Equistrong Tower Design

The September 11, 2001 events attracted the attention of civil engineers of the world to the problem of safety of towers and skyscrapers. According to recent studies, the WTC collapse was caused by man-made explosions on a critical floor located much lower than the floors hit by terrorist planes which supports the wide-spread rumor in the U.S. that MASAD agents used the aftermath mess-up after the crush of the planes, put some explosives in the critical floor and detonated them in a while. These or any other possible calamities must be technically treated which can be achieved by drastic increase of safety factor of tower design. In the present paper a new approach to the optimal design of towers is advanced based on the principle of equistrength. Introductive Section 1 provides a short overview of the theory of equistrong structures given in the book by Cherepanov and Ershov (1977). In Section 2, a continuum model is used for the design of equistrong towers. The same problem is studied in Section 3 with an account of the discrete, floor-by-floor structure of equistrong towers. Conclusion emphasizes that the equistrong tower designs allow developers to achieve the maximum possible safety factor. Current designs of skyscrapers including WTC towers are as primitive as the Tower of Babylon

Parametric Generation of Second Sound by First Sound in Superfluid Helium

We report the first experimental observation of parametric generation of second sound (SS) by first sound (FS) in superfluid helium in a narrow temperature range in the vicinity of $T_\lambda$. The temperature dependence of the threshold FS amplitude is found to be in a good quantitative agreement with the theory suggested long time ago and corrected for a finite geometry. Strong amplitude fluctuations and two types of the SS spectra are observed above the bifurcation. The latter effect is quantitatively explained by the discreteness of the wave vector space and the strong temperature dependence of the SS dissipation length.Comment: 4 pages, 4 postscript figures, REVTE

Gender differences in health-related quality-of-life are partly explained by sociodemographic and socioeconomic variation between adult men and women in the US: evidence from four US nationally representative data sets

The purpose of this study was to describe gender differences in self-reported health-related quality-of-life (HRQoL) and to examine whether differences are explained by sociodemographic and socioeconomic status (SES) differentials between men and women. Data were from four US nationally representative surveys: US Valuation of the EuroQol EQ-5D Health States Survey (USVEQ), Medical Expenditure Panel Survey (MEPS), National Health Measurement Study (NHMS) and Joint Canada/US Survey of Health (JCUSH). Gender differences were estimated with and without adjustment for sociodemographic and SES indicators using regression within and across data sets with SF-6D, EQ-5D, HUI2, HUI3 and QWB-SA scores as outcomes. Women have lower HRQoL scores than men on all indexes prior to adjustment. Adjusting for age, race, marital status, education and income reduced but did not remove the gender differences, except with HUI3. Adjusting for marital status or income had the largest impact on estimated gender differences. There are clear gender differences in HRQoL in the United States. These differences are partly explained by sociodemographic and SES differentials

Documented procedure «Control of nonconforming product» in anticipation of the re-certification of the management system of the organization

Ресертификация система менеджмента организации на соответствие требованиям ГОСТ Р ИСО 9001:2015 обязывает обновлять и актуализировать документацию СМК для результативного и эффективного прохождения как внутреннего, так и внешнего аудитаRecertification of the organization's management system for compliance with GOST R ISO 9001:2015 requires to update or keep current the documentation of the QMS for efficient and ef-fective flow of both internal and external audi

Modification of Structure and Strength Properties of Permanent Joints Under Laser Beam Welding with Application of Nanopowder Modifiers

In the paper we present the results of experimental study of specially prepared nanosize metal-ceramic compositions impact upon structure, microhardness and mechanical properties of permanent joints produced by laser-beam welding of steel and titanium alloy plates

First-principles method for calculating the rate constants of internal-conversion and intersystem-crossing transitions

A method for calculating the rate constants for internal-conversion (k(IC)) and intersystem-crossing (k(ISC)) processes within the adiabatic and Franck-Condon (FC) approximations is proposed. The applicability of the method is demonstrated by calculation of k(IC) and k(ISC) for a set of organic and organometallic compounds with experimentally known spectroscopic properties. The studied molecules were pyrromethene-567 dye, psoralene, hetero[8]circulenes, free-base porphyrin, naphthalene, and larger polyacenes. We also studied fac-Alq(3) and fac-Ir(ppy)(3), which are important molecules in organic light emitting diodes (OLEDs). The excitation energies were calculated at the multi-configuration quasi-degenerate second-order perturbation theory (XMC-QDPT2) level, which is found to yield excitation energies in good agreement with experimental data. Spin-orbit coupling matrix elements, non-adiabatic coupling matrix elements, Huang-Rhys factors, and vibrational energies were calculated at the time-dependent density functional theory (TDDFT) and complete active space self-consistent field (CASSCF) levels. The computed fluorescence quantum yields for the pyrromethene-567 dye, psoralene, hetero[8]circulenes, fac-Alq(3) and fac-Ir(ppy)(3) agree well with experimental data, whereas for the free-base porphyrin, naphthalene, and the polyacenes, the obtained quantum yields significantly differ from the experimental values, because the FC and adiabatic approximations are not accurate for these molecules.Peer reviewe

Fracture toughness in some hetero-modulus composite carbides: carbon inclusions and voids. Advances in Applied Ceramics

Fracture toughness of ceramics in some cases can be significantly improved by the inclusion of low-modulus phase and even voids. Structure and mechanical characteristics of dense ceramic composites synthesised by reactive hot pressing of TiC-B4C powder mixtures at 1800 - 1950°С under 30MPa during 16 minutes are investigated. X-Ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (SEM and EDX) have shown that during hot pressing solid phase chemical interaction 2TiС + B4C = 2TiВ2 + 3С has occurred resulting in TiB2-TiC-C, TiB2-C or TiB2-B4C-C hetero-modulus composite formation with approximately 1μm carbon precipitates. The volume of such precipitated carbon can reach 35 vol. %. The fracture toughness depends on the precipitate size and amount of graphite precipitation and has a distinct maximum K1C = 10MPa∙m1/2 at nearly 7 vol. % . Such fracture toughness behaviour is explained by the proposed model of crack propagation and the model-based assessment of hetero-modulus ceramic fracture toughness. It is shown that voids and low modulus carbon inclusions blunt the cracks and can increase ceramic toughness. The later has been demonstrated in the another carbon containing ceramic Cr2AlC, so named MAX phase material, when thin film fracture resistance increases as the ceramic was deposited to be porous

Bose-Einstein condensation of magnons under incoherent pumping

Bose-Einstein condensation in a gas of magnons pumped by an incoherent pumping source is experimentally studied at room temperature. We demonstrate that the condensation can be achieved in a gas of bosons under conditions of incoherent pumping. Moreover, we show the critical transition point is almost independent of the frequency spectrum of the pumping source and is solely determined by the density of magnons. The electromagnetic power radiated by the magnon condensate was found to scale quadratically with the pumping power, which is in accordance with the theory of Bose-Einstein condensation in magnon gases