 3.6 and 4.4. Apparent velocities are generally observed to decrease with increasing time after the S wave in the seismograms. Phases arriving less than about 8 sec after the S wave have apparent velocities comparable to the S wave and appear to be body waves multiply reflected under the receiver site or reflected by crustal interfaces. For times 10 to 30 sec after the direct S wave, we observe long-period (1 to 6 sec) arrivals with apparent velocities decreasing from 2.5 to 0.8 km / sec. We interpret these arrivals to be surface waves and conclude that these surface waves produce the long duration of shaking observed on the aftershock records. Much of the energy in the 40 sec after the S-wave is coming approximately from the direction of the source, although some arrivals have backazimuths as much as 60° different from the backazimuths to the epicenters. Two of the aftershocks show arrivals coming from 30 to 40° more easterly than the epicenters. This energy may have been scattered from outcrops along the southeastern edge of the basin. In contrast, the deepest aftershock studied (d = 17 km) displays later arrivals with backazimuths 30 to 40° more westerly than the epicenter. A distinct arrival for one of the aftershocks propagates from the southwest, possibly scattered from the western edge of the basin. Synthetic seismograms derived from a plane-layered crustal model do not produce the long-period Love waves observed in the waveforms of the ML 4.4 aftershock. These Love waves may be generated by the conversion of incident S waves or Rayleigh waves near the edge of the basin.
Time domain waveform inversion—A frequency domain view: How well we need to match waveforms?
Authors: Der Zoltan A. , Shumway Robert H. , Hirano Michael R. 
Published: September 2021

AbstractWaveform modeling in the time domain matches the various frequency components of seismic signals unevenly; the agreement is better at low frequencies and becomes progressively worse towards higher frequencies. The net effect of this kind of time-domain modeling is that the resolution in the spatial details of the source is less than optimal since the high-frequency components of the signal with their short wavelengths to resolve finer details do not fit the data. These problems are demonstrated by numerical simulations and by the reanalysis of some aspects of the El Golfo earthquake in using a new seismic imaging technique based on a generalization of an f-k algorithm. This procedure computes a statistic that can be used to derive confidence limits of the parameters sought in the inversion, thus providing a quantitative measure of the uncertainties in the results.
Rate of Scoliosis Correction After Anterior Spinal Growth Tethering for Idiopathic Scoliosis
Authors: Takahashi Yohei , Saito Wataru , Yaszay Burt , Bartley Carrie E. , Bastrom Tracey P. , Newton Peter O. 
Published: September 2021

Background:
The purpose of the present study was to evaluate associations between changes in segmental vertebral coronal angulation (screw angulation) and overall height after anterior spinal growth tethering for the treatment of idiopathic scoliosis and to compare the rates of coronal angulation change using the preoperative Sanders stage.

Methods:
Patients with idiopathic scoliosis who underwent anterior spinal growth tethering between 2012 and 2016 and had ≥2 years of follow-up were retrospectively studied. We calculated each segment’s screw angulation rate of change (degrees/month) and each patient’s height velocity (cm/month) between each of the visits (3 to 12 visits/patient) and divided the visits into 4 groups by postoperative duration (<1 year, 1 to 2 years, >2 to 3 years, >3 years). Patients were divided into 2 groups according to the preoperative Sanders stage. Generalized estimating equations and repeated-measures correlation were utilized for analyses with non-independent samples.

Results:
We analyzed 23 patients (16 female, 7 male) with a mean age (and standard deviation) of 12.2 ± 1.6 years who had right thoracic idiopathic scoliosis (mean, 53° ± 8°). All patients were immature at the time of surgery (Risser stage 0 or 1, Sanders stage 2 or 3). The mean duration of follow-up was 3.4 ± 1.1 years (range, 2 to 5 years). The rate of change for each segment’s screw angulation after anterior spinal growth tethering was −0.16°, −0.14°, −0.05°, and 0.03° per month (with negative values indicating a reduction in scoliosis) for <1 year, 1 to 2 years, >2 to 3 years, and >3 years, respectively (p ≤ 0.001), and the mean height velocity was 0.65, 0.57, 0.30, and 0.19 cm per month for <1 year, 1 to 2 years, >2 to 3 years, and >3 years, respectively (p < 0.001). Changes in screw angulation correlated with height increases after anterior spinal growth tethering (r = −0.46, p < 0.001). Scoliosis correction for patients in the Sanders stage-2 group continued for 3 years (0.23°, 0.23°, and 0.09° per level per month for the first 3 years, respectively) and occurred at more than twice the rate for patients in the Sanders stage-3 group, for whom scoliosis correction ceased 2 years postoperatively (0.11° and 0.09° per level per month for the first 2 years, respectively).

Conclusions:
Scoliosis correction was associated with overall height changes and occurred primarily within 2 to 3 years after surgery in this cohort of largely Risser stage-0 patients. The correction rate was 2.8° per segment per year for the first 2 years in the Sanders stage-2 group, compared with 1.2° per segment per year for the Sanders stage-3 group. Surgical timing that considers the patient’s skeletal maturity is an important factor in generating proper postoperative correction after anterior spinal growth tethering.

Level of Evidence:
Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
Kajian Yuridis Putusan Mahkamah Agung dalam Penyelesaian Sengketa Pada Perusahaan Leasing Dengan Badan Penyelesaian Sengketa Konsumen
Authors: Azizah Agustine 
Published: September 2021

The purpose of this study for reviewed the dispute resolution between the finance company and the consumer decided by BPSK in the case of Supreme Court Decision Number 210 K/Pdt.Sus-BPSK/2015 and examine the consideration of the Supreme Court Judge stating that BPSK is not authorized to decide case in between consumer financing companies.This research is normative descriptive who use secondary data and collecting data use literature study. Data analysis use interactive model.The result of the research indicates that the Supreme Court Decision Number 210 K/Pdt.Sus- BPSK/2015 in the case of special dispute on consumer dispute between First Indo American Leasing Branch Bandung ("First Indo Finance") with BPSK Bandung and Neva Rahmansyah, SE stated that The Supreme Court rejected the appeal from the First Appeal Applicant of PT First Indo American Leasing Bandung ("First Indo Finance") and amended the decision of Bandung District Court Number 461/Pdt.G/2014/PN Bdg. dated December 24, 2014 so that it is clear that the Supreme Court accepted the exception of the petitioners and stated that BPSK is not authorized to examine and adjudicate the case and to punish the Cassation Applicant Applicant to pay the court fee in the appeal level stipulated at Rp 500,000 (five hundred thousand rupiahs). Consideration of the Supreme Court Judge stating that BPSK is not authorized to decide the case in the case between the finance company and the consumer because the legal relationship between the Plaintiff and the Defendant constitutes a joint financing agreement with the fiduciary transfer of property, which implements civil law relationships and does not include consumer disputes as provided in the Act Number 8 Year 1999 on Consumer Protection so that the dispute arising from the implementation of the consumer financing agreement is a dispute agreement which is the authority of the District Court.
Innovative Techniques for Optimization of Far-Field Diverter Materials to Enhance Fracture Geometry in Carbonate Reservoirs
Authors: Shah Maunish , Koster Nicholas A. , Clark Connor , Shah Subhash N. 
Published: September 2021

Abstract
The technique of employing specialized particulates for far-field diversion is well-established during hydraulic fracturing treatments in unconventional formations and is being investigated for use in conventional formations. Far-field diverters (FFD) divert fluid away from the wellbore far into the formation. The injection of FFD at the beginning of the treatment provides an additional stress barrier between the producing interval and adjacent layers by depositing at the layer boundaries where higher leak-off is encountered. The ensuing restriction in height growth maximizes fracture extension within the producing zone, optimizing geometry for increased hydrocarbon production while limiting excess water. Polylactic Acid (PLA) polymer is self-degradable, compatible with reservoir fluids, and has a variety of compositions for different temperature applications. Blending proppant with PLA has been seen to significantly improve the strength of the deposited far-field diverter. Therefore, PLA powder and silica proppant are blended to develop Generation-1 far-field diverter (FFD-Gen1). However, many silica proppants have greater density than PLA, leading to separation during transport which prevents these two components from depositing evenly at the upper fracture boundary. This results in a situation in which excessive downward growth is prevented while upward growth is left unchecked. For this reason, both components need to be simultaneously deposited in order to develop an effective seal. Generation-2 far-field diverter (FFD-Gen2) is developed by replacing silica proppant of FFD-Gen1 with a deformable proppant having a density nearly equal to the polymer, which enables uniform deposition on all adjacent formation boundaries where leakoff is encountered. The deformable characteristic improves the pressure withstanding capacity of the diverter pack.
The deposition and degradation behaviors are investigated in the laboratory by performing HTHP filter press and plug stability experiments. Experimental findings suggest that the primary selection criteria for acceptable performance are the material's mechanical properties. This methodology is used to select the appropriate FFD materials to optimize fracture geometry in carbonate reservoirs. Successful applications prevent excessive water production and substantially increase hydrocarbon production as illustrated in a three well case studies.
Enhancing Matrix Acid Stimulation Using Ultrasonic Waves
Authors: Khaldi Mohammed H. , Caliskan Sinan , Noui-Mehidi Mohamed N. 
Published: September 2021

Abstract
The present paper is concerned with improving matrix acidizing in carbonate formation. For this purpose, ultrasonic waves were added to conventional matrix acid stimulation to increase the acid reach inside the rock. This concept is based on a phonophoresis effect of the acid, applying a similar concept in pushing the stimulation acid deeper in the formation during matrix acidizing. This effect will have a great benefit in reaching larger stimulated areas and increasing the overall well productivity. Extensive laboratory experiments have shown that the rate of penetration of the acid when exposed simultaneously to ultrasonic wave irradiation reached almost 90% more than the acid only. This phenomena has been investigated through the use of CT scan analysis on the core samples. The penetration was instantaneous and rapid in reaching deeper length of the plug sample.
Learnings from Building a Vendor Agnostic Automated Directional Drilling System
Authors: Thomas Philip Titto , Ziatdinov Sergey 
Published: September 2021

Abstract
The post COVID-19 era will undoubtedly present paradigm shifts in operational planning and execution and advanced automation will become an important factor. However, drilling automation without directional drilling (Cayeux 2020) capability will exclude the use of automation in a vast number of fields where precise placement of the wellbore has shifted from a luxury to a necessity. This is important in unconventional plays where automation can make a step change in operational outcomes (Chmela 2020). However, most efforts in automating directional drilling are using bespoke rigs (Slagmulder 2016) and bespoke bottom hole assembly (BHA) that limit operational options. The goal is in designing systems that enable directional drilling automation (Chatar 2018) with existing BHAs.
This paper will look at three challenges that were identified and overcome to deploy a vendor agnostic system for automating the directional drilling (DD) process. The three challenges identified here are as follows:Using any mud motor including low-cost motors in a closed loopIntegration with an existing measurement and logging while drilling (MLWD) systemAbility to roll out automation systems on any operations with existing rigs
The system is a modification of an operator’s autonomous drilling system (Rassenfoss 2011), designed to use existing rigs, BHAs and have minimum footprint on the rigs for operational use. The system will have a dedicated connection to the rig’s programmable logic controller (PLC) via common industrial protocols including Modbus, EthernetIP or Profinet, a physical connection the MLWD receiver and a brain box with a cloud connection to aggregate, process data and send commands to the rig PLC to execute directional commands.
A vendor agnostic system will increase adoption of automated technologies and further drive improvements in operational and business performance.
Greenstick Well Engineering: Sustainability Index for Asset Value Chain Management
Authors: Samuel Robello , Adari Rishi , Srinivasan Nagaraj 
Published: September 2021

Abstract
Environmental impacts due to exploration to the abandonment of oil and gas wells are a major focus when the wells are planned and drilled. However, there is no industry standard to quantify the impact due to complex indicators and associated variables. So, it is necessary to have an assessment framework and a methodology with the help of the digital transformation that provides an integrative index. This index allows a baseline to estimate the benchmarking for the well engineering not only during planning but also in real-time as the well is drilled and produced.
This paper presents and validates a new model for the sustainability index for well design and engineering in the life cycle of the well. This proposed method avoids some of the vagueness of well’s sustainability and can be used and applied practically. It is based on various metrics and weightage assigned when a well is planned, designed, and engineered. Evaluating the index for well engineering is based on the following elements: environmental impact, well design and engineering, functionality and optimization impact, impact of well and maintenance costs, health and safety impact, societal impact. Each element contains sub-elements. This process involves individual indexing through backpropagation of neural networks combined with bat algorithm to obtain the final overall index.