Welding defect detection from radiography images with a cepstral approach

This paper presents a new approach for feature extraction from radiography images acquired with gamma rays in order to detect weld defects. In this approach, images are lexicographically ordered into 1D signals. Then, Mel-Frequency Cepstral Coefficients (MFCCs) and polynomial coefficients are extracted from these signals, one of their transforms, or both of them. Discrete Wavelet Transform (DWT), Discrete Cosine Transform (DCT), and Discrete Sine Transform (DST) are tested and compared for efficient feature extraction. Neural networks are used for feature matching in the proposed approach. Sixteen radiography images containing seventy three weld defects are used to evaluate the performance of the proposed approach. For performance evaluation, the tested images are degraded by Gaussian, impulsive, speckle, or Poisson noises with and without blurring. The experimental results show that the proposed approach can be used in a reliable way for automatic defect detection from radiography images in the presence of noise and blurring.     

Integrated enhancement- and depletion-mode FET's inmodulation-doped Si/SiGe heterostructures

We present results of enhancement and depletion mode transistors fabricated on the same layer structure of Si/SiGe, without using gate recess. The current in the enhancement mode device is controlled by a p-n junction, while that of the depletion-mode device is controlled by a Schottky barrier. A peak transconductance of 327 mS/mm and 417 mS/mm has been achieved in 0.5-μm gate length depletion and enhancement-mode transistors, respectively     

Fabrication and characterization of an InAlAs/InGaAs/InP ringoscillator using integrated enhancement- and depletion-modehigh-electron mobility transistors

The fabrication and characterization of an 11-stage ring oscillator utilizing integrated enhancement- and depletion-mode (E/D-mode) high-electron mobility transistors (HEMT's) in the lattice-matched InAlAs/InGaAs/InGaAs material system is demonstrated. The 0.5-μm gate length depletion-mode HEMT's (D-HEMT's) used in the circuit exhibit a threshold voltage (V_T) of -365 mV with a standard deviation of 19 mV, while the enhancement-mode HEMT's (E-HEMT's) with identical gate length display a V_T of 195 mV with a standard deviation of only 9 mV. The unity current gain cutoff frequency (f_t) for both devices is 70 GHz. The extremely high uniformity of the threshold voltages of these devices allowed for the implementation of a ring oscillator utilizing direct coupled FET logic (DCFL). At a supply voltage of 0.4 V, a room temperature propagation delay time (τ_pd) of 22.4 ps/stage, and a corresponding power dissipation of 120 μW/stage is measured, yielding a power delay product (PDP) of 2.65 fJ/stage. To the best of the authors knowledge, this is the first demonstration of a circuit employing E/D-HEMT technology in the lattice-matched InP-based material system     

0.3-μm gate-length enhancement mode InAlAs/InGaAs/InPhigh-electron mobility transistor

The fabrication and performance of ultra-high-speed 0.3-μm gate-length enhancement-mode high-electron-mobility transistors (E-HEMT's) are reported. By using a buried platinum-gate technology and incorporating an etch-stop layer in the heterostructure design, submicron E-HEMT devices exhibiting both high-threshold voltages and excellent threshold voltage uniformity have been achieved. The devices demonstrate a threshold voltage of +171 mV with a standard deviation of only 9 mV. In addition, a maximum DC extrinsic transconductance of 697 mS/mm is measured at room temperature. The output conductance is 22 mS/mm, which results in a maximum voltage gain (g_m/g₀ ) of 32. The devices show excellent RF performance, with a unity current-gain cutoff frequency (f_t) of 116 GHz and a maximum frequency of oscillation (f_max) of 229 GHz. To the best of the authors' knowledge, these are the highest reported frequencies for lattice-matched E-HEMT's on InP     

Silicone glazing for solar applications in rural areas

Silicone glazing is a translucent glass fabric reinforced material which was produced by coating silicone resin 1-2577 on an open weave leno fabric in a coating tower constructed in Basaisa village, Al Sharkiya Governorate, Egypt. The unique feature of the tower used in this work is the utilization of solar energy for both powering its coating mechanism through the use of a photovoltaic module, and also heating its curing chamber. The optical and mechanical properties of silicone glazing were studied. Silicone glazing is found to have a solar transmission of 90%, an ultraviolet cut-off at 270 nm, and an infrared cut-off at 8.0 μm. The material has a high tensile strength, particularly along the fill and the wrap directions of the reinforcing fabric. The tensile strength tested at 0.8 strain rate is 50, and 80 pli (pounds per lineal inch) at the fill and the wrap directions, respectively. Silicone glazing was found suitable for many solar applications such as greenhouse screen, space solar heating, solar food driers, and skylights in buildings, especially in rural areas.     

Application of doppler broadening of annihilation radiation technique to evaluate the microhardness variations during isochronal annealing of Al and Al (Mn) alloys

Doppler broadening measurements have been carried out to study the isochronal annealing of cold-worked commercial pure Al (99.5%) and Al-1 wt.% Mn alloys. The deduced line shape and wing parameters are investigated in the range from room temperature to 823 K and correlated with the corresponding microhardness measurements. The vacancy migration and the effect of the precipitated Al₆ Mn in Al (Mn) alloys could be probed as a function of annealing temperature. Three stages of microstructures can be distinguished in both Al and Al (Mn) alloys, which are recovery, partial recrystallization, and complete recrystallization. The line shape parameter-wing parameter (S-W) map indicates the same behavior in both alloys at high temperature. However, at low temperatures, Al (Mn) shows different behavior from the linear trajectory Al alloy.     

Nourin-Associated miRNAs: Novel Inflammatory Monitoring Markers for Cyclocreatine Phosphate Therapy in Heart Failure

Background: Cyclocreatine phosphate (CCrP) is a potent bioenergetic cardioprotective compound known to preserve high levels of cellular adenosine triphosphate during ischemia. Using the standard Isoproterenol (ISO) rat model of heart failure (HF), we recently demonstrated that the administration of CCrP prevented the development of HF by markedly reducing cardiac remodeling (fibrosis and collagen deposition) and maintaining normal ejection fraction and heart weight, as well as physical activity. The novel inflammatory mediator, Nourin is a 3-KDa formyl peptide rapidly released by ischemic myocardium and is associated with post-ischemic cardiac inflammation. We reported that the Nourin-associated miR-137 (marker of cell damage) and miR-106b-5p (marker of inflammation) are significantly upregulated in unstable angina patients and patients with acute myocardial infarction, but not in healthy subjects. Objectives: To test the hypothesis that Nourin-associated miR-137 and miR-106b-5p are upregulated in ISO-induced “HF rats” and that the administration of CCrP prevents myocardial injury (MI) and reduces Nourin gene expression in “non-HF rats”. Methods: 25 male Wistar rats (180–220 g) were used: ISO/saline (n = 6), ISO/CCrP (0.8 g/kg/day) (n = 5), control/saline (n = 5), and control/CCrP (0.8 g/kg/day) (n = 4). In a limited study, CCrP at a lower dose of 0.4 g/kg/day (n = 3) and a higher dose of 1.2 g/kg/day (n = 2) were also tested. The Rats were injected SC with ISO for two consecutive days at doses of 85 and 170 mg/kg/day, respectively, then allowed to survive for an additional two weeks. CCrP and saline were injected IP (1 mL) 24 h and 1 h before first ISO administration, then daily for two weeks. Serum CK-MB (U/L) was measured 24 h after the second ISO injection to confirm myocardial injury. After 14 days, gene expression levels of miR-137 and miR-106b-5p were measured in serum samples using quantitative real-time PCR (qPCR). Results: While high levels of CK-MB were detected after 24 h in the ISO/saline rats indicative of MI, the ISO/CCrP rats showed normal CK-MB levels, supporting prevention of MI by CCrP. After 14 days, gene expression profiles showed significant upregulation of miR-137 and miR-106b-5p by 8.6-fold and 8.7-fold increase, respectively, in the ISO/saline rats, “HF rats,” compared to the control/saline group. On the contrary, CCrP treatment at 0.8 g/kg/day markedly reduced gene expression of miR-137 by 75% and of miR-106b-5p by 44% in the ISO/CCrP rats, “non-HF rats,” compared to the ISO/Saline rats, “HF rats.” Additionally, healthy rats treated with CCrP for 14 days showed no toxicity in heart, liver, and renal function. Conclusions: Results suggest a role of Nourin-associated miR-137 and miR-106b-5p in the pathogenesis of HF and that CCrP treatment prevented ischemic injury in “non-HF rats” and significantly reduced Nourin gene expression levels in a dose–response manner. The Nourin gene-based mRNAs may, therefore, potentially be used as monitoring markers of drug therapy response in HF, and CCrP—as a novel preventive therapy of HF due to ischemia.     

Development of the Monolayer Silicon Solar Cell Based on Photonic Crystals

Silicon - In the present paper, we have designed a structure of the PIN silicon solar cell. We optimize the thickness of each layer of the PIN silicon solar cell, and its effect on the optical...