Stoyanka Kyzyl-Alma 2 – novy pamyatnik epokhi verkhnego paleolita zapadnogo tyan-shanya

in Vestnik NGU (2010), 9(5), 111-123

A straightforward calculation method for the fire resistance of reinforced concrete columns

Conference (1995, August 21)

Straightforward synthesis of isopropylidenediphenylsulfurane and application to industrially viable stereoselective synthesis of deltamethrin insecticide

in Synthesis (1990), (4), 275-278

We describe three stereoselective syntheses of deltametrin, one of the most potent industrially available insecticides, from γ-alkoxy-α,β-unsaturated carbonyl compounds, isopropyldiphenylsulfonium ... [more ▼]

We describe three stereoselective syntheses of deltametrin, one of the most potent industrially available insecticides, from γ-alkoxy-α,β-unsaturated carbonyl compounds, isopropyldiphenylsulfonium tetrafluoroborate and potassium tert-butoxide. [less ▲]

Strain Evolution in the Single Point Incremental Forming Process: Digital Image Correlation Measurement and Finite Element Prediction

in International Journal of Material Forming (2011)

Incremental Sheet Forming (ISF) is a relatively new class of sheet forming processes that allow the manufacture of complex geometries based on computer-controlled forming tools in replacement (at least ... [more ▼]

Incremental Sheet Forming (ISF) is a relatively new class of sheet forming processes that allow the manufacture of complex geometries based on computer-controlled forming tools in replacement (at least partially) of dedicated tooling. This paper studies the straining behaviour in the Single Point Incremental Forming (SPIF) variant (in which no dedicated tooling at all is required), both on experimental basis using Digital Image Correlation (DIC) and on numerical basis by the Finite Element (FE) method. The aim of the paper is to increase understanding of the deformation mechanisms inherent to SPIF, which is an important issue for the understanding of the high formability observed in this process and also for future strategies to improve the geometrical accuracy. Two distinct large-strain FE formulations, based on shell and first-order reduced integration brick elements, are used to model the sheet during the SPIF processing into the form of a truncated cone. The prediction of the surface strains on the outer surface of the cone is compared to experimentally obtained strains using the DIC technique. It is emphasised that the strain history as calculated from the DIC displacement field depends on the scale of the strain definition. On the modelling side, it is shown that the mesh density in the FE models plays a similar role on the surface strain predictions. A good qualitative agreement has been obtained for the surface strain components. One significant exception has however been found, which concerns the circumferential strain evolution directly under the forming tool. The qualitative discrepancy is explained through a mechanism of through-thickness shear in the experiment, which is not fully captured by the present FE modelling since it shows a bending-dominant accommodation mechanism. The effect of different material constitutive behaviours on strain prediction has also been investigated, the parameters of which were determined by inverse modelling using a specially designed sheet forming test. Isotropic and anisotropic yield criteria are considered, combined with either isotropic or kinematic hardening. The adopted constitutive law has only a limited influence on the surface strains. Finally, the experimental surface strain evolution is compared between two cones with different forming parameters. It is concluded that the way the plastic zone under the forming tool accommodates the moving tool (i.e. by through-thickness shear or rather by bending) depends on the process parameters. The identification of the most determining forming parameter that controls the relative importance of either mechanism is an interesting topic for future research. [less ▲]

Strain reduction in selectively grown CdTe by MBE on nanopatterned silicon on insulator (SOI) substrates

in Journal of Electronic Materials (2008), 37(9), 1255-1260

Silicon-based substrates for the epitaxy of HgCdTe are an attractive low-cost choice for monolithic integration of infrared detectors with mature Si technology and high yield. However, progress in ... [more ▼]

Silicon-based substrates for the epitaxy of HgCdTe are an attractive low-cost choice for monolithic integration of infrared detectors with mature Si technology and high yield. However, progress in heteroepitaxy of CdTe/Si (for subsequent growth of HgCdTe) is limited by the high lattice and thermal mismatch, which creates strain at the heterointerface that results in a high density of dislocations. Previously we have reported on theoretical modeling of strain partitioning between CdTe and Si on nanopatterned silicon on insulator (SOI) substrates. In this paper, we present an experimental study of CdTe epitaxy on nanopatterned (SOI). SOI (100) substrates were patterned with interferometric lithography and reactive ion etching to form a two-dimensional array of silicon pillars with similar to 250 nm diameter and 1 mu m pitch. MBE was used to grow CdTe selectively on the silicon nanopillars. Selective growth of CdTe was confirmed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Coalescence of CdTe on the silicon nanoislands has been observed from the SEM characterization. Selective growth was achieved with a two-step growth process involving desorption of the nucleation layer followed by regrowth of CdTe at a rate of 0.2 angstrom s(-1). Strain measurements by Raman spectroscopy show a comparable Raman shift (2.7 +/- 2 cm(-1) from the bulk value of 170 cm(-1)) in CdTe grown on nanopatterned SOI and planar silicon (Raman shift of 4.4 +/- 2 cm(-1)), indicating similar strain on the nanopatterned substrates. [less ▲]

Strained Si-on-insulator for advanced CMOS devices

Poster (2007)

Strained silicon on wafer level by wafer bonding: materials processing, strain measurements and strain relaxation

Conference (2008)

Strained silicon-on-insulator - Fabrication and characterization

in ECS Transactions (2007), 6

SSOI substrates were successfully fabricated using He+ ion implantation and annealing to relax thin (< 500nm) SiGe buffer layers, bonding and layer transfer processes to realize strained-Si layers onto ... [more ▼]

SSOI substrates were successfully fabricated using He+ ion implantation and annealing to relax thin (< 500nm) SiGe buffer layers, bonding and layer transfer processes to realize strained-Si layers onto oxide layers. The reduced thickness of the SiGe buffer possess numerous advantages such as reduced process costs for epitaxy and for reclaim of the handle wafer if the layer splitting is initiated in the SiGe/Si interface. The electron mobilities in the fabricated SSOI layers were measured using transistors with different gate lengths. An electron mobility of ~530 cm2 /Vs was extracted, being much higher than in non-strained SOI substrates. Furthermore, an 80% drive current (IDSAT) improvement has been measured for long channel devices. [less ▲]

Stranding of marine mammals: operations guide and necropsy procedures

in Annales de Médecine Vétérinaire (2002), 146(5, OCT-NOV), 261-276

The strange case of the massive binary HD 149404

in Astronomy and Astrophysics (2001), 368

We report the analysis of an extensive set of high-resolution spectroscopic observations of the massive binary system HD 149404. We compare different techniques to measure the radial velocities of the ... [more ▼]

We report the analysis of an extensive set of high-resolution spectroscopic observations of the massive binary system HD 149404. We compare different techniques to measure the radial velocities of the heavily blended absorption lines and we derive a new orbital solution. The absorption lines display strong variability that slightly affects the orbital solution and the determination of the spectral types of the components of the binary. We find that the primary is probably of spectral type O7.5 I(f), while the secondary is most likely an ON9.7 I supergiant. The secondary seems to be the most evolved component of the system and its current evolutionary status could best be explained if the system has undergone a Roche lobe overflow episode during the past. The secondary could actually still be rather close to filling its critical volume and this could lead to an enhanced mass loss of the secondary. The spectrum of HD 149404 displays many emission lines some of which show phase-locked line profile variations. In particular, the Halpha line displays a double-peaked morphology at orbital phases near conjunction. We investigate the radial velocity behaviour of the emission lines and we find that some of them must be formed in an interaction region. We propose a simple model where some of the optical emission lines arise in a heavily bended shock region. Based on observations collected at the European Southern Observatory (La Silla, Chile) and at the Cerro Tololo Inter-American Observatory (CTIO). [less ▲]