Heavy-Ion Beam Acceleration of Two-Charge States from an Ecr Ion Source

This paper describes a design for the front end of a superconducting (SC) ion linac which can accept and simultaneously accelerate two charge states of uranium from an ECR ion source. This mode of operation increases the beam current available for the heaviest ions by a factor of two. We discuss the 12 MeV/u prestripper section of the Rare Isotope Accelerator (RIA) driver linac including the LEBT, RFQ, MEBT and SC sections, with a total voltage of 112 MV. The LEBT consists of two bunchers and electrostatic quadrupoles. The fundamental frequency of both bunchers is half of the RFQ frequency. The first buncher is a multiharmonic buncher, designed to accept more than 80% of each charge state and to form bunches of extremely low longitudinal emittance (rms emittance is lower than 0.2 keV/u nsec) at the output of the RFQ. The second buncher is located directly in front of the RFQ and matches the velocity of each charge-state bunch to the design input velocity of the RFQ. We present full 3D simulations of a two-charge-state uranium beam including space charge forces in the LEBT and RFQ, realistic distributions of all electric and magnetic fields along the whole prestripper linac, and the effects of errors, evaluated for several design options for the prestripper linac. The results indicate that it is possible to accelerate two charge states while keeping emittance growth within tolerable limits.Comment: LINAC2000, MOD0

Modernization of government management in empires of new time: comparative political analysis

The article deals with the issues related to the modernization of public administration in the imperial states of modern times. Russian, British and Ottoman empires as states implementing various strategies of modernization and improvement of public administration were chosen as examples. The success of modernization reforms of the administration is one of the essential conditions for maintaining stability and development of the imperial political system, formalizing the domination of the center in relation to the periphery. The Ottoman Empire failed to implement the policy of modernization of public administration in a timely and consistent manner. The British Empire was combined the strategies of centralization and decentralization of state management of its overseas colonies. The Russian Empire - a special imperial system -implemented, within the framework of the unitary state, the principle of centralization of the system of management, but its implementation in the development of the central bureaucratic apparatus of the empire was limited by the autocratic monarchy. At the same time, the Russian Empire was flexible in terms of differentiation of the management approaches. The article substantiates the conclusion that the imperial administration was an expression of centripetal political processes in the imperial system provided them and was an expression of the political power of the center which has an autocratic character in relation to the periphery. The processes associated with the administration of the Empire are concentrated in its center and implemented in addition to the will of the periphery. In institutional terms, the center of the empire is represented by general imperial authorities and management, in functional terms, the imperial power has exclusive administrative prerogatives associated with the concentration of resources of power and their distribution over the imperial hierarchy. The differentiation of administrative approaches shows the administrative and political specificity of the empire-state. In general the modernization of management empire became a significant factor in allowing the empire to most effectively carry out the concentration of political resources

In memory of Arkady Viktorovich Kryazhimskiy (1949-2014)

The article is devoted to the description of Academician Arkady Kryazhimskiy's life path. The facts of the scientific biography of Acad. Kryazhimskiy are presented with the emphasis on his outstanding contribution into the theory of dynamic inversion, the theory of differential games, and control theory. His personal talents in different spheres are also marked out

Reduction in ionic permeability of a silicone hydrogel contact lenses after one month of daily wear

[EN] Purpose. To compare the ionic permeability using the ionoflux method of new and worn samples of a silicone hydrogel contact lens material. Methods. An ionoflux experimental setup was established to measure the ionic permeability (NaCl) of soft contact lenses. Samples of a silicone hydrogel lens (Comfilcon A, Coopervision, Pleasanton, CA) with optical powers of -1.00, -1.50 and -4.75 diopters (D) were used in this study. Three samples of each power were measured after being worn for one month on a daily wear basis. Lenses were cleaned and disinfected every night using multipurpose disinfecting solutions. Three samples of new lenses from the same batch and the same optical power were also measured to evaluate the effect of lens wear on the ionic permeability of the lens material. Before measurement, the lenses were equilibrated with a 1 M NaCl solution during one week before of each measurement. Results. Lens power had minimal effect on the ionic permeability of a modern silicone hydrogel contact lens with the -1.00 lens having a 15% lower permeability compared to the other two lenses. After one month of lens wear the apparent ionic permeability for lenses with -1.50 D decreased by 15%. In the case of -1.00 and -4.75 D lenses there was a decrease of 26%. Conclusions. The ionic permeability of silicone hydrogel lenses of different optical powers was not significantly different. Worn lenses present a significant reduction of the ionic permeability after a month of wear. The potential effect this reduction on lens movement and discomfort associated to lens wear should be further evaluated.The authors have no proprietary interest in any of the materials mentioned in this article. This work was funded in part by FEDER through the COMPTETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of projects PTDC/SAU-BEB/098391/2008, PTDC/SAU-BEB/098392/2008 and the Strategic Project PEST-C/FIS/UI607/2011.Ferreira Da Silva, AR.; Compañ Moreno, V.; Gonzalez-Meijome, JM. (2015). Reduction in ionic permeability of a silicone hydrogel contact lenses after one month of daily wear. Materials Research Express. 2(6). https://doi.org/10.1088/2053-1591/2/6/065007S26Yoon, S. C., & Jhon, M. S. (1982). The transport phenomena of some model solutes through postcrosslinked poly(2-hydroxyethyl methacrylate) membranes with different tactic precursors. Journal of Applied Polymer Science, 27(8), 3133-3149. doi:10.1002/app.1982.070270834Yasuda, H., Lamaze, C. E., & Ikenberry, L. D. (1968). Die Makromolekulare Chemie, 118(1), 19-35. doi:10.1002/macp.1968.021180102MURPHY, S., HAMILTON, C., & TIGHE, B. (1988). Synthetic hydrogels: 5. Transport processes in 2-hydroxyethyl methacrylate copolymers. Polymer, 29(10), 1887-1893. doi:10.1016/0032-3861(88)90407-7Nicolson, P. C., & Vogt, J. (2001). Soft contact lens polymers: an evolution. Biomaterials, 22(24), 3273-3283. doi:10.1016/s0142-9612(01)00165-xMonticelli, M. V., Chauhan, A., & Radke, C. J. (2005). The Effect of Water Hydraulic Permeability on the Settling of a Soft Contact Lens on the Eye. Current Eye Research, 30(5), 329-336. doi:10.1080/02713680590934085Guan, L., Jiménez, M. E. G., Walowski, C., Boushehri, A., Prausnitz, J. M., & Radke, C. J. (2011). Permeability and partition coefficient of aqueous sodium chloride in soft contact lenses. Journal of Applied Polymer Science, 122(3), 1457-1471. doi:10.1002/app.33336Cheng, M.-L., & Sun, Y.-M. (2005). Observation of the solute transport in the permeation through hydrogel membranes by using FTIR-microscopy. Journal of Membrane Science, 253(1-2), 191-198. doi:10.1016/j.memsci.2005.01.017CHHABRA, M., PRAUSNITZ, J., & RADKE, C. (2007). A single-lens polarographic measurement of oxygen permeability (Dk) for hypertransmissible soft contact lenses. Biomaterials, 28(30), 4331-4342. doi:10.1016/j.biomaterials.2007.06.024González-Méijome, J. M., López-Alemany, A., Almeida, J. B., & Parafita, M. A. (2009). Surface AFM microscopy of unworn and worn samples of silicone hydrogel contact lenses. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 88B(1), 75-82. doi:10.1002/jbm.b.31153González-Méijome, J. M., López-Alemany, A., Almeida, J. B., & Parafita, M. A. (2008). Dynamic in vitro dehydration patterns of unworn and worn silicone hydrogel contact lenses. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 90B(1), 250-258. doi:10.1002/jbm.b.31279Pozuelo, J., Compañ, V., González-Méijome, J. M., González, M., & Mollá, S. (2014). Oxygen and ionic transport in hydrogel and silicone-hydrogel contact lens materials: An experimental and theoretical study. Journal of Membrane Science, 452, 62-72. doi:10.1016/j.memsci.2013.10.010Wolffsohn, J. S., Hunt, O. A., & Basra, A. K. (2009). Simplified recording of soft contact lens fit. Contact Lens and Anterior Eye, 32(1), 37-42. doi:10.1016/j.clae.2008.12.00

Optimal control for sustainable consumption of natural resources

In this paper we study optimal policies for a central planner interested in maximizing utility in an economy driven by a renewable resource. It is shown that the optimal consumption path is sustainable only when the intrinsic growth rate of the resource is greater than the social discount rate. The model is formulated as an infinite horizon optimal control problem. We deal with the mathematical details of the problem, develop a precise notion for optimality and establish the existence of optimal control at least when the condition for sustainability is met. We apply the appropriate version of the Pontryagin maximum principle and show a numerical simulation of the optimal feedback law. In the end we present the results along with physical interpretations

LUMINESCENCE OF CADMIUM SULFIDE QUANTUM DOTS IN FLUOROPHOSPHATE GLASSES

Cadmium sulfide quantum dots are perspective materials in optics, medicine, biology and optoelectronics. Fluorophosphate glasses, doped with cadmium sulfide quantum dots, were examined in the paper. Heat treatment led to the formation of quantum dots with diameters equal to 2.8 nm, 3.0 nm and 3.8 nm. In view of such changes in the quantum dots size the fundamental absorption edge shift and the luminescence band are being displaced to the long wavelengths. Luminescence lifetime has been found to be dependent on the registration wavelength in the range from 450 to 700 nm. Obtained fluorophosphate glasses with CdS quantum dots can find their application as fluorescent materials with intensive luminescence band and long excited-state natural lifetime

Mathematical modeling of bulk and directional crystallization with the moving phase transition layer

This paper is devoted to the mathematical modeling of a combined effect of directional and bulk crystallization in a phase transition layer with allowance for nucleation and evolution of newly born particles. We consider two models with and without fluctuations in crystal growth velocities, which are analytically solved using the saddle-point technique. The particle-size distribution function, solid-phase fraction in a supercooled two-phase layer, its thickness and permeability, solidification velocity, and desupercooling kinetics are defined. This solution enables us to characterize the mushy layer composition. We show that the region adjacent to the liquid phase is almost free of crystals and has a constant temperature gradient. Crystals undergo intense growth leading to fast mushy layer desupercooling in the middle of a two-phase region. The mushy region adjacent to the solid material is filled with the growing solid-phase structures and is almost desupercooled. © 2021 The Authors. Mathematical Methods in the Applied Sciences published by John Wiley & Sons, Ltd.Russian Science Foundation, RSF: 21-79-10012The authors gratefully acknowledge financial support from the Russian Science Foundation (project no. 21-79-10012). Open Access funding enabled and organized by Projekt DEAL