Simulation Model of Fragmentation Risk

In this chapter, a simulation model for fragmentation risk assessment due to a cylindrical tank explosion is presented. The proposed fragmentation methodology is based on the application of Monte Carlo simulation and probabilistic mass method. The probabilities of generating fragments during the explosion of the tank were estimated regardless of the available accident data. Aleatoric and epistemic uncertainty due to tank fragmentation has been identified. Generating only one fragment is accompanied by aleatoric uncertainty. The maximum fragmentation probability corresponds to the generation of two fragments with a total mass between 1200 kg and 2400 kg and is 17%. The fragment shape was assessed on the basis of these data and fracture lines. Fragmentation mechanics has shown that kinematic parameters are accompanied by epistemic uncertainty. The range of the fragments in the explosion of the tank has a Weibull distribution with an average value of 638 m. It is not justified to assume the initial launch angle with a uniform distribution, since its direction is defined by the shape of the fragment. The presented methodology is generally applicable to fragmentation problems in the process industry.

Recent results on B → μ+μ− decays with the CMS experiment

Results on [Formula: see text] decays with the CMS experiment are reported, using 61 fb[Formula: see text] of data recorded during LHC Run 1 and 2016. With an improved muon identification algorithm and refined unbinned maximum likelihood fitting methods, the decay [Formula: see text] is observed with a significance of 5.6 standard deviations. Its branching fraction is measured to be [Formula: see text], where the first error is the combined statistical and systematic uncertainty and the second error quantifies the uncertainty of the [Formula: see text] and [Formula: see text] fragmentation probability ratio. The [Formula: see text] effective lifetime is [Formula: see text]. No evidence for the decay [Formula: see text] is found and an upper limit of [Formula: see text] (at 95% confidence level) is determined. All results are consistent with the standard model of particle physics.

Sleep stage dynamics in young patients with sleep bruxism

Study Objectives We hypothesized that sleep stage dynamics are different in patients with sleep bruxism (SB) and that these changes are associated with the occurrence of rhythmic masticatory muscle activity (RMMA). Methods Fifteen healthy controls and 15 patients with SB underwent overnight polysomnography. Sleep variables and survival curves of continuous runs of each sleep stage were compared between the groups. Stage transition dynamics and the probability of stage fragmentation were analyzed for three epochs before and after the epoch with RMMA. Survival curves of continuous runs of each sleep stage, terminated with or without RMMA, were also compared. Results There were no significant differences in sleep variables between the groups, except for shorter sleep latency, shorter rapid eye movement (REM) latency, and longer total N1 duration in SB patients than in controls. REM sleep and N2 were significantly less continuous in SB patients than in controls. In the SB group, stage fragmentation probability was significantly increased for the epoch with RMMA compared with the baseline for all stages. Meanwhile, the occurrence of RMMA did not affect the continuity of N2 or REM; however, the occurrence of RMMA was preceded by more continuous N3 runs. Conclusions Sleep stage dynamics differed between SB patients and controls. RMMA does not result in sleep disruption but is likely associated with dissipation of sleep pressure. Less continuity of REM sleep in SB may provide insights into the underlying pathophysiological mechanisms of SB, which may be related to REM sleep processes such as cortical desynchronized states or brainstem activation.

Production asymmetry of open charm mesons within unfavoured ragmentation scenario

We consider unfavoured light quark/antiquark to D meson fragmentation. We discuss nonperturbative effects for small transverse momenta. The asymmetry for D+ and D- production measured by the LHCb collaboration provides natural constraints on the parton (quark/antiquark) fragmentation functions. We find that already a fraction of $q/\overline q \to D$ fragmentation probability is sufficient to account for the measured asymmetry. Large D-meson production asymmetries are found for large xF which is related to dominance of light quark/antiquark $q/\overline q \to D$ fragmentation over the standard c → D fragmentation. As a consequence, prompt atmospheric neutrino flux at high neutrino energies can be much larger than for the conventional c → D fragmentation. The latter can constitute a sizeable background for the cosmic neutrinos claimed to be observed recently by the IceCube Observatory.

Spin-dependent fragmentation functions of gluon splitting into heavy quarkonia considering three different scenarios

Heavy quarkonium production is a powerful implement to study the strong interaction dynamics and QCD theory. Fragmentation is the dominant production mechanism for heavy quarkonia with large transverse momentum. With the large heavy quark mass, the relative motion of the heavy quark pair inside a heavy quarkonium is effectively nonrelativistic and it is also well known that their fragmentation functions can be calculated in the perturbative QCD framework. Here, we analytically calculate the process-independent fragmentation functions for a gluon to split into the spin-singlet and spin-triplet [Formula: see text]-wave heavy quarkonia using three different scenarios. We will show that the fragmentation probability of the gluon into the spin-triplet bound-state is the biggest one.

Resonant IR Photon Induced Dissociation in Organic Molecules with Chain-like Substructures

A nonstatistical model for the resonant IR photon induced dissociation of organic molecules by IR photons is suggested. The model is based on the excimol theory for molecules which contain chains of identical diatomic dipole groups. IR photon radiation can induce resonantly collective vibrational excitations (excimols) in these molecular substructures. The accumulation of several excimols in the molecular chain causes a local heating of the molecule and its fragmentation on a time scale of several hundreds of femtoseconds. An analytical expression for the fragmentation probability is derived and analysed.

THE EFFECT OF SURFACE TEMPERATURE IN THE FRAGMENTATION OF H2 AT SURFACES

A model calculation is presented using quantum wave packets that examines the fragmentation of H 2 on a metal surface. We include two spatial dimensions in the calculation, the molecule-surface distance and the vibrational coordinate. Two electronic states are considered corresponding to molecular and atomic states. We have investigated the dynamics in our previous studies of this system which have shown that it is possible for quantum interference to occur giving rise to oscillations in the atomic fragmentation energy distributions. In these studies we have investigated the effect of potential topology and initial vibrational state on the atomic fragmentation. We now extend this model to include surface temperature by using a surface mass model which is analogous to a classical "cube" model. It is shown that including surface temperature does not wash out the interference and oscillations are still found. The temperature dependence of the atomic fragmentation probability is shown to be dependent on the potential topology.