Effect of copper additions in directly quenched titanium–boron steels

The present study concerns the effect of copper additions on the microstructural evolution and mechanical properties of directly quenched Ti–B steels. Ti and B are added as microalloying elements with an aim of achieving adequate austenite hardenability and Cu is added to retard the austenite (γ) → ferrite (α) transformation. Therefore, the microalloying and Cu additions together allow the transformation of austenite to occur at a lower temperature, resulting in a finer microstructure containing martensitic constituents. The direct-quenching route is adopted with an aim of facilitating the nucleation of the constituent phases from the deformed austenite. In order to circumvent the hot-shortness due to the Cu addition, 0.79 wt% Ni has been added to one of the 1.5 wt% Cu microalloyed steels. The present study has demonstrated that the Ni-containing 1.5Cu–Ti–B steel is capable of providing an attractive combination of strength and ductility comparable to the high strength varieties of HSLA steels in directly quenched condition.     

Formula for two-carrier third-order intermodulation distortion in semiconductor laser diodes

Formulas for the two-carrier third-order intermodulation distortion in semiconductor lasers have been reported by many authors. The authors refine the formula further and illustrates the difference in results arising from the refinement, for typical laser parameters.<>     

Cut off frequency and transit time analysis of lightly doped drain (LDD) MOSFETs

Analytical model for the transconductance, cut off frequency, transit time and fringing capacitance of LDD MOSFETs is presented with a simple approach. The analysis is carried out considering the LDD device as a conventional MOSFET with a series resistance [Z.-H. Liu et al., Threshold voltage model for submicrometer MOSFETs. IEEE Trans Electron Devices 1993; ED-40: 86–94] and a simple closed form expressions for cut off frequency and transit time is obtained. The total gate capacitance, i.e. the geometric and fringing capacitance, is calculated for both LDD and non-LDD devices and lower fringing capacitance is reported in LDD devices. Lower cut-off frequencies and higher transit time are reported in LDD devices for the same channel length.     

Silicon power MOSFET at low temperatures: A two-dimensional computer simulation study

Understanding how the structure of the unit-cell affects the cryogenic performance of a Si power Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is an important step toward optimizing of the device for cryogenic operations. In this paper, numerical simulations of the Si power Double Diffused MOSFET’ (DMOS) are performed at room temperature and cryogenic temperatures. Physically based models for temperature dependent silicon properties are employed in the simulations. The performances of power DMOS’ with various unit-cell structures are compared at both room temperature and low temperatures. The effect of the cell structure on the on-resistance and breakdown voltage of the device are analyzed. The simulation results suggest that the device optimized for room temperature operation can be further optimized at cryogenic temperatures.     

Fabrication and characteristics of tapes and test magnets made from Ag-Clad Bi-2223 superconductors

Pb_0.4Bi_1.8Sr₂Ca_2.2Cu₃O_x (Bi-2223) precursor powder was prepared by a solid-state reaction of carbonates and oxides of lead, bismuth, strontium, calcium, and copper, and the powder was then used to fabricate silver-clad tapes by the powder-in-tube technique. Transport critical current density (J_c) values>4×10⁴ A/cm² at 77K and 2×10⁵ A/cm² at 4.2 and 27K have been achieved in short tape samples. Long lengths of tape were tested by winding them into pancake coils. Recently, we fabricated a test magnet by stacking ten pancake coils, each containing three 16m lengths of rolled tape, and tested it at 4.2, 27 and 77K. A maximum generated field of 2.6 T was measured in zero applied field at 4.2K and the test magnet generated significant self-field in background fields up to 20 T. The results are discussed in this paper.     

Enhancement of modulation bandwidth of laser diodes by injection locking

In this letter, we suggest a new method for significantly enhancing the intrinsic bandwidth of a laser diode through the use of an injection locking technique. Our analysis shows that for moderate and high-injection levels, the bandwidth of a laser diode can be increased to several times its free-running bandwidth.     

Preparation and characterization of low-halogen and nonhalgoen fire-resistant low-smoke (FRLS) cable sheathing compound from blends of functionalized polyolefins and PVC

An attempt is made to develop a novel series of cable sheathing compounds with variation in chlorine content and sufficient fire retardance and unique low-smoke characteristics. These are prepared by blending PVC and functionalized polyolefins in different compositions. PE and EPDM have been functionalized by grafting dibutyl maleate (DBM) using DCP as initiator. FRLS compounds made from PVC-functionalized polyolefin blends possess the special characteristics of low-smoke, low-acid-gas generation, increased fire retardance, and improved volume resistivity, which are much better in comparison with a typical PVC sheathing compound. Thermoplastic elastomer (TPE) based nonhalogen FRLS compounds are also reported. The mechanisms for grafting, polymer-polymer and polymer-filler interactions have been presented.     

The differential effect of polymyxin B1 on guinea pig lung mitochondrial and microsomal glycerophosphate acyltransferase

The activities of guinea pig lung mitochondrial and microsomal glycerophosphate acyltransferase differed in sensitivity to polymyxin B₁. At an antibiotic concentration of 1 mg/ml, the mitochondrial enzyme activity was stimulated twofold, but the microsomal enzyme activity was completely inhibited. Furthermore, the mitochondrial enzyme activity was stimulated by polymyxin B₁ without the addition of exogenous acyl-CoA. Additional experiments ruled out the possibility of polymyxin B₁ acting as a substrate for the mitochondrial acyltransferase. These results suggest either that the polymyxin B₁ sensitivity of mitochondrial and microsomal glycerophosphate acyltransferase is different or that their accessibility to substrates is different because the two isoenzymes are located differently in the different phospholipid microenvironment of the membranes.     

Synthesis and densification of magnesium aluminate spinel: effect of MgO reactivity

Stoichiometric magnesium aluminate spinel was synthesized by reaction sintering of alumina with caustic and sintered magnesia. The volume expansion of 5–7% during MgAl₂O₄ formation was utilized to identify the starting temperature of spinel formation and densification by high temperature dilatometry. The magnesia reactivity was determined by measurement of crystallite size and specific surface area. Caustic magnesia and sintered magnesia behave differently vis-à-vis phase formation and densification of spinel. Densification of stoichiometric Mag-Al spinel was carried out between 1650 and 1750 °C. Attempts were made to correlate the MgO reactivity with microstructure and densification of spinel.     

3D computer vision based on machine learning with deep neural networks: A review

Recent advances in the field of computer vision can be attributed to the emergence of deep learning techniques, in particular convolutional neural networks. Neural networks, partially inspired by the brain's visual cortex, enable a computer to “learn” the most important features of the images it is shown in relation to a specific, specified task. Given sufficient data and time, (deep) convolutional neural networks offer more easily designed, more generalizable, and significantly more accurate end‐to‐end systems than is possible with previously employed computer vision techniques. This review paper seeks to provide an overview of deep learning in the field of computer vision with an emphasis on recent progress in tasks involving 3D visual data. Through a backdrop of the mammalian visual processing system, we hope to also provide inspiration for future advances in automated visual processing.