The RFOFO Ionization Cooling Ring for Muons

Practical ionization cooling rings could lead to lower cost or improved performance in neutrino factory or muon collider designs. The ring modeled here uses realistic three-dimensional fields. The performance of the ring compares favorably with the linear cooling channel used in the second US Neutrino Factory Study. The normalized 6D emittance of an ideal ring is decreased by a factor of approximately 240, compared with a factor of only 15 for the linear channel. We also examine such \textit{real-world} effects as windows on the absorbers and rf cavities and leaving empty lattice cells for injection and extraction. For realistic conditions the ring decreases the normalized 6D emittance by a factor of 49.Comment: 27 pages, 18 figures and 5 tables. Submitted to Phys. Rev. ST-A

Scientific, institutional and personal rivalries among Soviet geographers in the late Stalin era

Scientific, institutional and personal rivalries between three key centres of geographical research and scholarship (the Academy of Sciences Institute of Geography and the Faculties of Geography at Moscow and Leningrad State Universities) are surveyed for the period from 1945 to the early 1950s. It is argued that the debates and rivalries between members of the three institutions appear to have been motivated by a variety of scientific, ideological, institutional and personal factors, but that genuine scientific disagreements were at least as important as political and ideological factors in influencing the course of the debates and in determining their final outcome

The study of methods for analysis burning torch infrared images

The paper describes the results of the study of methods for analysis burning torch infrared images obtained by an infrared camera in the band of electromagnetic wavelengths of 1.5-5.1 μm. It was shown that the known infrared image analysis methods cannot provide the quantitative parameters extraction that could describe combustion process. In addition, it was figured out that the known methods are time-consuming and cannot run in real time. As a result, nowadays the combustion control system that uses optical control of torch parameters in infrared band cannot be designed. In our study we analyzed the pixels quantity distribution density in the range of [520,560] relative Celsius degrees on each frame of the initial infrared sequence of burning torch. It was shown that the pixels quantity distribution has the bimodal distribution law and can be described by three local extremes coordinates: two maximums and a minimum located between them. The pixels that have relative degrees values in the range from 520 degrees to the value of the minimum’s abscissa and from the value of the minimum’s abscissa to 560 degrees relatively form two separate zones on the burning torch visualization. It was demonstrated that time-domain series constructed from frame-by-frame calculated local extremes coordinates of the P(T) distributions are stationary random sequences. This result allows to use these time-domain series as quantitative parameters of the torch combustion. It was shown that the local minimum’s abscissa value of the P(T) distribution with a relative error of 2.8 % is a constant value equal to 536.3 relative degrees. This allows to count the pixels quantity of each of the separate zones without using time-consuming Rosenblatt – Parzen estimation and run data processing in real time. © 2020 National Research Nuclear University. All rights reserved

Pulsating combustion: Theoretical and empirical substantiation of ecological effect

There are two primary parameters that characterize operation of modern energy generation units that burn fuel, namely - unit efficiency and the amount of noxious emissions. Usually units that operate at the maximum efficiency produce maximum potential emissions of noxious substances (as NOx) into the atmosphere. This work provides theoretical substantiation for control of the combustion process by superimposing controlled irregularities to the fuel supply rate in order to suppress NOx generation while retaining the unit's technical parameters and cost efficiency. The substantiation uses known empirically obtained NOx generation dependency from the air excess ratio. Evaluation of the generated NOx content was performed using numerical integration of the composed time sequences describing changes in the NOx concentration in the combustion products for various types of control actions. Evaluation of bands of operating frequencies for the proposed method of combustion control are presented. The proposed theoretical substantiation made it possible to determine conditions and technics for experimental work. © 2017 Author(s)

Chaotic synchronization of coupled electron-wave systems with backward waves

The chaotic synchronization of two electron-wave media with interacting backward waves and cubic phase nonlinearity is investigated in the paper. To detect the chaotic synchronization regime we use a new approach, the so-called time scale synchronization [Chaos, 14 (3) 603-610 (2004)]. This approach is based on the consideration of the infinite set of chaotic signals' phases introduced by means of continuous wavelet transform. The complex space-time dynamics of the active media and mechanisms of the time scale synchronization appearance are considered.Comment: 11 pages, 7 figures, published in CHAOS, 15 (2005) 01370

Imaging spontaneous imbibition in full Darcy‐scale samples at pore‐scale resolution by fast X‐ray tomography

Spontaneous imbibition is a process occurring in a porous medium which describes wetting phase replacing nonwetting phase spontaneously due to capillary forces. This process is conventionally investigated by standardized, well-established spontaneous imbibition tests. In these tests, for instance, a rock sample is surrounded by wetting fluid. The following cumulative production of nonwetting phase versus time is used as a qualitative measure for wettability. However, these test results are difficult to interpret, because many rocks do not show a homogeneous but a mixed wettability in which the wetting preference of a rock varies from location to location. Moreover, during the test the flow regime typically changes from countercurrent to cocurrent flow and no phase pressure or pressure drop can be recorded. To help interpretation, we complement Darcy-scale production curves with X-ray imaging to describe the differences in imbibition processes between water-wet and mixed-wet systems. We found that the formation of a spontaneous imbibition front occurs only for water-wet systems; mixed-wet systems show localized imbibition events only. The asymmetry of the front depends on the occurrence of preferred production sites, which influences interpretation. Fluid layers on the outside of mixed-wet samples increase connectivity of the drained phase and the effect of buoyancy on spontaneous imbibition. The wider implication of our study is the demonstration of the capability of benchtop laboratory equipment to image a full Darcy-scale experiment while at the same time obtaining pore-scale information, resolving the natural length and time scale of the underlying processes

Effects of thermal fluctuation and the receptor-receptor interaction in bacterial chemotactic signalling and adaptation

Bacterial chemotaxis is controlled by the conformational changes of the receptors, in response to the change of the ambient chemical concentration. In a statistical mechanical approach, the signalling due to the conformational changes is a thermodynamic average quantity, dependent on the temperature and the total energy of the system, including both ligand-receptor interaction and receptor-receptor interaction. This physical theory suggests to biology a new understanding of cooperation in ligand binding and receptor signalling problems. How much experimental support of this approach can be obtained from the currently available data? What are the parameter values? What is the practical information for experiments? Here we make comparisons between the theory and recent experimental results. Although currently comparisons can only be semi-quantitative or qualitative, consistency is clearly shown. The theory also helps to sort a variety of data.Comment: 26 pages, revtex. Journal version. Analysis on another set of data on adaptation time is adde