Theoretical analysis of telescopic oscillations in multi-walled carbon nanotubes

A simplified theory of the telescopic oscillations in multiwalled carbon nanotubes is developed. The explicit expressions for the telescopic force constants (longitudinal rigidity) and the frequencies of telescopic oscillations are derived. The contribution of small-amplitude telescopic oscillations to the nanotubes low temperature specific heat is estimated.Comment: 14 pages, 5 figure

Solar Spectral Irradiance Changes During Cycle 24

We use solar spectra obtained by the Ozone Monitoring Instrument (OMI) on board the Aura satellite to detect and follow long-term (years) and short-term (weeks) changes in the solar spectral irradiance (SSI) in the 265-500 nm spectral range. During solar Cycle 24, in the relatively line-free regions the SSI changed by approximately 0.6% +/- 0.2% around 265 nm. These changes gradually diminish to 0.15% +/- 0.20% at 500 nm. All strong spectral lines and blends, with the notable exception of the upper Balmer lines, vary in unison with the solar "continuum." Besides the lines with strong chromospheric components, the most involved species include Fe I blends and all prominent CH, NH, and CN spectral bands. Following the general trend seen in the solar "continuum," the variability of spectral lines also decreases toward longer wavelengths. The long-term solar cycle SSI changes are closely, to within the quoted 0.1%-0.2% uncertainties, matched by the appropriately adjusted short-term SSI variations derived from the 27 day rotational modulation cycles. This further strengthens and broadens the prevailing notion about the general scalability of the UV SSI variability to the emissivity changes in the Mg II 280 nm doublet on timescales from weeks to years. We also detect subtle deviations from this general rule: the prominent spectral lines and blends at lambda approximately or greater than 350 nm show slightly more pronounced 27 day SSI changes when compared to the long-term (years) trends. We merge the solar data from Cycle 21 with the current Cycle 24 OMI and GOME-2 observations and provide normalized SSI variations for the 170-795 nm spectral region

Maritime activity in the high north – the range of unwanted incidents and risk patterns

Author's accepted version (post-print).This is the accepted manuscript (post-print) of the article Marchenko, N., Borch, O. J., Markov, S. V. & Andreassen, N. (2015). Maritime activity in the high north – the range of unwanted incidents and risk patterns. Proceedings – International Conference on Port and Ocean Engineering under Arctic Conditions available at http://www.poac.com/PapersOnline.htm

Maritime Safety in The High North - Risk and Preparedness

Author's accepted version (postprint).This is an Accepted Manuscript of an article published by the International Society of Offshore and Polar Engineers in ISOPE - International Society of Offshore and Polar Engineers. Proceedings on 07/2016, available online: http://www.isope.org/publications/proceedings/ISOPE/ISOPE%202016/index.ht

Maritime activity and risk patterns in the High North : MARPART Project Report 2

This report provides a discussion on dominating risk factors, risk types and probability of unwanted incidents in the Arctic region. It also provides a coarse-grained evaluation of the potential consequences of different incidents in the northern sea areas of Russia, Norway, Greenland, and Iceland. The risk assessment build upon statistics on vessel activity, case studies of real incidents, and expert evaluation of defined situations of hazard and accident (DSHA). The evaluations of this study may serve as a platform for more detailed assessments, and as input for discussions on priority areas in respect to safety measures and emergency preparedness. In the Marpart Project, the risk assessments have a special role as input into the analyses of emergency management capabilities, and the need for special government efforts in cross-border cooperation

Maritime activity in the High North : current and estimated level up to 2025 : MARPART Project Report 1

This report analyzes the current commercial and governmental activity in the sea regions north of the Polar Circle from the Northern Sea Route to the North West Passage. The study embraces sea and coastal areas of the North West of Russia, Northern Norway and around Svalbard, Iceland and Greenland. It includes an overview of types of vessels and other objects involved in different activities, and the volume of traffic connected to different types of activities, such as fisheries, petroleum, tourism, navy and research. Furthermore, this report estimates the maritime activity level in the area the next ten years, or until 2025, and the potential development of the regional preparedness system

Structure-related bandgap of hybrid lead halide perovskites and close-packed APbX3 family of phases

Metal halide perovskites APbX3 (A+ = FA+ (formamidinium), MA+ (methylammonium) or Cs+, X- = I-, Br-) are considered as prominent innovative components in nowadays perovskite solar cells. Crystallization of these materials is often complicated by the formation of various phases with the same stoichiometry but structural types deviating from perovskites such as well-known the hexagonal delta FAPbI3 polytype. Such phases are rarely placed in the focus of device engineering due to their unattractive optoelectronic properties while they are, indeed, highly important because they influence on the optoelectronic properties and efficiency of final devices. However, the total number of such phases has not been yet discovered and the complete configurational space of the polytypes and their band structures have not been studied systematically. In this work, we predicted and described all possible hexagonal polytypes of hybrid lead halides with the APbI3 composition using the group theory approach, also we analyzed theoretically the relationship between the configuration of close-packed layers in polytypes and their band gap using DFT calculations. Two main factors affecting the bandgap were found including the ratio of cubic (c) and hexagonal (h) close-packed layers and the thickness of blocks of cubic layers in the structures. We also show that the dependence of the band gap on the ratio of cubic (c) and hexagonal (h) layers in these structures are non-linear. We believe that the presence of such polytypes in the perovskite matrix might be a reason for a decrease in the charge carrier mobility and therefore it would be an obstacle for efficient charge transport causing negative consequences for the efficiency of solar cell devices