Ideal MHD stability of helically symmetric magnetic islands

A new version of the MHD_NX code, that computes the ideal MHD stability of helically symmetric equilibria with arbitrary topology of magnetic surfaces, was applied to the investigation of equilibrium magnetic islands in tokamak-like conditions. Any helical deformation of the plasma boundary shape from a circular cylinder results in the breaking of topology of the helical flux level lines and appearance of magnetic islands at the place of the magnetic surface q = m/n in the original large aspect ratio tokamak equilibrium, provided that the helical pitch is the same for the equilibrium and magnetic lines at the resonant surface. A solution family of the generalized Grad-Shafranov equation with a linear dependence of the source current density on the helical flux was employed to compute equilibria with various chains of islands. Internal ideal MHD modes resonant to the corresponding island chain (longitudinal wave number nh = 0 in the helical coordinates) are found to be robustly unstable for m = 1 and m = 2 boundary deformations, while stable for higher plasma shape poloidal harmonics m ≥ 3

МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ АДСОРБЦІЙНОГО ЗАБРУДНЕННЯ В ЗАВАНТАЖЕННІ ЗНЕЗАЛІЗНЮВАЛЬНИХ ФІЛЬТРІВ

In the article the scheme of immobilization and transformation of iron forms is presented for underground water deferrization. The clarification block of the general model of physico-chemical deferrization of water is presented, taking into account the nonlinear effects of mass exchange. Separately the block of nonlinear problem of adsorption and transformation of iron oxide is considered. Using the method of dynamic averaging of the desired characteristic, approximate solutions are obtained. Executed the quantitativeanalysis of changes of the relative concentrations of free and adsorbed ferrous iron and the discrepancy between the corresponding exact and approximate solutions is estimated. The accumulation of adsorbed iron in the download is calculated.В статье приведена схема иммобилизации и трансформации форм железа при обезжелезивании подземных вод. Представлен осветительный блок общей модели физико-химического обезжелезивания воды с учетом нелинейных эффектов массообмена. Отдельно рассмотрен блок нелинейной задачи адсорбции и трансформации закиси железа. Используя метод динамического осреднения искомой характеристики, полученные приближенные ее решения.Проведен количественный анализ изменений относительных концентраций свободного и адсорбированного двухвалентного железа и оценено расхождение между соответствующими точными и приближенными решениями. Рассчитано накопления адсорбированного железа в загрузке.В статті наведено схему іммобілізації та трансформації форм заліза при знезалізненні підземних вод. Представлено освітлювальний блок загальної моделі фізико-хімічного знезалізнення води з врахуванням нелінійних ефектів масообміну. Окремо розглянутий блок нелінійної задачі адсорбції і трансформації закису заліза. Використовуючи метод динамічного осереднення шуканої характеристики, отримані наближені її розв’язки. Проведений кількісний аналіз змін відносних концентрацій вільного і адсорбованого двовалентного заліза та оцінена розбіжність між відповідними точними та наближеними розв’язками. Розраховано накопичення адсорбованого заліза в завантаженні

Under-expanded jets and dispersion in high pressure CO2 releases from an industrial scale pipeline

The widespread implementation of carbon capture and storage (CCS) in industry will require extensive long-distance CO2 pipeline networks to integrate the component technologies. The potential for pipeline rupture and leakage, possibly resulting in catastrophic accidents, will inevitably increase as networks become more extensive. The study of near-field source terms and dispersion behavior after pipeline rupture is an essential foundation of CO2 pipeline risk assessment and will provide effective technical support for the implementation of large-scale CCS projects and contribute to pipeline safety. In the CO2QUEST project under-expanded CO2 jets, cloud dispersion characteristics and the formation of dry ice particles in the near field were investigated during releases from a 258 m long, fully instrumented pipeline. Experimental data including cloud temperature, CO2 concentration and the visual evolution of the cloud (recorded on film), was gathered to investigate cloud behavior and to support future work in the field of CO2 pipeline safety. Experiments included the release of gaseous and dense phase CO2 through three orifice diameters: 15 mm, 50 mm and Full Bore Rupture (FBR). The lower limit of gaseous CO2 concentration for adverse effects in humans is 5% v/v. Safety distances from the release, based on this threshold concentration limit, are determined and reported for each experiment conducted

Динамика неньютоновского осциллятора

For an explanation of curves of rotation of spiral galaxies the changed form of the second law of Newton is offered. For the purpose of possible experimental registration in terrestrial conditions of the changed law the model of non-newtonian oscillator is offered. Precisely and in various approximations the task about oscillations of non-newtonian oscillator is solved.Для объяснения наблюдаемых кривых вращения спиральных галактик предложена измененная форма второго закона Ньютона. С целью возможной экспериментальной проверки в земных условиях справедливости предлагаемого закона движения рассматривается модель неньютоновского осциллятора. Точно и в различных приближениях решена задача о колебаниях неньютоновского осциллятора

Prospects for detecting gravitational waves at 5 Hz with ground-based detectors

We propose an upgrade to Advanced LIGO (aLIGO), named LIGO-LF, that focuses on improving the sensitivity in the 5-30 Hz low-frequency band, and we explore the upgrade's astrophysical applications. We present a comprehensive study of the detector's technical noises and show that with technologies currently under development, such as interferometrically sensed seismometers and balanced-homodyne readout, LIGO-LF can reach the fundamental limits set by quantum and thermal noises down to 5 Hz. These technologies are also directly applicable to the future generation of detectors. We go on to consider this upgrade's implications for the astrophysical output of an aLIGO-like detector. A single LIGO-LF can detect mergers of stellar-mass black holes (BHs) out to a redshift of z~6 and would be sensitive to intermediate-mass black holes up to 2000 M_\odot. The detection rate of merging BHs will increase by a factor of 18 compared to aLIGO. Additionally, for a given source the chirp mass and total mass can be constrained 2 times better than aLIGO and the effective spin 3-5 times better than aLIGO. Furthermore, LIGO-LF enables the localization of coalescing binary neutron stars with an uncertainty solid angle 10 times smaller than that of aLIGO at 30 Hz, and 4 times smaller when the entire signal is used. LIGO-LF also significantly enhances the probability of detecting other astrophysical phenomena including the tidal excitation of neutron star r-modes and the gravitational memory effects.Comment: 5 pages, 6 figures, published in PR

Benchmarks for the Forward Observables at RHIC, the Tevatron-run II and the LHC

We present predictions on the total cross sections and on the ratio of the real part to the imaginary part of the elastic amplitude (rho parameter) for present and future pp and pbar p colliders, and on total cross sections for gamma p -> hadrons at cosmic-ray energies and for gamma gamma-> hadrons up to sqrt{s}=1 TeV. These predictions are based on an extensive study of possible analytic parametrisations invoking the biggest hadronic dataset available at t=0. The uncertainties on total cross sections, including the systematic errors due to contradictory data points from FNAL, can reach 1.9% at RHIC, 3.1% at the Tevatron, and 4.8% at the LHC, whereas those on the rho parameter are respectively 5.4%, 5.2%, and 5.4%.Comment: 11 pages, 2 figures, 4 tables, RevTeX

Research progress on fracture control of accidental leakage and decompression in CO2 pipeline transportation

Pipeline is the optimal way in transporting large amounts of carbon dioxide (CO2) in CCUS (carbon capture, utilization and storage) technology industrial chain. In this paper, the research progress on decompression and fracture propagation of CO2 pipeline leakage was reviewed from aspects of experiment and computer simulation. The influence of phase state, pipe material and buried condition on crack propagation was analyzed. The influence of equation of state (EOS), impurity factor and theoretical model on experimental and simulation calculation were discussed. The EOS suitable for the establishment of decompression wave prediction model was summarized and the theoretical method and simulation software of fluid-structure coupling research, as well as the technical documentations for the design of CO2 transport pipelines, were mentioned. The scientific problems that need to be studied further in CO2 pipeline leakage decompression and fracture propagation control were summarized. Prospecting the research contents that need to be carried out include: ①establishing the EOS calculation model of multivariate mixture at three phase point and phase line, ②seting up the coupling relationship between the thermal properties of CO2 and crack propagation furtherly, ③establishing the stop criterion of pipeline fracture, and ④developing and optimizing the special crack stop devices to avoid fracture propagation for CO2 transportation pipelines

Competing ideologies of Russia's civil society

Many analysts and public opinion makers in the West conflate the notions of Russia’s non-systemic liberal opposition and the country’s civil society. Indeed, despite garnering the support of a minority of Russia’s population, non-systemic liberal opposition represents a well-organized civic group with a clearly articulated agenda and the ability to take action. Yet, does Russia’s civil society end there? A closer look at the country’s politics shows that Russia has a substantial conservative-traditionalist faction that has also developed agenda for action and formulated opinions. This group is anti-liberal rather than illiberal ideologically and pro-strong state/pro a geopolitically independent Russia rather than pro-Kremlin politically. The interaction between liberal and conservative civic groups represents the battle of meanings, ideas, and ethics, and ultimately determines the future trajectory of Russia’s evolution. Thus, the analysis of Russia’s civil society must represent a rather more nuanced picture than a mere study of the liberal non-systemic opposition. This article will examine the complexity of Russia’s civil society scene with reference to the interplay between the liberal opposition and conservative majority factions. The paper will argue that such complexity stems from ideological value pluralism that falls far beyond the boundaries of the liberal consensus, often skewing our understanding of political practice in Russia

Optimization of the snowflake diverted equilibria in the TCV tokamak

In support of the TCV experimental campaign aiming at studying H-mode plasmas with snowflake (SF) divertor, free boundary equilibrium and stability studies were performed with the SPIDER and KINX codes. Due to the high flexibility of plasma shaping capabilities of TCV, SF divertor conditions can be reached for various plasma geometries. However, at high plasma current some configurations require poloidal field (PF) coil currents close to the machine limit. This is particularly important when the equilibrium sensitivity to the edge pedestal profiles, which is higher than for standard X-point configurations, is taken into account. That is why the configuration optimization should also include the profile sensitivity study when planning the shot scenario