Robust speaker identification using artificial neural networks

This research mainly focuses on recognizing the speakers through their speech samples. Numerous Text-Dependent or Text-Independent algorithms have been developed by people so far, to recognize the speaker from his/her speech. In this thesis, we concentrate on the recognition of the speaker from the fixed text i.e. Text-Dependent . Possibility of extending this method to variable text i.e. Text-Independent is also analyzed. Different feature extraction algorithms are employed and their performance with Artificial Neural Networks as a Data Classifier on a fixed training set is analyzed. We find a way to combine all these individual feature extraction algorithms by incorporating their interdependence. The efficiency of these algorithms is determined after the input speech is classified using Back Propagation Algorithm of Artificial Neural Networks. A special case of Back Propagation Algorithm which improves the efficiency of the classification is also discussed

A Conceptual Study to Identify the Problems & Challenges in Current Training Systems in it Industries

Purpose: To understand the problems and challenges faced by organization today on current training systems. The purpose of this research was to describe factors affecting the employee to participate in training & development programs in the organization. Theoretical Framework: The framework is formulated based on relationship between current training trends and its associated problems & challenges.   Design/Methodology/Approach: A total of 227 employees from various organizations based in Techno Park and InfoPark based in Kerala. Simple random sampling technique was used, and factor analysis performed to test the hypothesis. Online Questionnaires were used for data collection and analysed using descriptive statistics like percentages and presented using tables, charts, and figures.   Findings: The study established that traditional training methods won’t be much effective and serves the need of current generation. Custom tailor-made training design and methods are highly recommended to make the training programs effective and that create interest among employees to upskill themselves through training and development opportunities provided by organizations.   Research, Practical & Social implications: This study helps the organization and top management to understand the learning gap of employees due to difference in training trends. It will also help employees to perform well adopting to latest training trends which in turn results high productivity.   Originality/value: This article is a contribution to the Human Resource/Training Department to propose the challenges and its solutions for practitioners and trainers

In vitro models for airway epithelial cell culture

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 40-41).This work is about the development of a physiologically relevant model of the human airway. Various factors such as the cell model, physiochemical factors such as the cell substrate properties including its stiffness, shear stress, stretch, the air-liquid interface and the biochemical factors in the medium influence the biology of the cells. The aim of this work is to closely approximate conditions in an in vivo situation by engineering the above conditions in to the in vitro platform. An assay to introduce the cell substrate properties was developed in a glass bottomed petri dish type culture as well as a microfluidic device culture. The influence of the cell substrate on airway epithelial cell monolayer formation was investigated in detail by changing the stiffness of the substrate independently by changing the gel concentration, the gel formation pH and the height of the gel from a hard substrate. Further, we found that biochemical growth factors have a huge role in cell monolayer formation. A real-time measurement of monolayer integrity using electrical resistance measurements was developed. A shear stress application platform was developed and a stretch application platform was designed. The applications of such a platform with the inclusion of various physiologically relevant factors include the study of physiologic evolution of microbes such as the influenza virus.by Vivek Sivathanu.S.M

Disrupting dynamic f-actin enhances skeletal muscle contraction due to mechanical softening

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Cataloged from PDF version of thesis.Includes bibliographical references (pages 128-135).Skeletal muscle wasting disorders such as sarcopenia affect the daily mobility of millions of aging people globally due to decreased muscle mass and decreased muscle efficiency. In this study we discover a novel target to improve the efficiency of skeletal muscle by targeting the dynamic f-actin cytoskeleton. Using two model systems, an ex-vivo mouse muscle model and a novel in vitro optogenetic skeletal muscle micro-tissue model, we show that disruption of the dynamic f-actin cytoskeleton using small molecule actin dynamics inhibitors leads to a persistent 2-fold improvement in muscle active contractility. We explored possible drawbacks of f-actin disruption, including loss of mechanical integrity, cell death, and intracellular organelle damage. None of these downsides actually present themselves with f-actin disruption. Muscle fatigue resistance however does seem to be slightly affected. We performed a detailed characterization of the cytoskeletal modifications that occur during f-actin disruption using dose-response-recovery studies, live f-actin imaging, fluorescence recovery after photobleaching and more targeted f-actin disruption. Using these studies we conclude that treatments which shorten f-actin filaments seem to improve contraction. We also uncovered previously unidentified roles of branched and tropomyosin stabilized f-actin in force transmission. Biomechanical testing at the cell level using AFM and at the tissue level using a micro-tensile test shows a drop in mechanical stiffness that correlates well with a corresponding improvement in muscle force. We ruled out a range of alternate hypotheses involving changes to sarcomeric proteins and energetic activity, that could explain the force improvement, concluding that the force improvement due to f-actin disruption is due to mechanical softening of the cells which pose to a lower resistance to their own contraction. As a potential application, we show that a weak 3D printed muscle powered biological robot starts walking with f-actin disruption. This target has significant therapeutic potential in muscle disorders due to its disease non-specificity. We conclude by discussing possible future experiments that could reveal the best therapeutic applications. Key words: Muscle strength, f-actin, cytoskeleton, Skeletal Muscle Tissue Engineering, Muscle Disorders.by Vivek Sivathanu.Ph. D

Engineered 3D vascular and neuronal networks in a microfluidic platform

Neurovascular coupling plays a key role in the pathogenesis of neurodegenerative disorders including motor neuron disease (MND). In vitro models provide an opportunity to understand the pathogenesis of MND, and offer the potential for drug screening. Here, we describe a new 3D microvascular and neuronal network model in a microfluidic platform to investigate interactions between these two systems. Both 3D networks were established by co-culturing human embryonic stem (ES)-derived MN spheroids and endothelial cells (ECs) in microfluidic devices. Co-culture with ECs improves neurite elongation and neuronal connectivity as measured by Ca 2+ oscillation. This improvement was regulated not only by paracrine signals such as brain-derived neurotrophic factor secreted by ECs but also through direct cell-cell interactions via the delta-notch pathway, promoting neuron differentiation and neuroprotection. Bi-directional signaling was observed in that the neural networks also affected vascular network formation under perfusion culture. This in vitro model could enable investigations of neuro-vascular coupling, essential to understanding the pathogenesis of neurodegenerative diseases including MNDs such as amyotrophic lateral sclerosis.National Science Foundation (U.S.) (Grant CBET-0939511

Flame Radiation, Structure, and Scalar Properties in Microgravity Laminar Fires

Results from microgravity combustion experiments conducted in the Zero Gravity Research Facility (ZGF) 5.18 second drop facility are reported. The results quantify flame radiation, structure, and scalar properties during the early phase of a microgravity fire. Emission mid-infrared spectroscopy measurements have been completed to quantitatively determine the flame temperature, water and carbon dioxide vapor concentrations, radiative emissive power, and soot concentrations in microgravity laminar methane/air, ethylene/nitrogen/air and ethylene/air jet flames. The measured peak mole fractions for water vapor and carbon dioxide are found to be in agreement with state relationship predictions for hydrocarbon/air combustion. The ethylene/air laminar flame conditions are similar to previously reported results including those from the flight project, Laminar Soot Processes (LSP). Soot concentrations and gas temperatures are in reasonable agreement with similar results available in the literature. However, soot concentrations and flame structure dramatically change in long-duration microgravity laminar diffusion flames as demonstrated in this report

SURFACE FLASHOVER STUDIES AND ELECTRIC FIELD COMPUTATIONS TO OPTIMIZE THE DESIGN OF CONDUCTOR-SOLID INSULATOR GEOMETRY IN VACUUM.

The surface flashover strength of cylindrical and conical solid insulators has been investigated in ultra-high vacuum (\u3c 10(\u27-8) Torr) using DC, AC (60 Hz) and lightning impulse and a combination of a DC and impulse and a DC and AC. In general the DC and the impulse flashover voltages for a fixed length of the insulator are almost the same (within (+OR-)5%) and the AC flashover voltage is lower than the DC and the impulse. The combined DC (+OR-) 1.2/50 (mu)s impulse flashover voltage of cylindrical and conical solid insulators in vacuum is influenced by the applied DC pre-stress. A DC pre-stress causes an increase in the subsequent flashover values of the AC superimposed on DC. In general the flashover voltage of solid insulators are independent of the pressure in the range 10(\u27-8) to 6 x 10(\u27-3) Torr. The effects of ultra-violet (UV) light on the electrical performance of solid insulator in vacuum has been studied. The UV irradiation on solid insulator-vacuum interface degrades the electrical performance of the insulator. A method for calculating the DC surface flashover voltage of cylindrical insulators based on the assumption that the discharge occurs in a layer of desorbed gases from the insulator surface has been proposed. The effect of surface charge accumulation on the field distribution has been studied by assuming different patterns of surface charge distributions. The results showed that for a heterocharge accumulation the electric field is enhanced at both the cathode and the anode electrode junctions and for a homocharge accumulation the field enhancement is on the surface of the insulator away from the electrode junctions. In the case of a positive charge accumulation throughout the surface of the solid insulator, an enhancement in the field is found at the cathode and a reduction in the field value at the anode. The electric field distribution along the solid insulator-vacuum interface is computed and analyzed for a cylindrical insulator with metal inserts, cylindrical insulator placed in recessed electrodes, cylindrical insulator with convex curved edges, cylindrical insulator with concave curved edges and cylindrical insulator with metal inserts and placed in recessed electrodes. The electrode-insulator geometry which gives the best performance has been suggested.Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1983 .P553. Source: Dissertation Abstracts International, Volume: 44-09, Section: B, page: 2852. Thesis (Ph.D.)--University of Windsor (Canada), 1983

A Tomographic Method for the Reconstruction of Local Probability Density Functions

A method of obtaining the probability density function (PDF) of local properties from path integrated measurements is described. The approach uses a discrete probability function (DPF) method to infer the PDF of the local extinction coefficient from measurements of the PDFs of the path integrated transmittance. The local PDFs obtained using the method are compared with those obtained from direct intrusive measurements in propylene/air and ethylene/air diffusion flames. The results of this comparison are good

Flame Structure and Scalar Properties in Microgravity Laminar Fires

Recent results from microgravity combustion experiments conducted in the Zero Gravity Facility (ZGF) 5.18 second drop tower are reported. Emission mid-infrared spectroscopy measurements have been completed to quantitatively determine the flame temperature, water and carbon dioxide vapor concentrations, radiative emissive power, and soot concentrations in a microgravity laminar ethylene/air flame. The ethylene/air laminar flame conditions are similar to previously reported experiments including the Flight Project, Laminar Soot Processes (LSP). Soot concentrations and gas temperatures are in reasonable agreement with similar results available in the literature. However, soot concentrations and flame structure dramatically change in long duration microgravity laminar diffusion flames as demonstrated in this paper