This study discusses ultrasonic and impact-echo methods as the most common nondestructive methods for determining concrete durability based on sound vibration velocity. It also reveals the influence ...of the signal of an acoustic surface wave on the accuracy of measuring resonant frequency in the spectrum of a cubic compact concrete sample. A through-transmission impact method is proposed to measure sound vibration velocity in cubic test concrete samples and determine concrete durability via an acoustic nondestructive method. An impactor and a receiving transducer are placed on opposite sides of the cube, several measurements are made at different positions of the impactor (or receiving transducer), and results of partial measurements are subjected to multiplicative processing to eliminate sound vibration and reduce errors in determining concrete durability.
Linear elastic deformation of the two-dimensional triangular lattice with multiple vacancies is considered. Closed-form analytical expressions for displacement field in the lattice with doubly ...periodic system of vacancies are derived. Effective elastic moduli are calculated. The results are compared with the ones obtained by molecular dynamics simulations of a lattice with random distribution of vacancies. At low vacancy concentrations, less than 4%, random and periodic distributions of vacancies produce the same effect on elastic moduli. One of the main goals is to examine the possibilities and limitations of modelling of the lattice with vacancies by an elastic continuum with holes. It is found that the effective elastic properties are modelled adequately, provided the shape of the holes is chosen appropriately. On the contrary, the strain field, in particular, strain concentration differs significantly.
Status of the GAMMA-400 project Galper, A.M.; Adriani, O.; Aptekar, R.L. ...
Advances in space research,
01/2013, Letnik:
51, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100MeV–3TeV is presented. The angular resolution of the instrument, 1–2° at Eγ∼100MeV and ∼0.01° at ...Eγ>100GeV, its energy resolution ∼1% at Eγ>100GeV, and the proton rejection factor ∼106 are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.
At present, both in Russia and abroad, a new line of work is developed to comprehensively automate the functions of monitoring and controlling security systems, life support and technological ...processes of potentially dangerous, unique and technically complex objects (high-risk objects), which can also include car interchanges tunnel type. However, these works are unsystematic and do not fully solve the prevention and liquidation issues of emergency situations at the above-mentioned facilities. Moreover, in case of incorrect design of the above-mentioned systems, they can contribute to the deaths of people on the site and beyond. This is confirmed by the accidents' statistics at these facilities including the road junctions of the tunnel type. The accidents causes' analysis at high-risk facilities showed that they are largely stipulated by the incorrect definition of vulnerability (threats) assessment for the designed facilities and the facilities under construction. Thus, the model development for assessing the vulnerability of tunnel-type road junctions is an urgent task. To achieve this goal, the main causes of emergencies at tunnel type road junctions are considered and based on them, using a system analysis method and experimental theory, a three-dimensional model that allows, with the expert assessments, to determine the susceptibility of tunnels to various threats types, is developed and tested.
We present the measurement of the intrinsic hadronic contamination at the CERN SPS H4 beamline configured to transport electrons and positrons at 100 GeV/c. The analysis, performed using data ...collected by the NA64-e experiment in 2022, is based on calorimetric measurements, exploiting the different interaction mechanisms of electrons and hadrons in the NA64 detector. We determined the contamination by comparing the results obtained using the nominal electron/positron beamline configuration with those from a dedicated setup, in which only hadrons impinged on the detector. We also obtained an estimate of the relative protons, anti-protons and pions yield by exploiting the different absorption probabilities of these particles in matter. We cross-checked our results with a dedicated Monte Carlo simulation for the hadron production at the primary T2 target, finding a good agreement with the experimental measurements.
The SPASCHARM experiment is aimed at a systematic study of the nucleon spin structure and the spin dependence of the strong interaction of antimatter and matter with matter at energies up to 45 GeV. ...As part of the first stage of the experiment, the study of the spin properties of hadrons will take place in a beam of negatively charged hadrons on existing beamline 14 at the operating SPASCHARM setup at the U70 facility. At the second stage, the production of polarized beams of protons and antiprotons is envisaged in beamline 24A of the U-70 accelerator facility. A polarized antiproton beam will certainly become a unique beam in the world. It is planned to measure single-spin asymmetries in dozens of reactions, both on hydrogen and on various nuclei. At the SPASCHARM facility, it is also possible to measure the transverse polarization of hyperons and elements of the spin density matrix of vector mesons. The spin structure of the nucleon will be investigated in the study of quarkonium production to determine the contribution of gluons to the proton spin. The presence of two types of polarized beams and eight types of nonpolarized beams (π
±
,
K
±
,
p
,
,
d
,
C
), in combination with a polarized target, expands the range of studies of polarization phenomena and enhances the uniqueness of the project.
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