Electrostatics of nanowire transistors

The electrostatics of nanowire transistors are studied by solving the Poisson equation self-consistently with the equilibrium carrier statistics of the nanowire. For a one-dimensional, intrinsic nanowire channel, charge transfer from the metal contacts is important. We examine how the charge transfer depends on the insulator and the metal/semiconductor Schottky barrier height. We also show that charge density on the nanowire is a sensitive function of the contact geometry. For a nanowire transistor with large gate underlaps, charge transferred from bulk electrodes can effectively "dope" the intrinsic, ungated region and allow the transistor to operate. Reducing the gate oxide thickness and the source/drain contact size decreases the length by which the source/drain electric field penetrates into the channel, thereby, improving the transistor characteristics.     

Numerical prediction of the performance,combustion and emission characteristics of a CI engine using different biodiesels

An attempt has been made to investigate numerically the energetic, combustion and environmental performances of a single-cylinder naturally aspirated direct injection diesel engine using the commercial software, Diesel-RK. Diesel and five different biodiesels, namely jatropha biodiesel, soybean biodiesel, palm stearin biodiesel, karanja biodiesel and rapeseed biodiesel, are used separately as fuels in this study. Experiments have also been conducted with diesel and palm stearin biodiesel to validate the predicted results. The experimental and the numerical results match both qualitatively and quantitatively with slight deviations. The analysis of the numerical results shows that the engine performance deteriorates with the use of different biodiesels as fuels. Brake thermal efficiency decreases by 3% (maximum) in case of palm stearin biodiesel. On the other hand, brake specific fuel consumption and brake specific energy consumption increase and the maximum values are found to be 25.8 and 3.6%, respectively. Among the biodiesels, jatropha biodiesel showed the best performance and palm stearin biodiesel showed the worst. When the combustion characteristics were compared, it was noted that both the ignition delay period and the heat release rate decrease to some extent for different biodiesels compared to diesel. The use of biodiesel gives a cleaner exhaust compared to that of diesel, and jatropha biodiesel gives the cleanest exhaust in terms of particulate matter and smoke emissions. However, the formation of nitrogen oxides increases with the use of biodiesels and the maximum increase was noted with rapeseed biodiesel.     

Magnetic measurements,Raman and infrared spectra of metal–ligand complex derived from $$\hbox {CoCl}_{2}\cdot \hbox {6H}_{2}\hbox {O}$$ and 2-benzoyl pyridine

Nanocrystalline complex of \(\hbox {CoCl}_{2}\cdot 6\hbox {H}_{2}\hbox {O}{-}2\)-benzoyl pyridine is prepared by chemical route. Each component of the desired complex is identified by analysing the X-ray diffractograms. Energy-dispersive X-ray analysis (EDX) data confirmed the presence of the desired elements of the sample. Theoretical optimized structure of the complex was derived using ab initio density functional level of theory (DFT) method of calculation. The average nanocrystallite size estimated from the XRD data is \(\sim \)43 nm. Static magnetic property of the complex is studied in the temperature range from 300 K down to 14 K. The estimated magnetic moment of the complex is high when compared to that of the free ion magnetic moment of \(\hbox {Co}^{2+}\) and this is attributed to the less effect of the crystal field acting on the ion in the organic complex due to which orbital moments are not fully quenched. The magnetic property of the complex is also remarkably enhanced compared to that of the diamagnetic 2-benzoyl pyridine which may be suitable for applications in devices. FTIR and Raman spectra of the ligand, 2-benzoyl pyridine and the synthesized complex are recorded at room temperature, which not only confirm the presence of each phase in the complex, but some interesting results are also extracted from the analyses of different Raman active modes of the complex.     

An electrical study of chrysotile asbestos

The dielectric constant (K) and dielectric loss (tan ) of preheated chrysotile asbestos up to 900°C were measured in the frequency range 10² to 10⁵ Hz. TheK and tan values were also measured as a function of temperature for hot pressed powdered pellets of chrysotile asbestos. The d.c. conductivity of hot pressed powdered pellets of chrysotile asbestos was also measured as a function of temperature. Dynamic d.c. conductivity was measured in the temperature range 58 to 580° C. The results have been discussed and attempts made to establish a correlation between the structural changes with the variation of dielectric properties.     

Surface morphology and composition of films grown by size-selected Cu nanoclusters

We report the investigation of morphology and composition of copper nanocluster films deposited on Si substrates. The nanoclusters are formed in an aggregation tube at room temperature and magnetron sputtering source is used to get negatively charged Cu-clusters' beam which is subsequently mass-filtered to get size-selected cluster on the substrates as soft-landing process of deposition. For composition of the films, X-ray photoelectron spectroscopy (XPS) technique is used. For morphological changes of the films both scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses are carried out. Additionally, Energy Dispersive X-ray (EDX) spectra support the compositional and structural informations of the film. The analysis of Cu nanoclusters' films reveals that initial nucleation of Cu clusters takes place in the form of isolated islands and the arrival of subsequent Cu clusters onto Si substrates has preferential aggregation around the preceding clusters forming a mound structure.     

Word boundary detection based on suprasegmental features: A case study on Bangla speech

This paper proposes a method for detecting word boundaries in continuous speech signal for Standard Colloquial Bengali (SCB), commonly referred to as Bangla. Bangla is a bound stress language with stress on the first syllable. Stress introduces its signature on the supra-segmental parameters of the speech signal, which may help to detect the word boundary in the continuous speech signal. The parameters used in this present study are: (1) Difference of the nucleus vowel duration across the syllable boundary, (2) Difference of the normalized nucleus vowel power across the syllable boundary, (3) Normalized F ₀ difference across the syllable boundary, (4) Difference of the average normalized F ₀ across the syllable boundary, (5) Difference of the normalized maximum periodic power of nucleus vowels across the syllable boundary, (6) Onset duration of the nucleus vowel. Altogether 225 sentences spoken by five native Bangla informants of both the sexes, in the age group of 20–50 years in normal laboratory environment are used in this study. These sentences contain 2734 syllables and 1103 words, sentence terminal words being excluded. A recognition score of 87.8% with a classifier, based on a distance function, weighted by inverse of variance is reported. Both speaker dependent as well as speaker independent studies are included.     

Monolithic fabrication of electro-fluidic polymer microchips

Integration of electronic wiring with microfluidic chips is an important process as it allows electrical interactions with the fluidic media, for example required for resistive and capacitive sensing. It is also necessary in order to implement various actuation and control mechanisms such as pumping, electrophoresis and temperature control. Typically electrical wire traces are added to microfabricated fluidic chips using metal deposition processes that are carried out after the fluidic chip has been fabricated. The process for adding the wiring is complicated and is limited to select metals that can be deposited by evaporation or sputtering. We present a single step method for integrating electrical wires into polymer microfluidic chips that are fabricated by a hot embossing process. This process can flexibly embed any kind of commercially available metal wire with a microfluidic chip and the wiring may be integrated to come into surface contact with the fluid or may be embedded in close proximity to (but insulated from)the fluid paths for example for local heating purposes. This method significantly reduces total processing time and is thus a valuable method for wire integration into polymer chips. We demonstrate two applications—a microelectrolysis chip and a heater chip that were fabricated using this methodology. The design, fabrication process and the initial test results are presented.     

Entanglement assisted classical capacity of a class of quantum channels with long-term memory

In this paper we evaluate the entanglement assisted classical capacity of a class of quantum channels with long-term memory, which are convex combinations of memoryless channels. The memory of such channels can be considered to be given by a Markov chain which is aperiodic but not irreducible. This class of channels was introduced by Datta and Dorlas in (J. Phys. A, Math. Theor. 40:8147–8164, 2007), where its product state capacity was evaluated.      

Performance validation tests on 80 K bubble type of shields for SST-1

The 80 K thermal shields of Steady State Superconducting Tokamak (SST-1) minimize the steady state heat loads on the superconducting magnet system at 4.5 K from ambient. Uniform temperature, vacuum and cryo compatibility is desired for the 80 K shields. In order to meet these requirements, the bubble/embossed type of design concept is adopted. This design ensures lower pressure drop and better temperature uniformity within ±5 K. Special attention has been given for preventing direct radiation on the magnet system. As part of performance validation tests, a group of 80 K thermal shields have undergone rigorous testing protocols and procedures. The temperature distribution, helium leak tightness and insulation resistance tests have been carried out for SST-1 thermal shields before final assembly of the machine. The test design, procedures and results of the 80 K thermal shields will be discussed in this paper.     

Enhancement of fluorine doped amorphous carbon thin films from microwave surface wave plasma activated above room temperature

Fluorinated amorphous carbon (a-C:F) thin films were synthesized above room temperature by microwave surface wave plasma chemical vapour deposition (MW SWP CVD). The effect of deposition temperature on optical, electrical, chemical and bonding properties of the a-C:F films were studied by ultraviolet–visible spectroscopy (UV–VIS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS), Raman spectrometry and TEM measurements. The film exhibits high transparency and decrease in optical band gap with increasing deposition temperature. FTIR study shows the increase in CC and decrease in C–Fx bonds of the films with increasing deposition temperature. Raman study shows some important structural changes in the films due to fluorine incorporation. XPS result shows the shift of carbon peak to higher binding energy due to carbon fluorine link to the films. TEM shows the increasing graphitic layer in the films with increasing deposition temperature.