Publication7

Micropumps form the heart of several microfluidic systems like micro total analysis system (µTAS) and drug delivery devices, which have resulted from the advancement of silicon micromachining technology. Among the different available types of micropumps, valveless micropumps are better suited for biological applications as they do not have flow-rectifying valves and are less prone to clogging and wear. However, their main drawback is low thermodynamic efficiency. This can be improved if we have a better understanding of the effects of geometry on the performance. This forms one of the objectives of this work. This chapter describes the activity on the design and development of valveless micropumps. A numerical parametric study of the performance of valveless micropumps has been carried out and is presented to bring out the effects of different geometrical parameters. Based on these design approaches, silicon-based micropumps are fabricated and characterized. The performance of one of these micropumps is compared with designed value in this work.

Researchers have identified the dependency structure matrix (DSM) as a potential tool to explicitly identify iteration blocks and to evaluate the resulting sequence. Factors such as duration of activity, duration of rework, location of feedback variables, size of block, and number of loops within a block influence the overall duration of a project. The present study traces a pattern underlying the behavior of the block in evaluating the execution sequence. To achieve this objective, a database is generated for two-activity and three-activity DSMs by using a Monte-Carlo simulation based approach. The results of the model are analyzed to determine the placement of activity and rework probabilities that can achieve minimal duration of a project. © 2014 American Society of Civil Engineers.

In Heterogeneous cellular networks (HetNets), co-channel interference is a major concern due to the co-existence of multiple base stations with overlaid regions. Edge users are typically the victims because of high interference exposure. To counter this high interference, picocells communicate with the edge users in protected subframes (PSF). The severity of the problem intensifies in case of hotspot deployment, where picocells cannot provide coverage to the entire hotspot, thus forming a dense ring of macrocell users around picocells. We argue that these macrocell users are also victims, constituting a significant victim user population in hotspot deployment. We propose that, along with the macrocell muting during PSF, picocells should also be operated in cooperative manner with macrocell, and be barred from transmission during some of the subframes for protection of these macrocell victim users. We define a utility function to find the optimal values of PSF density for both macrocell and picocells, which would increase victim user throughput thereby enhancing system fairness. Exhaustive simulations illustrate that the proposed scheme improves victim user throughput significantly, while maintaining the overall system capacity. © 2014 IFIP.

Alignment of optical components is one of the important requirements in any optical system. Decentration of a component, like a lens, in the path of the beam, would introduce aberrations of various types. This would affect the measurement accuracy in the optical system such as an interferometer. In this work, we have analyzed the influence of decentration of an optical component on the wavefront in an optical system. The various aberrations caused due to the shifting of the axis of a lens in the path of an optical wavefront have been measured using a Shack Hartmann Wavefront Sensor and their influence studied. One of the lenses in the optical system is moved or decentered in transverse direction by 500 μm in steps of 50 μm. Decentration was done for all four quadrants. For each step, wavefront data is been taken and data was analyzed. Defocus, horizontal coma, vertical coma and spherical aberration were analyzed, apart from peak-to-valley and RMS values. Results showed that the error introduced is minimal up to 300 μm decentration, above which the aberrations were quite large. The experimental results and analyses are presented.

The influence of low energy laser peening on fatigue lives of Ti-6Al-4V was investigated. Laser peening was carried out on Ti-6Al-4V samples. Laser peened samples were characterized by residual stress analysis, surface roughness measurements, X-ray diffraction, optical microscopy, nanoindentation hardness tests, scanning and transmission electron microscopy and fatigue testing. Laser peening resulted in the formation of nanocrystallites on the surface and near surface regions with associated increase in hardness and introduction of compressive residual stress. Owing to positive influence of nanostructured surface and compressive residual stress, fatigue lives of the laser peened samples were significantly increased compared to the unpeened samples.

A Lewis acid catalyzed tandem nucleophilic addition/oxa-Michael reaction was developed for the synthesis of cis-2,6-disubstituted tetrahydropyran (THP) derivatives in good yields with excellent diastereoselectivities. The strategy was successfully used in the construction of THP derivatives with three stereocenters in a highly stereoselective fashion. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two-dimensional flow over a circular cylinder placed in-line behind a control rod of the same diameter is studied with and without the influence of a plane wall. Thermal patterns observed during various vortex shedding modes are discussed in detail. POD analysis of temperature data reveals that, with the decrease in wall height, modal structures are moved closer to the cylinder surface, which increases the heat transfer fluctuation. The plane wall increases the heat transfer from the bottom surface of the cylinder and decreases the heat transfer from the top surface, while the rotation of control rod contributes in an opposite manner. As the cylinder is moved closer to the wall, the time-averaged Nusselt number increases for a stationary control rod. In the case of a rotating control rod, the rotation of the control rod acts in the opposite sense to nullify this wall effect. © 2014 Taylor & Francis Group, LLC.

HMM based speech synthesis (HTS) is a state-of-the art approach to text-to-speech synthesis. Segmentation of the training data is essential for building any text-to-speech system. Most conventional text-to-speech systems use phones as the basic unit of synthesis and use a speech recogniser to automatically segment the data at the phone level. As Indian languages are low resource languages, accurate transcriptions are difficult to obtain owing to paucity of data. Manual labeling at the phone level is not only laborious but also inaccurate. HMM based flat start segmentation doesn't work well at the sentence level. In this paper we propose an event driven approach to obtain better phone boundaries. Syllable-like events are detected in the speech signal and matched with syllabified transcription of the text. The syllables are converted to phoneme sequences and Baum-Welch embedded re-estimation is restricted to the syllable-level. Subjective evaluations indicate that the proposed system has a lower word error rate compared to that of a conventional system that uses flat start for obtaining phone boundaries. © 2014 IEEE.

The aim of this study is to investigate the response of metro tunnel systems subjected to internal blast loading using Explicit Finite Element analysis. Usually, these metro systems consist of two tunnels running parallel to each other. The recent terror strikes exposed the vulnerability of tunnels to explosion. In this study, a typical metro system with two tunnels of 5m diameter running parallel to each other is considered. The tunnels are embedded in clayey stratum with a burial depth of 9m below the ground surface. The tunnel-soil interaction was also considered in this numerical model. The effect of parameters like explosive quantity and tunnel spacing on the response of tunnels was investigated. The explosion tunnel yields for the explosive quantity greater than 50 kg of TNT. The influence of blast wave on the adjacent tunnel is less for the spacing greater than 2.2 times the internal diameter of the tunnel.

Alzheimer's disease (AD) is a leading cause of dementia in elderly adults. In this, the white matter (WM) tracts in brain are disintegrated leading to loss of important cognitive functionality. Recent analysis have shown that early diagnosis of AD is still a challenging task. Although several reports are available, tractography remains the most promising and clinically relevant method for in-vivo study of WM tracts. In tractography, continuous WM pathways are reconstructed from voxel based models of discrete fiber orientation generated using diffusion tensor images. In this work an attempt has been made to classify AD using average length of tracts, a significant feature extracted from tractographic brain maps. The diffusion weighted images for AD and matched controls were obtained from ADNI, an international open access repository for Alzheimer's study. Data from equal number of AD and controls were used for this study. Fiber tracking was performed for the whole brain using tract based spatial statistics algorithm. ICBM Mori Labels 1 atlas provided in the Network Analysis option of ExploreDTI was used to divide the WM into 48 anatomical regions. Classification was performed using random forest, random tree and decision stumps, and their performance indices were compared. The results show that all the classifiers are able to classify AD and controls using the extracted feature. An accuracy of 78.4% is obtained using decision stumps. Random forest and random tree provide an increased accuracy of 96% and 97% respectively. The precision and recall is also found to be higher for random forest and random tree as compared to decision stumps. These results suggest that random forest and random tree are suitable for classification of AD and controls using average tract length as a feature. In this paper, the introduction, objectives, materials and methods, results and discussions and conclusions are presented in detail. Copyright 2014, ISA All Rights Reserved.

A spanning tree of an unweighted graph is a minimum average stretch spanning tree if it minimizes the ratio of sum of the distances in the tree between the end vertices of the graph edges and the number of graph edges. We consider the problem of computing a minimum average stretch spanning tree in polygonal 2-trees, a super class of 2-connected outerplanar graphs. For a polygonal 2-tree on n vertices, we present an algorithm to compute a minimum average stretch spanning tree in O(n logn) time. This also finds a minimum fundamental cycle basis in polygonal 2-trees. © 2014 Springer International Publishing Switzerland.

Enterprise Resource Planning or ERP integrates the data of all business areas within the organization. It is a complex technology involving different type of end users and implementing it in developing countries like India makes it even more difficult owing to the cultural and social differences. Effective usage of ERP leads to its success. However, degree of usage depends on many individual, organizational and technological factors. The post-ERP implementation is found to have impact on the user behavior and hence it is also essential to understand the impacts of the acceptance on the individual. This paper identifies the factors that affect the usage of ERP. A conceptual research framework is proposed to find the combined effect of the individual, organizational and technological factors on the ERP usage using the Technology Acceptance Model (TAM). The model also seeks to find out the impact of usage of ERP on panoptic empowerment, job satisfaction and individual performance.

A fault detection and classification scheme that uses probabilistic inference based on multiway continuous hidden Markov models (MCHMM) which is capable of capturing complex system dynamics and uncertainty is proposed. A set of observations from normal and faulty runs of the system was collected and used to generate the training dataset. The training data is assumed to follow a finite Gaussian mixture model. The number of mixture components and associated parameters for the optimal Gaussian mixture fit of the observed data was computed subsequently by clustering using the Figueiredo-Jain algorithm for unsupervised learning. The segmental k-means algorithm was used to compute the HMM parameters. The applicability of the proposed scheme is investigated for the case of an inverted pendulum system and a fluidized catalytic cracker. The monitoring results for the above cases with the proposed scheme was found to be superior to the multiway discrete hidden Markov model (MDHMM) based scheme in terms of the accuracy of fault detection, especially in case of noisy observations. © 2014 American Institute of Chemical Engineers.

Low signal to noise ratio and low contrast are the major limitations for segmentation, image analysis and interpretation of medical thermal images. In this work, an attempt has been made to improve and preserve the inter-regions edges by effectively removing the noise without blurring and hence, to extract the breast tissues from infrared images using level sets based on improved edge information. Gaussian filter is a linear, homogenous diffusion process that performs smoothing operation at each location that blurs the edge information resulting in difficulty of detection and localization of edges. To avoid smoothing across boundaries, an anisotropic diffusion based smoothing filter is used. This enables smoothing within the region by preserving sharp region boundaries. The performance improvement of the diffusion filter is verified and validated by extracting the breast tissues. The segmentation of regions of interests (ROIs) is performed by evolving the initial level set function based on this improved edge information. The extracted ROIs are compared with the corresponding four sets of ground truth images. The results show a good agreement of the segmented ROIs with ground truths. Further, the performance of the segmentation method is analyzed across inter person variations by calculating quantitative measures based on overlap and the statistics of regional similarities. It is observed that the segmentation method could able delineate the accurate regions of interest irrespective to the limitations of thermal images such as lack of clear edges. Average accuracy of 98% of regional similarity is obtained between segmented ROIs and ground truth images. Therefore, the enhanced edge detail seems to be useful to improve the performance of segmentation algorithm which could be used during breast cancer screening for early detection of tumor. © 2014 Elsevier Ltd.

The inlet air flow rates of a naturally aspirated engine can be enhanced by proper synchronization of the pressure fluctuations to obtain maximum air flow rate. Single cylinder diesel engine is considered as a test case for this study. 1-D simulation software AVL-BOOST is used for predicting the air flow rates in intake duct. Using this validated simulation model, theoretical correlations from wave theories are used to explain the arrival of pressure pulses at the intake valve. The pressure pulsations at the port for different lengths of the intake duct are analyzed. It is found that, a weighted combination of one or more effects results in a peak in volumetric efficiency and it cannot always be determined from a single correlation. The effects of diameter of the intake duct on the air flow rates are also studied. The air flow rates for each crank angle are calculated based on gas dynamic relations and these numerical calculations are validated against the simulation model. The calculations are then extended, to analyze the choking effects based on a non-dimensional number. Its predominance during the early stage of intake is identified and it increased with decreasing diameter of intake duct.

Crystallographic studies of the fluorinated tetraarylporphyrin 5,10,15,20-tetrakis(2′,3′,5′,6′-tetrafluoro-N, N-dimethyl-4-anilinyl)porphyrin and its metal complexes [MTF4DMAP; M = 2H·2H2O, 1; NiII·THF, 2; Cu II·5H2O, 3; and ZnII·(THF) 2, 4; THF = tetrahydrofuran] are reported. To analyse the weak intermolecular interactions, we have used a combination of energy decomposition analysis and Hirshfeld surface analysis, which allowed us to elucidate the nature of various close contacts. The energy decomposition analysis shows that dispersive interactions involving fluorine atoms significantly contribute to the stabilizing intermolecular interactions. Cooperative weak interactions such as C-F···H/C/F, C-H···π and H···H are responsible for the formation and stabilization of the supramolecular self assemblies. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In today's regime of information overload, it is reasonable to model a human executing routine tasks such as responding to emails as a priority queue. Humans typically prioritize task execution based on intrinsic motivators such as interest in the task, as well as extrinsic motivation stemming from the importance of the task to the sender. We view the human priority queue from the perspective of a principal-agent problem and characterize the effect of misalignment between the task sender's and task receiver's priorities. Our model provides insights into how different levels of misalignment affect delays of tasks of varying importance. Further, our approach starts to quantitatively address the effect of human dynamics in routine communication tasks, such as responding to emails. © 2014 IEEE.

In this work, isometric contraction of triceps brachii muscles are analyzed using surface electromyography (sEMG) signals and multifractals. The signals are recorded from 20 healthy adult volunteers at three different angles of elbow flexions namely 30°, 60° and 90° using standard experimental protocol. The recorded signals are preprocessed and subjected to Multifractal Detrended Fluctuation Analysis (MF-DFA). The three extracted MF-DFA features namely, peak exponent event, rare exponent event and smooth exponent event, are used for further analysis. The results show that multifractal spectrum response are distinct for all the three angles of flexion. It is observed that multifractal spectrum is shifting from higher order exponents to lower order with the increase in the angle of flexion. The features are statistically highly significant between 30° and 90° flexion. The smooth exponent is found to be statistically highly significant for both 60°-90° and 30°-90° flexion. It appears that this method of multifractal technique is an useful approach to understand muscle contractions in fatigue and in varied clinical conditions. © 2014 MIPRO.

Nanocomposite coating films have been increasingly used in industrial applications because of their unique mechanical and physical properties. Residual stresses generated during the growth of sputter-deposited thin films due to a strain mismatch between the film and the substrate may lead to significant failure problems. Large residual stresses may generate buckling, delamination and film fracture. Although buckles with cracks in thin films have been experimentally observed, their origins are still not well understood. In this work, finite element simulations in Abaqus/Explicit are employed to study buckling and cracking in Ti-Si-N films on a silicon substrate. Residual stresses in the film are generated using two loading methods: 1) Eigenstrain is applied via a temperature field; 2) An initial stress field is applied. Cracking is modelled using an elastic material model with a brittle fracture criterion that takes into account the tensile strength of the material to initiate damage. It is found that while both loading methods lead to similar buckling patterns and stresses, an initial stress field generates premature film failure and thus the thermal field loading should be used. The numerical model fairly predicted the cracking patterns observed in the experiments. © (2014) Trans Tech Publications, Switzerland.

Capacitance-to-Digital Converter (CDC) ICs available in the market use square wave excitation signals but a sinusoidal excitation is preferred in various applications, such as ice detection, liquid level measurement, humidity measurement, proximity sensing, etc. A dual slope technique based CDC that employs a sinusoidal excitation has been reported recently, but it requires a large number of excitation cycles, to complete an accurate conversion. This paper presents an improved CDC that employs a specially designed method to achieve high accuracy even when a much smaller number of excitation cycles, than the reported scheme, are employed to complete the conversion. A prototype CDC has been developed and tested. In comparison with an existing CDC, the new CDC achieved a substantial reduction (by a factor of 4000) in the number of excitation cycles during integration period, resulting in an improved update rate. Worst case error observed from the prototype CDC was less than 0.24%.