NUMERICAL MODELING OF A STRESS-STRAIN STATE OF A GAS PIPELINE WITH COLD BENDING OFFSETS ACCORDING TO IN-LINE INSPECTION

Knowledge of the current stress-strain state of any section of the pipeline allows you to make informed decisions on its operation, maintenance and repair, as well as on the prediction of the technical condition. The task of determining the characteristics of the stress-strain state of a gas pipeline section that has cold bend offsets (CBO) according to in-line inspection (ILI) is considered. The bent part of CBO is characterized by the presence of residual stresses and deformations in the wall of the offset, which contribute to the overall level of the stress-strain state of the gas pipeline operating under external and internal loads. Using the results of in-line diagnostics, numerical modeling and a solution, the change in the values of longitudinal stresses, is determined and the need to take into account residual stresses in the zone of elastic-plastic deformations of cold bend offsets is shown

Estimates in Beurling--Helson type theorems. Multidimensional case

We consider the spaces $A_p(\mathbb T^m)$ of functions $f$ on the $m$ -dimensional torus $\mathbb T^m$ such that the sequence of the Fourier coefficients $\hat{f}=\{\hat{f}(k), ~k \in \mathbb Z^m\}$ belongs to $l^p(\mathbb Z^m), ~1\leq p<2$. The norm on $A_p(\mathbb T^m)$ is defined by $\|f\|_{A_p(\mathbb T^m)}=\|\hat{f}\|_{l^p(\mathbb Z^m)}$. We study the rate of growth of the norms $\|e^{i\lambda\varphi}\|_{A_p(\mathbb T^m)}$ as $|\lambda|\rightarrow \infty, ~\lambda\in\mathbb R,$ for $C^1$ -smooth real functions $\varphi$ on $\mathbb T^m$ (the one-dimensional case was investigated by the author earlier). The lower estimates that we obtain have direct analogues for the spaces $A_p(\mathbb R^m)$

Assessment of internal pressure effect, causing additional bending of the pipeline

Article justifies accounting for internal pressure effect in the pipeline, causing additional bending of the pipeline. According to some scientists, there is an erroneously used concept of the equivalent longitudinal axial force (ELAF) Sx, which depends on working pressure, temperature stresses, and joint deformations of pipelines with various types of soils. However, authors of the article use ELAF Sx concept at construction of mathematical model of stress-strain state (SSS) for complex section of the trunk pipeline, and also reveal it when analyzing the results of calculating the durability and stability of the pipeline. Analysis of SSS for calculated section of the pipeline was carried out for two statements of the problem for different values of operation parameters. In the first statement, effect of internal pressure causing bending of the pipeline is taken into account, and in the second it is neglected. It is shown that due to effect of ELAF Sx at p0 = 9.0 MPa, Dt = 29 °C extreme value of bend increases by 54 %, extreme values of bending stresses from span bending moment increase by 74 %, and extreme value of bending stresses from support bending moment double with regard to corresponding SSS characteristics of the pipeline. In case of neglecting the internal pressure effect causing additional bending of the pipeline (second statement of the problem), error in calculating the extreme value of bend is 35 %, extreme value of bending stresses from span bending moments is 44 %, and extreme value of bending stresses from support bending moments is 95 %

ENERGY EFFICIENCY IMPROVEMENT OF SMALL HEAT OUTPUT HOT-WATER BOILERS

Article describes some boiler construction solutions for hot-water boilers of small heat output that give together with reliability improvement get the increase of boilers’ efficiency. Experiments approved that usage of bi-radiated furnace screens in KVa series boilers can give from 70.5 to 72.2 % of all heat power of the boiler. KVa-0.1 hot-water boiler thermal tests results showed that boiler’s efficiency rate on nominal power output is 93.12 %. Thermal tests of KSGn-0.63 and KSGn-1.16 boiler with bi-radiated screens approved that the efficiency rate on “small fire” mode is about 93 % and on nominal power output is about 92 %.В работе представлены некоторые конструктивные решения для водогрейных котлов малой мощности, позволяющие, наряду с повышением надежности водогрейных котлов, повысить их эффективность. Экспериментально получено, что использование двусветных экранов в котлах КВа позволяет снимать от 70,5 до 72,2 % от общей тепловой мощности котла. Результаты испытаний водогрейного котла КВа-1,0 показали, что КПД котла при расчетной нагрузке составил 93,12 %. Теплотехнические испытания котлов КСГн-0,63 и КСГн-1,16 с двусветными экранами показали, что КПД котлов на малом горении составляли порядка 93 %, а на нагрузках, близких к номинальным, порядка 92 %

Orbital effects of a monochromatic plane gravitational wave with ultra-low frequency incident on a gravitationally bound two-body system

We analytically compute the long-term orbital variations of a test particle orbiting a central body acted upon by an incident monochromatic plane gravitational wave. We assume that the characteristic size of the perturbed two-body system is much smaller than the wavelength of the wave. Moreover, we also suppose that the wave's frequency is much smaller than the particle's orbital one. We make neither a priori assumptions about the direction of the wavevector nor on the orbital geometry of the planet. We find that, while the semi-major axis is left unaffected, the eccentricity, the inclination, the longitude of the ascending node, the longitude of pericenter and the mean anomaly undergo non-vanishing long-term changes. They are not secular trends because of the slow modulation introduced by the tidal matrix coefficients and by the orbital elements themselves. They could be useful to indepenedently constrain the ultra-low frequency waves which may have been indirectly detected in the BICEP2 experiment. Our calculation holds, in general, for any gravitationally bound two-body system whose characteristic frequency is much larger than the frequency of the external wave. It is also valid for a generic perturbation of tidal type with constant coefficients over timescales of the order of the orbital period of the perturbed particle.Comment: LaTex2e, 24 pages, no figures, no tables. Changes suggested by the referees include

Inferring possible magnetic field strength of accreting inflows in EXor-type objects from scaled laboratory experiments

Aims. EXor-type objects are protostars that display powerful UV-optical outbursts caused by intermittent and powerful events of magnetospheric accretion. These objects are not yet well investigated and are quite difficult to characterize. Several parameters, such as plasma stream velocities, characteristic densities, and temperatures, can be retrieved from present observations. As of yet, however, there is no information about the magnetic field values and the exact underlying accretion scenario is also under discussion. Methods. We use laboratory plasmas, created by a high power laser impacting a solid target or by a plasma gun injector, and make these plasmas propagate perpendicularly to a strong external magnetic field. The propagating plasmas are found to be well scaled to the presently inferred parameters of EXor-type accretion event, thus allowing us to study the behaviour of such episodic accretion processes in scaled conditions. Results. We propose a scenario of additional matter accretion in the equatorial plane, which claims to explain the increased accretion rates of the EXor objects, supported by the experimental demonstration of effective plasma propagation across the magnetic field. In particular, our laboratory investigation allows us to determine that the field strength in the accretion stream of EXor objects, in a position intermediate between the truncation radius and the stellar surface, should be of the order of 100 G. This, in turn, suggests a field strength of a few kilogausses on the stellar surface, which is similar to values inferred from observations of classical T Tauri stars

Achene slime content in some taxa of Matricaria L. (Asteraceae)

The achenes of Matricaria aurea and two varieties of M. chamomilla (var. chamomilla and var. recutita) have slime cells on the surface and they are characterized by slime envelope formation during hydration. The slime in these taxa is composed of pectins and cellulose. The slime could play important role in the distribution and colonisation of new habitats in Matricaria taxa

Small Molecule Activation by Uranium Tris(aryloxides): Experimental and Computational Studies of Binding of N-2, Coupling of CO, and Deoxygenation Insertion of CO2 under Ambient Conditions

Previously unanticipated dinitrogen activation is exhibited by the well-known uranium tris(aryloxide) U(ODtbp)(3), U(OC6H3-Bu-2(t)-2,6)(3), and the tri-tert-butyl analogue U(OTtbp)(3), U(OC6H2-Bu-3(t)-2,4,6)(3), in the form of bridging, side-on dinitrogen complexes [U(OAr)(3)](2)(mu-eta(2):eta(2)-N-2), for which the tri-tert-butyl N-2 complex is the most robust U-2(N-2) complex isolated to date. Attempted reduction of the tris(aryloxide) complex under N-2 gave only the potassium salt of the uranium(III) tetra(aryloxide) anion, K[U(OAr)(4)], as a result of ligand redistribution. The solid-state structure is a polymeric chain formed by each potassium cation bridging two arenes of adjacent anions in an eta(6) fashion. The same uranium tris(aryloxides) were also found to couple carbon monoxide under ambient conditions to give exclusively the ynediolate [OCCO](2-) dianion in [U(OAr)(3)](2)(mu-eta(1):eta(1)-C2O2), in direct analogy with the reductive coupling recently shown to afford [U{N(SiMe3)(2)}(3)](2)(mu-eta(1):eta(1)-C2O2). The related U-III complexes U{N(SiPhMe2)(2)}(3) and U{CH(SiMe3)(2)}(3) however do not show CO coupling chemistry in our hands. Of the aryloxide complexes, only the U(OC6H2-Bu-3(t)-2,4,6)(3) reacts with CO2 to give an insertion product containing bridging oxo and aryl carbonate moieties, U-2(OTtbp)(4)(mu-O)(mu-eta(1):eta(1)-O2COC6H2-Bu-3(t)-2,4,6)(2), which has been structurally characterized. The presence of coordinated N-2 in [U(OTtbp)(3)](2)(N-2) prevents the occurrence of any reaction with CO2, underscoring the remarkable stability of the N-2 complex. The di-tert-butyl aryloxide does not insert CO2, and only U(ODtbp)(4) was isolated. The silylamide also reacts with carbon dioxide to afford U(OSiMe3)(4) as the only uranium-containing material. GGA and hybrid DFT calculations, in conjunction with topological analysis of the electron density, suggest that the U-N-2 bond is strongly polar, and that the only covalent U -> N-2 interaction is pi backbonding, leading to a formal (U-IV)(2)(N-2)(2-) description of the electronic structure. The N-N stretching wavenumber is preferred as a metric of N-2 reduction to the N-N bond length, as there is excellent agreement between theory and experiment for the former but poorer agreement for the latter due to X-ray crystallographic underestimation of r(N-N). Possible intermediates on the CO coupling pathway to [U(OAr)(3)](2)(mu-C2O2) are identified, and potential energy surface scans indicate that the ynediolate fragment is more weakly bound than the ancillary ligands, which may have implications in the development of low-temperature and pressure catalytic CO chemistry