Effect of epitaxial realignment on the leakage behavior of arsenic-implanted,as-deposited polycrystalline Si-on-single crystal Si diodes

When dopants are indiffused from a heavily implanted polycrystalline silicon film deposited on a silicon substrate, high thermal budget annealing can cause the interfacial “native” oxide at the polycrystalline silicon-single crystal silicon interface to break up into oxide clusters, causing epitaxial realignment of the polycrystalline silicon layer with respect to the silicon substrate. Anomalous transient enhanced diffusion occurs during epitaxial realignment and this has adverse effects on the leakage characteristics of the shallow junctions formed in the silicon substrate using this technique. The degradation in the leakage current is mainly due to increased generation-recombination in the depletion region because of defect injection from the interface.     

Simulation of single phase non-Newtonian flow characteristics of heavy crude oil through horizontal pipelines

The effect of diameter, velocity, and temperature on flow properties of heavy crude oil in three horizontal pipelines using computational fluid dynamics (CFD) was studied. The flow characteristics were simulated by using CFD software, ANSYS Fluent 6.2. The mesh geometry of the pipelines having inner diameter of 1, 1.5, and 2 inch were created by using Gambit 2.4.6. From grid independent study, 221, 365 mesh sizes were selected for simulation. The CFD ANSYS Fluent 6.2 Solver predicted the flow phenomena, pressure, pressure drop, wall shear stress, shear strain rate, and friction factor. A good agreement between experimental and CFD simulated values was obtained.     

Multiple-band large-signal characterization of millimeter-wave double avalanche region transit time diode

A large-signal method based on non-sinusoidal voltage excitation model is used to study the DC and RF characteristics of Double Avalanche Region (DAR) Silicon Transit Time diode. A large-signal simulation program based on drift-diffusion model is developed for this study. The simulation results show the existence of several distinct negative conductance bands in the admittance characteristics separated by positive conductance. Thus the DAR device is capable of delivering RF power not only at the design frequency but also at several frequency bands higher than the design frequency band in the mm-wave regime. A comparative study with DDR Si device designed to deliver RF power at a particular mm-wave frequency band shows that DAR Si device is capable of delivering significantly higher RF power not only at the designed mm-wave frequency band, but also at higher frequency bands.     

Role of methods of blending on polymer–polymer compatibility

The role of methods of blend preparation on polymer-polymer compatibility was investigated. Three different types of methods of blending, such as solution-casting, melt-mixing, and coprecipitation, were applied for three types of blend systems, viz., poly(vinyl chloride-co-vinyl acetate) (VYHH)/polystyrene (PS), VYHH/poly(styrene-co-acrylonitrile) (SAN), and VYHH/poly(methyl methacrylate) (PMMA) by measuring their glass transition temperatures (T_g) by a differential scanning calorimeter (DSC). It has been found that compatibility of the polymers depends on the method of blending and compatibility also varies from one blend system to another. Among the various types of blending methods, the coprecipitation method of blending gives the best compatibility result. © 1996 John Wiley & Sons, Inc.     

Studies on sulfur vulcanization of natural rubber accelerated combinedly with 2-mercaptobenzothiazole and diphenylguanidine both in presence and absence of dicumyl peroxide

Sulfuration of natural rubber (NR) by the binary accelerator 2-mercaptobenzothiazole (MBT) and diphenylguanidine (DPG) both in presence and in absence of ZnO and stearic acid with or without dicumylperoxide (DCP) was studied in detail. It was observed that the rate of decomposition of DCP in presence of both MBT and DPG is quite similar to that with MBT alone. The reduction of crosslinking depends also on MBT only. Through DPG has no influence on the decomposition rate, it reacts with MBT during the vulcanization process and suppresses the retardation caused by MBT on the DCP vulcanization. In accordance with the initial additiveness of crosslinking in systems containing DCP, the free sulfur decrease, and the rapidity of crosslink formation the vulcanization process of MBT-DPG-S-NR systems was interpreted in terms of a polar mechanism induced by the complex MSH₂NR′R″. In mixtures containing DCP together with sulfur, MBT, DPG, ZnO, and stearic acid, the initial stage of crosslinking is additive as indicated by a mixed reaction as well as by a methyl iodide treatment of the vulcanizates. Comparison with single accelerators shows a pronounced synergistic effect. This is because of the enhanced activity of the MBT-ZnO-stearic acid complex due to DPG which also induces polar sulfuration of NR by forming the active complex MSH₂NR′R″. In presence of ZnO and stearic acid, DCP cannot increase the net crosslink density but suppresses the reversion so much pronounced in its absence.     

Evaluation of Enhanced Heat Transfer Within a Four Row Finned Tube Array of an Air Cooled Steam Condenser

Air cooled steam condensers (ACSC) consist of finned-tube arrays bundled in an A-frame structure. Inefficient performance under extreme temperature operating conditions is a common problem in ACSCs. The purpose of this study was to improve the heat transfer characteristics of an annular finned-tube system for better performance in extreme climatic conditions. Perforations were created on the surface of the annular fins to increase heat transfer coefficient (h). Mesh generation and finite volume analyses were performed using Gambit 2.4.6 and Fluent 6.3 with an RNG k–? turbulent model to calculate pressure drop (ΔP), heat flux (q), and heat transfer coefficient (h). Solid (no perforations) finned-tubes were simulated with free stream velocity ranging between 1 m/s–5 m/s and validated with the published data. Computations were performed for perforations at 30° interval starting at ±60°, ±90°, ±120°, ±150°, and ±180° from the stagnation point. Five cases with single perforation and three cases with multiple perforations were evaluated for determining the maximum q and h, as well as minimum ΔP. For the perforated case (perforations starting from 60° at interval of 30°), the fin q and h performance ratios increased by 5.96% and 7.07%, respectively. Consequently, the fin ΔP performance ratio increased by 11.87%. Thus, increased q and h is accompanied with a penalty of higher ΔP. In contrast, a single perforation location at 120° provided favorable results with a 1.70% and 2.23% increase in q and h performance ratios, respectively, while there was a relatively smaller increase (only 1.39%) of ΔP performance ratio. Perforations in the downstream region at ±120°, ±150°, and ±180° also resulted in a similar favorable outcome. Furthermore, the spacing of the fins along the arms of an A-frame ACSC was altered to decrease ΔP across the finned-tube array. Fin spacing in the A-frame structure with sparsely spaced fins in the center resulted in a 1.80% reduction in ΔP. Thus, penalty in ΔP for a perforated fin can possibly be offset by changing the fin spacing along the arms of an A-frame structure.     

A Wide Learning Approach for Interpretable Feature Recommendation for 1-D Sensor Data in IoT Analytics

Machine Intelligence Research - This paper presents a state of the art machine learning-based approach for automation of a varied class of Internet of things (IoT) analytics problems targeted on...     

My words for your pizza: An analysis of persuasive narratives in online crowdfunding

We analyze charity requests registered on the Random Acts of Pizza online community and examine the content of postings and non-content characteristics to identify features that are associated with the success of donation. We find that the presence of rational and credible appeals in a message increases the likelihood of receiving a donation, whereas the mere presence of negative emotional appeal does not do so. Our research is useful for those who like to make persuasive charity requests on online platforms.