Method of Noncontact Calibration of the Robotic Ultrasonic Tomograph

The method of calibration of robotic ultrasonic tomograph with the construction of the trajectory of movement of the robot-manipulator on the object of control by using 3D-scanner is described. This method can significantly accelerate the process of calibration of tomograph and prevent possible displacement of the object during calibration. The algorithm of transition from use of a contact method of calibration of the tomograph to noncontact calibration is offered. Experimental data of application of this algorithm show a positive result: the time of research of object considerably decreases. Results of researches prove the practical relevance of the presented work and high efficiency of application of robotic ultrasonic tomography for nondestructive testing of objects of different forms

Quality Estimation of Dry Grinding of Skiving Cutters With Organic Bonding Diamond Wheels

Engineering process preparation requires proper preparation of cutting tools. It influences not only the performance of the tools but also the quality of workpiece surface machining. One of the promising environmentally friendly trends of mechanical treatment is grinding without using lubricating cooling liquid. This method can considerably influence the quality of cutting tools grinding. Smoothing skiving turning is an effective treatment method providing high efficiency and workpiece quality. Proper preparation of cutting edges is especially important in this process. For that purpose we have carried out a research in grinding changeable carbide inserts for skiving turning by means of grinding wheels with different grain size. The influence of different combinations of wheels on roughness of the inserts front and rear surfaces and quality of cutting edge was studied with the help of laser confocal microscopy

The low-frequency response in the surface superconducting state of ZrB12_{12} single crystal}

The large nonlinear response of a single crystal ZrB$_{12}$ to an ac field (frequency 40 - 2500 Hz) for $H_0>H_{c2}$ has been observed. Direct measurements of the ac wave form and the exact numerical solution of the Ginzburg-Landau equations, as well as phenomenological relaxation equation, permit the study of the surface superconducting states dynamics. It is shown, that the low frequency response is defined by transitions between the metastable superconducting states under the action of an ac field. The relaxation rate which determines such transitions dynamics, is found.Comment: 7 pages, 11 figure

High power ultranarrow linewidth picosecond laser system based on tapered fiber amplifier and gain-switched DFB laser diode

We experimentally demonstrate the highest spectral brightness for the pulsed fiber lasers to the best of our knowledge in a compact high power and pulse energy laser system consisting of a DFB laser diode as a master oscillator and a high-power fiber amplifier based on a double-clad active tapered fiber (T-DCF). Due to the unique properties of T-DCF, this system provides more than 1 MW of peak power and pulse energy of more than 60 μJ at a frequency of 500 kHz while maintaining a spectral width of less than 0.1 nm. The spectrum broadening limits the further power scaling of the laser system. The system is capable of delivering up to 150 W average power at 10 MHz pulse repetition rate with 0.14 nm linewidth. We also demonstrate the second harmonic generation of 532 nm with over 30 W at 10 MHz repetition rate and 14.5 W at 500 kHz. The experimental results reveals that the narrow linewidth system based on a DFB laser diode and a T-DCF amplifier is an excellent and robust solution for material processing and Raman spectroscopy.acceptedVersionPeer reviewe

Large mode area double-clad ytterbium-doped spun tapered fiber

We performed a comparative study of Yb-doped double-clad large mode area (MFDD31 _m) spun tapered fibers with different pitch lengths. A novel type of spun tapered fibers with constant pitch lengths of 7.5, 15, and 30 mm, internal birefringence as low as ∼10-8, and perfect output beam quality (M2 < 1.2) has been manufactured and investigated. We demonstrated the efficient direct amplification of a picosecond pulsed signal (95 ps/100 MHz, 1064 nm) in the spun active tapered fiber with optimized geometry providing an average output power of 71W(gain 32 dB, 74% slope efficiency). Efficient green light generation (∼D532 nm) with 17Waverage power (1.7 μJ) and 80 pm linewidth was demonstrated using the developed master oscillator power amplifier system.acceptedVersionPeer reviewe

Strontium Substituted Tricalcium Phosphate Bone Cement: Short and Long‐Term Time‐Resolved Studies and In Vitro Properties

Due to a significant influence of strontium (Sr) on bone regeneration, Sr substituted beta-tricalcium phosphate (Sr-TCP) cement is prepared and investigated by short- and long-term time-resolved techniques. For short-term investigations, energy-dispersive X-ray diffraction, infrared spectroscopy, and, for the first time, terahertz time-domain spectroscopy techniques are applied. For long-term time-resolved studies, angular dispersive X-ray diffraction, scanning electron microscopy, mechanical tests, and behavior in Ringer solution are carried out. After 45 min of the cement setting, the Sr-TCP phase is no longer detectable. During this time period, an appearance and constant increase of the final brushite phase are registered. The compressive strength of the Sr-TCP cement increases from 4.5 MPa after 2 h of setting and reaches maximum at 13.3 MPa after 21 d. After cement soaking for 21 d in Ringer solution, apatite final product, with an admixture of brushite and TCP phases is detected. The cytotoxicity aspects of the prepared cement are investigated using NCTC 3T3 fibroblast cell line, and the cytocompatibility-by human dental pulp mesenchymal stem cells. The obtained results allow to conclude that the developed Sr-TCP cement is promising for biomedical applications for bone tissue

Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of $t\overline{t}$, $W+b\overline{b}$ and $W+c\overline{c}$ is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 $\pm$ 0.02 \mbox{fb}^{-1}. The $W$ bosons are reconstructed in the decays $W\rightarrow\ell\nu$, where $\ell$ denotes muon or electron, while the $b$ and $c$ quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions