Usage of Ray Tracing Transfer Matrix to Mitigate the Stray Light for ITER Spectroscopy

Stray light formed by the reflection of photons on inner wall from a bright divertor region can be a serious issue in spectroscopic measurement systems in ITER. In this study, we propose a method to mitigate the influence of stray light using a ray tracing analysis. Usually, a ray tracing simulation requires a time consuming runs. We constructed transfer matrices based on the ray tracing simulation results and used them to demonstrate the influence of stray light. It is shown that the transfer matrix can be used to reconstruct the emission profile by considering the influence of the stray light without any additional ray tracing runs. Mitigation of the stray light in ITER divertor impurity monitor was demonstrated, and a method of prediction of the stray light level for the scrape off layer spectroscopy from divertor region was proposed. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Entanglement is not necessary for perfect discrimination between unitary operations

We show that a unitary operation (quantum circuit) secretly chosen from a finite set of unitary operations can be determined with certainty by sequentially applying only a finite amount of runs of the unknown circuit. No entanglement or joint quantum operations are required in our scheme. We further show that our scheme is optimal in the sense that the number of the runs is minimal when discriminating only two unitary operations.     

Unbiased global optimization of Lennard-Jones clusters for N < or =201 using the conformational space annealing method

We apply the conformational space annealing method to the Lennard-Jones clusters and find all known lowest energy configurations up to 201 atoms, without using extra information of the problem such as the structures of the known global energy minima. In addition, the robustness of the algorithm with respect to the randomness of initial conditions of the problem is demonstrated by ten successful independent runs up to 183 atoms. Our results indicate that this method is a general and yet efficient global optimization algorithm applicable to many systems.     

Transfer hydrogenation using recyclable polymer-supported formate (PSF): Efficient and chemoselective reduction of nitroarenes

Summary Nitroarenes can be reduced in high yields to the corresponding anilines by transfer hydrogenation using a stable H-donor, polymer-supported formate (PSF) in combination with palladium acetate (catalytic). The reactions occur at 100–120^∘C in dimethyl-formamide and the PSF can be recycled for at least three runs. The procedure is chemoselective for nitro group; ester, ketone, aldehyde, and halide substituents on aromatic ring remain unaffected.     

Solar neutrino flux measurements by the Soviet-American gallium experiment (SAGE) for half the 22-year solar cycle

We present measurements of the solar neutrino capture rate on metallic gallium in the Soviet-American gallium experiment (SAGE) over a period of slightly more than half the 22-year solar cycle. A combined analysis of 92 runs over the twelve-year period from January 1990 until December 2001 yields a capture rate of 70.8 _?5.2 ^+5.3 (stat) _?3.2 ^+3.7 (sys) SNU for solar neutrinos with energies above 0.233 MeV. This value is slightly more than half the rate predicted by the standard solar model, 130 SNU. We present the results of new runs since April 1998 and analyze all runs combined by years, months, and bimonthly periods beginning in 1990. A simple analysis of the SAGE results together with the results of other solar neutrino experiments gives an estimate of (4.6±1.2)× 10¹⁰ neutrinos cm^?2 s^?1 for the flux of the electron pp neutrinos that reach the Earth without changing their flavor. The flux of the pp neutrinos produced in thermonuclear reactions in the Sun is estimated to be (7.6 ± 2.0) × 10¹⁰ neutrinos cm^?2 s^?1, in agreement with the value of (5.95±0.06)×10¹⁰ neutrinos cm^?2 s^?1 predicted by the standard solar model.     

Iterative retrieval of one-dimensional x ray wave field using a single intensity measurement

The problem of retrieving a complex function from the modulus of its Fourier transform has non-unique solutions in one dimension. Therefore iterative phase retrieval methods cannot in general be confidently applied to one-dimensional problems, due to the presence of ambiguities. We present a method for a posteriori reduction of the ambiguities based on the correlation analysis of the solution of a large number of runs of an iterative phase retrieval algorithm with different random starting phases. The method is applied to experimentally measured diffraction patterns from an x ray waveguide illuminated by hard x rays. We demonstrate the possibility of retrieving the complex wave field at the exit face of the waveguide and compare the result with theoretical prediction.     

Q parameter estimation using numerical simulations for linear and nonlinear transmission systems

We compare the Q parameter obtained from scalar, semi-analytical and full vector models for realistic transmission systems. One set of systems is operated in the linear regime, while another is using solitons at high peak power. We report in detail on the different results obtained for the same system using different models. Polarisation mode dispersion is also taken into account and a novel method to average Q parameters over several independent simulation runs is described.     

Modeling the interactions between light and crystallizing polymer during fast cooling

In this work, an experimental set-up able to quench thin polymer films whilst recording the sample thermal history as well as the overall and depolarized light intensities of a laser beam emerging from the sample is described. The interactions between the light beam and the crystallizing material have been modeled accounting for absorption and scattering phenomena. The proposed model was found to be able to reproduce the experimentally observed behavior of light intensities and it was validated by comparison with conventional DSC analysis. On the basis of this model, a method to obtain crystallinity evolution is proposed and applied to some fast cooling runs. The method was applied to quenching runs of an iPP carried out under cooling conditions more than one order of magnitude faster than those allowed for the DSC technique. The crystallization temperature dependence upon cooling rate was obtained from these runs in a cooling rate range never before explored. PACS 81.05.Lg; 81.70.Fy     

Active Learning Approach to Optimization of Experimental Control

We present a general machine learning based scheme to optimize experimental control.The method utilizes the neural network to learn the relation between the control parameters and the control goal, with which the optimal control parameters can be obtained.The main challenge of this approach is that the labeled data obtained from experiments are not abundant.The central idea of our scheme is to use the active learning to overcome this difficulty.As a demonstration example, we apply our method to control evaporative cooling experiments in cold atoms.We have first tested our method with simulated data and then applied our method to real experiments.It is demonstrated that our method can successfully reach the best performance within hundreds of experimental runs.Our method does not require knowledge of the experimental system as a prior and is universal for experimental control in different systems.     

New secondary-scattering correction in DISORT with increased efficiency for forward scattering

We present an alternative method to calculate the directional distribution after secondary scattering of light in an atmosphere, and apply it to the correction developed by Nakajima and Tanaka (1988) [1] as implemented in the DISORT radiative transfer solver. This method employs the scattering phase functions directly, instead of expanding over their Legendre moments as in the original formulation, and hence is not compromised in cases where a prohibitive number of moments is required to maintain accuracy. The new approach is designed to be particularly efficient in the strongly forward-scattering case, which arises for example in problems involving cloud-ice or dust particles. We have implemented this in a newly rewritten C-code version of DISORT that provides additional computational efficiencies via dynamic and cache-aware memory allocation. The new version uses less memory and runs considerably faster than the original, while producing results with equal or greater accuracy.     

Statistical distribution and time correlation of stock returns runs

In this paper, we focus on the statistical features and time correlation of runs which is defined as a sequence of consecutive gain/loss (rise/fall) stock returns. By studying daily data of the Dow Jones industrial average (DJIA), we get the following points: firstly, the distribution of length and magnitude of stock returns runs both follow an exponential law; secondly, runs length do lack significant time correlation, while runs magnitude exhibit a slow decay of time correlation with long persistence up to several months, which implies existence of volatility clustering. We expect the above properties may add new members to the family of stylized facts about stock returns.     

The Eulerian-Lagrangian Method with Accurate Numerical Integration

This paper is devoted to the study of the Eulerian-Lagrangian method (ELM) for convection-diffusion equations on unstructured grids with or without accurate numerical integration. We first propose an efficient and accurate algorithm to calculate the integrals in the Eulerian-Lagrangian method. Our approach is based on an algorithm for finding the intersection of two non-matching grids. It has optimal algorithmic complexity and runs fast enough to make time-dependent velocity fields feasible. The evaluation of the integrals leads to increased precision and the unconditional stability. We demonstrate by numerical examples that the ELM with our proposed algorithm for accurate numerical integration has the following two features: firstly, it is much more accurate and more stable than the ones with traditional numerical integration techniques and secondly, the overall cost of the proposed method is comparable with the traditional ones.     

Application of statistical methods for analysis of heavy-ion reactions in the framework of a dinuclear system model

Heavy-ion reactions are investigated by statistical methods in the framework of a dinuclear system model (DNS). Synthesis of superheavy elements in cold and hot fusion reactions on Pb and Bi targets, as well as in incomplete fusion reactions, is considered. We also take a look at production of neutron-deficient isotopes and pre-scission neutron emission in quasifission reactions. The results of calculations are compared with the available experimental data. The sensitivity of these results to the method of calculation of the level density and to various theoretical predictions of nuclear properties is analyzed.     

Eikonal Reaction Theory for One- and Two-Neutron Removal Reactions

We present an accurate method of treating neutron removal reactions and it’s applications. According to the method, the nuclear and Coulomb breakup processes are consistently treated by the method of the continuum discretized coupled channels. This method is referred to as the eikonal reaction theory (ERT). We analyze the two types of removal reactions of ³¹Ne and ⁶He with ERT.     

Production of fragments with and without strangeness within a combined BUU + SMM approach

The formation of hypernuclei in hadron-induced reactions and in heavy-ion collisions within a combination of a covariant transport model and a statistical fragmentation approach is investigated. We study the applicability and limitations of such a hybrid approach by comparing fragmentation data in heavy-ion collisions and proton-induced reactions. It turns out that the combined approach describes fairly well multiplicities and momentum spectra of fragments. We thus extend the model by including strangeness degrees of freedom in the fragmentation process, modeled by a phase-space coalescence method. We provide theoretical predictions on spectra and on inclusive cross sections of light hypernuclei for the future experiments on hypernuclear physics at the new GSI facility.     

Modelling of electrification in steady state and transient regimes

A microscopic model of electrification phenomena in steady state and transient regimes has been developed. The model has been applied for analysis of experimental data failing to be explained in the frame of classical macroscopic approach. Various boundary conditions have been studied regarding the possibility of experiential data fitting. The hybrid boundary condition has been suggested for explaining steady state and transient experiments. The proposed boundary condition can be related to the coexistence of two reactions on the active surface. The first reaction runs under the diffusion control (fast reaction) and the second one is limited by the kinetics (slow reaction).     

Development of the reaction time accelerating molecular dynamics method for simulation of chemical reaction

We present a novel and efficient method to integrate chemical reactions into molecular dynamics to simulate chemical reaction systems. We have dubbed this method RTAMD, an acronym for reaction time accelerating molecular dynamics. The methodology we propose here requires no more than the knowledge of the empirical intermolecular potentials for the species at play as well as the elementary reaction path among them. Bond formation during the simulation is performed by changing the inter-atomic potentials from those of the non-bonded species to those of the bonded ones, and a reaction is deemed to occur by the distance separating the bond forming atoms. In this way the energy barrier for a reaction is no longer considered; the estimation of the reaction rate, however, is possible by introducing the principles of the transition state theory. The simplicity of the present scheme to simulate chemical reactions enables it to be used in large-scale MD simulations involving a large number of simultaneous chemical reactions and to evaluate kinetic parameters. In this paper, the basic theory of the method is presented and application to simple equiatomic reaction system where the reaction rates were estimated was illustrated.     

Distinguishing between Dirac and Majorana neutrinos in neutral-current reactions

We calculate cross sections for neutral-current reactions initiated by massive Dirac and Majorana neutrinos and analyze such reactions as a possible new method of distinguishing between these types of neutrinos.     

Atomic processes in vacancy island motion on Ag(111)

We present results of molecular dynamics simulations of the motion of monatomic-deep vacancy islands on Ag(111), using interaction potentials from the embedded atom method. The individual processes appearing in a large set of runs, at three different temperatures, are identified. From the statistics thus collected, we find that the predominant mechanism underlying the diffusion of vacancy islands on Ag(111) is the diffusion of atoms along the periphery of the vacancy islands.