Optimizing the discrete time quantum walk using a SU(2) coin

We present a generalized version of the discrete time quantum walk, using the SU(2) operation as the quantum coin. By varying the coin parameters, the quantum walk can be optimized for maximum variance subject to the functional form $\sigma^2 \approx N^2$ and the probability distribution in the position space can be biased. We also discuss the variation in measurement entropy with the variation of the parameters in the SU(2) coin. Exploiting this we show how quantum walk can be optimized for improving mixing time in an $n$-cycle and for quantum walk search.Comment: 6 pages, 6 figure

Antihydrogen Formation via Antiproton Scattering with Excited Positronium

Use of CCC method to calculate for the first time very accurate cross sections for Hbar formation in antiiproton-Ps collisions close to threshold for a numebr of excited Ps states. Discovery of novel 1/E behaviour for the cross ections near thresold for excited states

Evaluation of Temperature Gradient in Advanced Automated Directional Solidification Furnace (AADSF) by Numerical Simulation

A numerical model of heat transfer using combined conduction, radiation and convection in AADSF was used to evaluate temperature gradients in the vicinity of the crystal/melt interface for variety of hot and cold zone set point temperatures specifically for the growth of mercury cadmium telluride (MCT). Reverse usage of hot and cold zones was simulated to aid the choice of proper orientation of crystal/melt interface regarding residual acceleration vector without actual change of furnace location on board the orbiter. It appears that an additional booster heater will be extremely helpful to ensure desired temperature gradient when hot and cold zones are reversed. Further efforts are required to investigate advantages/disadvantages of symmetrical furnace design (i.e. with similar length of hot and cold zones)

Numerical modeling of HgCdTe solidification: Effects of phase diagram, double-diffusion convection and microgravity level

A numerical model of HgCdTe solidification was implemented using finite the element code FIDAP. Model verification was done using both experimental data and numerical test problems. The model was used to evaluate possible effects of double-diffusion convection in molten material, and microgravity level on concentration distribution in the solidified HgCdTe. Particular attention was paid to incorporation of HgCdTe phase diagram. It was found, that below a critical microgravity amplitude, the maximum convective velocity in the melt appears virtually independent on the microgravity vector orientation. Good agreement between predicted interface shape and an interface obtained experimentally by quenching was achieved. The results of numerical modeling are presented in the form of video film

Numerical Modeling of HgCdTe Solidification: Effects of Phase Diagram, Double-Diffusion Convection and Microgravity Level

Melt convection, along with species diffusion and segregation on the solidification interface are the primary factors responsible for species redistribution during HgCdTe crystal growth from the melt. As no direct information about convection velocity is available, numerical modeling is a logical approach to estimate convection. Furthermore influence of microgravity level, double-diffusion and material properties should be taken into account. In the present study, HgCdTe is considered as a binary alloy with melting temperature available from a phase diagram. The numerical model of convection and solidification of binary alloy is based on the general equations of heat and mass transfer in two-dimensional region. Mathematical modeling of binary alloy solidification is still a challenging numericial problem. A Rigorous mathematical approach to this problem is available only when convection is not considered at all. The proposed numerical model was developed using the finite element code FIDAP. In the present study, the numerical model is used to consider thermal, solutal convection and a double diffusion source of mass transport

Experimental analysis of end mill axis inclination and its influence on 3D areal surface texture parameters

[EN] The surface quality of machined parts depends highly on the surface texture that reflects the marks of the tool during the cutting process. The traditional theoretical approach indicates that these marks are related to the cutting parameters (e.g. cutting speed, feed, depths of cut), the machining type, the part material, the tool, etc. The influence of these factors has been widely studied by researchers and they have been considered in milling process models proposed to predict the final surface texture. Nevertheless, if an accurate prediction is desired, these milling models must include different geometrical errors influencing the cutting edges path on the part. In this paper, we present the results of a study showing the influence of real mill-axis inclination on 3D surface texture. Therefore, experiments with simple, end mill tool operation, with constant cutting parameters and four different cutting directions (the directions that we labelled as North, South, East, and West) in accordance with the machine coordinate system were performed. Using optical 3D areal surface texture measurement techniques with the Bruker Contour device, we obtained areal surface texture parameters for analysis. Descriptive statistical analysis and one-way ANOVA analysis were performed to detect the factor significances and their influence on 3D areal surface texture parameters. The results from ANOVA and graphical analysis clearly identified tool-axis inclination in the South and West directions. If a relationship between tool-axis inclination and surface texture parameters can be demonstrated, this calculation can be included in the model of 3D surface texture formation. Improving the mathematical model with all possible errors occurring in high speed machining operations helps to obtain more precise texture parameter Sz results for simple end mill operation. The model is suitable for complicated machining operations with ball end mill tools.Logins, A.; Rosado Castellano, P.; Torims, T.; Gutiérrez, SC.; Sergejev, F. (2017). Experimental analysis of end mill axis inclination and its influence on 3D areal surface texture parameters. Proceedings of the Estonian Academy of Sciences. 66(2):194-201. doi:10.3176/proc.2017.2.09S19420166

Morphological and organic spectroscopic studies of a 44-million-year-old leaf beetle (Coleoptera: Chrysomelidae) in amber with endogenous remains of chitin

This study details the quality of preservation of amber deposits in the Eocene. Through Baltic amber crack-out studies using Synchrotron Micro-Computed Tomography and Scanning Electron Microscopy it was found that the cuticle of a specimen of leaf beetle (Crepidodera tertiotertiaria (Alticini: Galerucinae: Chrysomelidae)) is exceptionally well preserved. Spectroscopic analysis using Synchrotron Fourier Transform Infrared Spectroscopy suggests presence of degraded α -chitin in multiple areas of the cuticle, and Energy Dispersive Spectroscopy supports the presence of organic preservation. This remarkable preservation is likely the result of several factors such as the favourable antimicrobial and physical shielding properties of Baltic amber as compared to other depositional media, coupled to rapid dehydration of the beetle early in its taphonomic process. We provide evidence that crack-out studies of amber inclusions, although inherently destructive of fossils, are an underutilised method for probing exceptional preservation in deep time

Computational Controversy

Climate change, vaccination, abortion, Trump: Many topics are surrounded by fierce controversies. The nature of such heated debates and their elements have been studied extensively in the social science literature. More recently, various computational approaches to controversy analysis have appeared, using new data sources such as Wikipedia, which help us now better understand these phenomena. However, compared to what social sciences have discovered about such debates, the existing computational approaches mostly focus on just a few of the many important aspects around the concept of controversies. In order to link the two strands, we provide and evaluate here a controversy model that is both, rooted in the findings of the social science literature and at the same time strongly linked to computational methods. We show how this model can lead to computational controversy analytics that have full coverage over all the crucial aspects that make up a controversy.Comment: In Proceedings of the 9th International Conference on Social Informatics (SocInfo) 201

Analyzing Ideological Communities in Congressional Voting Networks

We here study the behavior of political party members aiming at identifying how ideological communities are created and evolve over time in diverse (fragmented and non-fragmented) party systems. Using public voting data of both Brazil and the US, we propose a methodology to identify and characterize ideological communities, their member polarization, and how such communities evolve over time, covering a 15-year period. Our results reveal very distinct patterns across the two case studies, in terms of both structural and dynamic properties