Final Velocity Research Articles

Flocking dynamics for a multiagent system involving task strategy

Collective behavior sometimes requires forming a particular formation or reaching a certain velocity to accomplish a specific task, such as bird migration. In this paper, we investigate the collective migration model, which consists of two parts: Cucker–Smale type interaction and target velocity. Each agent has a strategy to allocate limited energy to group interaction and velocity tracking. In this case, if the system achieves monocluster flocking then the final velocity is equal to target velocity. When the strategy is invariant, we show that 1/2 is a critical threshold which is consistent with the classical Cucker–Smale model. When the strategy is time varying, we provide a time‐varying strategy named threshold strategy to ensure that for any initial state the system achieves monocluster flocking and the final velocity reaches target velocity. In addition, the case of multiple target velocities is considered. According to the theory of bicluster flocking, we obtain a sufficient framework to guarantee that the system achieves bicluster flocking and two groups would reach their target velocities, respectively.

INFLUENCE OF THE DEGREE FLOODING AND COMPRESSION CROSS-SECTION OF A HYDRAULIC STRUCTURE WITH UNSTEADY LIQUID MOVEMENT

The article is devoted to topical issues of the influence of hydraulic structures on the behavior of channel flow. Issues related to the operation of hydraulic structures located on irrigation canals were considered: - the influence of the degree of flooding on the elements of unsteady movement in open channels; - the influence of flow compression on the elements of unsteady motion in open flows. Quantitative assessment of the impact degree of flooding and compression on the elements of the flow during steady motion was carried out taking into account the recommendations of prof. Bolshakova VO, which are based on the use of the method of prof. Vasilieva OF The question influence of hydraulic structures on the behavior of the channel flow was solved using the equations of Saint-Venan by the numerical method, namely the method of run by the implicit-difference scheme. To close the system when using this method, the following conditions were taken into account: a - initial; b - left and right boundary conditions. The initial conditions are the presence of uniform movement in the channel. The left boundary condition is determined by the schedule of water supply to the channel, which has the form of a triangular hydrograph. The right boundary condition is determined by the known formula of a spillway with a wide threshold. The initial data were obtained from field observations. Quantitative assessment of the impact of flooding and flow compression on the final flow, velocity and depth results was performed. The issue of distribution of the support along the channel bed, which was formed due to the compression of the flow, was solved using the recommendations of E.V. Eremenko. The equation of flow continuity was considered - under the condition of changing the volume of water in the elementary section of the channel. The time of increase in the volume of water due to compression was determined from the formula obtained in the calculation process. Based on the condition that the time factor is a known value, it is possible to obtain a mathematical expression that determines the length of the propagation of the compression effect. Thanks to the obtained formulas, the calculated graphs of the relative maximum depth depending on the degree of flooding were constructed. With the help of these graphs it is possible to solve the problem of water supply in irrigation canals in the presence of flooding and compression of the flow (in case of unsteady movement).

Effects of small-sided games and running-based high-intensity interval training on body composition and physical fitness in under-19 female soccer players

BackgroundThe aim of this study was to compare the effects of small-sided games (SSGs) and running-based high-intensity interval training (HIIT) on the body composition and physical fitness of youth female soccer players.MethodsThis study followed a randomized parallel study design. Twenty-four female soccer players (age: 18.63 ± 2.36 years) were randomly allocated to two training groups (SSG, n = 12; and HIIT, n = 12). The training intervention had a duration of eight weeks, consisting of three training sessions per week. Players were assessed twice (pre- and post-intervention) for anthropometrics, vertical (countermovement jumps, CMJ; and drop jumps, DJ) and horizontal jumping (single, triple and crossover hop), sprinting (10- and 30-m), change-of-direction (COD), COD deficit and final velocity at 30–15 Intermittent Fitness Test (VIFT). A covariance analysis (ANCOVA) was used to determine differences between the groups in the effect on post-intervention by controlling for covariates (pre-intervention). The within-group analysis (time) was performed using a paired t-test, while the between-group analysis per assessment moment was performed using an independent t-test.ResultsThe between-group analysis with ANCOVA revealed that there are no significant differences between the SSG and HIIT groups in the post-intervention for any outcome (p > 0.05). The within-group analysis revealed significant improvements in both the SSG and HIIT groups in CMJ (p < 0.05), single, triple and crossover hops (p < 0.05), RSI DJ 30-cm and RSI DJ 40-cm (p < 0.05), VIFT (p < 0.05) and COD (p < 0.05).ConclusionsSSG and HIIT are both effective for improving vertical and horizontal jumping ability, change-of-direction, and aerobic capacity status measured at a progressive and intermittent multistage test in youth soccer players.

Dynamic extension of the Keldysh-Rutherford model for attoclocks

The classical Keldysh-Rutherford (KR) model of the attoclock [A. W. Bray et al., Phys. Rev. Lett. 121, 123201 (2018)] was introduced to interpret attosecond angular streaking on atomic hydrogen in the low laser intensity regime. In this model, the photoelectron acquires its final velocity immediately after exiting the tunnel and then scatters elastically on the Coulomb field of the residual ion. In the present work, we make a dynamic extension of the KR model and consider a gradual acceleration of the photoelectron by the driving laser field. By doing so, we observe and explain a significant displacement of the peaks of the angular distribution of the mean photoelectron momentum and the angular resolved ionization probability. These peaks should be close within the original KR model.

Microgeophysics and geomatics data integration reveals the internal fracturing conditions of the statue of Ramses II (Museo Egizio, Torino, Italy)

The combined acquisition of 3D ultrasonic tomography and radar scans is growing for cultural heritage diagnostics. Both methods proved to be efficient in the detection and location of fractures and weaknesses within the investigated artefacts. Although the two techniques are widely applied together, an integrated approach for data interpretation is still missing. We present the results of radar and ultrasonic prospections carried out on the statue of the young Ramses II, an absolute masterpiece of the Egyptian art preserved in the collection of the Museo Egizio of Torino (Italy). Geophysical results are incorporated within the 3D model of the statue retrieved from total station measurements, ground-based and handheld laser scanning. A data integration approach is then proposed for the joint interpretation of the geophysical results, exploiting the final ultrasonic velocity model and radar attribute analysis (i.e. local dissimilarity computation) to define a combined damage index. The proposed methodology is efficient in fracture detection and location and improves the readability of the final results also for non-expert geophysical interpreters, offering guidance to the museum for preservation and restoration of the masterpiece.

A hybrid physics and machine learning approach for velocity prediction

Elastic well logs play an important role in reservoir characterization in the subsurface. However, due to the high expense of drilling, only a few wells are drilled to limited depths, making it difficult to understand the deposition and execute geophysical activities such as building background models for seismic inversion and property models for seismic forward modeling. We begin with P-velocity prediction between the wells and extension along the wellbore to tackle this problem. A hybrid workflow is introduced based on seismic and available P-velocity logs, including well-log decomposition, relative rock physics, seismic forward modeling, feature engineering based on seismic transform, optimal attribute selection, and machine learning network training and prediction. In this hybrid workflow, relative P-velocity instead of absolute P-velocity is used for labeling. The rock-physics study and seismic forward modeling contribute to label augmentation. The machine learning approach assists in discovering the relationship between the relative P-velocity and the optimal seismic attributes. Under physics rules, the predicted relative velocity through the trained network is integrated with the compaction trend to estimate the final absolute velocity. This hybrid workflow is applied to a case study of sand-shale sequences in northern China. The model-based deterministic inversion and data-driven machine learning approaches are also compared. The results of blind well testing indicate that the data-driven approach lacks generalization capability and fails to predict extension in some blind wells. The physics-based inversion performs differently in blind wells in different locations. By contrast, P-velocity prediction with the hybrid workflow improves prediction accuracy in all blind wells, horizontally and vertically. The results indicate that this hybrid workflow promises interpolating and extending elastic well logs when the deposition environment does not vary significantly. Further studies are recommended to discuss the applicability of this workflow.

Physically Constrained 2D Joint Inversion of Surface and Body Wave Tomography

Joint inversion of different geophysical methods is a powerful tool to overcome the limitations of individual inversions. Body wave tomography is used to obtain P-wave velocity models by inversion of P-wave travel times. Surface wave tomography is used to obtain S-wave velocity models through inversion of the dispersion curves data. Both methods have inherent limitations. We focus on the joint body and surface waves tomography inversion to reduce the limitations of each individual inversion. In our joint inversion scheme, the Poisson ratio was used as the link between P-wave and S-wave velocities, and the same geometry was imposed on the final velocity models. The joint inversion algorithm was applied to a 2D synthetic dataset and then to two 2D field datasets. We compare the obtained velocity models from individual inversions and the joint inversion. We show that the proposed joint inversion method not only produces superior velocity models but also generates physically more meaningful and accurate Poisson ratio models.

Elongated Magma Plumbing System Beneath the Coso Volcanic Field, California, Constrained by Seismic Reflection Tomography

AbstractThe magma plumbing in the lower crust beneath the Coso volcanic field (CVF) remains controversial, largely because of the absence of high‐resolution lower crustal velocity models. For the first time, we develop a high‐resolution crustal P‐wave velocity model for the Coso‐Ridgecrest region by jointly inverting 137,992 first P and 8,636 PmP travel‐time data using an eikonal equation‐based seismic reflection tomography method. More than half of the PmP travel times are picked from earthquakes after the 2019 Mw 7.1 Ridgecrest earthquake. Such abundant PmP travel times significantly improve the resolution of the lower crust. Our final velocity model reveals a prominent low‐velocity body sitting right beneath the CVF at 5–20 km depths, which we interpret as a rhyolite magma reservoir that supplies heat flux to the hot springs and also feeds the volcanic activities at Coso. We find that the upper‐middle crustal low‐velocity body dips southwards into the lower crust, extending to regions beneath the Indian Wells Valley and the Garlock Fault at depth greater than 20 km. We ascribe the lower crustal low‐velocity body (more than 4% Vp reduction) to a basaltic magma reservoir that connects the melts in the uppermost mantle with the eruptible rhyolitic reservoir at shallower depths. The basaltic magma reservoir constitutes an important part of a continuous N‐S elongated crustal magma plumbing system beneath the CVF, formed as a combined result of local extension, faulting, and stress distribution.

On the Selection of Wavelet Models in the Simulation of Seismic Accelerograms through Evolutionary Optimization

A numerical procedure, based on an evolutionary optimization algorithm, has been proposed by the authorsfor the simultaneous generation of the three components of the seismic ground acceleration. The methodology allowsthe determination of a train of seismic waves modeled by three different waveforms, for the generation of groundseismic acceleration components. The parameters of each wave, i.e., amplitude, frequency, duration, arrival time anddirection, are determined using an evolutionary optimization algorithm. Although no theoretical justification is knownby the authors for the generation, at the seismic source, of specific initial waveforms, both in case of fracture or ofsliding with friction, waveform acceleration components that satisfy the condition of zero final velocity should inprinciple be preferred. The latter is a physical restriction that is automatically satisfied by anti-symmetrical functions,thus eliminating the need to correct the baseline of simulated accelerograms. The error of fit of simulated accelerogramsgenerated by three different waveforms proposed in the literature was herein determined by comparison with actualseismic records. On that basis, estimations of the expected error of the evolutionary optimization algorithm inengineering applications are presented.

Experimental investigation of the near-surface flow dynamics in downburst-like impinging jets

Downbursts are strong downdrafts that originate from thunderstorm clouds and create vigorous radial outflows upon hitting the ground. This study is part of the comprehensive experimental research on downburst outflows produced as large-scale impinging jets in the WindEEE Dome simulator at Western University, Canada. The 2800 tests carried out form the largest database of experimental measurements on downburst winds developed thus far, which is made available to the public in its whole and described in detail in a complementary study. Therefore, the current manuscript merely focuses on the data post-processing outcomes and interpretation of results from a selected subset of measurements. Impinging jets are here simulated as transient phenomena in which velocity time series are characterized by a sudden ramp-up of velocity, followed by the velocity peak, a short statistically stationary region, and the final velocity slowdown, as it is expected to occur in the actual downbursts. A dominant velocity peak that was systematically observed in all velocity records is associated with the radial advection of the primary vortex in the outflow. Depending on the radial distance from the downdraft, the primary vortex was sometimes preceded by a secondary, much smaller, vortex close to the surface. Vertical profiles of mean velocity and turbulence intensity are for the first time characterized through the extent of a downburst-like event in the spatiotemporal domain. Particularly, these profiles rapidly change in relation to the passage of the primary vortex and consequent variation of the surface layer thickness. This study lays out a foundation for an experimental model of non-stationary downburst outflows to come.

Assessment of the fetoplacental complex and hemostasis system status in perinatal care of pregnant women with fetal congenital malformations

Research objective: to assess the morpho-functional status of the fetoplacental complex and hemostasis system in pregnant women with congenital malformations in the fetus to prevent antenatal fetal death and determine further tactics of management and delivery.Materials and methods. The state of fetoplacental circulation was studied in 120 pregnant women with fetal congenital malformations in the third trimester by Doppler assessment of blood flow in the umbilical artery (UA) and middle cerebral artery (MCA) in the fetus, with resistance index, pulse index and maximum systolic and terminal diastolic velocities ratio. The functional activity of the hemostasis system was assessed by low-frequency piezoelectric thromboelastography. Morphological examination of the placenta was performed. The control group included 25 pregnant women without fetal congenital malformations.Results. In case of Doppler flow disturbances in UA and combination of these disturbances with hypercoagulability, the probability of antenatal fetal death if there were congenital malformations ranged from 2–3 to 7–14 days (r = 0.51 and r = 0.55, respectively). A high risk of antenatal fetal death occurred with blood flow disorders in the UA and MCA (r = 0.70), as well as with blood flow disorders in the UA in combination with hypercoagulation and inhibition of fibrinolysis (r = 0.78). The highest risk of antenatal death occurred in case of impaired blood flow in the MCA with hypercoagulation and inhibition of fibrinolysis (r = +0.99).An urgent delivery within a day is indicated when there are blood flow disorders in the UA or MCA, combined with hypercoagulation and inhibition of fibrinolysis. The respiratory distress syndrome is treated by administering a surfactant at gestational ages up to 34 weeks. Delivery within 2–3 days is indicated in case of impaired blood flow in the UA and hypercoagulation, this allows preventing of respiratory distress syndrome with corticosteroids if the gestational age is less than 34 weeks. Conclusions. In pregnant women with fetal congenital malformations, significant disturbances in blood flow in the UA (increased resistance index and maximum systolic and final diastolic velocities ratio) and decreased pulse index in the MCA were revealed, which indicates intrauterine hypoxia and centralization of blood flow. The functional activity of the hemostasis system was characterized by an increase in the blood coagulation potential in the vascular-platelet, a coagulation unit, which was accompanied by morphological and functional changes in the placenta in response to hypoxia.Implementation of the proposed algorithm for perinatal support of pregnant women with fetal congenital malformations and placental dysfunction helps to optimize pregnancy management and delivery, reduce perinatal morbidity and mortality.

Comparing the physical effects of combining small-sided games with short high-intensity interval training or repeated sprint training in youth soccer players: A parallel-study design

Most of the research combining small-sided games (SSGs) with high-intensity interval training (HIIT) is using the short or long forms of HIIT. However, other types of HIIT as repeated sprint training (RST) could enhance different stimuli. The purpose of the current research was to analyze the within- and between-group variations of physical fitness and body composition of two combined training interventions: (i) SSGs combined with a short high intensity interval training (sHIIT); and (ii) SSGs combined with a RST. This study followed a randomized parallel study design. Twenty-eight youth soccer players (age: 17.3 ± 0.5) belong to the same team were assigned equally to two intervention groups: SSG + sHIIT versus SSG + RST. Training intervention lasted 4 weeks, with a 2-session/week frequency. The players were tested twice, once before and after the intervention with the following tests: skinfolds (fat mass); Sargent jump test (SJT); standing long jump; sprinting time at 10-, 20-, or 30-m; 5-0-5 for time and deficit; 30-15 intermittent fitness test (30-15IFT) based on the final velocity, and repeated sprint ability (RAST) for peak, minimum, average power, and fatigue index. A mixed analysis of variance was conducted to considering factor × time effect. Between-group analysis revealed no significant differences at baseline and post-intervention period for fat mass, sprinting time at 10-, 20-, and 30-m, change-of-direction (COD) time and deficit, SJT and standing long jump, final velocity at 30-15IFT and RAST peak, average power, and fatigue index ( p &gt; 0.05). Within-group analysis revealed that both groups significantly reduced fat mass ( p ≤ 0.001), SJT ( p ≤ 0.001), standing long jump ( p ≤ 0.001), sprint time at 10- and 20-m ( p ≤ 0.001), 30-m ( p = 0.002), COD time ( p ≤ 0.001) and deficit ( p &lt; 0.05), RAST average ( p &lt; 0.05), and final velocity 30-15IFT ( p ≤ 0.001). Only SSG + RST had significant improvements on COD deficit and peak power ( p &lt; 0.05). The result of the current research suggests that either SSG + sHIIT or SSG + RST are effective for improving physical fitness in youth soccer players, with a multiple beneficial effect on locomotor profile, speed and COD, jumping performance and repeated sprint ability.

Mathematical model and experiment analysis of pressure fluctuation inside dual-stack drainage system in residential buildings.

The final velocity was put forward to study the water flow characteristics inside the building drainage system; however, it is more suitable for low-rise and multi-storey buildings, not for high-rise buildings. This study revealed the drainage transient characteristics of a double stack drainage system in high-rise residential buildings. Based on the final velocity, the air-water interaction mechanism and two-phase flow conditions in high-rise residential drainage stacks were discussed. An influence model of drainage system flow rate on pressure fluctuation under the change of state parameters such as ventilation rate, pipe wall roughness and building height was established. The pressure limit and flow rate data were obtained through full-scale experiments. The pressure limit and flow rate model were simplified to Pn = A ċ Q2 + B ċ Q1:81 + C. After the data were verified, the fitting coefficients A, B and C were linear to the floor height.

Velocity calibration by incremental pseudomaster events for single-well microseismic monitoring

The velocity model plays a critical role in accurately determining microseismic event locations during hydraulic fracturing. Conventional velocity optimization methods, such as updating the velocity model using perforation shots, have the drawback of weak ray coverage during single-well monitoring. The microseismic events distributed in different areas can broaden the ray coverage and help improve the accuracy of the velocity model, whereas only a few perforation shots are available for a given stage. We have developed an incremental pseudomaster (IPM) method to reduce the velocity errors. The master event location technique is used to determine the positions of representative events in each iteration of the IPM method. These events then act as new pseudomasters to further optimize the velocity model using Bayesian inference. With progressive iterations, the number of pseudomaster events increases and their distribution range expands. The accuracy of the velocity model continuously improves, which means that the final IPM-based velocity model, generated based on the pseudomasters distributed throughout the study area, more accurately locates all microseismic events than the perforation shot alone method. One synthetic example and one field test have been conducted, and the results demonstrate that the IPM method could overcome the drawbacks of weak ray coverage and improve the accuracy of the inverted velocity model and event locations.

Aerodynamic of a probe using an inflatable braking device during its descent in mars atmosphere

For reentry in Mars atmosphere, inflatable braking devices are interesting as they do not use rigid heat shields, parachutes, or retrorockets which limits the mass to send into space. This paper focuses on one MetNet probe, to validate the use of inflatable braking device geometry. This study shows the results on aerodynamic coefficients determined using different solvers from OpenFOAM software in distinct configurations exposing that small deformations of the braking device in the stages of the probe’s reentry should not threatens the mission. Finally, this study shows final velocity determined using a Python program and compared with expected values on different locations on Mars’s surface to ensure that the probe survives its descent.

Explosively Formed Projectile from Stepped Casing Shaped Charge: Formation Mechanism of Canted Fins

ABSTRACT Canted fins can significantly improve the flight stability and the on-target accuracy of Explosively Formed Projectiles (EFP). The current work uses the effective charge theory to derive the formation of periodic tails from shaped charge with stepped casing by considering the detonation impulse. According to the established model, the distribution of velocity along the circumference of the liner increases linearly with the square root of the casing thickness. There are two stages in the formation of canted fins influenced by the stepped casing: (1) the distribution of velocity along the circumference of the liner upon initiation, and (2) the torsion and folding of the liner edge during deformation. Numerical simulation was carried out with LS-DYNA for shaped charge (56 mm in diameter) with regular and stepped casing. The expansion of the casing and the deformation of the liner with velocity distribution at initial times were compared between the regular and the stepped casing. The distribution regularities and the final velocity of the canted fin EFP from the simulation agree well the established velocity distribution model. Soft recovery experiments were also carried out to prove the feasibility of using shaped charge with stepped casing.

Wind–pellet shear sailing

A propulsion concept in which a spacecraft interacts with both a stream of high-velocity macroscopic pellets and the mass of the interplanetary or interstellar medium is proposed. Unlike previous pellet-stream propulsion concepts, the pellets are slower than the spacecraft and are accelerated backwards as they are overtaken by it, imparting a forward acceleration on the spacecraft. This maneuver is possible due to the interaction with a fixed medium (e.g., interstellar medium); as the spacecraft travels through the medium, it is able to extract power from the relative wind blowing over the spacecraft. As viewed from the rest frame, the kinetic energy of the pellets is transferred to the spacecraft; the source of energy for the propulsive maneuver (i.e., whether the source is the pellets or the wind) is thus reference-frame dependent. This concept relies upon the relative velocities (or shear) between the pellet stream and the fixed medium in order to concentrate the energy of the pellets into the spacecraft and is therefore termed wind–pellet shear sailing. The equations governing the mass ratio of pellets to the spacecraft and its dependence on the final spacecraft velocity are derived, analogous to the classical rocket equation; the critical role of the efficiency of the power extraction and transfer process is identified. Natural sources of energy (photon and particle fluxes from the sun) are considered as a means to accelerate the pellets, produced from in-situ sources of material in the solar system, to velocities of 1000 to 6000 km/s. Techniques for onboard generation of power via electromagnetic interaction with the interstellar medium (ISM) are reviewed, with a repetitively stroked plasma magnet being identified as a promising approach. The necessity of the spacecraft to detect and track the pellets as they are overtaken dictates the desired properties of the pellets. Pellet pushers (i.e., accelerators) on board the spacecraft are also preliminarily explored in their engineering considerations, with electric field accelerators of charged nanometric particles, Lorentz-force accelerated ionized pellets, or expansion of vaporized pellets via a nozzle being highlighted as potential approaches. A preliminary mission profile is defined in which a 500-kg scientific payload is delivered to orbit about α-Centauri, using wind–pellet shear sailing as the intermediate stage to bring the spacecraft from 2% to 5.5% of c, with a total mission duration (launch to arrival) of 27 years. The concept design illustrates the potential for synergy at the low-velocity end with advanced solar photon or solar-wind sailing and at the high-velocity end with the q-drive concept.

A variational approach for picking optimal surfaces from semblance-like panels

We propose and examine a variational method for determining optimal velocity fields from semblance-like volumes using continuation. The proposed approach finds a minimal-cost surface through a volume, which often corresponds to a velocity field within a semblance scan. This allows picked velocity fields to incorporate information from gathers that are spatially near the midpoint in question. The minimization process amounts to solving a nonlinear elliptic partial differential equation, which is accomplished by changing the elliptic problem to a parabolic one and solving it iteratively until it converges to a critical point which minimizes the cost functional. The continuation approach operates by using a variational framework to iteratively minimize the cost of a velocity surface through successively less-smoothed semblance scans. The method works because a global minimum for the velocity cost functional can only exist when the semblance scan varies smoothly in space and convexly in the parameter being scanned. Using a discretization of the functional with a limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm, we illustrate how the continuation approach is able to avoid local minima that would typically capture the iterative solution of an optimal velocity field determined without continuation by applying the method to seismic processing of a field data set from the Viking Graben. We then use a field data set from the Gulf of Mexico to show how the final velocity model determined by the method using continuation is largely independent of the starting velocity model, producing something resembling a global minimum. Finally, we demonstrate the versatility of the variational picking approach by using it to automatically interpret a seismic horizon from the Heidrun Field.

Relativistic theory to Compton effect for spectroscopic detector

We report here a theoretical proof of the limiting value of the velocity of target/particle responsible for various photon–electron interactions in the Compton scattering experiment which may be carried out in various applications such as gamma-ray spectroscopy. Compton scattering deals with the collision of photons with a target particle where both energy and momentum are transferred to the particle while the photon moves with reduced energy and a change of momentum. Here, the changed energy of a photon depends on the angle between the incident axis and scattered photon (θ), the rest mass of the electron, and the frequency of the photon before the collision. However, when some initial velocity is provided to an electron that is at rest initially, then in such cases, the particle obeys limiting value on velocity for a particular energetic photon to follow Compton scattering. In such cases, the changed frequency of photons also depends on the initial and final velocity of nonstationary electrons during a collision, including the angle (φ′) between the recoil electron and incident axis. Here, we have presented the derivations to calculate the recoil velocity of the nonstationary electron. These terms are the accurate solution of the Compton shift. We have tried to calculate the upper limit or limiting values of the initial velocity of the target particle in Compton scattering. Further, we have computationally demonstrated that there is a dependence of scattered photon frequency on initial velocity of target particle (u) and mass of the target particle (m) at a higher scattering angle. Finally, numerical simulations were carried out with particles such as an electron, pion (+/-, 0) to verify the greater degree of accuracy of the particles in spectroscopic detectors such as gamma-ray spectroscopy and other high energy spectroscopic techniques.

Lower crust structures and dynamics of southern California revealed by first P and PmP traveltime data

The lower crust plays an important role in coupling the upper mantle force to the brittle upper crust at transform plate boundary regions. Yet, the tomographic resolution in the lower crust is typically much lower than the upper crust, given that most earthquakes take place at seismogenic depths. Here, we present a new P-wave velocity model of the entire crust in southern California by jointly inverting arrival times of first P and Moho reflected PmP waves. A total of 29,512 robust PmP arrivals are picked by a new semi-automatic workflow, forming the largest earthquake-sourced PmP dataset in southern California to date. Such abundant PmP arrivals remarkably improve the resolution of middle and lower crust in tomographic imaging. Our final velocity model reveals prominent low-velocity anomalies beneath the Eastern California Shear Zone (ECSZ) and south of the Coso Volcanic Field (CVF) in the lower crust. We attribute the low velocities beneath the ECSZ to deep fluid concentration which not only triggers major crustal earthquakes but may also contribute to the long-term development of the shear zone. While the low-velocity anomaly south of the CVF may imply the deep magma source of the CVF is located to its south.