Collision Point Research Articles

Numerical calculation of the Lorentz force detuning and the pressure sensitivity for the HL-LHC crab cavity

Crab cavities are fundamental components of the HL-LHC upgrade project. These Radio Frequency cavities, operated at the appropriate frequency, ‘tilt’ the proton bunches to increase the luminosity at the collision points IP1 (ATLAS) and IP5 (CMS). Two different superconducting crab cavities were developed: RF Dipole (RFD) for horizontal deflection and Double Quarter Wave (DQW) for vertical deflection. During operation, the cavity walls are deformed due to the loading conditions. This deformation changes the electro-magnetic field inside the cavity and consequently its RF frequency. In the present study, the numerical evaluation of the Lorentz Force Detuning (LFD) and the Pressure Sensitivity (PS) of the DQW cavity, using COMSOL Multiphysics, is presented. The LFD is the fundamental frequency change of the cavity due to the electro-magnetic forces acting on its walls, while the PS is the frequency shift when the cavity is subjected to pressure fluctuations of the helium bath. Finally, a comparison with the results measured during the cold test of the manufactured cavities, and with the previous simulations results obtained for the RFD cavity is done.

Kinetic analysis of efficient energy conversion in table tennis sports

Abstract Improving the accuracy and stability of players’ stroke speed and stroke landing point and maximizing the energy conversion have become important tasks in table tennis skill practice. This paper analyzes the forces during ball collision and the energy conversion law of its motion state and proposes to measure and identify the key mechanical parameters of table tennis motion from the aspects of batting speed, rotation, and batting angle. The 3D coordinates of the ball are reconstructed, and the parameters are measured in the translational and rotational states of the ball, respectively. The UKF state estimator is used to construct the system process equations of the table tennis ball motion model, and the mathematical expressions are further derived to obtain the kinematic-based post-collision trajectory prediction model of the table tennis ball. The accuracy of the model in predicting the trajectory of the table tennis ball movement is evaluated by the distribution of the error points of the collision points of the table tennis ball, and it is known through experiments that the range of the error of the collision point prediction of the table tennis ball by the method used in this paper is in the range of (x±0.05, y±0.05) m, which is smaller than that estimated by the traditional table tennis ball physical model, and the model’s prediction accuracy is good. After analyzing the motion trajectories with different angular velocities, drag coefficients, initial velocities, and exit angles, the optimal hitting speed of a curved circle ball is obtained as V=15m/s.

Simulations and measurements of collisional losses with Pb beams at the LHC

For about one month per operational year, the Large Hadron Collider (LHC) at CERN works as a heavy-ion collider. Four one-month Pb-Pb runs have been executed so far as well as two p-Pb runs. The LHC heavy-ion programme is scheduled to continue in the future, featuring increased luminosity and beam energy. Beam losses caused by ions fragmenting in the collision process risk introducing performance limitations. Losses occur immediately downstream of the collision points as well as at other locations in the ring, through multi-turn beam dynamics processes and interactions with ring collimators. This paper presents first simulations of collisional loss patterns for nuclear beams using a new simulation approach that relies on the SixTrack-FLUKA coupling simulation tool, including nuclear fragmentation and electron capture in the collisions. Simulations of the 2018 Pb-Pb and 2016 p-Pb runs are compared against experimental data and the prediction of collisional losses for future Pb-Pb and p-Pb runs is shown.

Right-Moving Supercell Tornadogenesis during Interaction with a Left-Moving Supercell’s Rear-Flank Outflow

Abstract On the local afternoon of 29 May 2012, a long-lived, right-moving (RM) supercell formed over northwestern Oklahoma and turned roughly southeastward. For >3 h, as it moved toward the Oklahoma City, Oklahoma, metro area, this supercell remained nontornadic and visually high-based, producing a nearly tornadic gustnado and a swath of significantly severe, sometimes giant hail up to 5 in. (12.7 cm) in diameter. Meanwhile, a left-moving (LM) supercell formed over southwestern Oklahoma about 100 mi (161 km) south-southwest of the RM storm, and moved northeastward, with a rear-flank gust front that became well defined on radar imagery as the LM storm approached southern and central parts of the metro. The authors, who had been observing the RM supercell in the field since genesis, surmised its potential future interaction with the LM storm’s trailing gust front about 1 h beforehand. We repositioned to near the gust front’s extrapolated collision point with the RM mesocyclone, in anticipation of maximized tornado potential, then witnessed a small tornado from the RM mesocyclone immediately following its interception of the boundary. Synchronized radar and photographic images of this remarkable sequence are presented and discussed in context of more recent findings on tornadic supercell–boundary interactions, with implications for operational utility. Significance Statement Supercells—well-organized, rotating thunderstorms mainly found in midlatitudes—commonly produce the largest hail, along with damaging gusts and most tornadoes. In radar imagery and photographs, we show the characteristics and merger of two supercell types: left-moving and right-moving, with respect to winds aloft. As the left-moving storm’s trailing gust front interacted with the right-mover’s mesocyclone, the latter strengthened quickly, soon producing a tornado. Observed evolution of these storms supports idealized numerical and conceptual models for supercell behavior and interactions with storm-scale boundaries, and may be useful in short-fused tornado forecast and warning operations.

Research on Information Modeling Technology of Assembly Building for Future Trends

Abstract In recent years, the informatization technology of BIM and digital twin has been applied to the field of assembled buildings, especially the advantages of BIM technology applied in the construction industry are gradually emerging. Therefore, this paper takes assembly building as the object and cost control as the purpose of conducting research. Firstly, it introduces the application of BIM technology in assembly building, and secondly, the collision process in BIM technology is optimized by the MLS-MPM algorithm. Economic benefit analysis is carried out on the informative modeling of BIM technology in assembly building, and finally, the constructed model is applied to the basement design stage, the construction production and transportation stage, and the construction stage to evaluate its project benefits. The results show that on the basis of Revit software modeling, the Revit model was imported into Navisworks, and a total of 619 collision points were found in the basement. It is found that the collision results of pipe diameters below DN50 have little impact on the actual construction; pipe diameters above DN50 have a great impact on the elevation in the actual construction, which requires collision detection and drawing modification. The analysis of the economic benefits of information technology modeling in assembly buildings found that it can create benefits of up to 50,200 yuan during the design phase. The build production and transportation phase results in the creation of 58,800,000yuan in benefits. Optimizing schedule and cost control leads to 36,000 yuan and 13,500yuan benefits in the construction phase, respectively. This study is very important to provide a reference for the application of information technology in assembly buildings for future trends.

Ergonomic analysis of the classroom using the LiDAR system

This article presents an innovative method of using LiDAR technology to analyze and measure the current ergonomic conditions of a university classroom. The purpose of this research is to provide a detailed analysis of the working environment and to identify collision points, proposing changes and improvements to meet the rules and standards of ergonomic correctness. The outcome of this analysis is a 3D model containing detailed information about the current state of the environment. This model was subsequently utilized to identify ergonomic deficiencies, which formed the basis for proposed modifications. The article also discusses the applications of modern LiDAR technology, its functions, and accessibility for ordinary users, as well as accessibility on individual software platforms.

Vorticity wave interaction, Krein collision, and exceptional points in shear flow instabilities.

We relate the model of vorticity wave interaction to Krein collision, PT-symmetry breaking, and the formation of exceptional points in shear flow instabilities. We show that the dynamical system of coupled vorticity waves is a pseudo-Hermitian system with nonreciprocal coupling terms. Krein signatures of the eigenvalues are illustrated as the signs of the action of the vorticity waves. Interaction between positive-action and negative-action vorticity waves then corresponds to the Krein collision between eigenvalues with opposite Krein signatures, the spontaneous breaking of PT symmetry, and the formation of exceptional points. The control parameter of the PT-symmetry-breaking bifurcation is the ratio between frequency detuning and coupling strength of the vorticity waves. The critical behavior near the exceptional points is described as a transition between phase-locking and phase-slip dynamics of the vorticity waves. The phase-slip dynamics correspond to nonmodal, transient growth of perturbations in the regime of unbroken PT symmetry, and the phase-slip frequency Ω∝|k-k_{c}|^{1/2} shares the same critical exponent with the phase rigidity of system eigenvectors.

ВИРАЖАЛЬНИЙ ПОТЕНЦІАЛ СЛОВА В ЛІТЕРАТУРІ ФОРМАЛЬНИХ ОБМЕЖЕНЬ

Formal constraints are inherent to literature since its beginnings. Every author has to solve the problem of choosing the fi tting lexical options from the multitude of lexical and semantical variants. Focusing on a certain topic or the desire to express thoughts and emotions of a certain directivity immediately shape the necessity of con-straints for the author. Creative freedom and the perceived constraints form a dialectic pair and paradoxically contribute to the true enrichment of the literary genre. The key focus of the advocates of Oulipo are theory and practice of constraint. The received results of the creative work allow to intensify the observations of word and language as objects of boundless attention. Through lingual experiments and ver-bal discoveries, it has been possible to approach the understanding of the world and the person in it oftentimes in the form of play.The work on language and its potential inventory continues since the founding of Oulipo and till today. The authors strive to research spoken word and written word graphics resources. Through combining seemingly incompatible things (poetry and mathematics, the funny and the serious, strenuous work and lighthearted play), the collision of diff erent contexts and senses occurs. Totally new senses that manifest the limitlessness of literary art are born and burst.The interest in formal structures and verbal experiments is most often seen on the col-lision point of diff erent literary phenomena or epochs. The following conditions are crucial for the functioning of constrained writing: 1) the presence of the original (preferably but not necessarily precedent) text; 2) architectonic and semantic transformation of the initial text; 3) experimental and creative nature of contemporary author’s work; 4) intensifi cation of intellectual communicative game; 5) cultivation of appendant and additional complexities.

On a set of tests for numerical methods of integrating differential equations, based on the Calogero system

Based on the completely integrable Calogero dynamical system, which describes the one-dimensional many-body problem, a tool for testing difference schemes has been developed and implemented in the original fdm package integrated into the Sage computer algebra system. This work shows how the developed tools can be used to examine the behavior of numerical solutions near the collision point and how to study the conservatism of the difference scheme. When detecting singularities using Alshina’s method, a difficulty was discovered associated with false order fluctuations. One of the main advantages of this set of tests is the purely algebraic nature of the solutions and integrals of motion.

Turbo roundabout - An alternative to classic two lane roundabout

Traffic congestion and the questionable safety of two-lane roundabouts are two justified criteria for the introduction of turbo roundabouts. The increase in capacity, which also results in an increase in the level of service, is a positive aspect of this alternative type of roundabout. Also, reduced number of conflict and collision points at the exits and intersections at the turbo roundabout as well as lower vehicle speed, increase safety, compared to classic two-lane intersection. The mentioned advantages justify the need for improving existing overloaded roundabouts.Therefore, the subject of this article is the reconstruction of the existing two–lane roundabout with two entrances and exits, in Podgorica, at the intersection of “Josipa Broza Tita Street” and “V Proleterske brigade Street”, into a turbo roundabout.

An exact, coordinate independent classical firewall transformation

A proposal for resolving the black hole information paradox was recently put forward by ’t Hooft in the form of his firewall transformation. Although this proposal has begun to gain some limited traction, its physical foundation is still somewhat obscure. Here we develop a classical Hamiltonian analog, which is oriented towards quantization, by using the canonical formalism developed by Arnowitt, Deser, and Misner (ADM). We use a model of two null, spherical shells in a Schwarzschild black hole background, and within our ADM formalism we are able to characterize the dynamics of the entire system, especially at the point of collision, and we reproduce the related Dray–’t Hooft–Redmount formula. Finally, we are able to find a classical analog for ’t Hooft’s firewall transformation. Unlike ’t Hooft’s firewall transformation and previous classical analogs, the classical firewall transformation we obtain is free from approximation and maintains the coordinate independence of the ADM formalism. We leave to future work the quantization of the theory.

Effects of delay time on crack coalescence between two boreholes

Delayed detonation widely occurs in rock blasting, which has a significant influence on the propagation and interaction of explosion-induced stress waves. This affects the rock fracture interconnection between adjacent boreholes in controlled blasting. In this study, the effects of delay time on crack coalescence between two blastholes in contour blasting are experimentally, theoretically and numerically investigated. The rock cracking in two-hole blasting on 200 × 200 × 50 mm granite plate is first experimentally examined, in which the delay time is determined by high-speed photography and the rock fracturing is identified by digital image correlation. Then, two-hole blasting with delayed initiation is analytically modelled, and the fracture propagation behaviours in blast tests are explained based on the evolution of explosion-generated stress waves and peak stress distribution between two holes. Subsequently, 3D finite element models are built in LS-DYNA to simulate the evolution of explosion-produced pressure, rock fracturing and energy dissipation in two-hole controlled blasting with delayed initiation. The results indicate that in two-hole contour blasting, the stress superposition zone, which produces local stress enhancement in the vicinity of the stress wave collision point, moves closer to the later detonated hole. The superposed stress facilitates the preferential extension of blast-created cracks along the connection line of boreholes, and the crack from the later detonated hole extends farther than that from the first detonation hole. The optimal crack coalescence in contour blasting archives when the delay time allows stress waves to approximately propagate through the hole spacing.

Post-giant impact planetesimals sustaining extreme debris discs

ABSTRACT Extreme debris discs can show short-term behaviour through the evolution and clearing of small grains produced in giant impacts, and potentially a longer period of variability caused by a planetesimal population formed from giant impact ejecta. In this paper, we present results of numerical simulations to explain how a planetesimal populated disc can supply an observed extreme debris disc with small grains. We simulated a sample of giant impacts from which we form a planetesimal population. We then use the N-body code rebound to evolve the planetesimals spatially and collisionally. We adopt a simplistic collision criteria in which we define destructive collisions to be between planetesimals with a mutual impact velocity that exceeds two times the catastrophic disruption threshold, V*. We find that for some configurations, a planetesimal populated disc can produce a substantial amount of dust to sustain an observable disc. The semimajor axis at which the giant impact occurs changes the mass added to the observed disc substantially, while the orientation of the impact has less of an effect. We determine how the collision rate at the collision point changes over time and show that changes in semimajor axis and orientation only change the initial collision rate of the disc. Collision rates across all discs evolve at a similar rate.

Impact craters formed by spinning granular projectiles.

Craters formed by the impact of agglomerated materials are commonly observed in nature, such as asteroids colliding with planets and moons. In this paper, we investigate how the projectile spin and cohesion lead to different crater shapes. For that, we carried out discrete element method computations of spinning granular projectiles impacting onto cohesionless grains for different bonding stresses, initial spins, and initial heights. We found that, as the bonding stresses decrease and the initial spin increases, the projectile's grains spread farther from the collision point, and in consequence, the crater shape becomes flatter, with peaks around the rim and in the center of the crater. Our results shed light on the dispersion of the projectile's material and the different shapes of craters found on Earth and other planetary environments.

Bayesian acoustic emission time-difference method for locating the collision point of sweeping robot shell

The existing source localization based on acoustic emission technology often depends on the assumption of constant wave velocity inside the material. However, this assumption is hardly satisfied in actual engineering. The uncertainty of wave velocity can easily lead to low localization accuracy of sweeping robots. To overcome these deficiencies, a complete probability multi-directional measurement method based on the Bayesian inference mechanism is proposed. In the proposed method, based on the Bayesian probabilistic model, the extracted sensor time difference is subjected to probabilistic inference using the coordinate input model to determine the posterior distribution of the source’s position and wave velocity of the given arrival time. Compared with the traditional time-difference method, the proposed method achieves excellent results and outperforms the standard time-difference method in localization accuracy and anti-interference. In addition, the proposed method can conveniently, quickly, and effectively determine the location of the colliding point without considering the source emission time and wave velocity. The research in this paper provides an effective method for solving the collision localization problem of the sweeping robot shell under the acoustic emission time and wave velocity are unknown.

River Reach: Chicagoland, riverine reflections and settler harm-reduction poetry

Both case report and epic, ‘River Reach’ is an exploratory anamnesis that presents a metamodern embodied reflection of systems entanglement – exposing attunements to and longings for a place-based riverine kinship capable of addressing a national heritage of displacements, immigrations, and enslavement. To improve state compliance with the US Clean Water Act, Graue Mill dam on Salt Creek at Fullersburg Woods (Oak Brook, IL) will be removed in coming months for creek restoration and re-realignment, creating a point of collision and potential among pasts and futures. ‘River Reach’ is a hyperlocal example of a practical, approachable step toward decolonial poetry and community – examining the insularities and permeabilities of whiteness while encouraging personal, deliberate engagement in the preparatory work required for recalibrating national identity cooperatively. As a centering poem for settler harm reduction and an adjunctive tool for collective action, the piece invites participants into a mimetic rehabitation of relationship through nature. ‘River Reach’ may be performed collectively in collaboration with movement, audiovisual elements, and facilitated reader/audience participation.

A Novel Approach for Car Accident Detection and Analysis Using AIML Techniques

Abstract: In the context of escalating concerns regarding road safety, this study introduces an automated traffic accident detection and analysis framework that utilizes surveillance footage. The approach synergistically combines the Motion Interaction Field (MIF) model and YOLO v5 algorithm to achieve accurate crash detection and precise vehicle classification. The primary objective is to develop an autonomous system for identifying and evaluating traffic events captured by security cameras. The MIF model extracts valuable insights from interactions among moving objects within images and videos, tailored explicitly for detecting damaged vehicles. Localization of damaged vehicles is achieved using the YOLO v5 algorithm, complemented by perspective transformation to enable vertical image representation. The unbiased finite impulse response (UFIR) technique, notable for its insensitivity to statistical noise data, effectively determines vehicle motion. Furthermore, this work delves into an in-depth analysis of car crashes, estimating impact speed and point of collision from an aerial perspective. This work encompasses meticulous accident clip analysis, precise car direction determination, and error identification. The outcomes underscore the potential of the proposed framework to revolutionize accident detection and analysis, contributing to heightened road safety and streamlined traffic management strategies.

Experimental research on self-initiation process of rotating detonation wave by high-temperature ethylene-rich gas

This study investigates an experimental process of high-temperature ethylene-rich gas and air for rotating detonation. After abandoning the pre-detonator method, the high-temperature ethylene-rich gas was injected and collided with the outer wall to create a localized high temperature and pressure region that ignited the gas mixture to form the deflagration state. Whether it is a single deflagration flame or double deflagration flame, it is eventually transformed through the deflagration-to-detonation transition (DDT) process into a double detonation wave. With propagation and collision of the double waves, the injection pressure increases, which results in shortening the self-initiation delay time. The equivalence ratio, gas temperature, and mass flow rate affect the success ratio of self-initiation. Rotating detonation engine (RDE) can be successfully initiated in the equivalence ratio range of 0.82 to 1.69. Equivalence ratio and gas temperature increase the propagation velocity of rotating detonation wave (RDW), for maximum RDW velocity of 1324.61 m/s, the gas temperature is 1021.3 °C. At the double wave collision point, a new weak RDW appears that decreases the RDE operating stability and a periodic quenching and re-initiation of RDW phenomenon occurs at that point.

The external time-of-flight wall for CEE experiment

A heavy-ion collision facility called the cooler storage ring (CSR) external-target experiment (CEE) is scheduled in Lanzhou, China. The time measurement of the charged particles at the forward angle will be conducted by the external time-of-flight (eTOF) subsystem, which is built with multigap resistive plate chambers (MRPC). This work describes the tasks, performance criteria, detector layout, and prototype test results while outlining the technical design and development status of the CEE-eTOF wall. The effectiveness of the wall design has been validated using a FairRoot-based simulation, which is an essential part of the verification. With a 3.2 times 1.6~textrm{m}^2 coverage, a 60 ps overall time resolution, and a 2.6 m distance from the collision point, the eTOF wall enables the particle identification, system triggering, and event selection in cooperation with other related detectors. A novel structure called sealed MRPC will be applied to the subsystem. The design considerations of this type, prototype test, and results are also described in this paper.

CERRT: A Mobile Robot Path Planning Algorithm Based on RRT in Complex Environments

In complex environments, path planning for mobile robots faces challenges such as insensitivity to the environment, low efficiency, and poor path quality with the rapidly-exploring random tree (RRT) algorithm. We propose a novel algorithm, the complex environments rapidly-exploring random tree (CERRT), to address these issues. The CERRT algorithm builds upon the RRT approach and incorporates two key components: a pre-allocated extension node method and a vertex death mechanism. These enhancements aim to improve vertex utilization and overcome the problem of becoming trapped in concave regions, a limitation of traditional algorithms. Additionally, the CERRT algorithm integrates environment awareness at collision points, enabling rapid identification and navigation through narrow passages using local simple sampling techniques. We also introduce the bidirectional shrinking optimization strategy (BSOS) based on the pruning optimization strategy (POS) to further enhance the quality of path solutions. Extensive simulations demonstrate that the CERRT algorithm outperforms the RRT and RRV algorithms in various complex environments, such as mazes and narrow passages. It exhibits shorter running times and generates higher-quality paths, making it a promising approach for mobile robot path planning in challenging environments.