Effect of gate length on DC performance of AlGaN/GaN HEMTs grown by MBE

The DC performance of AlGaN/GaN high electron mobility transistors grown by plasma-assisted molecular beam epitaxy was investigated for gate lengths in the range 0.1–1.2 μm. On 0.25 μm gate length devices we obtained 40 V_DS operation with >50 mA peak I_D. The peak drain current density was 0.44 A/mm for 100 μm gate width devices with 1.2 μm gate lengths. The extrinsic transconductance (g_m) decreased with both gate length and gate width and was 75 mS/mm for all gate widths for 0.25 μm devices. E-beam written gates typically produced a slightly lower Schottky barrier height than optically patterned gates.     

IoT & AI Enabled Three-Phase Secure and Non-Invasive COVID 19 Diagnosis System

Corona is a viral disease that has taken the form of an epidemic and is causing havoc worldwide after its first appearance in the Wuhan state of China in December 2019. Due to the similarity in initial symptoms with viral fever, it is challenging to identify this virus initially. Non-detection of this virus at the early stage results in the death of the patient. Developing and densely populated countries face a scarcity of resources like hospitals, ventilators, oxygen, and healthcare workers. Technologies like the Internet of Things (IoT) and artificial intelligence can play a vital role in diagnosing the COVID-19 virus at an early stage. To minimize the spread of the pandemic, IoT-enabled devices can be used to collect patient’s data remotely in a secure manner. Collected data can be analyzed through a deep learning model to detect the presence of the COVID-19 virus. In this work, the authors have proposed a three-phase model to diagnose covid-19 by incorporating a chatbot, IoT, and deep learning technology. In phase one, an artificially assisted chatbot can guide an individual by asking about some common symptoms. In case of detection of even a single sign, the second phase of diagnosis can be considered, consisting of using a thermal scanner and pulse oximeter. In case of high temperature and low oxygen saturation levels, the third phase of diagnosis will be recommended, where chest radiography images can be analyzed through an AI-based model to diagnose the presence of the COVID-19 virus in the human body. The proposed model reduces human intervention through chatbot-based initial screening, sensor-based IoT devices, and deep learning-based X-ray analysis. It also helps in reducing the mortality rate by detecting the presence of the COVID-19 virus at an early stage.     

Comments on “transmission techniques for digital terrestrialTV broadcasting” [and reply]

We are responding to the paper by Sari et al. (see ibid., vol.33, no.2, p.100, 1995), referred to as SKJ, in which it is claimed that single-carrier (SC) transmission with frequency-domain equalization (FDE) is generally superior to coded orthogonal frequency-division multiplexing (COFDM) for terrestrial broadcasting. After pointing out a few additional considerations and briefly discussing the questions of carrier frequency offset and the effect of transmitter nonlinear distortion, we deal with the main issue: the performance of the two systems in the presence of strong echoes as would be encountered in single-frequency networks (SFNs). Any high performance communication system should incorporate sophisticated error-correction methods to achieve the desired performance. Therefore, a comparison based on uncoded or even trellis-coded transmission performance, as presented in SKJ, does not properly represent the tradeoffs involved in SC vs. COFDM terrestrial broadcast. A comparison should be based upon the most powerful practical coding system. For example, based on existing knowledge, a concatenated block and trellis coding system that incorporates adequate interleaving and maximum-likelihood decoding (using channel state information) offers a good solution. Using these techniques, we give an example of the performance of both kinds of systems with echoes ranging up to 0 dB. We find that it is possible to make the bit error rate of both systems improve with large echoes. SKJ reply that the basic message they want to convey through their article is that a well designed single-carrier system (with frequency-domain equalization) achieves similar performance to COFDM while avoiding its two well known problems of sensitivity to nonlinear distortion and carrier synchronization difficulties     

Investigating the Effect of Process Parameter on the Properties of Rf Sputtered pSi Thin Film by Taguchi and ANOVA Analysis

Silicon - Boron doped pSi was deposited on Si substrate in the RF magnetron sputtering system by varying three process parameters, namely-sputtering power, working pressure, and Ar gas flow rate....     

Effect on de-hydrogenation efficiency on doping of rare earth elements (Pr,Nd, Gd,Dy) in MgH2 – A density functional theory study

Effect on de-hydrogenation efficiency on doping of rare earth elements Pr, Nd, Gd and Dy in MgH₂ was studied using density functional theory. Specific storage capacity both in terms of volumetric and gravimetric capacity was also studied. Volumetric capacity was shown to decrease with the trends Dy > Gd > Nd > Pr, in accordance with the increase of unit cell volume, while gravimetric capacity was shown to decrease with the same trend in accordance with their atomic mass number. Analysis of density of states exhibits the presence of H-s states across Fermi energy, only for nearest neighbor H-atoms of rare earth (RE) dopants. These states are formed due to the delocalization of H-s states arising from the shorter MgH bond length, while Mg remain connected with a nearest neighbor H of RE dopant and due to the superposition and hence polarization of H-s states with f-orbital of RE elements across Fermi energy. Accordingly, H₂ desorption can be predicted to occur only from the nearest neighbor H atoms of RE dopant. Pr and Nd were shown to affect the dehydrogenation efficiency similarly as La and Ce doping in MgH₂ as obtained in our previous work. It is seen that Pr and Nd doping will reduce the H₂ desorption temperature as La and Ce in MgH₂, while, Gd and Dy doping will act negatively by increasing the de-sorption temperature even in comparison to pure MgH₂.     

Interpreting and Applying Experimental Data for Plate-Fin Surfaces: Problems with Power Law Correlation

The absence of reliable and theoretically consistent correlations for the prediction of the thermohydraulic performance of plate-fin surfaces from the definition of surface structure is placing a constraint upon plate-fin exchanger design. Many workers have made direct use of the experimental data without fully appreciating the limitations imposed by the way in which the experiments have been conducted. The dangers of such a practice are exposed. The data of Kays and London are then re-analyzed using established heat transfer theory. The comparison between the predicted and reported friction factor and j factor data is good. The predictions compare favorably with experimental measurements over laminar, transitional, and turbulent flow regimes. Predictions for heat transfer in the transitional flow regime can be improved if the transition occurs at a lower Reynolds number. The new equations can be used in design with greater confidence than the use of experimental data alone.     

Simplex and duplex PCR assays for species specific identification of cattle and buffalo milk and cheese

A polymerase chain reaction, amplifying a fragment of the mitochondrial DNA D loop region was developed for species specific detection of cattle and buffalo milk. The method was simultaneously extended for detection of HTST pasteurized milk samples and cheeses of bovine and buffalo origin. A common forward primer was used with two different species specific reverse primers that resulted amplification of a 126 bp and 226 bp products for cattle and buffalo, respectively, in simplex as well as in multiplex polymerase chain reaction. The primers successfully amplified DNA extracted by conventional protocol from minimal amount of raw milk, heat treated milk and cheese of either bovine or buffalo origin. The primers showed a high degree of specificity. The sensitivity of the assay was excellent with detection level of 0.1 percent adulteration of cow and buffalo milk or cheese (0.15 ng buffalo and 0.04 ng cattle DNA). The assay represents a sensitive and simple method for identification of adulteration in milk and cheese.     

Runtime and language support for compiling adaptive irregular programs on distributed-memory machines

In many scientific applications, arrays containing data are indirectly indexed through indirection arrays. Such scientific applications are called irregular programs and are a distinct class of applications that require special techniques for parallelization. This paper presents a library called CHAOS, which helps users implement irregular programs on distributed-memory message-passing machines, such as the Paragon, Delta, CM-5 and SP-1. The CHAOS library provides efficient runtime primitives for distributing data and computation over processors; it supports efficient index translation mechanisms and provides users high-level mechanisms for optimizing communication. CHAOS subsumes the previous PARTI library and supports a larger class of applications. In particular, it provides efficient support for parallelization of adaptive irregular programs where indirection arrays are modified during the course of computation. To demonstrate the efficacy of CHAOS, two challenging real-life adaptive applications were parallelized using CHAOS primitives: a molecular dynamics code, CHARMM, and a particle-in-cell code, DSMC. Besides providing runtime support to users, CHAOS can also be used by compilers to automatically parallelize irregular applications. This paper demonstrates how CHAOS can be effectively used in such a framework. By embedding CHAOS primitives in the Syracuse Fortran 90D/HPF compiler, kernels taken from the CHARMM and DSMC codes have been automatically parallelized.     

An interactive evolutionary multi-objective optimization and decision making procedure

With the advent of efficient techniques for multi-objective evolutionary optimization (EMO), real-world search and optimization problems are being increasingly solved for multiple conflicting objectives. During the past decade of research and application, most emphasis has been spent on finding the complete Pareto-optimal set, although EMO researchers were always aware of the importance of procedures which would help choose one particular solution from the Pareto-optimal set for implementation. This is also one of the main issues on which the classical and EMO philosophies are divided on. In this paper, we address this long-standing issue and suggest an interactive EMO procedure which will involve a decision-maker in the evolutionary optimization process and help choose a single solution at the end. This study uses many year’s of research on EMO and would hopefully encourage both practitioners and researchers to pay more attention in viewing the multi-objective optimization as a aggregate task of optimization and decision-making.     

Discovery and validation of urinary biomarkers for prostate cancer

Only 30% of patients with elevated serum prostate specific antigen (PSA) levels who undergo prostate biopsy are diagnosed with prostate cancer (PCa). Novel methods are needed to reduce the number of unnecessary biopsies. We report on the identification and validation of a panel of 12 novel biomarkers for prostate cancer (PCaP), using CE coupled MS. The biomarkers could be defined by comparing first void urine of 51 men with PCa and 35 with negative prostate biopsy. In contrast, midstream urine samples did not allow the identification of discriminatory molecules, suggesting that prostatic fluids may be the source of the defined biomarkers. Consequently, first void urine samples were tested for sufficient amounts of prostatic fluid, using a prostatic fluid indicative panel (“informative” polypeptide panel; IPP). A combination of IPP and PCaP to predict positive prostate biopsy was evaluated in a blinded prospective study. Two hundred thirteen of 264 samples matched the IPP criterion. PCa was detected with 89% sensitivity, 51% specificity. Including age and percent free PSA to the proteomic signatures resulted in 91% sensitivity, 69% specificity.