Residual Velocity Research Articles

Zonostrophic turbulence in the subsurface oceans of the Jovian and Saturnian moons

In order to characterize the global circulation of the subsurface ocean of Jovian and Saturnian moons, we analyse the properties of 21 three-dimensional simulations of Boussinesq thermal convection in a rapidly rotating spherical shell. Flow is driven by an adverse temperature contrast imposed across the domain, and is subjected to no-slip boundary conditions. We cover a region of parameter space previously unexplored by global simulations, both in terms of rapid rotation and vigour of convective forcing, closer to, yet still admittedly far from, the conditions appropriate for the subsurface ocean of Ganymede, Europa, Enceladus, and Titan. Our most extreme simulations exhibit a dynamic global circulation that combines powerful east–west zonal jets, planetary waves, and vortices. A spectral analysis of the kinetic energy distribution performed in cylindrical geometry reveals a high degree of anisotropy of the simulated flows. Specifically, the axisymmetric zonal energy spectra follow a steep −5 slope in wavenumber space, with the energy amplitude exclusively controlled by the rotation rate. In contrast, the non-axisymmetric residual spectra display a gentle −5/3 slope, with the energy amplitude controlled by the thermal buoyancy input power. This spectral behaviour conforms with the theory of zonostrophic turbulence, as coined by Sukoriansky et al. (2002), and allows us to propose tentative extrapolations of these findings to the more extreme conditions of icy satellites. By assuming that kinetic energy dissipates via Ekman friction at the ice–ocean boundary, we predict an upper bound for the geostrophic zonal velocity ranging from a few centimetres per second for Enceladus to about one metre per second for Ganymede, with residual velocities smaller than the zonal velocity by an order of magnitude on each moon. These predictions yield typical jets size approaching the ocean depth of Titan, Ganymede and Europa and 10 to 40% of the ocean depth on Enceladus.

Data-driven modeling for residual velocity of projectile penetrating reinforced concrete slabs

The penetration of projectiles into reinforced concrete (RC) structures is crucial for defense technology. However, accurately estimating the resistance of RC structures to projectile penetration is challenging due to complex parameter nonlinearities. This paper proposes a data-driven modeling methodology that combines validated finite element (FE) simulations with machine learning (ML) algorithms to investigate the penetration resistance of RC slabs against projectiles. The methodology employs an extreme learning machine (ELM) network to identify extreme conditions characterizing penetration resistance, reducing data requirements, and improving prediction efficiency. Predicted results from the ELM network are then used as input for a recurrent neural network (RNN) to predict residual velocity curves over time, a crucial metric for evaluating penetration resistance. To cover various loading scenarios, 64 sets of FE models with different incident velocities, caliber-radius-head (CRH), and projectile masses are developed based on available experimental studies. The Johnson-Holmquist II model and Johnson-Cook model are employed for concrete and steel, respectively, to describe material behavior at high strain rates. The FE prediction results form a training sample database, and ML models are established using CRH, incident velocity, and projectile mass as input layers and projectile residual velocity as the output layer. The results demonstrate high Pearson correlation coefficients of 0.984 and 0.991 for the ELM and RNN prediction results, respectively, with numerical simulation results. The proposed networks provide accurate and efficient alternatives to time-consuming FE simulations for predicting projectile penetration performance. This strategy offers a new ML-based method for rapid evaluation, particularly for in-situ applications.

Research on the factors influencing the process of prefabricated fragments penetrating finite thickness concrete

The damage to the back of the target plate is a phenomenon that occurs when concrete is subjected to high-speed impact. In order to study the motion parameters of prefabricated spherical fragments penetrating finite thickness concrete targets at high speeds and the occurrence rules of concrete damage, as well as the impact of target back damage on the motion of fragments, experiments were conducted on 100 mm finite thickness concrete targets with prefabricated spherical fragments. The concrete model parameters in LS-DYNA were modified based on the residual velocity of fragments, and numerical simulations were conducted on the penetration of prefabricated fragments with different impact velocities and concrete target plates with different thicknesses. By analyzing the location of concrete target plate damage, the relationship between concrete thickness and concrete damage was obtained; Combining the motion parameters of fragment penetration process, the phenomenon of concrete collapse was linked to fragment motion, and the influence of concrete thickness on fragment motion parameters was analyzed. The results indicate that the thickness of the finite thickness concrete target plate and the penetration speed of fragments have a significant impact on the damage state of the target back, and further affect the motion change response stage during the penetration process of prefabricated fragments.

A study of high-velocity penetration on icy lunar regolith simulants

Understanding the mechanical response of a high-speed penetrator penetrating icy lunar regolith (ILR) is essential for designing penetrators in lunar permanently shadowed regions and interpreting the detection data from the device. Experimental research on the penetrators is limited in engineering due to the difficulties in preparing large-scale icy lunar regolith simulants (ILRS). Such limitation urges the need to construct a theoretical model and verify a numerical simulation model based on the scaled-down penetration experimental results, which provide insights into the mechanical response of penetrator penetrating ILR. Projectile penetration experiments were conducted on ILRS targets with four typical water content levels in a cryogenic chamber at 110 K. The experimental results show that the ILRS with higher water content exhibits greater brittleness and a faster crack growth rate. Consequently, the diameters of cratering and scabbing areas are augmented on the target surface upon projectile penetration. Moreover, increased mechanical strength decreases the plugging height on the ILRS targets. Based on the projectile residual velocities, the equivalent target strength parameter R were calculated and fitted to a functional relationship with the uniaxial compressive strength. RHT model parameters were calibrated using the test results of the dynamic and static mechanical properties of the simulants. Numerical simulation of projectile penetration into semi-infinite and thick targets were conducted using the calibrated model. The simulation results demonstrate high consistency with the experimental and theoretical calculations, indicating the effectiveness of the constitutive model in describing the mechanical response of the ILRS under projectile penetration.

The Sun’s Large-Scale Flows I: Measurements of Differential Rotation & Torsional Oscillation

We have developed a comprehensive catalog of the variable differential rotation measured near the solar photosphere. This catalog includes measurements of these flows obtained using several techniques: direct Doppler, granule tracking, magnetic pattern tracking, global helioseismology, as well as both time-distance and ring-diagram methods of local helioseismology. We highlight historical differential rotation measurements to provide context, and thereafter provide a detailed comparison of the MDI-HMI-GONG-Mt. Wilson overlap period (April 2010 – Jan 2011) and investigate the differences between velocities obtained from different techniques and attempt to explain discrepancies. A comparison of the rotation rate obtained by magnetic pattern tracking with the rotation rates obtained using local and global helioseismic techniques shows that magnetic pattern tracking measurements correspond to helioseismic flows located at a depth of 25 to 28 Mm. In addition, we show the torsional oscillation from Sunspot Cycles 23 and 24 and discuss properties that are consistent across measurement techniques. We find that acceleration derived from torsional oscillation is a better indicator of long-term trends in torsional oscillation compared to the residual velocity magnitude. Finally, this analysis will pave the way toward understanding systematic effects associated with various flow measurement techniques and enable more accurate determination of the global patterns of flows and their regular and irregular variations.

Ballistic impact modeling of woven composites using the microplane triad model with meso-scale damage mechanisms

Existence of undulating fill and warp yarns in woven composite laminae introduces complex unit cell geometries and multi-scale interactions among the constituents. Due to these, the failure process involves various meso-scale constituent-level failure modes under complex loading scenarios such as ballistic impact. This can be challenging to model via conventional macro-scale damage tensor-based models. This challenge is tackled here via the adaptation of the previously developed multi-scale microplane triad model to ballistic impact of woven composites. The model can resolve meso-scale constituent level details (including yarn undulations) and predict not only the elastic constants of a woven lamina but also its fracturing behavior. In the present adaptation, only two damage laws are formulated, one for the fibers and one for the matrix. This enables the model to embody the correct values of the intralaminar mode I and II fracture energies of the woven lamina. The model is calibrated using constituent and lamina level test data, and then used to predict the ballistic impact behavior of a single plain-woven lamina under a wide range of projectile impact velocities. The model is demonstrated to predict very well the projectile residual (rebound and exit) velocities, the energy dissipation, the major failure modes of the lamina and the corresponding extent of damage, as well as the ballistic limit and deformation cone wave propagation speeds. The model’s simple, conceptually clear architecture, and computational efficiency represent a major advantage compared to existing damage tensor-based models. The model is also extended to multi-layer thick section woven laminate impact, where the analyses consider both intralaminar and interlaminar failures. The predictions are found to be comparable to those from MAT162, a commercially available material model in LS-Dyna, with much better computational efficiency. Via detailed sensitivity studies, it is demonstrated that the mode I and II intralaminar fracture energies of the lamina are a crucial model input, necessary for accurate predictions of ballistic impact. Not knowing these can introduce significant uncertainty and therefore, their characterization is an absolute must. Finally, the optimal meshing considerations as well as the advantages and limitations of the microplane triad model are discussed.

Effect of hybrid strategies on the ballistic response of aramid/ultra-high molecular weight polyethylene woven fabrics

The increasing demand for advanced personal protection systems has motivated a considerable interest in hybrid woven fabrics and textile composites. However, the effectiveness of the combination method of fibers on ballistic performance remains uncertain, leaving the selection of an appropriate hybridization strategy unresolved. This study conducted a thorough comparison of the ballistic responses of hybrid aramid/ultra-high molecular weight polyethylene (UHMWPE) woven fabrics, aiming to provide a comprehensive understanding of the hybridization effects. Specimens with inter-layer, intra-layer, and intra-yarn hybrid configurations were manufactured, and ballistic impact tests were performed via a light-gas gun. The residual velocity, energy absorption, dynamic penetration process, and perforation modes of the hybrid specimens were recorded at two selected impact velocities and then compared with those of non-hybrid specimens. The results demonstrated that the enhancement effect of hybridization varied with hybrid configuration and impact velocity. The interlacing of aramid yarns and UHMWPE yarns in intra-layer hybrid specimens did not promote the breakage of UHMWPE fibers, which was responsible for the inferior ballistic performance. In contrast, inter-layer hybridization and intra-yarn hybridization could overcome the insufficient friction of UHMWPE and the low mechanical properties of aramid, resulting in superior ballistic performance.

Study on the resistance of UHMWPE laminates against oblique penetration of projectiles

AbstractTo solve the problem of the wall panel of high‐performance shelters protecting against the oblique penetration of projectiles, ballistic experiments were carried out with ultra‐high molecular weight polyethylene (UHMWPE) laminates subjected to normal penetration by high‐velocity projectiles, and the deformation and failure characteristics of UHMWPE laminates were analyzed. The numerical model of the resistance of UHMWPE laminates against penetration of projectiles was established by using the finite element program LS‐DYNA. The validity of the numerical model was verified by the experimental results of damage morphology and the depth of depression of the target plate and the deformation of the warhead. On this basis, the ricochet angle and failure mode of the UHMWPE target plate against projectile penetration were studied numerically, and the impact of the angle of incidence on the residual kinetic energy and normal penetration displacement of the bullet, as well as the damage morphology of the UHMWPE target plate, was revealed by using simulation. The results showed that the ricochet angle of the bullet obliquely penetrating into the UHMWPE target plate was in the range of 45° to 50°; at the initial stage of projectile penetration, the shear fracture failure of the fiber layer mainly occurred at the striking face of the UHMWPE target plate. Under the impact of the warhead deformation, with the reduction of the residual velocity of the bullet, the failure mode gradually changed to the tensile and interlaminar cohesion failure of the fiber layer near the back face; When the angle of incidence was greater than the ricochet angle, the residual kinetic energy of the projectile increased slowly with the increase of the angle of incidence of the bullet and then went up approximately linearly; the normal displacement of the bullet obliquely penetrating into the UHMWPE target plate decreased slowly after reaching the peak, and the peak value of the normal penetration displacement decreased gradually with the increase of the angle of incidence, and the time to peak of the displacement shortened gradually. The damage area of the bulge on the back surface of the UHMWPE target plate after penetration decreased gradually with the increase of the angle of incidence. The research results can provide a theoretical reference for the application of UHMWPE laminates in the design of military bulletproof shelters and armor.

Experimental research on similarity deviation between prototype and model pumping systems

To investigate the reasons for the flowrate deviation of the prototype pumping systems between the measured value onsite and the calculated one by the similarity law, the energy characteristic relationship of the prototype and model pumping systems under different working conditions was compared and analyzed. It was pointed out that the hydraulic loss in the outlet passages caused by the residual velocity circulation is not similar. Using the method of vessel-mounted ADCP and water level gauges to measure the flowrates and heads of pumping stations, the energy characteristics of three typical pumping stations were obtained, and the comparisons with the characteristic curves of the pumping systems predicted by similarity law are made. It was found that there was a deviation between the two in most cases, and the similarity deviation of the elbow inlet and siphon outlet passages was greater than that of the straight pipe inlet and outlet passages. Meanwhile that the larger the blade angle (or the higher the rotational speed of pump), the greater the similarity deviation. Therefore, in the design of the pumping system, the energy characteristics of the model pumping system cannot be simply converted by the similarity law to predict the characteristics of the prototype pumping system, but the influence of different factors on the similarity deviation between the prototype and model pumping system should be considered carefully.

Numerical Prediction of Ballistic Performance of Thin Concrete Plate

This research explores the ability of 60[Formula: see text]mm thick reinforced concrete (RC) plates to resist impacts from ogive-nosed hard steel projectiles. The projectiles used in the present study have a diameter of 19[Formula: see text]mm, a length of 200[Formula: see text]mm, and a mass of 0.4[Formula: see text]kg impacted on the RC plates with incident velocities ranging from 92[Formula: see text]m/s to 161[Formula: see text]m/s. Numerical simulations were conducted using ABAQUS/Explicit finite element software to validate the experimental results. The Holmquist–Johnson–Cook (HJC) material model was employed to simulate the constitutive behavior of concrete, while the Johnson–Cook (JC) material model was used to simulate the material response of reinforcing steel bars. The residual velocities obtained from the simulations closely matched the actual experimental results, showing a polynomial correlation with the incidence velocities of the projectiles. Moreover, the experimentally and numerically determined ballistic limit for the 60[Formula: see text]mm thick RC plate was found to be 108[Formula: see text]m/s and 109.5[Formula: see text]m/s, respectively. In contrast, the ballistic limit calculated using empirical mathematical expressions was 107.4[Formula: see text]m/s. This alignment between predicted, calculated, and actual ballistic limits underscores the reliability and accuracy of both numerical and empirical approaches.

The penetration resistance behavior and corresponding size effects of ultra-high molecular weight polyethylene composite laminates

Focusing on the energy absorption characteristics of ultra-high molecular weight polyethylene (UHMWPE) fiber laminated panels, this study conducts ballistic tests and numerical simulations using 6 mm spherical projectiles to impact the UHMWPE laminated panels. The residual velocity characteristics, energy absorption patterns, and failure modes of the UHMWPE laminated panels under steel ball impacts were analyzed. The results show that the residual velocity of the steel ball increases with the increase of the incident velocity. In the velocity range near the ballistic limit velocity, the residual velocity of the steel ball increases sharply. When the incident velocity exceeds 340 m/s, the increase in residual velocity gradually slows down, tending towards a straight line. When the steel ball velocity is less than 330 m/s, the energy absorption of the UHMWPE laminated panels exhibits linear growth with increasing velocity, with a maximum energy absorption of 47.3 J. In the 327–340 m/s velocity range, the energy absorption of the laminated panels drops sharply from 47 J to around 30 J. In the 340 m/s–600 m/s velocity range, the decline in energy absorption gradually becomes more moderate, decreasing to around 20 J. Beyond 500 m/s, the energy absorbed by the UHMWPE laminated panels stabilizes with increasing velocity, and the fiber tensile failure is the main form of energy absorption of UHMWPE composite laminates under ballistic impact. The failure process of UHMWPE laminated panels presents a multi-stage failure mode, including fiber shear failure, tensile failure, and delamination. As the projectile’s incident velocity increases, the damage mechanism of the UHMWPE laminated panels transitions from tensile-dominated to shear plugging-dominated. Through similarity theory analysis, under certain conditions, the ballistic limit velocity and the dimensionless parameter of unit energy absorption for the UHMWPE laminated panels satisfy geometric similarity.

Numerical investigation on effect of different projectile nose shapes on ballistic impact of additively manufactured AlSi10Mg alloy

In the last few years, due to the superior mechanical qualities of Additive Manufacturing (AM) AlSi10Mg alloy to those of traditional casting process AlSi10Mg alloys, the application of AM technology has significantly increased. The ballistic impact research has a wide range of uses, notably in the mining, construction, spacecraft and defence sectors. This work focuses on analyzing the behavior of different projectile nose shapes on the AlSi10Mg alloy fabricated by AM. There are several projectile nose forms to consider, including blunt, hemispherical, conical, and ogive shapes. The impact of various projectile shapes on the ballistic limit of the additively created AlSi10Mg alloy is carefully examined in this study. All numerical simulations were carried out using LS-DYNA software, and the Johnson-Cook material and damage model were considered to assess the ballistic resistance behavior. The ballistic limit for various projectile shapes is computed using the Jonas-Lambert model, which describes the connection between residual velocity and starting projectile velocity. The results showed that, the ogive-shaped Projectile offers the highest ballistic limit, and the blunt projectile shows the lowest ballistic limit for a 5 mm thin target plate. The ballistic impact phenomenon showed plugging failure for the blunt nose projectile, the formation of plug and small fragments were observed in the case of hemispherical nose projectile, fragmenting failure is observed with radial necking in the case of conical nose projectile and petals are formed at the impacted zone in ogive nose shape projectile. Moreover, the ballistic limit of AM AlSi10Mg alloy was slightly higher compared to the ballistic limit of the die-cast AlSi10Mg alloy for the 7.62 mm AP bullet (core). Therefore, AM AlSi10Mg alloy may have equal or good ballistic properties compared to die-cast AlSi10Mg alloy.

Ballistic and Charpy impact performance of basalt fiber reinforced polymer composites

AbstractIn this study, the behavior of composite material produced using basalt, a natural fabric, under ballistic and Charpy impact loads was investigated. The damage resistance of target plates under ballistic loads is an important design parameter in the structures that will be exposed to these loads. Cross‐ply fiber‐reinforced composite plates were produced with different numbers of layers. The composite specimens are produced using the vacuum infusion method, cross‐ply laminated with 3, 6, 9, and 12 layers ([0/90]3, [0/90]6, [0/90]9, and [0/90]12). Carbon/Epoxy specimens were also produced in identical sequences to be used as comparison material. The study aimed to understand the absorbed energy under ballistic loads and the required energy level under the Charpy impact loads of Basalt/Epoxy composite specimens with different thicknesses. Ballistic loads are applied to the specimens using a test set‐up including the sample holder mechanism and a firing system. Charpy impact tests were conducted using a standard test machine. According to the results, for 12‐layer specimens, the residual velocity difference between Basalt/Epoxy and Carbon/Epoxy is approximately 1.5 times. For the Basalt/Epoxy plate, increasing number of layers from 3 to 12 increases the amount of energy absorbed approximately 13 times. Although this increase is approximately 19 times for the Carbon/epoxy plate, when Basalt/Epoxy and Carbon/Epoxy plates are compared, Basalt/Epoxy absorbs more energy for all layer numbers. For the Charpy impact cases, it has been observed that Basalt/Epoxy absorbs approximately 34% more energy for flat wise impact and approximately 24% more energy for edgewise impact.Highlights The behavior of composite material produced using basalt, a natural fabric. Cross‐ply fiber‐reinforced composite plates. Effect of different number of layers considered. The damage resistance of target plates under ballistic loads. Comparison of basalt and carbon‐reinforced composites.

Machine learning-based real-time velocity prediction of projectile penetration to carbon/aramid hybrid fiber laminates

Composite laminates subjected to dynamic impacts are usually investigated by experimental or numerical techniques. Numerical simulations, as an excellent complementary tool to experiments, are capable of reproducing microscopic results that cannot be observed in experiments, but require time-consuming calculations. Therefore, this work demonstrates the capability and efficiency of neural networks and decision tree models for the real-time prediction of projectile penetration of aramid/carbon hybrid fiber laminates impacted at variable angles for different initial velocities. To obtain accurate prediction models, a combination of experimental and finite element methods has been adopted and the experimentally validated finite element models have been used to provide data for training the prediction models. Consequently, the prediction model is able to accurately predict the residual velocity after projectile penetration of unknown hybrid laminates. The research demonstrates that using a large dataset generated by finite element analysis can help the prediction model to give more accurate predictions. The decision tree model outperforms the neural network model in known datasets, but the neural network model has better generalization capabilities of handling unknown feature inputs and giving accurate results.

Numerical modeling and simulation of cable barriers under vehicular impacts on a sloped median

Cable barriers are flexible barrier systems that are commonly used as median barriers in the United States for their general effectiveness and low installation and maintenance costs. The current cable median barrier (CMB) adopted by the North Carolina Department of Transportation was previously evaluated on flat terrain and found to satisfy the requirements of the National Cooperative Highway Research Program Report 350. Under in-service conditions (i.e., on a sloped median), the current CMB failed to stop small passenger cars in many incidents. The new roadside safety standard, Manual for Assessing Safety Hardware (MASH), recommends that CMBs be tested and/or evaluated on sloped medians. However, conducting full-scale crash tests on sloped median is extremely difficult and few experimental studies exist. In this study, finite element simulations were used to evaluate the performance of the current CMB design on a 6H:1V sloped median under MASH Test Level 3 conditions. To address the issue of vehicle underriding on the current CMB, two retrofit designs were developed and also evaluated on the sloped median. Two MASH compliant vehicles, a 1996 Dodge Neon and a 2006 Ford F250, were used to evaluate all three CMBs from both frontside and backside and with two initial impact points. The MASH exit-box criterion, MASH Evaluation criteria A, D, and F, vehicular responses, exit angles, and residual velocities were used to evaluate the CMB performance for structural adequacy, occupant risk, and post-impact trajectories. The simulation results showed that one of the retrofit designs could improve the CMB performance on a sloped median at MASH Test Level 3 conditions.

Impacts of Reclamation on Hydrodynamic and Suspended Sediment Transport in the Bohai Sea

AbstractSince the 1970s, extensive land reclamation has been carried out in the Bohai Sea. However, reclamation activities were prohibited in 2018. Using the MIKE3 numerical model, this study selected 1976 and 2018 as representative years before and after reclamation, respectively, and developed a highly accurate three‐dimensional hydrodynamic and sediment transport model for the Bohai Sea. The model was employed to access the effects of reclamation on tidal waves, tidal prism, residual current, tidal flux (TF), and suspended sediment flux (SSF). The results revealed that after reclamation, the amphidromic points of M2 and S2 shifted southward near Qinhuangdao, and eastward near the Yellow River estuary. The M2 amplitude in the Bohai Bay exhibited a maximum increase of 30 cm. In the Bohai Sea, the tidal prism decreased by 3.95%, suggesting a decrease in water exchange capacity. The TF in the Bohai Sea and Laizhou Bay decreased by 0.7% and 12%, respectively, while increasing by 16% in Bohai Bay and 12% in Liaodong Bay, primarily due to the variations in tidal waves. Furthermore, SSF decreased by 6% in the Bohai Sea, but increased by 125% in Bohai Bay and 114% in Laizhou Bay. The significant increase in SSF in Bohai Bay and Laizhou Bay was mainly attributed to the higher suspended sediment concentrations and the stronger residual current velocities near the Yellow River estuary. This study provides comprehensive insights into the impacts of reclamation on TF and SSF in the Bohai Sea, which could contribute to marine resource development and the planning of environmental restoration projects.

Eliminating the residual velocity divergence of spectral methods in channel turbulence

Eliminating the residual velocity divergence of spectral methods in channel turbulence

Eliminating the residual velocity divergence of spectral methods in channel turbulence

Eliminating the residual velocity divergence of spectral methods in channel turbulence

Parametric study in analysing the effect of spinning on the deformable projectiles undergoing impact

Projectiles spin as they move through the air due to the rifled barrels. The projectile consists of both translational and rotational velocities called spinning when the projectile reaches the target. In this parametric study dealing with influencing factors such as residual velocity, residual mass, residual energy etc. in analysing the effect of spinning on deformable projectiles undergoing impact are carried out based on the Finite Element Analysis (FEA) using commercial LS-DYNA software. The projectile and the target materials are considered deformable and modelled based on Johnson-Cook (JC) strength and failure models. Initially, the model is validated by using the experimental results available in the literature. The validated model is extended to study the effect of above cited parameters including projectile materials and target obliquity etc. on projectile spinning. In the present research, steel and lead materials are considered for the projectile. Al 7075-T651 material is considered for the target. The residual energy which is a function of residual mass and residual velocity has been computed for the projectile with different materials. It has been found that the projectiles made up of lead experienced more damage with the spin compared to steel. Accordingly, the lead material is not suitable for the projectile with spinning. Hence, the subsequent analysis is extended with the projectile made up of steel only and allowed to impact the target with different orientations. It has been observed that the projectile path is slightly deviating when it is impacted on an inclined target compared to normal impact conditions. So, the energy required to defeat the target with spin and without spin is evaluated to understand the spinning effectiveness. Based on the results obtained, it can be concluded that, for 90° target inclination, 1x spin is favourable compared to without spin that is, 0x. As the target inclination is decreased further, 2x spin is preferred compared to no spinning.

Influence of inter-river water diversion on estuary pollution control: A case study of Liaodong Bay

Long-term mass transport processes in offshore seas are controlled by seasonal residual currents. The Euler residual mass transport velocity field was calculated form seasonal residual current patterns in shallow sea area, comparing with polluted water changes in typical years. The following conclusions were made: closed local large loops of the Euler residual mass transport led to polluted waters in the northeast Liaodong Bay, and the bay's optimal physical self-purification occurred in winter (Euler residual mass transport diffuses polluted water masses) and spring (overall self-purification capacity of the bay plays a role after winter). The central waters were clean while pollutants were discharged into near-shore waters, leading to perennial pollution in some near-shore waters. Pollution in Liaodong Bay could be alleviated or eliminated via diversion of water from the Daliaohe River (flowing into the northeast corner of Liaodong Bay and carrying > 65% of the total amount of pollutants discharged into the top of the bay) into the Liaohe River and Daling River. The percentage of inorganic nitrogen carried by 10% of the flux of the Daliaohe River was 5.70% of that discharged into Liaodong Bay. If 10% of the flux of the Daliaohe River was discharged into the Daling River, the annual total environmental carrying capacity of inorganic nitrogen increased 4.48%. Many bays in the world have adjacent river flows, such as Gulf of Mexico, Gulf of Guinea, and Bay of Bengal. Based on the Euler residual mass transport field, the water transfer between adjacent rivers could make better use of the Euler residual mass transport capacity to mitigate the water pollution of the estuaries.