A Low Temperature Co-fired Ceramic (LTCC) Interposer Based Three-Dimensional Stacked Wire Bondless Power Module

The objective of this dissertation research is to develop a low temperature co-fired ceramic (LTCC) interposer-based module-level 3-D wire bondless stacked power module. As part of the dissertation work, the 3-D wire bondless stack is designed, simulated, fabricated and characterized. The 3-D wire bondless stack is realized with two stand-alone power modules in a half-bridge configuration. Each stand-alone power module consists of two 1200 V 25 A silicon insulated-gate bipolar transistor (IGBT) devices in parallel and two 1200 V 20 A Schottky barrier diodes (SBD) in an antiparallel configuration. A novel interconnection scheme with conductive clamps and a spring loaded LTCC interposer is introduced to establish electrical connection between the stand-alone power modules to connect them in series to realize a half-bridge stack. Process development to fabricate the LTCC based 3-D stack is performed. In traditional power modules, wire bonds are used as a top side interconnections that introduce additional parasitic inductance in the current conduction path and prone to failure mechanism under high thermomechanical stresses. The loop inductance of the proposed 3-D half-bridge module exhibits 71% lower parasitic inductance compared to a wire bonded module. The 3-D stack exhibits better switching performance compared to the wire bonded counterpart. The measurement results for the 3-D stack shows 30% decrease in current overshoot at turn-on and 43% voltage overshoot at turn-off compared to the wire bonded module. Through measurements, it has been shown that the conducted noise reduces by 20 dB in the frequency range 20-30 MHz for the 3-D stack compared to the wire bonded counterpart. A simulation methodology using co-simulation techniques using ANSYS EM software tools is developed to predict EMI of a power module. Hardware verification of the proposed simulation methodology is performed to validate the co-simulation technique. The correlation coefficient between the measurement and simulation is found to be 0.73. It is shown that 53% of the variability in the simulation can be explained by the simulated result. Moreover, the simulated and measured amplitudes of the EMI spectrum closely match with each other with some variations due to round-off errors due to the FFT conversion

Environmental Gas Sensors Based on Nanostructured Thin Films

Since the discovery of electron microscopes, nanomaterials and nanotechnology have been influencing academic and industrial research greatly for bringing out newer and better products with improved materials’ properties. In the field of environmental gas sensors too, the demonstration of nanomaterials for sensing various gases has become a common practice. Environmental gas pollution has turned out to be a huge concern in the society due to the progress of civilization. The awareness of health hazard for different toxic/polluting gases and rectification measure by imposing stricter norms has prompted extensive research to develop efficient gas sensors to detect trace level of pollution from various sources. Thin film, ultrathin film, and nanostructure materials of metal oxide semiconductor, polymer, metal, carbon nanotube, graphene, etc. with or without sensitizers have been investigated for sensing various toxic gases. New device structures have been fabricated to achieve high sensitivity, selectivity, fast response, etc. The microstructure and thickness of film are found to influence the performance greatly. Various methods of preparations and mechanism of sensing are being explored. All these aspects and the challenges were discussed in this chapter

Quantum Annealing: An Overview

In this review, after providing the basic physical concept behind quantum annealing (or adiabatic quantum computation), we present an overview of some recent theoretical as well as experimental developments pointing to the issues which are still debated. With a brief discussion on the fundamental ideas of continuous and discontinuous quantum phase transitions, we discuss the Kibble-Zurek scaling of defect generation following a ramping of a quantum many body system across a quantum critical point. In the process, we discuss associated models, both pure and disordered, and shed light on implementations and some recent applications of the quantum annealing protocols. Furthermore, we discuss the effect of environmental coupling on quantum annealing. Some possible ways to speed up the annealing protocol in closed systems are elaborated upon: We especially focus on the recipes to avoid discontinuous quantum phase transitions occurring in some models where energy gaps vanish exponentially with the system size.Comment: Final version; in pres

Is Attention always needed? A Case Study on Language Identification from Speech

Language Identification (LID) is a crucial preliminary process in the field of Automatic Speech Recognition (ASR) that involves the identification of a spoken language from audio samples. Contemporary systems that can process speech in multiple languages require users to expressly designate one or more languages prior to utilization. The LID task assumes a significant role in scenarios where ASR systems are unable to comprehend the spoken language in multilingual settings, leading to unsuccessful speech recognition outcomes. The present study introduces convolutional recurrent neural network (CRNN) based LID, designed to operate on the Mel-frequency Cepstral Coefficient (MFCC) characteristics of audio samples. Furthermore, we replicate certain state-of-the-art methodologies, specifically the Convolutional Neural Network (CNN) and Attention-based Convolutional Recurrent Neural Network (CRNN with attention), and conduct a comparative analysis with our CRNN-based approach. We conducted comprehensive evaluations on thirteen distinct Indian languages and our model resulted in over 98\% classification accuracy. The LID model exhibits high-performance levels ranging from 97% to 100% for languages that are linguistically similar. The proposed LID model exhibits a high degree of extensibility to additional languages and demonstrates a strong resistance to noise, achieving 91.2% accuracy in a noisy setting when applied to a European Language (EU) dataset.Comment: Accepted for publication in Natural Language Engineerin

Attentive Fusion: A Transformer-based Approach to Multimodal Hate Speech Detection

With the recent surge and exponential growth of social media usage, scrutinizing social media content for the presence of any hateful content is of utmost importance. Researchers have been diligently working since the past decade on distinguishing between content that promotes hatred and content that does not. Traditionally, the main focus has been on analyzing textual content. However, recent research attempts have also commenced into the identification of audio-based content. Nevertheless, studies have shown that relying solely on audio or text-based content may be ineffective, as recent upsurge indicates that individuals often employ sarcasm in their speech and writing. To overcome these challenges, we present an approach to identify whether a speech promotes hate or not utilizing both audio and textual representations. Our methodology is based on the Transformer framework that incorporates both audio and text sampling, accompanied by our very own layer called "Attentive Fusion". The results of our study surpassed previous state-of-the-art techniques, achieving an impressive macro F1 score of 0.927 on the Test Set.Comment: Accepted in 20th International Conference on Natural Language Processing (ICON

BRUCELLAR UVEITIS IN EASTERN INDIA

Objective: Brucellosis- one of the major zoonotic diseases, still remains an uncontrolled problem, in regions of high endemicity. Ophthalmic brucellosis is not studied and overlooked in most developing countries.  Considering the severe outcome of undiagnosed ophthalmic brucellosis, in this paper we made attempts to find out whether this disease still remains a health problem in a South East Asian developing country, where study of this disease is largely neglected.  Methods This study was carried out over a one year period from January 2015 to December 2015. Blood samples were collected from clinically confirmed cases of uveitis and they were subjected to five serological and one genus specific molecular investigations, for the detection of Brucella infection.Results Out of 20 uveitis cases, 4 (20%) cases confirmed as brucellar uveitis, by serological tests followed by PCR confirmation. After treatment of brucellosis all the four patients were recovered uneventfully.Conclusion: Brucella infection involving the eye is still a significant problem in South East Asian countries; hence in all uveitis cases in this reason brucellosis should be excluded by available laboratory tests.Government of India (Dept. of Biotechnology the major zoonotic diseases, still remains an uncontrolled problem, in regions of high endemicity. Ophthalmic brucellosis is not studied and overlooked in most developing countries.  Considering the severe outcome of undiagnosed ophthalmic brucellosis, in this paper we made attempts to find out whether this disease still remains a health problem in a South East Asian developing country, where study of this disease is largely neglected.   Methods This study was carried out over a one year period from January 2015 to December 2015. Blood samples were collected from clinically confirmed cases of uveitis and they were subjected to five serological and one genus specific molecular investigations, for the detection of Brucella infection.Results Out of 20 uveitis cases, 4 (20%) cases confirmed as brucellar uveitis, by serological tests followed by PCR confirmation. After treatment of brucellosis all the four patients were recovered uneventfully.Conclusion: Brucella infection involving the eye is still a significant problem in South East Asian countries; hence in all uveitis cases in this reason brucellosis should be excluded by available laboratory tests

Review on Growth and Characterization of Nonlinear Optical Organometallic Thiocyanate Crystals

Combinations of an inorganic distorted polyhedron with asymmetric conjugate organic molecules yield the organometallic compounds. Among them, organic thiocyanate crystals have attracted a great deal of attention for nonlinear optical device applications. The bimetallic thiocyanates of the type AB(SCN)4 for example, ZnCd(SCN)4, ZnHg(SCN)4, MnHg(SCN)4, and CdHg(SCN)4 are extremely interesting for optoelectronic applications. This article highlights present knowledge on growth parameters, physicochemical properties and nonlinear optical properties of several organometallic thiocyanate crystals. The chemical property and physical stability of these materials are compared, and the best results based on the review were reported. Information about the parameters, which are necessary for crystal growth has been summarized