Electronic structures of doped BaFe2_2As2_2 materials: virtual crystal approximation versus super-cell approach

Employing virtual crystal approximation and super-cell methods for doping, we have performed a comparative study of the electronic structures of various doped BaFe$_2$As$_2$ materials by first principles simulations. Both of these methods give rise to a similar density of states and band structures in case of hole doping (K doping in Ba site) and iso-electronic P doping in As site. But in case of electron doped systems with higher doping concentration, electronic structures, calculated using virtual crystal approximation approach deviates from that of the super-cell method. On the other hand in case of iso-electronic Ru doping implemented by virtual crystal approximation, an extra shift of the chemical potential in electronic structure in comparison to super-cell method is observed and that shift can be used to predict the correct electronic structure within virtual crystal approximation as reflected in our calculated Fermi surfaces. But for higher Ru doping concentration, simple shifting of chemical potential does not work as the electronic structure calculated by virtual crystal approximation approach is entirely different from that of the calculated by super-cell formalism.Comment: 10 pages, 17 figure

Dynamic update of a virtual cell for programming and safe monitoring of an industrial robot

A hardware/software architecture for robot motion planning and on-line safe monitoring has been developed with the objective to assure high flexibility in production control, safety for workers and machinery, with user-friendly interface. The architecture, developed using Microsoft Robotics Developers Studio and implemented for a six-dof COMAU NS 12 robot, established a bidirectional communication between the robot controller and a virtual replica of the real robotic cell. The working space of the real robot can then be easily limited for safety reasons by inserting virtual objects (or sensors) in such a virtual environment. This paper investigates the possibility to achieve an automatic, dynamic update of the virtual cell by using a low cost depth sensor (i.e., a commercial Microsoft Kinect) to detect the presence of completely unknown objects, moving inside the real cell. The experimental tests show that the developed architecture is able to recognize variously shaped mobile objects inside the monitored area and let the robot stop before colliding with them, if the objects are not too small

ANN Based Virtual Classification Model for Discriminating Active and Inactive Withanolide E Analogs against Human Breast Cancer Cell Line MCF-7

Withanolides are a group of natural C-28 steroids built on an ergostane skeleton and classified into two major groups according to their structural skeleton: (a) compounds with a beta-oriented side chain and (b) compounds with an alpha-oriented side chain. Withanolide E represents one of the members of the latter group. Classification of active compounds on the basis of pharmacophore against specific cancer cell line poses a serious concern at the primary stage of virtual screening. To overcome this problem we have developed an artificial neural network based virtual screening model for discriminating active and non-active Withanolide-E-like derivatives or analogs against human breast cancer cell line MCF-7. In the present work, a 2D chemical descriptors ensemble pharmacophore has been modelled on the basis of withanolide E structural featured molecules. The ANN structure activity based classification model could be useful for identification of active withanolide analogs as anticancer leads against MCF-7. This model can be used for predicting possible growth inhibitory concentration (logGI50) against breast cancer cell line MCF-7. The virtual screening tool “CanWithaANN” can be accessed at local network of CIMAP

Modeling a complex production line using virtual cells

This chapter presents modeling and simulation of a complex multistage multiproduct production line with four closed loop networks configuration, which also act as a virtual cell. This allows for a greater understanding of the functions within the production line through the simplification of the production flow with the addition of buffers between the cells. Virtual cells are crucial in this instance due to the dynamic configuration, which could help production system designers in optimizing the complex configuration of production

Downlink Rate Analysis for Virtual-Cell Based Large-Scale Distributed Antenna Systems

Despite substantial rate gains achieved by coordinated transmission from a massive amount of geographically distributed antennas, the resulting computational cost and channel measurement overhead could be unaffordable for a large-scale distributed antenna system (DAS). A scalable signal processing framework is therefore highly desirable, which, as recently demonstrated in \cite{Dai_TWireless}, could be established based on the concept of virtual cell. In a virtual-cell based DAS, each user chooses a few closest base-station (BS) antennas to form its virtual cell, that is, its own serving BS antenna set. In this paper, we focus on a downlink DAS with a large number of users and BS antennas uniformly distributed in a certain area, and aim to study the effect of the virtual cell size on the average user rate. Specifically, by assuming that maximum ratio transmission (MRT) is adopted in each user's virtual cell, the achievable ergodic rate of each user is derived as an explicit function of the large-scale fading coefficients from all the users to their virtual cells, and an upper-bound of the average user rate is established, based on which a rule of thumb is developed for determining the optimal virtual cell size to maximize the average user rate. The analysis is further extended to consider multiple users grouped together and jointly served by their virtual cells using zero-forcing beamforming (ZFBF). In contrast to the no-grouping case where a small virtual cell size is preferred, it is shown that by grouping users with overlapped virtual cells, the average user rate can be significantly improved by increasing the virtual cell size, though at the cost of a higher signal processing complexity

Simulation of an Axial Vircator

An algorithm of particle-in-cell simulations is described and tested to aid further the actual design of simple vircators working on axially symmetric modes. The methods of correction of the numerical solution, have been chosen and jointly tested, allow the stable simulation of the fast nonlinear multiflow dynamics of virtual cathode formation and evolution, as well as the fields generated by the virtual cathode. The selected combination of the correction methods can be straightforwardly generalized to the case of axially nonsymmetric modes, while the parameters of these correction methods can be widely used to improve an agreement between the simulation predictions and the experimental data.Comment: 9 pages, 3 figure