Computation of Resistive Wakefields

We evaluate longitudinal resistive wakefields for cylindrical beam pipes numerically and compare the results with existing approximate formul\ae. We consider an ultra-relativistic bunch traversing a cylindrical, metallic tube for a model in which the wall conductivity is taken to be first independent and second dependent on frequency, and we show how these can be included simply and efficiently in particle tracking simulations. We also extend this to higher order modes, and to the transverse wakes. This full treatment can be necessary in the design of modern nano-beam accelerators

A Gauss type functional equation

Gauss' functional equation (used in the study of the arithmetic-geometric mean) is generalized by replacing the arithmetic mean and the geometric mean by two arbitrary means

Coherent quantum effects through dispersive bosonic media

The coherent evolution of two atomic qubits mediated by a set of bosonic field modes is investigated. By assuming a specific encoding of the quantum states in the internal levels of the two atoms we show that entangling quantum gates can be realised, with high fidelity, even when a large number of mediating modes is involved. The effect of losses and imperfections on the gates' operation is also considered in detail.Comment: 7 pages, 10 figure

Rate-Independent Damage in Thermo-Viscoelastic Materials with Inertia

We present a model for rate-independent, unidirectional, partial damage in visco-elastic materials with inertia and thermal effects. The damage process is modeled by means of an internal variable, governed by a rate-independent flow rule. The heat equation and the momentum balance for the displacements are coupled in a highly nonlinear way. Our assumptions on the corresponding energy functional also comprise the case of the Ambrosio\u2013 Tortorelli phase-field model (without passage to the brittle limit). We discuss a suitable weak formulation and prove an existence theorem obtained with the aid of a (partially) decoupled time-discrete scheme and variational convergence methods. We also carry out the asymptotic analysis for vanishing viscosity and inertia and obtain a fully rate-independent limit model for displacements and damage, which is independent of temperature

Research on the morphology, biology, productivity and yields quality of the Amaranthus cruentus L. in the southern part of Romania

Currently, according to the specialists in the field, Amaranthus species are part of alternative agricultural crops recommended for organic farming. In this context, our scientific approach is to analyse the adaptability of these species in the specific conditions of the southern part of Romania (Reviga village, Ialomita County). Thus, for two consecutive years, two varieties of Amaranthus cruentus, namely ‘Bolivia 153’ and ‘Golden Giant’, were studied regarding: morphology, biology, cultivation technology, plant productivity and quality of yields in the organic farming conditions. After the study period, the ‘Golden Giant’ variety was characterized by the following: 8 days - sowing-emergence period; flowering start on 21 July; 124 days - vegetation period; 839.3 Growing Degree Days (GDD) (Σ t °C > 15 °C); 23.24 g - grains mass per plant; 1.375 g - Thousand Weight Grains (TWG); 2,647 kg ha-1 - grains yields. By comparison, ‘Bolivia 153’ variety plants were presented as follows: 11 days - sowing-emergence period; flowering start on 21 July; 127 days - vegetation period; 842.4 GDD; 22.09 g - grains mass per plant; 1.46 g TWG; 23.78 kg ha-1 - grains yields. In average, the chemical composition of Amaranthus cruentus grains was: 15.20% proteins; 51.70% starch; 5.96% lipids; 13.36% cellulose and 3.35% ash. In conclusion, the experimentation area proved to be favourable to Amaranthus cruentus cultivation, so that the tested varieties behaved well, had a fairly uniform emergences, and the good level of grains yields and quality

Analysis of the Steinmetz compensation circuit with distorted waveforms through symmetrical component-based indicators

This paper deals with the use of a set of indicators defined within a symmetrical component-based framework to study the characteristics of the Steinmetz compensation circuit in the presence of waveform distortion. The Steinmetz circuit is applied to obtain balanced currents in a three-phase system supplying a single-phase load. The circuit is analyzed without and with harmonic distortion of the supply voltages. The compensation effect is represented by the classical unbalance factor and by the Total Phase Unbalance (TPU) indicator defined in the symmetrical component-based framework. Comparing the two indicators, it is shown that the classical unbalance factor is insufficient to represent the effect of voltage distortion and fails to detect the lack of total unbalance compensation occurring with distorted waveforms. Correct information is provided by calculating the TPU indicator. © 2009 IEEE