Monitoring of resistance spot welding process

Контактне точкове зварювання є високопродуктивним процесом із високим рівнем автоматизації. Через це актуальними виявляються задачі, пов’язані з розробкою методів оцінювання якості процесу та його моніторингу. При цьому система має працювати в режимі реального часу, що дозволить ідентифікувати з’єднання, що не відповідають критеріям прийомки, протягом процесу зварювання або одразу після його завершення. Більш складною виявляється задача універсалізації таких систем, зокрема за рахунок використання простого обладнання з можливістю повної автоматизації процесу моніторингу та оцінювання. У дослідженні розглядали електричні параметри режиму зварювання, які визначають термічний цикл процесу та стан металу в зоні зварювання й характеристики його пластичності. Експерименти були проведені для зразків з різною якістю підготовки поверхонь перед зварюванням. Розроблений метод дозволяє також відслідковувати стан робочих поверхонь електродів та визначати виплески з високою точністю.Resistance spot welding is a process with high productivity and high level of automation. This rises a number of tasks re-lated to development of quality evaluation and process monitoring systems operating in real-time mode which would allow to detect non-compliant joints during the process run of shortly after it is finished. The more complex task is to make such system as much universal as possible, consisting of relatively simple equipment and with a possibility of full automation of evaluation process. Re-search was focused on electrical welding parameters which determine the thermal cycle of the welding process as well as the state of metal in the welding zone and its plasticity. Experiments were performed for work pieces with different pre-welding state of surface. Developed method also allows to monitor the state of working surfaces of electrodes and to detect splashes with a relatively high accuracy.Контактное точечная сварка является высокопроизводительным процессом с высоким уровнем автоматизации. Поэтому актуальными оказываются задачи, связанные с разработкой методов оценки качества процесса и его мониторинга. При этом система должна работать в режиме реального времени, что позволит идентифицировать соединения, которые не соответствуют критериям приемки, в течение процесса сварки или сразу после его завершения. Более сложной оказывается задача универсализации таких систем, в том числе за счет использования простого оборудования с возможностью полной автоматизации процесса мониторинга и оценки. В исследовании рассматривали электрические параметры режима сварки, которые определяют термический цикл процесса и состояние металла в зоне сварки и характеристики его пластичности. Эксперименты были проведены для образцов с разным качеством подготовки поверхностей перед сваркой. Разработанный метод позволяет также отслеживать состояние рабочих поверхностей электродов и определять выплески с высокой точностью

TECHNOGENIC WASTE AS A RAW MATERIAL FOR OBTAINING NANOSIZED SILICON DIOXIDE

The processes of the solid-state and hydrochemical fluorination process of alumina production from red mud and waste after wet magnetic separation of titanium magnetite ores by ammonium hydrogen fluoride was studied. Data on changes in the phase composition of the raw materials, the conditions of formation and decomposition of intermediate compounds were obtained.Работа выполнена при финансовой поддержке Комплексной программы фундаментальных научных исследований Президиума УрО РАН (проект № 15-11-3-20)

Gauge (non-)invariant Green functions of Dirac fermions coupled to gauge fields

We develop a unified approach to both infrared and ultraviolet asymptotics of the fermion Green functions in the condensed matter systems that allow for an effective description in the framework of the Quantum Electrodynamics. By applying a path integral representation to the previously suggested form of the physical electron propagator we demonstrate that in the massless case this gauge invariant function features a "stronger-than-a-pole" branch-cut singularity instead of the conjectured Luttinger-like behavior. The obtained results alert one to the possibility that construction of physically relevant amplitudes in the effective gauge theories might prove more complex than previously thought

Quantification of bound microbubbles in ultrasound molecular imaging

Molecular markers associated with diseases can be visualized and quantified noninvasively with targeted ultrasound contrast agent (t-UCA) consisting of microbubbles (MBs) that can bind to specific molecular targets. Techniques used for quantifying t-UCA assume that all unbound MBs are taken out of the blood pool few minutes after injection and only MBs bound to the molecular markers remain. However, differences in physiology, diseases, and experimental conditions can increase the longevity of unbound MBs. In such conditions, unbound MBs will falsely be quantified as bound MBs. We have developed a novel technique to distinguish and classify bound from unbound MBs. In the post-processing steps, first, tissue motion was compensated using block-matching (BM) techniques. To preserve only stationary contrast signals, a minimum intensity projection (MinIP) or 20th-percentile intensity projection (PerIP) was applied. The after-flash MinIP or PerIP was subtracted from the before-flash MinIP or PerIP. In this way, tissue artifacts in contrast images were suppressed. In the next step, bound MB candidates were detected. Finally, detected objects were tracked to classify the candidates as unbound or bound MBs based on their displacement. This technique was validated in vitro, followed by two in vivo experiments in mice. Tumors (n = 2) and salivary glands of hypercholesterolemic mice (n = 8) were imaged using a commercially available scanner. Boluses of 100 μL of a commercially available t-UCA targeted to angiogenesis markers and untargeted control UCA were injected separately. Our results show considerable reduction in misclassification of unbound MBs as bound ones. Using our method, the ratio of bound MBs in salivary gland for images with targeted UCA versus control UCA was improved by up to two times compared with unprocessed images

Microbubble Composition and Preparation for High-Frequency Contrast-Enhanced Ultrasound Imaging: In Vitro and in Vivo Evaluation

Although high-frequency ultrasound imaging is gaining attention in various applications, hardly any ultrasound contrast agents (UCAs) dedicated to such frequencies (>15 MHz) are available for contrast-enhanced ultrasound (CEUS) imaging. Moreover, the composition of the limited commercially available UCAs for high-frequency CEUS (hfCEUS) is largely unknown, while shell properties have been shown to be an important factor for their performance. The aim of our study was to produce UCAs in-house for hfCEUS. Twelve different UCA formulations A-L were made by either sonication or mechanical agitation. The gas core consisted of C4F10 and the main coating lipid was either 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC; A-F formulation) or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC; G-L formulation). Mechanical agitation r

USING OF 3D-MICROSCOPY IN MICROSURGERY

Work is executed at RFBR financial support, the project 15-29-04868

SYNTHESIS AND TECHNOLOGICAL STUDY OF RADIATION-RESISTANT ALLOYS BASED ON Al-Sc SYSTEM

Addition of small amounts of scandium, zirconium, and hafnium to aluminum and its alloys substantially increases their strength characteristics. It is economically beneficial to obtain light alloys containing expensive rare metals by synthesis using a high rate exchange reactions between the fluoride and chloride molten salts

QCD

We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics, double parton scattering, and backgrounds to Higgs production.Comment: 115 pages, Latex, 47 figures, to appear in the Report of the ``1999 CERN Workshop on SM Physics (and more) at the LHC'', S. Catani, M. Dittmar, D. Soper, W.J. Stirling, S. Tapprogge (convenors

SPIO labeling of endothelial cells using ultrasound and targeted microbubbles at diagnostic pressures

In vivo cell tracking of therapeutic, tumor, and endothelial cells is an emerging field and a promising technique for imaging cardiovascular disease and cancer development. Site-specific labeling of endothelial cells with the MRI contrast agent superparamagnetic iron oxide (SPIO) in the absence of toxic agents is challenging. Therefore, the aim of this in vitro study was to find optimal parameters for efficient and safe SPIO-labeling of endothelial cells using ultrasound-activated CD31-targeted microbubbles for future MRI tracking. Ultrasound at a frequency of 1 MHz (10,000 cycles, repetition rate of 20 Hz) was used for varying applied peak negative pressures (10–160 kPa, i.e. low mechanical index (MI) of 0.01–0.16), treatment durations (0–30 s), time of SPIO addition (-5 min– 15 min with respect to the start of the ultrasound), and incubation time after SPIO addition (5 min– 3 h). Iron specific Prussian Blue staining in combination with calcein-AM based cell viability assays were applied to define the most efficient and safe conditions for SPIO-labeling. Optimal SPIO labeling was observed when the ultrasound parameters were 40 kPa peak negative pressure (MI 0.04), applied for 30 s just before SPIO addition (0 min). Compared to the control, this resulted in an approximate 12 times increase of SPIO uptake in endothelial cells in vitro with 85% cell viability. Therefore, ultrasound-activated targeted ultrasound contrast agents show great potential for effective and safe labeling of endothelial cells with SPIO

Feasibility studies of the time-like proton electromagnetic form factor measurements with PANDA at FAIR

The possibility of measuring the proton electromagnetic form factors in the time-like region at FAIR with the \PANDA detector is discussed. Detailed simulations on signal efficiency for the annihilation of $\bar p +p$ into a lepton pair as well as for the most important background channels have been performed. It is shown that precision measurements of the differential cross section of the reaction $\bar p +p \to e^++ e^-$ can be obtained in a wide angular and kinematical range. The individual determination of the moduli of the electric and magnetic proton form factors will be possible up to a value of momentum transfer squared of $q^2\simeq 14$ (GeV/c)$^2$. The total $\bar p +p\to e^++e^-$ cross section will be measured up to $q^2\simeq 28$ (GeV/c)$^2$. The results obtained from simulated events are compared to the existing data. Sensitivity to the two photons exchange mechanism is also investigated.Comment: 12 pages, 4 tables, 8 figures Revised, added details on simulations, 4 tables, 9 figure