Gate Current Modeling and Optimal Design of Nanoscale Non-Overlapped Gate to Source/Drain MOSFET

In this paper, novel nanoscale MOSFET with Source/Drain-to-Gate Non-overlapped and high-k spacer structure has been demonstrated to reduce the gate leakage current for the first time. The gate leakage behaviour of novel MOSFET structure has been investigated with help of compact analytical model and Sentaurus Simulation. Fringing gate electric field through the dielectric spacer induces inversion layer in the non-overlap region to act as extended S/D region. It is found that optimal Source/Drain-to-Gate Non-overlapped and high-k spacer structure has reduced the gate leakage current to great extent as compared to those of an overlapped structure. Further, the proposed structure had improved off current, subthreshold slope and DIBL characteristic. It is concluded that this structure solves the problem of high leakage current without introducing the extra series resistance.     

A New Flexible Filter Bank for Low Complexity Spectrum Sensing in Cognitive Radios

Conventional filter bank-based spectrum sensing methods employ uniform discrete Fourier transform filter bank (DFTFB). In this paper, we propose a multi-stage coefficient decimation filter bank (MS-CDFB) for wideband spectrum sensing in cognitive radios. From an initial fixed-coefficient modal filter, a filter bank that has multiple passbands of either uniform or different passband widths can be obtained using coefficient decimation. Design examples show that proposed MS-CDFB offers a complexity reduction of about 30% over the DFTFB while giving a superior sensing accuracy than the latter. The complexity reduction of MS-CDFB over the DFTFB is 85%, if both the spectrum sensors are designed to produce identical sensing accuracies.     

Differential cross section calculations of positron and electron impact ionization of Ar (3p)

We report the distorted wave Born approximation results of triple differential cross section of Ar (3p) by positron and electron impact. We compare the results of our calculations with the recent available experimental and theoretical results. We also provide a comparison of our positron impact ionization results with the electron impact ionization results to understand the effect of projectile charge on the projectile-target interaction.     

A Local Contrast Fusion Based 3D Otsu Algorithm for Multilevel Image Segmentation

To overcome the shortcomings of 1D and 2D Otsu’s thresholding techniques, the 3D Otsu method has been developed. Among all Otsu’s methods, 3D Otsu technique provides the best threshold values for the multi-level thresholding processes. In this paper, to improve the quality of segmented images, a simple and effective multilevel thresholding method is introduced. The proposed approach focuses on preserving edge detail by computing the 3D Otsu along the fusion phenomena. The advantages of the presented scheme include higher quality outcomes, better preservation of tiny details and boundaries and reduced execution time with rising threshold levels. The fusion approach depends upon the differences between pixel intensity values within a small local space of an image; it aims to improve localized information after the thresholding process. The fusion of images based on local contrast can improve image segmentation performance by minimizing the loss of local contrast, loss of details and gray-level distributions. Results show that the proposed method yields more promising segmentation results when compared to conventional 1D Otsu, 2D Otsu and 3D Otsu methods, as evident from the objective and subjective evaluations.      

Specific contact resistance measurements of the screen-printed Ag thick film contacts in the silicon solar cells by three-point probe methodology and TLM method

The specific contact resistance of the screen-printed Ag contacts in the silicon solar cells has been investigated by applying two independent test methodologies such as three-point probe (TPP) and well-known transfer length model (TLM) test structure respectively. This paper presents some comparative results obtained with these two measurement techniques for the screen-printed Ag contacts formed on the porous silicon antireflection coating (ARC) in the crystalline silicon solar cells. The contact structure consists of thick-film Ag metal contacts patterned on the top of the etched porous silicon surface. Five different contact formation temperatures ranging from 725 to 825 °C for few minutes in air ambient followed by a short time annealing step at about 450 °C in nitrogen ambient was applied to the test samples in order to study the specific contact resistance of the screen-printed Ag metal contact structure. The specific contact resistance of the Ag metal contacts extracted based on the TPP as well as TLM test methodologies has been compared and verified. It shows that the extraction procedure based on the TPP method results in specific contact resistance, ρ _c  = 2.15 × 10⁻⁶ Ω-cm² indicating that screen-printed Ag contacts has excellent ohmic properties whereas in the case of TLM method, the best value of the specific contact resistance was found to be about ρ _c  = 8.34 × 10⁻⁵ Ω-cm². These results indicate that the ρ _c value extracted for the screen-printed Ag contacts by TPP method is one order of magnitude lower than that of the corresponding value of the ρ _c extracted by TLM method. The advantages and limitations of each of these techniques for quantitatively evaluating the specific contact resistance of the screen-printed Ag contacts are also discussed.     

Removal of alpha case on titanium alloy surfaces using chemical milling

Elevated temperature deformation processing of titanium such as during forging causes the formation of alpha case, a brittle layer on the processed components. Alpha case removal has been attempted by several methods, however, in-depth understanding of chemical milling to this end is not evident from the prevailing literature. This work therefore undertakes experimental analysis of chemical milling to remove alpha case generated on titanium alloys after deformation after forging. Several compositions of chemicals and heat treatment conditions for titanium work-material were evolved. Effectiveness of these methods and their applications in removing alpha case on forged titanium alloy were investigated by performing a series of experiments. After the alpha case removal, the titanium work surfaces were examined using optical and scanning electron microscopy as well as electron back scattered diffraction and X-ray diffraction. The optimum results achieved show that 8% HF and 10% HNO₃ solution with 13 min and 30-s etching time is more effective in completely removing alpha case layer by chemical etching of Ti-6Al-4V alloy work specimens heated in air at 930°C.     

Combined addition of nano diamond and nano SiO2, an effective method to improve the in-field critical current density of MgB2 superconductor

MgB₂ bulk samples added with nano SiO₂ and/or nano diamond were prepared by powder-in-sealed-tube (PIST) method and the effects of addition on structural and superconducting properties were studied. X-ray diffraction (XRD) analysis revealed that the addition caused systematic reduction in ‘a’ lattice parameter due to the substitution of C atoms at B sites and the strain caused by reacted intragrain nano particles of Mg₂Si as evinced by transmission electron microscope image. Scanning electron microscopy images showed distinct microstructural variations with SiO₂/diamond addition. It was evident from DC magnetization measurements that the in-field critical current density [J_C(H)] of doped samples did not fall drastically like the undoped sample. Among the doped samples the J_C(H) of co-doped samples were significantly higher and the best co-doped sample yielded a J_C, an order of magnitude more than the undoped one at 5 K and 8 T.     

Experimental Investigation of Ultrasonic Machining of an Alumina-Based Ceramic Composite

The aim of this article is to present the ultrasonic machining of an alumina-based engineering ceramic composite. The machining mechanism and the behavior of certain tool material and work material combinations with respect to penetration rate and tool-wear rate under the influence of different parameters in ultrasonic machining are discussed in this paper. The shocking movement and cutting mechanics of the abrasive particle under the tip of the vibrating tool have been observed using high-speed photographic equipment. The machined surface has been analyzed by using a scanning electron microscope. Surface roughness values were measured and plotted at entry and at exit of the holes for different types and sizes of holes using the surface roughness-measuring instrument "Perthometer."     

Protection of simple series and parallel systems with components of different values

We apply game theory, optimization, and reliability analysis to identify optimal defenses against intentional threats to system reliability. The goals are to identify optimal strategies for allocating resources among possible defensive investments, and to develop qualitative guidelines that reflect those strategies. The novel feature of the approach is the use of reliability analysis together with game theory and optimization to study optimal management of intentional threats to system reliability. Thus, this work extends and adapts the existing body of game-theoretic work on security to systems with series or parallel structures. The results yield insights into the nature of optimal defensive investments that yield the best tradeoff between investment cost and security. In particular, the results illustrate how the optimal allocation of defensive investments depends on the structure of the system, the cost-effectiveness of infrastructure protection investments, and the adversary's goals and constraints.