Direct printing of copper conductive micro-tracks by multi-nozzle electrohydrodynamic inkjet printing process

To overcome the limitation of low production speed of electrohydrodynamic (EHD) inkjet printing technology and to fabricate low cost electronic micro-structures, this paper presents the direct deposition of copper colloidal solution through the multi-nozzle EHD inkjet printing process. Multi-nozzle EHD inkjet printing head, consisting of five nozzles, was used for simultaneous printing of electrically conductive micro-tracks onto the glass substrate. Nozzle-to-nozzle distance and experimental conditions were optimized to prevent the interaction i.e., cross-talk between electrically charged neighboring jets. After sintering in inert (N₂ gas) atmosphere, printed tracks exhibited approximately five times larger resistivity (9.20 μΩ cm) than that of the bulk copper which is a remarkable achievement. These electrically conductive micro-tracks show the feasibility of multi-nozzle EHD inkjet printing technique using the copper nano-colloidal ink for low cost fabrication of microelectronic structures and devices.     

Performance of a Nongasketed Flange Joint under Combined Internal Pressure and Bending Loading

Performance of a bolted flange joint is characterized mainly due to its “strength” and “sealing capability.” A number of analytical and experimental studies have been conducted to study these characteristics only under internal pressure loading. A very limited amount of work is found in the literature under combined internal pressure and bending loading. Due to the ignorance of this external loading, i.e., bending loading, the optimized performance of the bolted flange joint cannot be achieved. The present design codes do not address the effects of bending loading on the structural integrity and sealing ability. To investigate joint strength and sealing capability under combined loading, an extensive comparative experimental and numerical study of a nongasketed flange joint is carried out and overall joint performance and behavior is discussed. Actual joint load capacity is determined under both the design and proof test pressure with maximum additional external bending loading that can be applied for safe joint performance. In addition, as experimentally it is impossible to test different flange joint sizes under combined loading application, hence finite element model developed and verified with the experimental results, presented in this paper can be used as base to study the behavior for different nongasketed flange joint sizes for different classes under combined pressure and bending loading.     

Stress appraisal in women with spinal cord injury: Supplementary findings through mixed methods.

A study was conducted to examine how women with spinal cord injury (SCI) perceive the stressors they encounter, and how cognitive appraisal is associated with coping and life satisfaction. Fifty women with SCI were interviewed regarding their experience with stress and coping. The interviews were then coded using a framework based on stress and coping theory (transactional model). The systematic application of quantitative methods to the coded interview data allowed for statistical analyses, which demonstrated that the context in which the women spoke about their experiences with various stressors was associated with coping strategies, time since injury, and life satisfaction. Although stress and coping are commonly seen as interacting constructs that influence quality of life outcomes, current findings suggest that appraisal of stressors in the context of loss (more common among women more recently injured) may have a direct impact on life satisfaction apart from any coping strategies put into effect. Interventions designed to facilitate coping with loss and enhance problem-solving skills, along with education about available resources, may foster a sense of empowerment after SCI and ultimately change how stressors are perceived and managed in order to dampen their negative impact on life satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nanoparticle surface as activation site

The immense surface-to-volume (S/V) ratio in nanoparticles leads to large surface energy density. These high densities play the role of sites for activities that are not triggered in bulk materials. Here we present some examples of such distinctive activities taking place at nanoparticle surfaces. Our first example involves the morphological changes in silkworm (Bombyx mori L.) nuclear polyhedrosis virus (BmNPV) brought about by lipophilic amorphous silica nanoparticles (LASN). Microscopy studies show that nanoparticles severely alter the structure of the virus envelope by a 'deflation' of the viral polyhedron and formation of elongated structures. The second example shows the spatial variation in aggregation potential with temperature, for dodecanethiol-capped Au nanoparticles on an amorphous polystyrene film surface. We find that on increasing the temperature from 32 degrees C to 50 degrees C the aggregating potential becomes almost completely confined to the film surface, whereas going over to 100 degrees C the confining potential is overcome and out-of-plane growth takes place. A tentative and qualitative explanation has been attempted.     

Numerical modeling the effects of overloading and underloading in fatigue crack growth

In this paper, the effects of overloading and underloading on fatigue crack growth were investigated. Numerical modeling was done by using finite element software. In this software, without using the remeshing technique, effect of crack tip plasticity in fatigue crack growth life was analyzed. Plasticity effects were considered by using three methods: COD method, U correction factor and J-integral. Calculated results for crack growth rates were compared with experimental data in literature. Results were obtained by COD method and U correction factor have good agreement but results form J-integral have not. We also study the effects of stress ratio (R) in plane stress and plane strain conditions. With increasing R, the fatigue life was increased. The extent of crack retardation is greater under plane stress than plane strain conditions. Underloading has not significant effects on fatigue crack growth rate. Underloading cause a little variation in plastic zones and so little effects on fatigue life.     

Experimental study of inlet manifold water injection on combustion and emissions of an automotive direct injection Diesel engine

This paper describes an experimental study conducted on a modern high speed common-rail automotive Diesel engine in order to evaluate the effects on combustion and pollutant emissions of water injected as a fine mist in the inlet manifold.     

Economics of hydrogen production and utilization strategies for the optimal operation of a grid-parallel PEM fuel cell power plant

This paper integrates the hydrogen production and utilization strategies with an economic model of a PEM fuel cell power plant (FCPP). The model includes the operational cost, thermal recovery, power trade with the local grid, and hydrogen management strategies. The model is used to determine the optimal operational strategy, which yields the minimum operating cost. The optimal operational strategy is achieved through estimation of the following: hourly generated power, thermal power recovered from the FCPP, power trade with the local grid, and hydrogen production. An evolutionary programming-based technique is used to solve for the optimal operational strategy. The model is tested using different seasonal load demands. The results illustrate the impact of hydrogen management strategies on the operational cost of the FCPP when subjected to seasonal load variation. Results are encouraging and indicate viability of the proposed model.     

Symbol error rate calculation and data pre‐distortion for 16‐QAM transmission over nonlinear memoryless satellite channels

This paper presents a simplified mathematical approach to evaluate the performance of any given circular constellation of 16‐level quadrature amplitude modulation (16‐QAM) in terms of symbol error rate (SER). Following this approach, with the aim to work with memoryless nonlinear satellite channels, a model is derived as a generalized form for both linear and nonlinear channels in the presence of down link additive white Gaussian noise (AWGN). The analysis provides means to calculate the optimal ring ratio (RR) and phase difference (PD) for several possible candidates of 16‐QAM circular constellations. The effects of RR and PD on the SER performance are investigated in the analysis. To overcome the nonlinear distortion, data pre‐distortion is taken into account in the study. The paper gives a general procedure for data pre‐distortion implementation for all circular 16‐QAM constellations. The analytical formulation has been extended for total degradation (TD) performance measure as a function of input back‐off (IBO) of the nonlinear amplifier. A SER performance‐comparison between different constellations for 16‐QAM systems has also been presented in this paper. The analytical results are validated by simulation. Copyright © 2006 John Wiley & Sons, Ltd.