Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

We study the stability of thin walled circular cylindrical shells subject to radial pressure loading. Towards this end, we first develop the equations of motion of these shells with predominant radial deflections. We identify additional terms in the shell equations of motion which have mostly been neglected in existing studies and ascertain their importance in predicting the correct static buckling pressure. For finite cylinders, incorporation of these terms results in the best prediction of the static buckling pressure. Furthermore, we also find that the assumed relationships between the in-plane displacements of a generic point and the in-plane displacements of the mid-surface, which change from one shell theory to the other, play a critical role in determining the correct onset of the buckling instability under radial loading. In particular, the Donnell shell theory which is very popular for the study of dynamic problems related to cylindrical shells does not predict the correct buckling pressure. We find that the Fl{\"{u}}gge-Lur{\'{e}}-Byrne theory is best suited for this purpose. Accordingly, the shell equations with the additional terms and the in-plane displacements related as per the Fl{\"{u}}gge-Lur{\'{e}}-Byrne shell theory have been used for the study of parametric instability of a cylinder subject to a uniform radially fluctuating pressure. Stability charts with respect to different combinations of the forcing parameters viz. the static component of the pressure, the amplitude and frequency of the fluctuating component of the pressure have been presented which can serve as design guideline for shells subject to fluctuating radial loads.

World University root node

Department of Mechanical Engineering

International Journal of Mechanical Sciences

Instabilities of thin circular cylindrical shells under radial loading

The combustion characteristics and emissions in IC engines are influenced by the fuel injection rate. The study of fuel injection rate profile thus becomes essential to improve engine performance. In the present study, the injection rate of GDI injectors was measured in terms of the instantaneous mass flow rate of fuel. A setup was fabricated to obtain the injection rate based on Bosch tube method. Multi-hole GDI injectors of two different manufacturers were used in this study and their performances were measured up to 175 bar of injection pressure. The injector energizing current, wave pressure and rail pressure data were acquired at the rate of 500 kHz on a common time scale. The injected mass value per pulse, obtained by integrating the discharge rate profile was compared with the average values of mass injected measured using a mass balance for both the injectors and their performance were compared. The hydraulic delay measured during injector closing was found to be more than that during injector opening for both the injectors. Injection rate values for any given energizing time was found to be higher for one of the injectors by both the rate profile method and the mass balance averaging method. © 2015 International Conference on Liquid Atomization and Spray Systems. All rights reserved.

ICLASS 2015 - 13th International Conference on Liquid Atomization and Spray Systems

Fuel injection rate measurement of gasoline direct injection (GDI) injectors

Supramolecular assemblies that help to preorganize reactant molecules have played an important role in the development of concepts related to the control of excited-state processes. This has led to a persistent search for newer supramolecular systems (hosts), and this review briefly presents our work with octa acid (OA) to a host to control excited-state processes of organic molecules. Octa acid, a water-soluble host, forms 1:1, 2:1, and 2:2 (host-guest) complexes with various organic molecules. A majority of the guest molecules are enclosed within a capsule made up of two molecules of OA whereas OA by itself remains as a monomer or aggregates. Luminescence and 1H NMR spectroscopy help to characterize the structure and dynamics of these host-guest complexes. The guest molecule as well as the host-guest complex as a whole undergoes various types of motion, suggesting that the guests possess freedom inside the confined space of the octa acid capsule. In addition, the confined guests are not isolated but are able to communicate (energy, electron, and spin) with molecules present closer to the capsule. The host-guest complexes are stable even on solid surfaces such as silica, clay, α-Zr phosphate, TiO2, and gold nanoparticles. This opens up new opportunities to explore the interaction between confined guests and active surfaces of TiO2 and gold nanoparticles. In addition, this allows the possibility of performing energy and electron transfer between organic molecules that do not adsorb on inert surfaces of silica, clay, or α-Zr phosphate. The results summarized here, in addition to providing a fundamental understanding of the behavior of molecules in a confined space provided by the host OA, are likely to have a long-range effect on the capture and release of solar energy. © 2014 American Chemical Society.

Department of Chemistry

Fulltext

Langmuir

Supramolecular photochemistry in solution and on surfaces: Encapsulation and dynamics of guest molecules and communication between encapsulated and free molecules

Ground-based microwave radiometers operating at frequencies near the 22.235 GHz (K-band) water vapor absorption line have been used extensively for remote sensing of water vapor in the troposphere, both the integrated amount and its profile. This paper explores the potential to use ground-based, zenith-pointing K-band radiometer measurements along with optimized background data sets consisting of radiosonde profiles to detect dynamic changes and gradients in water vapor profiles. To explore this capability, the HUMidity EXperiment 2011 (HUMEX11) was conducted at the U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Site near Lamont, OK, USA. This enables the choice of appropriate retrieval parameters to monitor temporal changes in atmospheric water vapor profiles. The results of this study illustrate that in a retrieval algorithm both the choice of the size of the background data set measured near the radiometer measurement time and the choice of atmospheric layer thickness affect the ability to remotely sense dynamic changes in water vapor. In general, it is found that background data sets of larger size provide better accuracy in a statistical sense but inhibit the ability to detect gradients. © 2015 IEEE.

Department of Electrical Engineering

IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing

Optimization of Background Information and Layer Thickness for Improved Accuracy of Water-Vapor Profile Retrieval from Ground-Based Microwave Radiometer Measurements at K-Band

We report a series of metal insulator semiconductor devices with embedded Pt nano particles (NPs) fabricated using a low temperature atomic layer deposition process. Optically sensitive nonvolatile memory cells as well as optical sensors: (i) varactors, whose capacitance-voltage characteristics, nonlinearity, and peak capacitance are strongly dependent on illumination intensity; (ii) highly linear photo detectors whose responsivity is enhanced due to the Pt NPs. Both single devices and back to back pairs of diodes were used. The different configurations enable a variety of functionalities with many potential applications in biomedical sensing, environmental surveying, simple imagers for consumer electronics and military uses. The simplicity and planar configuration of the proposed devices makes them suitable for standard CMOS fabrication technology. © 2015 AIP Publishing LLC.

Journal of Applied Physics

Optically sensitive devices based on Pt nano particles fabricated by atomic layer deposition and embedded in a dielectric stack

In contemporary orthogonal frequency division multiplexing (OFDM) systems, such as Long Term Evolution (LTE), LTE-Advanced, and WiMAX, a codeword is transmitted over a group of subcarriers. Since different subcarriers see different channel gains in frequency-selective channels, the modulation and coding scheme (MCS) of the codeword must be selected based on the vector of signal-to-noise-ratios (SNRs) of these subcarriers. Exponential effective SNR mapping (EESM) maps the vector of SNRs into an equivalent flat-fading SNR, and is widely used to simplify this problem. We develop a new analytical framework to characterize the throughput of EESM-based rate adaptation in such wideband channels in the presence of feedback delays. We derive a novel accurate approximation for the throughput as a function of feedback delay. We also propose a novel bivariate gamma distribution to model the time evolution of EESM between the times of estimation and data transmission, which facilitates the analysis. These are then generalized to a multi-cell, multi-user scenario with various frequency-domain schedulers. Unlike prior work, most of which is simulation-based, our framework encompasses both correlated and independent subcarriers and various multiple antenna diversity modes; it is accurate over a wide range of delays. © 2015 IEEE.

IEEE Transactions on Wireless Communications

Characterizing the impact of feedback delays on wideband rate adaptation

In this report, we have explored the acid-base bifunctional catalytic activity of iron oxohydroxides (FeOOH) by catalyzing deacetalization and Henry condensation reactions successively in a single pot. The crystalline polymorphs of FeOOH, namely goethite (α FeOOH), akaganèite (β FeOOH), lepidocrocite (γ FeOOH) and δ FeOOH, were chemically prepared and tested for the catalytic activity. All the polymorphs of FeOOH exhibited acid-base bifunctional catalytic activity. The relative selectivity for products varied with the polymorphs of FeOOH. Whereas α FeOOH produced benzaldehyde in high yield, the polymorphs β FeOOH, γ FeOOH and δ FeOOH showed high selectivity for trans-β-nitrostyrene. In addition, β FeOOH also exhibited a unique activity towards the formation of 1,3-dinitro-2-phenylpropane. The difference in the catalytic activity of FeOOH polymorphs was explained based on the strength and density of acidic and basic active sites on the surface. Selectivity for the products was tuned by changing the synthesis parameters of the catalysts and reaction conditions. © The Royal Society of Chemistry.

Catalysis Science and Technology

Tunable acid-base bifunctional catalytic activity of FeOOH in an orthogonal tandem reaction

This paper explores the consequences of introducing a piezoelectric gate barrier in a normal field-effect transistor. Because of the positive feedback of strain and piezoelectric charge, internal charge amplification occurs in such an electromechanical capacitor resulting in a negative capacitance. The first consequence of this amplification is a boost in the ON-current of the transistor. As a second consequence, employing the Lagrangian method, we find that using the negative capacitance of a highly compliant piezoelectric barrier, one can potentially reduce the subthreshold slope of a transistor below the room-temperature Boltzmann limit of 60 mV/decade. However, this may come at the cost of hysteretic behavior in the transfer characteristics. © 2014 IEEE.

IEEE Journal on Exploratory Solid-State Computational Devices and Circuits

Transistor Switches Using Active Piezoelectric Gate Barriers

Basophils are classically known for their pathogenic role in asthma and allergic skin conditions. However, reports suggest that basophil activation mediated by autoreactive IgE, thymic stromal lymphopoietin or Toll-like receptors has an important role in the pathogenesis of lupus nephritis, eosinophilic oesophagitis and IgG4-related diseases, respectively.