Recoil Analysis Research Articles

Ion Beam Analysis including ToF-ERDA of complex composition layers

When developing new materials for example, for high-temperature nuclear reactors with the potential of hydrogen production, that are characterized by radiation, high temperature and corrosion resistance, it is indispensable the knowledge of their detailed elemental composition and its possible variation with depth from surface. Several analytical methods based on different physical principles are used to determine the depth distribution of elements in the surface layers of materials. For the quantitative determination of elemental depth profile to a depth of several micrometres are applicable established Ion Beam Analysis (IBA) methods such as RBS, EBS, NRA and ERDA. Their advantage is that they are considered to be absolute and to a certain extent non-destructive. Each of these methods is advantageously used to analyse a certain range of elements, sometimes depending on the combination of other elements present. The recently commissioned Time of Flight Elastic Recoil Analysis (ToF-ERDA) measuring system at the Slovak University of Technology MTF in Trnava significantly enhanced the Ion Beam Laboratory capability of a comprehensive elemental analysis of thin films to the depth of hundreds of nanometres. Using the primary analysing 50 MeV Au beam, the depth profiles of all elements from W to H can be obtained within a single measurement. Analysis of complex samples using traditional IBA methods and high-energy ToF-ERDA is discussed and compared. The first measurements on the new ToF-ERDA installation are also presented.

A New Simulation Model for Recoil Analysis of Deep-Water Drilling Risers After Emergency Disconnection

A New Simulation Model for Recoil Analysis of Deep-Water Drilling Risers After Emergency Disconnection

Research Progress on Recoil Analysis and Control Technology of Deepwater Drilling Risers

The deepwater drilling riser is a very important and vulnerable connection between an offshore platform and subsea wellhead. Under some certain complex marine environment and operating conditions, the offshore platform may drift beyond the safe limitations or be driven away rapidly. In order to protect the safety of the platform, personnel and equipment, it is necessary to implement the emergency disconnection of the drilling riser. Since the riser is stretched under a normal connection, the riser will perform a recoil response under the combined effect of elastic potential energy and drilling fluid (mud) discharge frictional resistance after the emergency disconnection. There are complex mechanical mechanisms, influencing factors and difficult safety control problems in the recoil control process. Therefore, effectively controlling the recoil response of the deepwater drilling riser after emergency release has become one of the technical difficulties faced by deepwater drilling. The drilling mud discharge frictional resistance and tensioning force are important factors affecting the recoil response. It is necessary to develop a more general dynamic recoil model for the riser that considers the actual conditions of drilling mud discharge, floating platform motion and nonlinear tensioner factors. This paper introduces the research progress on the recoil analysis and control technology of the deepwater drilling riser, including the discharge, mechanical analysis model, the top tensioner system and control method of the recoil response, which provides a reference for future research on recoil response analyses and design of deepwater drilling risers.

Dynamic recoil response of tensioner and riser coupled in an emergency disconnection scenario

As the tension force provider for the riser system, the hydro-pneumatic tensioner system plays an essential role in riser recoil. However, Existing riser recoil analyses rarely adopt hydro-pneumatic tensioner, and main nonlinear characteristics of the tensioner, including internal friction, pressure loss of hydraulic oil flowing, and stroke limit, are almost ignored. In this paper, a recoil model that couples the nonlinear hydro-pneumatic tensioner and riser system is proposed to explore the recoil response under the action of these characteristics. A non-Newtonian mud discharge model in the concentric annular channel is developed and incorporated into the coupled model. Effects of the nonlinear characteristics of the tensioner on recoil behaviors are analyzed. Results show that internal friction and pressure loss increase the peak-to-peak value of the top tension, inhibit the recoil displacement in the recoil early stage, and advance the phase of recoil behaviors. The piston rod reaching the stroke limit will produce impact loads on the riser system, intensify the riser oscillation and result in dynamic compression of the riser. Some factors affecting the riser recoil involving the heave phase point, opening of the anti-recoil control valve, and mud density are identified on the basis of the proposed model.

An intelligent recoil controller for riser system based on fuzzy control theory

Riser recoil control is a complicated nonlinear control problem. An intelligent control methodology is proposed to control the complicated riser recoil response based on fuzzy control theory. A dynamic nonlinear model of drilling riser/tensioner coupling system is established for riser recoil analysis. The riser system is divided into several elements and the coupling effect between the riser and discharged mud is considered in the dynamic model. A fuzzy controller for the opening of the recoil control valve is designed for the riser recoil control. A comprehensive analysis method is proposed for riser recoil control simulation. Simulation results show that the designed fuzzy controller can effectively control the riser recoil response. The adaptability of the designed controller is also proved by the simulation results. The application of the designed controller can reduce the risk of accidents during riser recoil process.

Improved recoil dynamic analysis of the deepwater riser system after emergency disconnection

The riser recoil after emergency disconnection is a complicated multi-coupling process. However, most existing analytical models simplify the tensioner as a constant stiffness spring, divide the riser system into different finite element segments, and do not consider the coupling effect between the riser movement and the fluid discharge. An improved recoil dynamic model that couples the tensioner model, the riser finite element model (FEM), and the fluid discharge model is proposed to address the shortcomings of existing models. The model is solved by the Newmark–β integral method. The improvement of the model is verified from the aspects of the tensioner model, riser model, and coupling effect. Results show that the three aspects have great influences on the recoil analysis, and the improved model can efficiently identify the recoil characteristics. The recoil displacement of the improved model is lower than that of the simplified model with a constant stiffness spring. The riser simulated by a FEM with several segments can refine the axial stress along with different positions of the riser and capture the possible dynamic compression. The coupling effect exacerbates the oscillation of the discharged friction and suppresses the recoil response. The key factors influencing the recoil and fluid discharge, including the platform heave frequency and amplitude and the volume of the air pressure vessels (APVs) of the tensioner, are analyzed on the basis of the proposed model.

Recoil control of deepwater drilling riser system based on optimal control theory

Recoil of deepwater drilling riser system is a problem to be solved in offshore oil and gas engineering. Previous study focuses on the recoil analysis of deepwater drilling riser system rather on its recoil control. A recoil control method is proposed based on optimal control theory in this paper. A coupling recoil model of deepwater drilling riser system is established based on tensioner model, riser dynamic model and mud discharge model. Taking the displacement and velocity of each equivalent mass of the riser system as state variables, state-space equations for riser recoil control are then derived based on the established riser recoil model. The riser recoil controller is finally designed based on optimal control theory and linear quadratic regulator (LQR) control algorithm. Riser recoil response with controller and without controller is analyzed and compared with each other. The results show that the riser recoil response with controller is obviously less than that without controller. The designed riser recoil controller can control the riser recoil response effectively, which can decrease the recoil operation risk of the riser system.

Discrimination of electronic recoils from nuclear recoils in two-phase xenon time projection chambers

We present a comprehensive analysis of electronic recoil vs. nuclear recoil discrimination in liquid/gas xenon time projection chambers, using calibration data from the 2013 and 2014-16 runs of the Large Underground Xenon (LUX) experiment. We observe strong charge-to-light discrimination enhancement with increased event energy. For events with S1 = 120 detected photons, i.e. equivalent to a nuclear recoil energy of $\sim$100 keV, we observe an electronic recoil background acceptance of $<10^{-5}$ at a nuclear recoil signal acceptance of 50%. We also observe modest electric field dependence of the discrimination power, which peaks at a field of around 300 V/cm over the range of fields explored in this study (50-500 V/cm). In the WIMP search region of S1 = 1-80 phd, the minimum electronic recoil leakage we observe is ${(7.3\pm0.6)\times10^{-4}}$, which is obtained for a drift field of 240-290 V/cm. Pulse shape discrimination is utilized to improve our results, and we find that, at low energies and low fields, there is an additional reduction in background leakage by a factor of up to 3. We develop an empirical model for recombination fluctuations which, when used alongside the Noble Element Scintillation Technique (NEST) simulation package, correctly reproduces the skewness of the electronic recoil data. We use this updated simulation to study the width of the electronic recoil band, finding that its dominant contribution comes from electron-ion recombination fluctuations, followed in magnitude of contribution by fluctuations in the S1 signal, fluctuations in the S2 signal, and fluctuations in the total number of quanta produced for a given energy deposition.

Analysis of Chest-Compression Depth and Full Recoil in Two Infant Chest-Compression Techniques Performed by a Single Rescuer: Systematic Review and Meta-Analysis.

Pediatric cardiac arrest is associated with high mortality and permanent neurological injury. We aimed to compare the effects of the two-thumb (TT) and two-finger (TF) techniques in infant cardiopulmonary resuscitation (CPR) performed by a single rescuer. We searched PubMed, EMBASE, and CENTRAL for randomized control trials published before December 2019. Studies comparing the TT and TF techniques in infant CPR were included for meta-analysis. Relevant information was extracted for methodological assessment. Twelve studies were included. The TT technique was associated with deeper chest-compression depth (mean difference: 4.71 mm; 95% confidence interval: 3.61 to 5.81; p < 0.001) compared with the TF technique. The TF technique was better in terms of the proportion of complete chest recoil (mean difference: −11.73%; 95% confidence interval: −20.29 to −3.17; p = 0.007). CPR was performed on a manikin model, and the application of the results to real human beings may be limited. The TT technique was superior to the TF technique in terms of chest-compression depth, but with inferior chest full recoil. Future investigations should focus on modifying the conventional TT technique to generate greater compression depth and achieve complete chest recoil.

Flexibility investigation of a marine riser system based on an accurate and efficient modelling and flexible multibody dynamics

The flexibility of marine riser systems in deepwater settings is studied using flexible multibody dynamics with geometrically exact beam for static, eigen and recoil analyses. The aim is to form an accurate and efficient modelling method and the corresponding solution strategies/algorithms for considering the spatial flexibility of the marine riser and movable constraints simultaneously, where the former is usually oversimplified in rigid multibody dynamics based works and the latter is inefficient in the finite element method based works. Therefore, a geometrically exact beam with the Euler's rotation vector is adopted for the marine riser, and its uniform formulation with rigid bodies is presented together with the preconditioning and solving strategies in static, eigen and recoil cases. Some other technical details for speeding up the algorithm are also described, such as parallelisation, matrix sparsity and variable step size control. To verify the present algorithm, a model with a depth of 1547 m based on a real platform is built, here considering the hydrostatic and hydrodynamic loads on riser, hydro-pneumatic tensioner and platform motion. The numerical results are compared with the commercial software Deepriser, and up to 93% coincidence is obtained in all cases with six times speedup is achieved. In addition, an extended model with more details of the real system obtained by considering independent modelling of auxiliary lines is simulated in the recoil analysis with the presented algorithm, and the results show that ignoring the stiffness of the auxiliary lines in the traditional method and commercial software may lead to incorrect conclusions regarding the tension safety of the marine riser.

A Study on K2 Rifle Recoil Measurement and Analysis for Virtual Reality Marksmanship

A Study on K2 Rifle Recoil Measurement and Analysis for Virtual Reality Marksmanship

Coupling Effects of A Deep-Water Drilling Riser and the Platform and the Discharging Fluid Column in An Emergency Disconnect Scenario

As drilling operations move into remote locations and extreme water depths, recoil analysis requires more careful considerations and the incidence of emergency disconnect is increased inevitably. To accurately capture the recoil dynamics of a deep-water riser in an emergency disconnect scenario, researchers typically focus on modelling the influential subsystems (e.g., the tensioner, the mud discharge and seawater refilling process) which can be solved in the preprocessing, and then the determined parameters are transmitted into an existing global riser analysis software. Distinctively, the current study devotes efforts into the coupling effects resulting from that the suspended riser reacts the platform heave motion via the tensioner system in the course of recoil and the discharging fluid column follows the oscillation of the riser in the mud discharge process. Four simulation models are established based on lumped mass method employing different formulas for the top boundary condition of the riser and the discharging flow acceleration. It demonstrates that the coupling effects discussed above can significantly affect the recoil behavior during the transition phase from initial disconnect to the final hang-off state. It is recommended to develop a fully-coupled integrated model for recoil analysis and anti-recoil control system design before extreme deep-water applications.

Recoil analysis of deepwater drilling riser after emergency disconnection

In this paper, the mechanical model and governing equations for the recoil response of deepwater drilling riser are established based on the mass-spring-damping system with three degrees of freedom. The direct acting tensioner (DAT) and axial elongation of riser before disconnection the are taken as the boundary condition and initial condition of the mechanical model, respectively. The model can consider the influence of frictional resistance induced by drilling mud discharge and elastic potential energy due to axial elongation on the recoil response. The clearance between the Low Marine Riser Package (LMRP) and the blowout preventer (BOP) after disconnection is figured out through solving the governing equations. Then, the parameter sensitivity analysis is given to present a comprehensive understanding of the recoil response. Analysis results show that the phase difference has a significant influence on the recoil response. The most favorable phase difference is 60°. The possibility of collision between the LMRP and the BOP increases with water depth and amplitude of the DAT. The top tensioner has an optimal heave motion frequency, which is the most advantageous for implementing riser emergency disconnection. Corresponding measures should be taken to prevent spring stiffness of the DAT from decreasing. Besides, riser with large diameter and wall thickness is conducive to a safe disconnection.

In-situ tribochemical formation of self-lubricating diamond-like carbon films

Diamond-like carbon (DLC) films were tribochemically formed from ambient hydrocarbons on the surface of a highly stable nanocrystalline Pt-Au alloy. A sliding contact between an alumina sphere and Pt-Au coated steel exhibited friction coefficients as low as μ = 0.01 after dry sliding in environments containing trace (ppb) organics. Ex situ analysis indicated that the change in friction coefficient was due to the formation of amorphous carbon films, and Raman spectroscopy and elastic recoil analysis showed that these films consist of sp2/sp3 amorphous carbon with as much as 20% hydrogen. Transmission electron microscopy indicated these films had thicknesses exceeding 100 nm, and were enhanced by the incorporation of worn Pt-Au nanoparticles. The result was highly wear-resistant, low-friction DLC/Pt-Au nanocomposites. Atomistic simulations of hydrocarbons under shear between rigid Pt slabs using a reactive force field showed stress-induced changes in bonding through chain scission, a likely route towards the formation of these coatings. This novel demonstration of in situ tribochemical formation of self-lubricating films has significant impact potential in a wide range of engineering applications.

Effects of sp2/sp3 Ratio and Hydrogen Content on In Vitro Bending and Frictional Performance of DLC-Coated Orthodontic Stainless Steels

This study investigated a diamond-like carbon (DLC) coating formed on stainless steels (disk and wire specimens) using a plasma-based ion implantation/deposition method with two different parameters (DLC-1, DLC-2). These specimens were characterized using high-resolution elastic recoil analysis, microscale X-ray photoelectron spectroscopy and nanoindentation testing to determine the hydrogen content, sp2/sp3 ratio and mechanical properties of the coating. Three-point bending and frictional properties were estimated. DLC-1 had a diamond-rich structure at the external surface and a graphite-rich structure at the inner surface, while DLC-2 had a graphite-rich structure at the external surface and a diamond-rich structure at the inner surface. Mean mechanical property values obtained for the external surface were lower than those for the inner surface in both types of DLC-coated specimens. The hydrogen content of DLC-2 was slightly higher versus DLC-1. Both DLC-coated wires produced a significantly higher elastic modulus according to the three-point bending test versus the non-coated wire. DLC-2 produced significantly lower frictional force than the non-coated specimen in the drawing-friction test. The coating of DLC-1 was partially ruptured by the three-point bending and drawing-friction tests. In conclusion, the bending and frictional performance of DLC-coated wire were influenced by the hydrogen content and sp2/sp3 ratio of the coating.

Elastoplastic response and recoil of lattice structures under hyperbolic hardening

Elastoplastic response and recoil analyses for hexagonal honeycomb lattice structures are presented when hardening is described by a hyperbolic law. By exploiting the translational symmetry of the problem, the analysis is reduced to that of a thin beam under combined bending and axial loading coupled with the kinematics of lattice deformation and its relationship with cell wall deformation. A closed-form solution for the load-curvature relationship of a beam with rectangular cross-section is obtained. A systematic study of beam response, as the stress-strain curve of the constituent material approaches an ideal elastic-perfectly plastic law, is presented. The analysis is then applied to an infinite honeycomb sheet under remote tensile load to obtain the apparent non-linear structural response. Apparent recoil of such a lattice material upon unloading is also calculated in closed form, when unloading is assumed to take place along a linear stress-strain curve. The analytical results are in excellent agreement with the numerical calculations.

Elastoplastic response and recoil of honeycomb lattices

Abstract This paper presents elasto-plastic response and recoil analysis of two-dimensional honeycombs. The architecture studied here possesses cell wall bending as the dominant mechanism of deformation. Elasto-plastic analysis of cell walls, in conjunction with the kinematics of the deformation of the lattice, enables us to obtain closed form plastic response as well as recoil upon unloading. Elastic-perfectly plastic cell wall material is considered. A smooth apparent structural response is observed although the material model is piece-wise linear. The apparent Poisson's ratio of the porous honeycomb material, in the plastic regime, is derived from the lateral response calculation. In the non-linear regime of deformation, the Poisson's ratio of honeycombs remains independent of the apparent strain of the lattice. A parametric study of the non-linear response involving systematic changes in the parameters is carried out. This suggests the existence of non-dimensional groups that could provide response relationship valid for all geometric and material parameters . Scaling arguments are developed and a scaling ansatz is proposed which leads to data collapse, based upon which, a family of honeycombs can be analytically characterised for elasto-plastic response. Data collapse thus obtained provides a master-curve for structure-property relationship for plasticity of honeycombs which separates the individual cell wall mechanics from the lattice kinematics.

Discharging flow effect on the recoil response of a deep-water drilling riser after an emergency disconnect

To account for the discharging flow effect in recoil analysis of a drilling riser during an emergency disconnection scenario, researchers have developed two notable fluid column models (i.e. “SFM, Slug force model” and “WFCM, Whole fluid column model”) which can be solved in the pre-processing of an existing global riser analysis code. It is found that the “SFM” is developed based on the dynamical equilibrium of the internal drilling mud column, whereas the “WFCM” is established by analyzing the whole drilling mud and refilled seawater column. This study devotes efforts on the discharging flow effect on the recoil behaviour of a deep-water drilling riser employing “SFM” and “WFCM”. Large deviations are observed when comparing the results adopting these two fluid models, which can be contributed to the different resultant restoring forces exerted on the inner fluid columns. Nevertheless, same conclusions are drawn on the discharging flow effect, and the drag loading, mass loss and frontal force effects have been identified. An important finding is that when considering the inner fluid follows the oscillation of the riser, the recoil response of the riser can be affected remarkably, highlighting the great significance of this coupling effect.

Signal yields, energy resolution, and recombination fluctuations in liquid xenon

This work presents an analysis of monoenergetic electronic recoil peaks in the dark-matter-search and calibration data from the first underground science run of the Large Underground Xenon (LUX) detector. Liquid xenon charge and light yields for electronic recoil energies between 5.2 and 661.7 keV are measured, as well as the energy resolution for the LUX detector at those same energies. Additionally, there is an interpretation of existing measurements and descriptions of electron-ion recombination fluctuations in liquid xenon as limiting cases of a more general liquid xenon re- combination fluctuation model. Measurements of the standard deviation of these fluctuations at monoenergetic electronic recoil peaks exhibit a linear dependence on the number of ions for energy deposits up to 661.7 keV, consistent with previous LUX measurements between 2-16 keV with $^3$H. We highlight similarities in liquid xenon recombination for electronic and nuclear recoils with a comparison of recombination fluctuations measured with low-energy calibration data.

Measurement of Mechanical Tension at Cell-cell Junctions Using Two-photon Laser Ablation.

The cortical actomyosin cytoskeleton is found in all non-muscle cells where a key function is to control mechanical force (Salbreux et al., 2012). When coupled to E-cadherin cell-cell adhesion, cortical actomyosin generates junctional tension that influences many aspects of tissue function, organization and morphogenesis (Lecuit and Yap, 2015). Uncovering the molecular mechanisms underlying the generation of junctional tension requires tools for measuring it in live cells with a high spatio-temporal resolution. For this, we have set up a technique of laser ablation, in which we use the high power output of a two-photon laser to physically cut the actin cortex at the sites of cell-cell adhesion labeled with E-cadherin-GFP. Tension, thus is visualized as the outwards recoil of the vertices that define a junction after this was ablated/cut. Analysis of recoil versus time allows extracting parameters related to the amount of contractile force that is applied to the junction before ablation (initial recoil) and the ratio between elasticity of the junction and viscosity of the media (cytoplasm) in which the junctional cortex is immersed. Using this approach we have discovered how Src protein-tyrosine kinase (Gomez et al., 2015); actin-binding proteins such as tropomyosins (Caldwell et al., 2014) and N-WASP (Wu et al., 2014); Myosin II (Priya et al., 2015) and coronin-1B (Michael et al., 2016) contribute to the molecular apparatus responsible for generating tension at the cell-cell junctions. This protocol describes the experimental procedure for setting up laser ablation experiments and how to optimize ablation and acquisition conditions for optimal measurements of junctional tension. It also provides a full description, step by step, of the post-acquisition analysis required to evaluate changes in contractile force as well as cell elasticity and/or cytoplasm viscosity.