Stability radius of a vector integer linear programming problem: case of a regular norm in the space of criteria

A multicriteria integer linear programming problem of finding a Pareto set is considered. The set of feasible solutions is supposed to be finite. The lower and upper achievable bounds for the radius of stability are obtained using a stability criterion and the Minkowski–Mahler inequality and assuming that the norm is arbitrary in the space of solutions and is monotone in the space of criteria. Bounds for the radius of stability in spaces with the Holder metric are given in corollaries.     

Ab initio LCAO study of the atomic,electronic and magnetic structures and the lattice dynamics of triclinic CuWO4

The electronic, structural and phonon properties of antiferromagnetic triclinic CuWO₄ have been studied using the first-principles spin-polarized linear combination of atomic orbital (LCAO) calculations based on the hybrid exchange–correlation density functional (DFT)/Hartree–Fock (HF) scheme. In addition, the local atomic structure around both Cu and W atoms has been probed using extended X-ray absorption fine structure (EXAFS) spectroscopy. We show that, by using the hybrid DFT–HF functional, one can accurately and simultaneously describe the atomic structure (the unit cell parameters and the atomic fractional coordinates), the band gap and the phonon frequencies. In agreement with our EXAFS results, the LCAO calculations reproduce a strong distortion of both the CuO₆ and the WO₆ octahedra, which occur due to the first-order and second-order Jahn–Teller effects, respectively. We found that the HF admixture of 13–16%, which is implemented in the PBE0–13% and WCGGA–PBE-16% functionals, produces the best result for CuWO₄. The calculated properties agree well with the available experimental data provided by diffraction, optical, X-ray photoelectron and Raman spectroscopies.     

Special features of strain aging of sheet automobile IFBH steel

Strain aging of commercial sheet automobile IF steels is investigated. The aging process is studied by measuring the dynamic modulus of elasticity, the amplitude-independent dislocation internal friction, the mechanical properties, and the microhardness. Analysis of the results obtained reveals the complex mechanism of strain aging of the steels. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 38–45, January, 2007.     

Decidability of boundedness problems for Minsky counter machines

The decidability of boundedness problems for Minksy counter machines is studied. It is proved that, for Minsky machines with two counters, the boundedness problem is partially decidable and the problem of the total boundedness is not even partially decidable. For one-counter Minsky machines, these problems are decidable during a time polynomially depending on the total number of local states of the counter machine.     

An information-measurement system for preprocessing of photofluorographic images

An information-measurement system for preprocessing of photofluorographic images is proposed. It is shown that the efficiency of the preprocessing depends on the metrological parameters of the images. An algorithm for preprocessing of photofluorographic images is developed. Results from the application of the algorithm and the outlook for its use for future studies are presented.     

The output window of a large-area accelerator with an increased electron-beam current density

The results of theoretical and experimental investigations of a large-area accelerator with a new type of output window are presented. With this window, it is possible to increase the current density of the extracted electron beam, reduce the operating temperature of the foil, and extend its service life. A two-level support structure with cooling of each level is used for this purpose. The heat load of the foil mounted on the second level of the support structure that carries the main mechanical load is reduced by partial interception of the thermal power due to direct loss of the electron beam, which is released on the first level experiencing no mechanical load. The current loss at the structural elements of the output window is estimated, and the hydraulic characteristics and foil temperature in the output device are calculated. A higher current density of the beam extracted over the foil is attained in comparison with the conventional design of the support structure.     

Optimization of the Structure of a Heterogeneous Scintillator for Registration of Thermal Neutrons

Instruments and Experimental Techniques - The results of modeling and optimization of a composite scintillator for recording thermal neutrons are presented. The interaction of thermal neutrons and...     

Optical monitoring of technological parameters during molecular-beam epitaxy

It is shown that one can use low-coherence tandem interferometry to measure the substrate temperature during the course of molecular-beam epitaxy in the case of oblique incidence of the probing light onto the surface. The temperature conditions in the Ob??-M installation for growing heteroepitaxial structures of cadmium and mercury tellurides and in the RIBER SIVA-21 installation for the growth of silicon-germanium structures are investigated. Calibration curves relating the readings of the standard thermocouple fixed within the heater to the true substrate temperature in the range 0?C500°C are created.