Finite element modeling of frictionally restrained composite interfaces

The use of special interface finite elements to model frictional restraint in composite interfaces is described. These elements simulate Coulomb friction at the interface, and are incorporated into a standard finite element analysis of a two-dimensional isolated fiber pullout test. Various interfacial characteristics, such as the distribution of stresses at the interface, the extent of slip and delamination, load diffusion from fiber to matrix, and the amount of fiber extraction or depression are studied for different friction coefficients. The results are compared to those obtained analytically using a singular integral equation approach, and those obtained by assuming a constant interface shear strength. The usefulness of these elements in micromechanical modeling of fiber-reinforced composite materials is highlighted

Modeling and Validation of 4H-SiC Low Voltage MOSFETs for Integrated Circuit Design

Silicon Carbide is a promising wide bandgap material and gradually becoming the first choice of semiconductor for high density and high efficiency power electronics in medium voltage range (500-1500V). SiC has also excellent thermal conductivity and the devices fabricated with the material can operate at high temperature (~ 400 ⁰C). Thus, a power electronic system built with SiC devices requires less cooling requirement and saves board space and cost. The high temperature applications of SiC material can also be extended to space exploration, oil and gas rigging, aerospace and geothermal energy systems for data acquisition, sensing and instrumentation and power conditioning and conversion. But the high temperature capability of SiC can only be utilized when the integrated circuits can be designed in SiC technology and high fidelity compact models of the semiconductor devices are a priori for reliable and high yielding integrated circuit design. The objective of this work is to develop industry standard compact models for SiC NMOS and PMOS devices. A widely used compact model used in silicon industry called BSIM3V3 is adopted as a foundation to build the model for SiC MOSFET. The models optimized with the built-in HSPICE BSIM3V3.3 were used for circuit design in one tape-out but BSIM3V3 was found to be inadequate to model all of the characteristics of SiC MOSFET due to the presence of interface trapped charge. In the second tape-out, the models for SiC NMOS and PMOS were optimized based on the built-in HSPICE BSIM4V6.5 and a number of functioning circuits which have been published in reputed journal and conference were designed based on the models. Although BSIM4 is an enhanced version of BSIM3V3, it also could not model a few deviant SiC MOSFET characteristics such as body effect, soft saturation etc. The new model developed for SiC NMOS and PMOS based on BSIM4V7.0 is called BSIM4SIC and can model the entire range of device characteristics of the devices. The BSIM4SIC models are validated with a wide range of measured data and verified using the models in the simulation of numerous circuits such as op-amp, comparator, linear regulator, reference and ADC/DAC

Reaching the marginalised and socially isolated sex worker and sweeper communities of Tangail, Bangladesh

Sex workers and sweepers are socially isolated in Bangladesh. Sex workers are not economically deprived, but social elites or political forces as well as the religious leaders most of the time take stance against the sex workers. Though sex workers are comparatively affluent, they can’t live in the society with dignity and pride due to social stigma and isolation. They are also deprived of basic human rights including water, sanitation and hygiene services. On the other hand, sweepers are extremely poor and socially indispensible. They clean the shit of thousands, but their WaSH facilities are unhygienic and many times unusable. WaterAid in its Inclusion programme included both these communities and provided special support to ensure their WaSH rights in the respective communities. In this briefing paper, we will try to explore the different level of software and hardware interventions we have taken in our programme in different communities namely the sex workers and the sweepers of Tangail district

Design of microprocessor-based hardware for number theoretic transform implementation

Number Theoretic Transforms (NTTs) are defined in a finite ring of integers Z (_M), where M is the modulus. All the arithmetic operations are carried out modulo M. NTTs are similar in structure to DFTs, hence fast FFT type algorithms may be used to compute NTTs efficiently. A major advantage of the NTT is that it can be used to compute error free convolutions, unlike the FFT it is not subject to round off and truncation errors. In 1976 Winograd proposed a set of short length DFT algorithms using a fewer number of multiplications and approximately the same number of additions as the Cooley-Tukey FFT algorithm. This saving is accomplished at the expense of increased algorithm complexity. These short length DFT algorithms may be combined to perform longer transforms. The Winograd Fourier Transform Algorithm (WFTA) was implemented on a TMS9900 microprocessor to compute NTTs. Since multiplication conducted modulo M is very time consuming a special purpose external hardware modular multiplier was designed, constructed and interfaced with the TMS9900 microprocessor. This external hardware modular multiplier allowed an improvement in the transform execution time. Computation time may further be reduced by employing several microprocessors. Taking advantage of the inherent parallelism of the WFTA, a dedicated parallel microprocessor system was designed and constructed to implement a 15-point WFTA in parallel. Benchmark programs were written to choose a suitable microprocessor for the parallel microprocessor system. A master or a host microprocessor is used to control the parallel microprocessor system and provides an interface to the outside world. An analogue to digital (A/D) and a digital to analogue (D/A) converter allows real time digital signal processing

High pressure radio frequency plasma in a pulsed magnetic field

The high pressure plasma produced by an r.f. induction plasma torch has been investigated in a pulsed magnetic field using spectroscopy, high speed photography, inductive probes and a diamagnetic loop. Radiation and temperature of the plasma have been measured under various conditions of the torch and various intensities of the pulsed field. In most cases Joule-heating has been found the main mechanism of energy transfer to the plasma. From the decay of temperature in the plasma afterglow a value of radiative recombination in dense argon plasma has been found. Various properties of the torch in the absence of a pulsed magnetic field have also been investigated. These investigations cover gas breakdown at the torch initiation, measurements of the r.f. magnetic field in the plasma and the plasma instabilities. The measurements of the r.f. magnetic field provide information leading to estimates of plasma conductivity, electrical parameters and efficiency of the torch. The study of plasma instabilities reveals their sources and helps to suppress the acoustic noise from the torch. <p

A Description of the Phonology and Morphology of Kɔɖa, An Endangered Language of Bangladesh

This dissertation provides a preliminary description of the phonology and morphology of Kɔɖa [cdz], an endangered language of Bangladesh and one of the least described Munda languages of South Asia. It has four chapters: 1) Introduction, 2) Phonology, 3) Morphology, and 4) Kɔɖa in the Context of Language Contact. Chapter 1 provides a demographic overview of Kɔɖa speakers of Bangladesh, a discussion of Kɔɖa as a Munda language, a typological sketch of the language, a summary of previous work on Kɔɖa, and a summary of the fieldwork and methodology used in collecting data. Chapter 1 also previews the descriptive frameworks adopted to describe and explain the synchronic sound patterns and word classes of Kɔɖa. Chapter 2 provides a detailed description of the phonology of the language, including segmental and prosodic aspects of sound patterns. Chapter 3 presents a description of Kɔɖa word classes and word structure, including productive derivational and inflectional processes in the language. Finally, Chapter 4 presents a study of Kɔɖa in the context of language contact. Evidence for early Indic contact is observed, while more recent contact with Bangla has given rise to phonological and morphological features which might lead to classification of Kɔɖa as a mixed language

Impact of Globalization on Education Policy: Bangladesh Perspective

Globalization is a process, which has affected many areas of human life and it\u27s aided by the ICT. It has both positive and negative effects on education. These effects have been influenced our National Education Policy in 21st century. To identify the new issues and topics of education that was included in National Education Policy in 21st century of Bangladesh as an effect of globalization is the main objective of this paper. This Study was conducted following the qualitative research approach. In order to ensure the feasibility of the study, only two education policies which were formulated in 2000 and 2010, have purposively been selected for the study sample and the data has been analyzed qualitatively. Through this analysis, it has been found that the National Education Policy of Bangladesh was inspired by globalization. This paper will help to carry out further research on the similar topics in any other countries

The Anatomy of Bangla OCR System for Printed Texts using Back Propagation Neural Network

This paper is based on Bangla (National Language of Bangladesh) Optical Character Recognition process for printed texts and its steps using Back Propagation Neural Network. Bangla character recognition is very important field of research because Bangla is most popular language in the Indian subcontinent. Pre-processing steps that follows are Image Acquisition, binarization, background removal, noise elimination, skew angle detection and correction, noise removal, line, word and character segmentations. In the post processing steps various features are extracted by applying DCT (Discrete Cosine Transform) from segmented characters. The segmented characters are then fed into a three layer feed forward Back Propagation Neural Network for training. Finally this network is used to recognize printed Bangla scripts

Tumour Treating Fields (TTFs) for recurrent and newly diagnosed glioblastoma multiforme

In the last decade, significant advances have been made in Glioblastoma Multiforme treatment with the novel use of alternating electrical fields, also termed as tumour treating fields (TTFs). This modality has shown promising results in recurrent and newly diagnosed GBM patients, and according to some, may soon be considered an addition to the previously known \u27trifecta\u27 of GBM standard of care, i.e., surgery, chemo and radiation therapy.Here we review the existing data on TTF for both recurrent and newly diagnosed GBM. This review does not discuss the limitations of TTF, especially from compliance and cost point of view