Secondary electron emission yield in the limit of low electron energy

Secondary electron emission (SEE) from solids plays an important role in many areas of science and technology.1 In recent years, there has been renewed interest in the experimental and theoretical studies of SEE. A recent study proposed that the reflectivity of very low energy electrons from solid surface approaches unity in the limit of zero electron energy2,3,4, If this was indeed the case, this effect would have profound implications on the formation of electron clouds in particle accelerators,2-4 plasma measurements with electrostatic Langmuir probes, and operation of Hall plasma thrusters for spacecraft propulsion5,6. It appears that, the proposed high electron reflectivity at low electron energies contradicts to numerous previous experimental studies of the secondary electron emission7. The goal of this note is to discuss possible causes of these contradictions.Comment: 3 pages, contribution to the Joint INFN-CERN-EuCARD-AccNet Workshop on Electron-Cloud Effects: ECLOUD'12; 5-9 Jun 2012, La Biodola, Isola d'Elba, Ital

Quantifizierung des Einflusses von Schweißnahtimperfektionen durch Referenzproben

Für labortechnische Untersuchungen an ausgewählten Schweißnahtimperfektionen wurde für die Simulation der vorhandenen Struktur- und Kerbspannungen und für den experimentellen Nachweis eine Referenzprobe entwickelt und erprobt. Die Arbeit verfolgte das Ziel, den Einfluß kurzfristig erzeugter örtlicher plastischer Verformungen auf die Ermüdungsfestigkeit zu ermitteln, wie sie an Rund- und Längsnahten in zylindrischen Druckbehältern auftreten können. Durch die besondere Form der gekerbten Referenzprobe wurden die Imperfektion und die Geometrie der Schweißnähte reproduziert. Auf einem Hochfrequenzpulsator erfolgte die Durchführung der Schwingfestigkeitsversuche bei Zugschwellbeanspruchung an den Referenzproben. Es wurde ein FE-Modell für die Referenzprobe entwickelt und der Spannungszustand simuliert. Auf der Grundlage der FE-Analyse erfolgte entsprechend dem Kerbdehnungskonzept die Lebensdauerabschätzung. Die Versuchsergebnisse wurden mit den rechnerischen Ergebnissen für die Referenzproben verglichen und deren Übereinstimmung festgestellt

The technology of creation of the standard base for socio-economic dimensions

© Medwell Journals, 2016.Practice education standards for assessing and comparing (comparing/contrasting) heterogeneous properties of controlled processes of socio-economic spheres. Design technique and technology to create a reference framework for processes in socio-economic sphere and on this basis to apply for measuring operations scientific methods of metrology. In this researchers methods of imitating and semantic modeling in a complex with methods of the economical and statistical analysis are used. Possibility of creation of the expert system reproducing technical and operational properties of natural market metrology, formation of general estimated function and a comparable measure of productivity for a set of diverse and multidirectional indicators is discussed. The model of creation of reference base for private indicators providing an integrated rating assessment of a condition of various organizational structures and processes is developed. The conclusion is that in terms of multidirectional indicators the most viable scheme of management of organizational systems is the formation of the reference base, the formation of normative-evaluative, the synthesis of multidimensional processes to one-dimensionality of a single criterion

System analysis of generic and specific properties evaluation functions in the economy

Topic/theme Properties of evaluation functions in the economy, their system analysis, multidimensional process of change of status and the impact of socio-economic facilities to one-dimensional criterion. Objectives/targets To systematize the properties of naturally-market and expert-analytical Metrology state of the organizational systems, to divide them into generic-mu and species trait. Methodology In this work we used simulation methods-semantic modeling in complex with the methods of statistical and analytical analysis. Discussing the possibility of creating an expert system, reproducing the generic and specific properties of the Islands natural market Metrology, formation of universal evaluation functions and comparable measures of performance for a variety of particular indices. Results The developed model integration evaluation indicators providing a rating assessment of various organizational structures and processes. Conclusions/significance It is concluded that under the conditions of multi-directed indicators the most viable scheme of management of organizational systems is to reduce the multidimensionality of the processes to one dimensional uniform criterion

Magnetization and specific heat of TbFe3(BO3)4: Experiment and crystal field calculations

We have studied the thermodynamic properties of single-crystalline TbFe3(BO3)4. Magnetization measurements have been carried out as a function of magnetic field (up to 50 T) and temperature up to 350K with the magnetic field both parallel and perpendicular to the trigonal c-axis of the crystal. The specific heat has been measured in the temperature range 2-300K with a magnetic field up to 9 T applied parallel to the c-axis. The data indicate a structural phase transition at 192 K and antiferromagnetic spin ordering at 40 K. A Schottky anomaly is present in the specific heat data around 20 K, arising due to two low-lying energy levels of the Tb3+ ions being split by f-d coupling. Below TN magnetic fields parallel to the c-axis drive a spin-flop phase transition, which is associated with a large magnetization jump. The highly anisotropic character of the magnetic susceptibility is ascribed mainly to the Ising-like behavior of the Tb3+ ions in the trigonal crystal field. We describe our results in the framework of an unified approach which is based on mean-field approximation and crystal-field calculations.Comment: 10 pages, 10 figures, 20 references, accepted by Phys. Rev.

Integration of theoretical and clinical disciplines teaching as one of factors of medical knowledge efficacy

The article discusses the problem of medical students theoretical knowledge improvement that will significantly improve their clinical knowledge. The main factors that determine medical students’ positive motivation to study are considered. The authors prove that both theoretical and clinical disciplines teaching integration is possible as a result of complex approach to students teaching that will result in students’ knowledge survival on the higher courses. Leading role belongs to the theoretical departments which workers by writing textbooks and manuals, creating teaching multimedia programmes, using exact control and students' knowledge evaluation will provide the necessary motivational component of students’ further teaching on clinical departments. The integrated approach contributes to future profession single picture formation, motivates students to theoretical and clinical disciplines deep study. The future doctors teaching process reforming at Odessa National Medical University General and Clinical Pathological Physiology Department is given as an example.Authors guesses that new methodical methods of working with students in the practical work introduction, the change in the technology of teaching, the modification of the educational process, the approximation of theoretical knowledge to the patient's bed, the greater students interest in the positive end-goal - a correct diagnosis and cure of the patient - will allow to optimize the educational process and improve the quality of students’ training