MOSFET substrate current model for circuit simulation

A simple, accurate MOSFET substrate current model suitable for a circuit simulator is presented. The effect of substrate bias on substrate current is modeled without introducing additional parameters. The accuracy of this model is demonstrated by its ability to fit the experimental data for both standard and LDD devices with average errors of less than 6%. The new model is compared with the substrate current models reported in the literature. In addition, the temperature dependence of the substrate current in the range of 0-120°C is also modeled. The new model has been implemented in a circuit-level hot-electron reliability simulator, and the results obtained from simulation of an inverter circuit are presented     

Two new canonic single-CFOA oscillators with single resistor controls

Although a number of single current feedback op-amps (CFOA)-based single-resistance-controlled oscillators (SRCO) have appeared in earlier literature, only six of them are canonic (i.e., requiring only two capacitors and only three resistors). The object of this brief is to add to this list two new canonic single-CFOA-based SRCO configurations. An evaluation of these two new circuits has been carried out and their workability of has been confirmed by experimental results based upon AD844 CFOAs.     

Effect of nanoimprinted surface relief on Si and Ge nucleation and ordering

Surface relief formed by nanoimprinting and etching into a thermally grown SiO₂ layer on Si was used to position the initial nuclei formed by chemically vapor deposited Si and Ge. By controlling the deposition conditions, the surface diffusion length was adjusted to be comparable to or larger than the spacing between features, thus favoring nucleation adjacent to steps, rather than random nucleation. Random nucleation was further suppressed by a two-stage deposition process. Ge nucleation on oxide by chemical vapor deposition was enhanced by coating the oxide surface with an organic self-assembled monolayer (SAM) and by the nanoimprinted surface relief. The nanoimprinted surface relief also provides long-range order in the SAM.     

Effect of linker used in D–A–π–A metal free dyes with different π-spacers for dye sensitized solar cells

Two novel D–A–π–A metal free dyes with triphenylamine as donor, dithiophene-diketo-pyrrolo-pyrrole as acceptor unit, thiophene and phenyl π-conjugated bridges and a cyanoacetic acid as electron acceptor (TDPP1 and TDPP2 were denoted for thiophene and phenyl π-conjugated bridge, respectively) have been designed and used as sensitizers for DSSCs. Incorporation of dithiophene-diketo-pyrrolo-pyrrole, reduces the band gap significantly. The influence of π-conjugated bridge on optical and electrochemical properties were investigated. Results demonstrated that the absorption band of TDPP with thiophene π-conjugated bridge has red shifted due to the enhancement of electron donating ability of π-conjugated bridge. The DSSC based on TDPP1 shows prominent power conversion efficiency about 4.81%, which is higher that for TDPP2 (3.42%). The electrochemical impedance spectroscopy analysis reveal that the charge recombination resistance at the TiO₂/dye/electrolyte interface for the DSSC based on TDPP1 is higher than that for TDPP2, which improves both J_sc and V_oc. The PCE of the DSSC based on TDPP1 is further improved up to 6.34%, when deoxycholic acid (DCA) was employed as coadsorbant.     

Fractional Laplace transform

A new definition of the fractional Laplace transform is proposed as a special case of the complex linear canonical transform. The proposed fractional Laplace transform reduces to the conventional bilateral Laplace transform and the fractional Fourier transform exactly and hence is better suited for the definition of the fractional Laplace transform as compared to the other definitions proposed earlier in the literature. The advantage of the proposed transform as compared to the conventional Laplace transform lies in providing a free parameter which can be effectively exploited in the filtering and signal separation problems.     

A novel microstrip antenna loaded with EBG and ELC for bandwidth enhancement

This paper proposes the design of three compact antennas for WiMAX, WLAN and ISM band applications. Antenna 1 consists of a monopole radiating element with an electromagnetic band gap (EBG) structured ground. By employing the EBG structure, an ultra-wide band frequency of 2.4–4.8 GHz (66.66%) is achieved. Antenna 2 is configured with an electric-LC (ELC) element, which achieved an ultra-wide band (UWB) frequency of 2.38–4.91 GHz (69.41%). Antenna 3 is integrated with ELC and EBG together, in which a UWB frequency of 2.3–5.3 GHz (78.94%) is obtained with improved impedance matching. The three antennas have omnidirectional radiation patterns which cover the ISM band at 2.4 GHz and WiMAX at 2.5/3.5 GHz over the operating bands. The radiation efficiency is?>?75% throughout the operating bands of all the antennas. In addition to the WiMAX and ISM bands, antenna 3 covers WLAN in the 5.2 GHz band. The proposed design can be applied to wireless mobile communication systems, which have the advantage of ease of fabrication and compactness.

     

A simple unsupervised MRF model based image segmentation approach

A simple technique has been suggested to obtain optimal segmentation based on tonal and textural characteristics of an image using the Markov random field (MRF) model. The technique takes an initially over segmented image as well as the original image as its inputs and defines an MRF over the region adjacency graph (RAG) of the initially segmented regions. A tonal-region based segmentation technique due to Kartikeyan and Sarkar (1989) has been used for initial segmentation. The energy function has been defined over the first order cliques of the MRF. The essence of this approach is primarily based on quantitative values of the second order statistics, on region characteristics and consequently deciding upon the action of merging neighboring regions using the F-statistic. The effectiveness of our approach is demonstrated with wide variety of real life examples viz., indoor, outdoor and satellite and a comparison of its output with that of a previous work in the literature has been provided.     

The properties of annealed AlN films deposited by pulsed laser deposition

AlN films deposited on SiC or sapphire substrates by pulsed laser deposition were annealed at 1200°C, 1400°C, and 1600°C for 30 min in an inert atmosphere to examine how their structure, surface morphology, and substrate-film interface are altered during high temperature thermal processing. Shifts in the x-ray rocking curve peaks suggest that annealing increases the film density or relaxes the films and reduces the c-axis Poisson compression. Scanning electron micrographs show that the AlN begins to noticeably evaporate at 1600°C, and the evaporation rate is higher for the films grown on sapphire because the as-deposited film contained more pinholes. Rutherford backscattering spectroscopy shows that the interface between the film and substrate improves with annealing temperature for SiC substrates, but the interface quality for the 1600°C anneal is poorer than it is for the 1400°C anneal when the substrate is sapphire. Transmission electron micrographs show that the as-deposited films on SiC contain many stacking faults, while those annealed at 1600°C have a columnar structure with slightly misoriented grains. The as-deposited films on sapphire have an incoherent interface, and voids are formed at the interface when the samples are annealed at 1600°C. Auger electron spectroscopy shows that virtually no intermixing occurs across the interface, and that the annealed films contain less oxygen than the as-grown films.     

Preparation and characterization of the N and C monoferric lobes of buffalo lactoferrin produced by proteolysis using proteinase K

The two glycosylated N- and C-terminal lobes of buffalo lactoferrin have been produced by limited proteolysis using proteinase K. Lactoferrin is a single chain glycoprotein of molecular mass 80 kDa with two iron-binding sites and two structural lobes connected by a short peptide. Purified samples of lactoferrin, isolated from buffalo colostrum, were subjected to hydrolysis using trypsin, chymotrypsin, pepsin, subtilisin and proteinase K. The first three proteinases produced two major fragments of approximately 35 and 23 kDa together with small molecular mass peptides. Trypsin and chymotrypsin partly digested lactoferrin, while pepsin converted all the intact lactoferrin into fragments. Subtilisin hydrolysis produced fragments of 40 and 26 kDa together with low molecular mass peptides. However, SDS-PAGE of the proteinase K hydrolysis product gave a clear band at 40 kDa together with a band indicating a substantial quantity of low molecular mass peptides (< 14.4 kDa). Upon ion-exchange chromatography this product gave two major fractions, which were further purified by gel filtration and identified as the C and N lobes from their N-terminal sequences. Thus, the 40 kDa band in SDS-PAGE of the proteinase K hydrolysis product contained two fragments of equal molecular mass. On further hydrolysis with proteinase K, the N lobe was completely hydrolysed into low molecular mass peptides, while only a small fraction of the C lobe was converted into small products. This suggested that an inhibitory fragment was present in the C lobe that was released on hydrolysis to small fragments and prevented complete digestion of the C lobe by high-affinity binding to the active site of proteinase K. This fragment was isolated from the lactoferrin-proteinase K complex and its sequence determined to be Val-Ala-Gln-Gly-Gly-Ala-Ala-Gly-Leu-Ala. Circular dichroism studies indicated a high alpha-helical content in the native lactoferrin while comparatively lower helical structures were present in the N and C lobes. In addition, the iron saturations of the N and C lobes appeared to be lower than that of the native protein.     

Stochastic model of k-parallel service channels

With the enhanced rate of inflow of units, especially in randomly distributed batch sizes, service through parallel channels appears to be the optimal course for relieving congestion and reducing the waiting time of customers. Keeping this fact in view, this paper involves k-parallel service channels which operate together for dealing with the situation of bulk arrivals. The time-dependent and steady state behaviour of the queueing system is dealt with at length. Laplace transforms of the probability generating functions for queue length distributions are obtained and the steady state results are derived therefrom. Finally, some particular cases which can be derived from the main theorem are also discussed.