Collision Conditions Research Articles

Direct Identification of Acetaldehyde Formation and Characterization of the Active Site in the [VPO4 ].+ /C2 H4 Couple by Gas-Phase Vibrational Spectroscopy.

The gas‐phase reaction of the heteronuclear oxide cluster [VPO4].+ with C2H4 is studied under multiple collision conditions at 150 K using cryogenic ion‐trap vibrational spectroscopy combined with electronic structure calculations. The exclusive formation of acetaldehyde is directly identified spectroscopically and discussed in the context of the underlying reaction mechanism. In line with computational predictions it is the terminal P=O and not the V=O unit that provides the oxygen atom in the barrier‐free thermal C2H4→CH3CHO conversion. Interestingly, in the course of the reaction, the emerging CH3CHO product undergoes a rather complex intramolecular migration, coordinating eventually to the vanadium center prior to its liberation. Moreover, the spectroscopic structural characterization of neutral C2H4O deserves special mentioning as in most, if not all, ion/molecule reactions, the neutral product is usually only indirectly identified.

Radiative Contribution to p⊥ Broadening of Fast Partons in a Quark–Gluon Plasma

The contribution of radiative processes to the p⊥ broadening of fast partons in a quark–gluon plasma is investigated. Calculations are performed beyond the soft gluon approximation. It is shown that the radiative correction to 〈$$p_{ \bot }^{2}$$〉 in conditions of collision of heavy ions at RHIC and LHC is negative and can be comparable in absolute value with the nonradiative contribution. This prediction differs radically from the essentially positive contribution of radiative processes to the p⊥ broadening, which was predicted earlier in the literature.

Natural Quasi-Rendezvous and Evasive Maneuvers assisted by Atmospheric Drag

The study of evasive maneuvers of spacecraft in the face of the danger of collision with space debris is essential and important today due to the growth of missions at low altitudes (LEO). Bodies that orbit this region are affected by the Earth’s drag force. In this work, we present the results of numerical simulations for collision dynamics between spatial objects (operational vehicle and space debris) and investigate evasive maneuvers of the vehicle under the possibility of collision with a debris in atmospheric drag environment. We tested the evasive maneuvers for collision conditions in this environment using the exhaust velocity of the vehicle’s propulsion system. We find three important results: 1) evasive maneuvers are possible and the atmospheric drag can contribute to the removal of the collision objects in small and medium intervals of time; 2) for very small initial velocities, there are natural quasi-Rendezvous, under the action of gravity alone and drag; 3) propulsion in conjunction with drag can enable evasive maneuvers for various spatial debris sizes.

철근콘크리트 패널 내 철근과 고속 비상체의 충돌조건에 따른 관입깊이에 관한 수치해석 연구

본 해석적 연구에서는 철근콘크리트 패널 내 철근과 고속 비상체의 충돌조건에 따른 관입깊이를 분석하고자 하였다. 비선형 해석을 위하여 철근콘크리트 모델은 600×600×200 mm로 계획되었고, 철근은 40, 50, 100 mm 간격으로 배치되었다. 또한, 철근이 없는 무근 콘크리트 패널을 비교시험체로 해석하였다. 해석결과를 살펴보면, 무근 콘크리트 패널과 철근 간격 50, 100 mm인 철근콘크리트 패널의 관입깊이는 35 mm로 관찰되었지만, 철근 간격 40 mm인 철근콘크리트 패널의 관입깊이는 45 mm로 관찰되었다. 철근이 철근콘크리트 패널의 관입저항성능에 크게 영향을 끼치지 않는 것으로 나타났다. 따라서, 비상체와 철근의 비중심선충돌이 발생할 경우 더 깊은 관입깊이를 발생시킬 수 있다고 판단된다.

Impact Analysis of Go-Kart Bumper to Frontal Collision for Different Materials

The very basic inescapable ramification of using automobiles is that from now and then accidents will cause damage to it. In this advanced world, many modern materials have been introduced to the automobile body. A bumper is an edifice structure appertain to the front end and rear end of an automobile that covers the chassis. The bumper and the substructure chassis are the two components that take most of the impetus force during collision conditions. In this work, the bumper of a Go-Kart has been modelled and analysed using ANSYS R19.2 software. The model is analysed in various standard conditions for impact analysis using disparate materials namely Polyethalene, Epoxy Resin And Aluminium Alloy. Various parameters such as total deformation, equivalent stress, equivalent elastic strain have been observed and results were noted. The robustness of the component is determined by pinpointing the fragment or chunk that the breach will occur or where the equivalent stress is elevated when force is attached in front of the Go-Kart. The impact analysis under dynamic loading shows that Expoxy Resin material is more reliable for Go-Kart bumper as it is producing low distortion and has low stress and strain compared to other materials used.

Efficient Liberation of Ammonia from Thermal Reaction of ScNH+ Cations and Water.

Ammonia synthesis by using water as a hydrogen source is a challenging task. Laser-ablation-generated ScNH+ cations have been mass-selected using a quadrupole mass filter and reacted with H2O in a linear ion trap reactor under thermal collision conditions. Through mass spectrometry in conjunction with density functional theory calculations, we found that ammonia is released as the product in the reaction of ScNH+ with H2O, and this reaction is with high efficiency and selectivity, and the rate constant for the reaction is (1.14 ± 0.23) × 10-10 cm3 molecule-1 s-1, corresponding to the reaction efficiency of 15%. Metal imido complexes (*MNH) are one of the important intermediates in the currently reported NH3 synthetic reactions. The gas-phase ScNH+ cation can be a simplified model of *MNH over catalysts of NH3 synthesis, and the facile proton transfer mechanism obtained in this model system may offer fundamental mechanistic insights into how to design catalysts for ammonia production by using water as the hydrogen source under ambient conditions.

Strongly Intensive Variables and Long-Range Correlations in the Model With a Lattice in the Transverse Plane

In the framework of the quark–gluon string fusion model on the transverse lattice, we study a strongly intensive variable characterizing correlations between the number of particles produced in hadronic interactions in two observation windows separated by a rapidity interval. We show that in the case of independent identical strings, this variable is indeed strongly intensive. It depends only on string characteristics and is independent of trivial so-called volume fluctuations in the string number resulting, in particular, from inevitable impact parameter fluctuations. With string fusion effects causing the production of string clusters with new properties taken into account, this variable turns out to be equal to the weighted average of its values for different string clusters. The weighting coefficients depend on the collision conditions, and the variable loses its strongly intensive character. In the framework of this model in a realistic case with a nonuniform string distribution in the transverse plane, we find explicit analytic formulas for the asymptotic coefficients of long-range correlations between different quantities including an intensive one, the average transverse momentum. We analyze the properties of the obtained correlation coefficients, the studied strongly intensive variable, and also the possibilities of its experimental observation.

Parametric structural integrity assessment of a nuclear reactor reinforced containment and interior components under postulated aircraft collision conditions

The security of containment structures has been highlighted as a vital component of isolating and protecting internal devices in nuclear power plants from various hypothetical hazards. Despite several recent impressive studies focused on external events such as earthquake and aircraft crash, further elaborate numerical approaches are required to ensure confinement of radwaste materials against severe loads. In this paper, dynamic analyses were carried out to examine the influence of aircraft crashes on a typical reinforced concrete containment and interior components. Firstly, a specific referential force-time history was generated based on Riera function and compared with the impact force exerted by an artificial airplane through a finite element analysis combined with a smoothed-particle hydrodynamics of fuel for validation. Subsequently, systematic numerical analyses were carried out for the containment under diverse postulated aircraft collision conditions. Stresses and strains of each part were calculated, and displacements as well as damages of the concrete due to crushing and cracking were also evaluated through comparison of the corresponding allowable criteria. Moreover, effects of key parameters such as crash angles, locations, and velocities were investigated. As results, central part of the concrete wall was determined to be the most vulnerable and failure based on the conservative strain criteria was estimated at this region under 200 m/s of speed regardless of impact angles.

A dynamic CSFICA and feature‐based collision detection method in multichannel space‐based AIS

SummaryTo detect message collisions in multichannel spaced‐based automatic identification system (AIS), a dynamic complex symmetric fast independent component analysis (CSFICA) and feature‐based collision detection method is proposed in this paper. A fast and stable blind source separation algorithm, dynamic CSFICA, is utilized to separate signals dynamically and improve the signal‐to‐interference ratio (SIR) in each channel. A frequency and phase offset insensitive feature detection algorithm is used to calculate the test statistics in each channel. The false alarm is suppressed by applying the arithmetic to geometric mean (AGM) method, and test statistics of channels with sufficient signal quality are extracted to detect the preamble. Simulation results show that the proposed algorithm outperforms the reference feature detection algorithm under collision conditions and is insensitive to the SIR. The proposed algorithm is more resistant to false alarm caused by signal (FAS) than the differential correlation (DC) algorithm.

Dehydrogenation of Methane by Partially Oxidized Tungsten Cluster Cations: High Reactivity Comparable to That of Platinum Cluster Cations.

Gas-phase reactivity of pure and partially oxidized tungsten atomic and cluster cations, Wn+ (n = 1-6) and WnOm+ (n = 1-5, m ≤ 6), with methane is studied at the collision energies from 0.1 to 1.0 eV under single collision conditions. The dehydrogenation of CH4 (i.e., the release of H2) is observed for most of WnOm+, whereas Wn+ (n ≥ 2) are almost unreactive. This result indicates that the reactivity of tungsten clusters can be enhanced by the addition of oxygen atoms. Moreover, the reaction cross section of WnOm+ strongly depends on the cluster composition, and some clusters such as W2O3+, W3O+, W3O5+, and W5O3+ exhibit high reactivity. It turns out that the reactivity of these clusters is roughly comparable to that of the typical platinum cluster cations, which are one of the most reactive clusters toward methane dehydrogenation. The reactivity of Wn+ and WnOm+ toward CH4 can be explained by a simple model of their orbital energies and the potential energy diagrams obtained by using the density functional theory calculations. The calculations also suggest that the oxygen atom(s) in WnOm+ is like a spectator and the formation of a hydroxyl group is not necessary for the cleavage of C-H bonds in CH4.

Cluster-π Interactions Cause Size-Selective Reactivity of Cationic Silver Clusters with Acetylene: The Distinctive Ag7+[C2H2

Utilizing a customized multiple-ion laminar flow tube reactor in tandem with a triple quadrupole mass spectrometer, we report a study of the gas-phase reactivity of Agn+ clusters with acetylene. Well-resolved Agn+ clusters (n = 1-20) are produced by a self-designed magnetron sputtering source (MagS); however, on their reactions with acetylene under sufficient collisional conditions, only Ag7+[C2H2] is produced with a reasonable intensity. DFT calculations reveal that Agn+ clusters do not form strong Ag-C bonds with C2H2 and Ag7+[C2H2] bears larger binding energy than the other Agn+[C2H2] although within similar cluster-π interactions. Besides gas-phase reaction rate estimation, the relatively large noncovalent cluster-π interaction in Ag7+[C2H2] is fully demonstrated via topological analysis and natural bonding orbital analysis. Also, we illustrate both thermodynamically and kinetically favored channels in producing the Ag7+[C2H2]. This study helps in understanding metal-involved noncovalent bonds and how such weak interactions are able to tune the material function and biological activity.

Capturability of Impact-Angle Control Composite Guidance Law Considering Field-of-View Limit

A capture region of the composite guidance law is analyzed for a missile equipped with a strapdown seeker. The composite guidance law consists of a deviated pure pursuit guidance law and a pure proportional navigation guidance law to perform impact-angle control. The range of the field-of-view limit restricts the performance of the guidance law, which reduces the capture region. Based on the characteristics of the guidance law, the range of the achievable impact angle is investigated by considering the collision condition and the field-of-view limit. It is shown that the capture region is represented in terms of the relative initial position and terminal flight-path angle. Numerical simulations are performed to investigate the properties of the proposed capture region of the composite guidance law.

Fuzzy logic based approach for ship-bridge collision alert system

Abstract This paper proposes a fuzzy logic based approach for ship-bridge collision alert by considering ship particulars, bridge parameters and natural environment. It can be implemented in the decision support system for safe navigation or be included in the process of autonomous navigation. The ship-bridge collision conditions are analysed by considering the ship location, ship trajectory direction, ship distance to the bridge and ship speed. These factors, together with the natural environment, are treated as the input variables. The IF-THEN rules are then established after fuzzification of the input variables and are used for fuzzy inference to derive the ship-bridge collision risk. From the result analysis, the proposed approach can be used for improvement of the ship handling in the bridge waterway area.

Inducing locally structured ion energy distributions in intermediate-pressure plasmas

Ion energy distribution functions (IEDFs) incident upon material surfaces in radio frequency (rf) capacitively coupled plasmas are coupled to spatial and temporal sheath dynamics. Tailoring the ion energy distribution function within intermediate-pressure plasmas (≈133 Pa, 1 Torr), which find application in surface modification and aerospace industries, is challenging due to the collisional conditions. In this work, experimentally benchmarked 2D fluid/Monte-Carlo simulations are employed to demonstrate the production of structured IEDFs in a collisional (200 Pa 1.5 Torr argon) rf hollow cathode discharge. The formation of structures within the IEDFs is explained by an increase in the Ar+ ion-neutral mean-free-path and a simultaneous decrease in the phase-averaged sheath extension as the rf voltage frequency increases over 13.56–108.48 MHz for a constant rf voltage amplitude (increasing plasma power) and gas flow rate. Two distinct transitions in the shape of the IEDF are observed at 450 V, corresponding to the formation of “mid-energy” (60–180 eV) structures between 40.68 and 54.24 MHz and additional “high energy” (≳180 eV) structures between 81.36 and 94.92 MHz, with the structures within each region displaying a distinct sensitivity to the applied voltage amplitude. Transitions between these energy ranges occurred at lower applied voltages for increased applied voltage frequencies, providing increased control of the mean and modal ion energy over a wider voltage range. The capabitlity to extend the range of access to an operational regime, where the structured IEDFs are observed, is desirable for applications that require control of the ion-bombardment energy under collisional plasma conditions.

Elucidating the Chemical Dynamics of the Elementary Reactions of the 1-Propynyl Radical (CH3CC; X2A1) with Methylacetylene (H3CCCH; X1A1) and Allene (H2CCCH2; X1A1).

The reactions of the 1-propynyl radical (CH3CC; X2A1) with two C3H4 isomers, methylacetylene (H3CCCH; X1A1) and allene (H2CCCH2; X1A1), along with their (partially) deuterated counterparts were explored at collision energies of 37 kJ mol-1, exploiting crossed molecular beams to unravel the chemical reaction dynamics to synthesize distinct C6H6 isomers under single collision conditions. The forward convolution fitting of the laboratory data along with ab initio and statistical calculations revealed that both reactions have no entrance barrier, proceed via indirect (complex-forming) reaction dynamics involving C6H7 intermediates with life times longer than their rotation period(s), and are initiated by the addition of the 1-propynyl radical with its radical center to the π-electron density of the unsaturated hydrocarbon at the terminal carbon atoms of methylacetylene (C1) and allene (C1/C3). In the methylacetylene system, the initial collision complexes undergo unimolecular decomposition via tight exit transition states by atomic hydrogen loss, forming dimethyldiacetylene (CH3CCCCCH3) and 1-propynylallene (H3CCCHCCCH2) in overall exoergic reactions (123 and 98 kJ mol-1) with a branching ratio of 9.4 ± 0.1; the methyl group of the 1-propynyl reactant acts solely as a spectator. On the other hand, in the allene system, our experimental data exhibit the formation of the fulvene (c-C5H4CH2) isomer via a six-step reaction sequence with two higher energy isomers-hexa-1,2-dien-4-yne (H2CCCHCCCH3) and hexa-1,4-diyne (HCCCH2CCCH3)-also predicted to be formed based on our statistical calculations. The pathway to fulvene advocates that, in the allene-1-propynyl system, the methyl group of the 1-propynyl reactant is actively engaged in the reaction mechanism to form fulvene. Because both reactions are barrierless and exoergic and all transition states are located below the energy of the separated reactants, the hydrogen-deficient C6H6 isomers identified in our investigation are predicted to be synthesized in low-temperature environments, such as in hydrocarbon-rich atmospheres of planets and their moons such as Titan along with cold molecular clouds such as Taurus Molecular Cloud-1.

Research on the Crashworthiness of Regular Centurion 2M Barrier Based on the Arbitrary Lagrange-Euler Method

In this study, the crash-worthiness of a regular Centurion 2M barrier, which is a type of portable water-filled barrier (PWFB), is evaluated under different collision conditions. A numerical model of the regular Centurion 2M barrier, consisting of a plastic shell and water, was developed and validated. The validity of the numerical model is demonstrated by comparisons to experimental results. During the establishment of the finite element numerical model, the ALE (Arbitrary Lagrange-Euler) method was used to solve the problem of the fluid-structure interaction of the PWFB system. This model can be extended to a series of impact cases including an actual pick-up truck. Impact cases set six collision conditions according to different collision speeds and angles. The dynamic response of the collision between the pick-up truck and the PWFB process was investigated. From the analysis, we find that the greater the collision angle is, the greater the impact is on the collision result. According to the actual accident collision angle, setting the collision angle above 50° is satisfactory in most situations. In addition, a regular Centurion 2M barrier is just suitable for use on roads when the speed of vehicles is 20 km/h or less.

Doping Effects on the Reactivity of the MVO5– (M = V–Zn) Clusters in CO Oxidation Reaction

Doped metal oxide catalysts have important applications in heterogeneous catalysis, whereas the fundamental effects of doping on the reactivity of catalysts are elusive. Herein, benefiting from the study of a series of atomic clusters MVO5– (M = V–Zn) in catalytic CO oxidation by molecular O2 under thermal collision conditions, the crucial effects of doping on the electronic structure and then the catalytic reactivity of MVO5– were successfully rationalized by using mass spectrometry and theoretical calculations. We defined the energy gap of active orbitals that are closely related to electron transfer in MVO5– during CO oxidation. It was discovered that such an energy gap can modulate reaction thermodynamics, whereas the orbital overlap of MVO5– with CO controls the kinetics. The doped clusters MVO5– (M = Cr–Zn) have reduced energy gaps than that in host V2O5–, and doping can modify the orbital overlap of MVO5– (M = Cr–Zn) with CO. Only the MnVO5– and ZnVO5– clusters that have rational energy gaps and pr...

Clean and Efficient Transformation of CO2 to Isocyanic Acid: The Important Role of Triatomic Cation ScNH.

Achieving the desired selective transformations of the very stable CO2 into useful chemicals is quite important for the development of economically and environmentally sustainable synthetic methods. Herein, mass spectrometric experiments and quantum-chemical calculations have identified that ScNH+ reacts quite efficiently with CO2 under thermal collision conditions to exclusively yield ScO+ and isocyanic acid (HNCO). This is a novel reaction type in CO2 activation reactions mediated by gas-phase ions. In this reaction, the C═N double bond has also been formed for the first time in the gas phase. The mechanism of "migratory insertion" is proposed. Coupled with the previously reported reaction of Sc+ with NH3, HNCO can be synthesized under mild conditions from NH3 and CO2 in quite simple reactions. The mechanistic information gained in this gas-phase model reaction can offer fundamental insights relevant to corresponding processes and further guide on how to design brand new catalysts.

Distinct continental margins and associated stratigraphic architecture patterns during the seafloor spreading of South China Sea

In this paper we compare four types of stratigraphic architectures around the continental margins in the South China Sea (SCS) based on a plentiful of seismic profiles. The results indicate that stratigraphic patterns are not only related closely to structure regimes of peripheral of the SCS, but also are restrained by crust structure from continental crust to oceanic crust. In the extensional setting, depositional centres during the syn‐spreading stage are located in the strong extensional area. A wedge‐decrease continental crust represented by the Pearl River Mouth type is characterized by high deposition and subsidence rate during the syn‐rifting and syn‐spreading stages in the distal zone. And in the Zhongjiannan type with a continental ribbon, high deposition and subsidence rate during the syn‐rifting and syn‐spreading stages are present in the proximal zone. However, in the southern and eastern margins with compressional setting, the Liyue and Zengmu microcontinent blocks are separated from the South China with the seafloor spreading of SCS, in which a confined or relative thin syn‐spreading deposits are presence. High deposition and subsidence rate is closely related to the collision or subduction condition during the post‐spreading stage in the Liyue bank type and the Zengmu type, a huge progradational clinoforms are present along the subduction and collision margin. Therefore, this study shows distinct stratigraphic architecture in different continental rifted margins, distinct depositional and subsidence characteristics formed during the process of lithospheric rupture can provide an effective method for the study on the continental marginal sea in the western Pacific.

Whiplash Injury Conditions of Rear-End Collisions at Low-Speed

Whiplash Injury Conditions of Rear-End Collisions at Low-Speed