Stability of non-linear integrable accelerator

The stability of non-linear Integrable Optics Test Accelerator (IOTA) model was tested. The area of the stable region in transverse coordinates and the maximum attainable tune spread were found as a function of non-linear lens strength. Particle loss as a function of turn number was analyzed to determine whether a dynamic aperture limitation present in the system. The system was also tested with sextupoles included in the machine for chromaticity compensation. A method of evaluation of the beam size in the linear part of the accelerator was proposed.Comment: 10 p

Autoresonant excitation of Bose-Einstein condensates

Controlling the state of a Bose-Einstein condensate driven by a chirped frequency perturbation in a one-dimensional anharmonic trapping potential is discussed. By identifying four characteristic time scales in this chirped-driven problem, three dimensionless parameters $P_{1,2,3}$ are defined describing the driving strength, the anharmonicity of the trapping potential, and the strength of the particles interaction, respectively. As the driving frequency passes the linear resonance in the problem, and depending on the location in the $P_{1,2,3}$ parameter space, the system may exhibit two very different evolutions, i.e. the quantum energy ladder climbing (LC) and the classical autoresonance (AR). These regimes are analysed both in theory and simulations with the emphasis on the effect of the interaction parameter $P_{3}$. In particular, the transition thresholds on the driving parameter $P_{1}$ and their width in $P_{1}$ in both the AR and LC regimes are discussed. Different driving protocols are also illustrated, showing efficient control of excitation and de-excitation of the condensate

Rapid Prototyping of PEM Fuel Cell Bi-Polar Plates using 3D Printing and Thermal Spray Deposition

This article presents the results of exploratory research on novel methods for the fabrication of functional, metallic, gas flow, bi polar plates (BPP) for use in proton exchange membrane fuel cells (PEMFC). Low cost, high speed, additive manufacturing methods that combine 3D printing (3DP) and thermal spray (TS) technologies are described. Functional flow plates were manufactured by creating 3DP patterns and then depositing, and releasing, dense metals with TS methods. The new method yields dense metal plates, with interesting options for material choices and complex designs.Mechanical Engineerin

Absorption spectroscopy of massselected hydrocarbon and boron species in 6 K neon matrices

Matrix isolation spectroscopy is an important experimental technique used to characterize spectroscopically unstable species like ions and radicals. Species of interest can be frozen in a matrix for a long time and investigated using different spectroscopic methods in a wide range of wavelengths. Electronic and vibrational absorption spectroscopy provides information about the location and strength of transitions for the interrogated species, which is essential for subsequent gas phase studies. It is an important link in the following research sequence: ab initio calculations → matrix isolation studies → gas phase studies → comparison with astrophysical data. One should emphasize the “symbiosis” between matrix and gas phase research. Due to matrix effects like shifts and broadening, direct comparison of matrix spectra with those of ISM is not possible (gas phase measurements are needed); on the other hand, gas phase techniques are usually very restricted in their spectral range, and hence the need for matrix data as the basis for searching for transitions and their assignments. Several species which contain atoms that are abundant in cosmos were investigated in cold matrices as a part of this PhD. Using an electron impact cation source and diacetylene as a precursor it was possible to produce positively charged carbon chains terminated by one or several H atoms (C6H+, C8H+, C6H4+, C4H3+, C6H3+, C8H3+). However, one can not obtain bare carbon cations in this way (the probability that a carbon chain will not capture at least one H atom is very small at the given experimental conditions). Thus, different chlorinated hydrocarbons were used as precursors to produce such species as Cn+ (n = 6 – 9) and chlorine terminated carbon chains CnCl+ (n = 3 – 6). The disadvantage here is the need to always find a proper precursor for each ion. (Every single precursor has its own physical properties, e.g. melting temperature, and requires some modification in the experimental set-up.) It was also possible to spectroscopically characterize the B3 molecule in neon matrices. Either Cs sputter anion source or a laser ablation source without mass-selection were used for production. However, larger boron compounds were elusive in the case of the anion source, and laser vaporization alone proved difficult since one can not make any proper assignments without mass-selection. Therefore, one part of this work was devoted to the development of a laser ablation source, suitable to be coupled with the existing mass-selection experimental set-up. Such a source can provide a breakthrough in matrix isolation spectroscopy of species like larger boron molecules (> B3) and bare carbon cations. This source promises to be quite a universal tool, which can produce many species from one precursor; in contrast to the chlorinated hydrocarbons example. With this source, one will also be able to obtain efficient matrix concentrations of small species like C3+; this cation did not reveal any electronic absorptions in matrices, most likely due to its insufficient production in the cation source. Some progress in construction of this source has already been achieved. Bare carbon cations Cn+ (n = 1 – 8) were produced, however their yield must be significantly increased (e.g. the application of a pulsed valve is a promising solution)

The Russian Title Registration System for Realty and Its Effect on Foreign Investors

The recent privatization of real property is an important step in Russia\u27s transition from a planned to market economy. This privatization creates opportunities for foreigners in the Russian realty market. However, foreigners are not likely to enter this market unless rights to immovable property are certain and secure. This Comment describes the new Russian immovable property Registration Law and argues that, despite its drawbacks, it creates a workable system that will provide certainty and security in rights to Russian immovable property. Furthermore, the Comment advises foreign investors on how to avoid potential problems the new law creates

Concomitant diagnosis of immune deficiency and Pseudomonas sepsis in a 19 month old with ecthyma gangrenosum by host whole-genome sequencing.

X-linked agammaglobulinemia (XLA, OMIM#300300) is a rare monogenic primary immunodeficiency caused by mutations in the Bruton tyrosine kinase (BTK) gene. XLA is characterized by insufficient immunoglobulin levels and susceptibility to life-threatening bacterial infections. We report on a patient that presented with ecthyma gangrenosum and septicemia. Rapid trio whole-genome sequencing (rWGS) revealed an apparently de novo hemizygous pathogenic variant (c.726dupT; p.Ile243TyrfsTer15) in the BTK gene. Metagenomic analysis of rWGS sequences that did not align to the human genome revealed 770 aligned to the Pseudomonas aeruginosa PAO1 genome. The patient was diagnosed with XLA and pseudomonal sepsis

Sliding mode control of a three-DOF robotic system driven by DC motors

U ovom radu, predloženo je upravljanje u kliznom režimu kretanjem robotskog sistema sa 3 stepena slobode pogonjen jednosmernim motorima. Prvenstveno je projektovan kontroler u kliznom režimu i koji je baziran na PD kliznoj površi. Numeričke simulacije su sprovedene sa ciljem ilustrovanja osobina robusnosti predloženog sistema upravljanja kao i značaja smanjenja izlaznih oscilacija chattering-free datog robotskog sistema. Konačno, simulacioni primer pokazuje izvodljivost i efikasnost predloženog pristupa.This paper proposes a sliding mode control of a 3-DOF robotic system driven by DC motors. Primarily, a conventional sliding mode controller based on a pd sliding surface is designed. Numerical simulations have been carried out to show the proposed control system's robustness properties as well as the significance of the proposed control which resulted in reducing output oscillations (chattering-free) of the given robot. Finally, a simulation example shows the feasibility and effectiveness of the proposed approach

Sliding mode control of a three-DOF robotic system driven by DC motors

U ovom radu, predloženo je upravljanje u kliznom režimu kretanjem robotskog sistema sa 3 stepena slobode pogonjen jednosmernim motorima. Prvenstveno je projektovan kontroler u kliznom režimu i koji je baziran na PD kliznoj površi. Numeričke simulacije su sprovedene sa ciljem ilustrovanja osobina robusnosti predloženog sistema upravljanja kao i značaja smanjenja izlaznih oscilacija chattering-free datog robotskog sistema. Konačno, simulacioni primer pokazuje izvodljivost i efikasnost predloženog pristupa.This paper proposes a sliding mode control of a 3-DOF robotic system driven by DC motors. Primarily, a conventional sliding mode controller based on a pd sliding surface is designed. Numerical simulations have been carried out to show the proposed control system's robustness properties as well as the significance of the proposed control which resulted in reducing output oscillations (chattering-free) of the given robot. Finally, a simulation example shows the feasibility and effectiveness of the proposed approach