The Effects of Modeling on Simulator Performance

Gate-level simulators are usually thought of in terms of their benefits to logic designers, while behavioral simulators are considered to be the province of system architects. However, the behavioral modeling capabilities of a multilevel gate/behavioral simulator significantly enhanced the performance and accuracy of what are essentially gate-level simulations. The Behave simulator is a multilevel simulator that can simulate circuits at several levels of abstraction?behavioral level, gate level, or a mixture. Zero delay and rank order capability are also available in Behave and can be used to advantage. For example, in a simulation of an array multiplier involving 10,000 vectors, the time decreased from 16 hours to 38 minutes, simply because the elements were rank ordered. This range of processing is possible because of the flexibility in software for general-purpose CPUs.     

Organic Thin‐Film Transistors Based on Tolyl‐Substituted Oligothiophenes

Thin films based on the tolyl‐substituted oligothiophenes 5,5′′‐bis(4‐methylphenyl)‐2,2′:5′,2′′‐terthiophene ( 1 ), 5,5′′′‐bis(4‐methylphenyl)‐2,2′:5′,2′′:5′′,2′′′‐quaterthiophene ( 2 ) and 5,5′′′′‐bis(4‐methylphenyl)‐2,2′:5′,2′′:5′′,2′′′:5′′′,2′′′′‐quinqethiophene ( 3 ) exhibit hole‐transport behavior in a thin‐film transistor (TFT) configuration, with reasonable mobilities and high current on/off (I_on/I_off) ratios. Powder X‐ray diffraction (PXRD) reveals that these films, grown by vacuum deposition onto the thermally grown silicon oxide surface of a TFT, are highly crystalline, a characteristic that can be attributed to the general tendency of phenyl groups to promote crystallinity. Atomic force microscopy (AFM) reveals that the films grow layer by layer to form large domains, with some basal domain areas approaching 1000 μm². The PXRD and AFM data are consistent with an “end‐on” orientation of the molecules on the oxide substrate. Variable‐temperature current–voltage (I–V) measurements identified the activation regime for hole transport and revealed shallow level traps in thin films of 1 and 2 , and both shallow and deep level traps in thin films of 3 . The activation energies for thin films of 1 , 2 , and 3 were similar, with values of E_a = 121, 100, and 109 meV, respectively. The corresponding trap densities were N_trap/N_v = 0.012, 0.023, and 0.094, where N_trap is the number of trap states and N_v is the number of conduction states. The hole mobilities for the three compounds were similar (μ ? 0.03 cm² V^–1 s^–1), and the I_on/I_off ratios were comparable with the highest values reported for organic TFTs, with films of 2 approaching I_on/I_off = 10⁹ at room temperature.     

Performance of Smart Antenna Under Different Fading Conditions

Optimizing the current distribution of an evenly spaced antenna array has shown to be an efficient approach for reducing side lobe levels. In this article, the Tchebyscheff distribution-based antenna array synthesis approach is combined with an adaptive signal processing algorithm for beamforming and side lobe level reduction in smart antennas in various fading situations. The performance of smart antennas in uniformly spaced linear, planar, circular, and semi-circular arrays are evaluated. The presence of Rayleigh and Rician channels is examined in the network. The least mean square (LMS) and normalised least mean square (NLMS) algorithms are applied as adaptive algorithms. In fading environments, the NLMS algorithm with Tchebyscheff distribution outperforms than the LMS algorithm with Tchebyscheff distribution, with a side lobe level decrease of 11.23 dB. The lowest side lobe achieved with the NLMS algorithm with Tchebyscheff distribution is???45.59 dB for uniform planar array.

     

Remote sensing of alpine treeline ecotone dynamics and phenology in Arunachal Pradesh Himalaya

Global warming is inducing the elevational alpine treeline ecotone (ATE) to migrate to higher elevations in the Himalaya. Prior research on ATE dynamics has been primarily based on field inventory and studied at the community level. The potential of using remote sensing and geographic information system for the delineation of the treeline ecotone has been explored. In this study, we used satellite-derived Normalized Difference Vegetation Index (NDVI) data from Landsat-1/2 Multispectral Scanner (MSS), Resourcesat-1/2 Linear Imaging Self Scanning Sensor (LISS-III), and National Oceanographic and Atmospheric Administration-Advanced Very High-Resolution Radiometer (NOAA-AVHRR) to investigate long-term ATE dynamics. Satellite remote sensing of treeline in Arunachal Pradesh Himalaya revealed an upward shift over the past four decades. The ATE has shifted c. 452 m ± 74 m upward in vertical dimension at a rate c. 113 m decade^?1. Furthermore, the land surface phenology along ATE and forest area has changed significantly over the past 33 years. The significant positive trend in length of the growing season (LOS; p < 0.05) and delay in the end of the growing season (EOS) was observed. The start of the growing season (SOS) had a negative tendency with non-significant linear trend. The treeline upward shift and significant lengthening of the growing season at ATE and forest area indicate changing climatic patterns and processes.     

Decoder driven side information generation using ensemble of MLP networks for distributed video coding

Multimedia Tools and Applications - This paper proposes an ensemble of multi-layer perceptron (MLP) networks for side information (SI) generation in distributed video coding (DVC). In the proposed...     

Prioritizing test scenarios from UML communication and activity diagrams

Due to the large size and complexity of software, exhaustive testing becomes impossible. Hence, testing must be done in an optimized way keeping in mind factors, such as requirements of the customer, cost and time. For this, there is a need to generate test cases and exercise them to gain maximum throughput by uncovering defects. Test case/scenario prioritization is a well known and efficient technique to ensure the software quality. Prioritization of test scenarios helps in early detection of bugs. In this paper, we present an integrated approach and a prioritization technique to generate cluster-level test scenarios from UML communication and activity diagrams. In our approach, we first construct a tree representation of communication diagrams, and then a tree representation of activity diagrams. We convert them into an intermediate tree named as COMMACT tree. We, then carry out a post-order traversal of the constructed tree for selecting conditional predicates from the intermediate tree. Then, we propose an algorithm to generate test scenarios from the constructed tree. Next, the necessary information, such as method-activity sequence, associated objects, and constraint conditions is extracted from test scenario. The test sequences are a set of theoretical paths starting from initialization to end, while taking conditions (pre- and post-condition) into consideration. Each generated test sequence corresponds to a particular scenario of the considered use case. The third phase is to generate test scenarios from the tree satisfying the message–activity path test adequacy criteria. Preliminary results obtained on a case-study indicate that the technique is effective in extracting the critical scenarios from the communication and activity diagrams. Our approach generates redundant test scenarios and still achieves adequate test coverage.     

Independent field-oriented control of two split-phase induction motors from a single six-phase inverter

Split-phase (six-phase) induction motor stator windings consist of two sets of three phase windings, which are spatially phase separated by 30 electrical degrees. Due to mutual cancellation of the air gap flux for all the 6n/spl plusmn/1 (n=1,3,5...) order harmonic voltages, called zero sequence components, large harmonic currents are generated in the stator phases. Only the 12n/spl plusmn/1 (n=0,1,2,3...)-order harmonic voltage components contribute toward the air gap flux and electromagnetic torque production in the machine. In this paper, a novel scheme is proposed where two six-phase induction motors are connected in series with proper phase sequence so that the zero sequence component voltages of one machine act as torque and flux producing components for the other. Thus, the two six-phase motors can be independently controlled from a single six-phase inverter. A vector control scheme for the dual motor drive is developed and experimentally verified in this paper.     

Synthesis and spectroscopic studies on novel Cu(II)–Cu(II) binuclear adducts. EPR evidence for ferromagnetic interactions

EPR investigations on two solid complexes [Cu(1-amidino-O-2-methoxyethylurea)₂]₂(H₂O)₂(SO₄)₂ (1) and [Cu(1-amidino-O-2-ethoxyethylurea)₂]₂(H₂O)₂(SO₄)₂ (2) indicated the formation of ferromagnetically coupled binuclear complexes (S = 1) having the isotropic exchange interaction constant J values of 59 and 50 cm⁻¹. The angle between the Cu–Cu direction and the parallel direction (ξ) of the complex 1 has been evaluated. The IR studies suggest the presence of tetrahedral sulfate ion in the complexes. When the EPR spectra were recorded in the temperature range 300–475 K, it was observed that the triplet-state EPR signal disappeared completely and irreversibly at ca. 450 K for complex 1 and at ca. 475 K for complex 2 with the appearance of a new signal attributable to the mononuclear complex (S = 1/2).     

Power generation using cotton stalk-derived producer gas in diesel engines

In this study, the potential of cotton stalks as feedstock for a gasifier is analyzed. The emissions and performance characteristics of the gasifier–engine system is analyzed by running the engine at different loads. These characteristics of the dual fuel diesel engine are compared to those under different load conditions. Specific fuel consumption in the dual fuel mode of operation is favorable at all load conditions. CO emissions are much higher in the case of the dual fuel (diesel + gas) mode of operation as compared to that of diesel-only mode, and the level of NOx emissions is drastically reduced in the case of dual fuel mode.