Improving the wear resistance of titanium-bronze friction couples by plastic deformation

Conclusion To improve the antifriction properties and the fatigue strength of friction couples of titanium and AMts9-2 bronze we recommend the use of roller or ball burnishing as the final operation.Translated from Metallovedonie i Termicheskaya Obrabotka Metallov, No. 1, pp. 77–78, January, 1974.     

Investigation of the coupling coefficients of stripline resonators in combline filters on a suspended substrate

Expressions for the frequency-dependent coupling coefficients of codirectional resonators used in a miniature design of a stripline filter on a suspended substrate are derived. The obtained expressions fully reflect the specific features of the frequency response of the analyzed structure. It is shown that the numerical analysis of a 1D model of this device performed in the quasi-static approximation provides sufficiently good agreement with experimental results. The influence of the design parameters of the analyzed structure on the frequency-selective properties of band-pass filters designed on the basis of this structure is theoretically investigated, and the capabilities for a substantial improvement of the selectivity of such devices are demonstrated.     

Switching effect in Si-CdS heterojunctions synthesized in highly nonequilibrium conditions

The results of the investigation of electrical properties and processes of the formation of heterojunctions on crystalline Si substrate cooled to negative centigrade temperatures is reported. The data of technology, electron diffraction analysis, and electrical investigations are given. The effect of conductivity switching is revealed in heterojunctions based on two-phase CdS films, and conditions for the formation of amorphous CdS films and amorphous CdS films with crystalline inclusions are determined. It is demonstrated that the results are in agreement with the soliton model.     

X-ray diffraction analysis and scanning micro-Raman spectroscopy of structural irregularities and strains deep inside the multilayered InGaN/GaN heterostructure

High-resolution X-ray diffraction analysis and scanning confocal Raman spectroscopy are used to study the spatial distribution of strains in the In _x Ga_{1 − x} N/GaN layers and structural quality of these layers in a multilayered light-emitting diode structure produced by metal-organic chemical vapor deposition onto (0001)-oriented sapphire substrates. It is shown that elastic strains almost completely relax at the heterointerface between the thick GaN buffer layer and In _x Ga_{1 − x} N/GaN buffer superlattice. It is established that the GaN layers in the superlattice are in a stretched state, whereas the alloy layers are in a compressed state. In magnitude, the stretching strains in the GaN layers are lower than the compressive strains in the InGaN layers. It is shown that, as compared to the buffer layers, the layers of the superlattice contain a smaller number of dislocations and the distribution of dislocations is more randomly disordered. In micro-Raman studies on scanning through the thickness of the multilayered structure, direct evidence is obtained for the asymmetric gradient distributions of strains and crystal imperfections of the epitaxial nitride layers along the direction of growth. It is shown that the emission intensity of the In _x Ga_{1 − x} N quantum well is considerably (more than 30 times) higher than the emission intensity of the GaN barrier layers, suggesting the high efficiency of trapping of charge carriers by the quantum well.     

Radiation effects and interphase interactions in ohmic and barrier contacts to indium phosphide as induced by rapid thermal annealing and irradiation with γ-ray 60Co photons

The radiation resistance of Au-Pd-Ti-Pd-n ⁺⁺-InP ohmic contacts and Au-TiB _x -n-n ⁺-n ⁺⁺-InP barrier contacts—both initial and subjected to a rapid thermal annealing and irradiated with ⁶⁰Co γ-ray photons with doses as high as 10⁹ R—has been studied. Before and after external effects, the electrical characteristics of the barrier and ohmic contacts, distribution profiles for components, and phase composition in the metallization layers have been measured. In ohmic Pd-Ti-Pd-Au contacts subjected to rapid thermal annealing and irradiation, a significant distortion of the layered structure of metallization occurs; this distortion is caused by the thermal and irradiation-stimulated transport of Pd over the grain boundaries in polycrystalline Ti and Au films. However, the specific contact resistance ρ _c does not change appreciably, which is related to a comparatively unvaried composition of the contact-forming layer at the Pd-n ⁺-InP interface. In the initial sample and the sample subjected to the rapid thermal annealing at T = 400°C with the Au-TiB _x -n-n ⁺-n ⁺⁺-InP barrier contacts and irradiated with the dose as high as 2 × 10⁸ R, a layered structure of metallization is retained. After irradiation with the dose as high as 10⁹ R, in the samples subjected to a rapid thermal annealing at T = 400°C, the layered structure of metallization becomes completely distorted; however, this structure is retained in the initial sample. The electrical properties of the contact structure appreciably degrade only after irradiation of the sample preliminarily subjected to a rapid thermal annealing at T = 400°C.     

Calibration of the LHCb electromagnetic calorimeter using the technique of neutral pion invariant mass reconstruction

Calibration of the electromagnetic calorimeter for the LHCb experiment is aimed at measuring the electron and photon energies with an accuracy of 2% or better. A number of calibration techniques are sequentially used for this purpose. One of these techniques is based on reconstruction of the π⁰ meson invariant mass in a two-photon decay. Using this procedure, it is possible to calibrate the electromagnetic calorimeter in the transverse energy range of 300–1500 MeV. An important advantage of this technique is its independence of the states of the other LHCb spectrometer systems. Statistics sufficient for attaining the declared purpose can be rapidly acquired owing to the large cross section of neutral pion production in deep inelastic events. The algorithm has been implemented as a part of the LHCb software. The calibration procedure using neutral pions takes no more than 2 weeks and helps achieve the required accuracy.     

Calculation of the deformation properties of materials made of chemical fibres

A comparatively simple repeating element whose relative deformation corresponds to the deformation of the entire sample can be distinguished in many materials made of chemical (including rigid-chain) fibres. A simple program based on the MATLAB mathematics package that allows calculating the relative deformation of each element and consequently also the deformation of the sample is described. The result of calculating the deformation of a repeating element consisting of two circles of different radius twisted to opposite sides is reported as an example of running the program.     

Autostochastic system of coupled microwave generators

Equations are presented describing a system of coupled generators, taking into account the feedback delay and time lag in each partial generator. The delay in the coupling elements between the generators is also taken into account. A numerical analysis of the dynamics of one, two, and three generators is performed. It is shown that chaotization of the oscillations occurs more readily in a coupled system of two or three generators than in the case of a single generator. This is confirmed by the results of experiments on transistor microwave generators. It is found that noise fluctuations can be obtained in a system of three coupled transistor generators over a broad range of frequencies in the centimeter wavelength range. Pis’ma Zh. Tekh. Fiz. 25, 33–38 (April 26, 1999)