Performance of an RTL contactor for gas-liquid systems: Effective interfacial area and volumetric mass transfer coefficient by oxidation of sodium sulphite solution

Effective interfacial area a and volumetric liquid-side mass transfer coefficient k_La of an RTL contactor were obtained at different stirring speeds by absorption of oxygen from air into 0.8 kmol/m³ sodium sulphite solution, in the presence of Co⁺⁺ ions. The values of a and k_La ranged from 80 to 150 m²/m³ and 0.0003 to 0.00053 s^?1, respectively, when stirrer speed was increased from 8 to 40 rpm. When k_L alone was evaluated, it was found to be practically constant, irrespective of stirring speed.     

Mechanisms of enhanced UV photosensitivity via hydrogen loading in germanosilicate glasses

Germanosilicate glasses soaked in high pressure hydrogen at low temperature exhibit markedly increased photoinduced refractive index changes when exposed to 248 nm UV radiation. The mechanisms involved include both photolytically and thermally driven reactions between hydrogen and germania, forming OH and deep UV absorbing species.<>     

Concept of Functionally Graded Materials for Advanced Thermal Barrier Coating Applications

This feature article explores the concept of creating functionally graded metal-ceramic composite microstructures for thermal barrier coatings used in gas-turbine applications. From a thermomechanical perspective, this concept offers the possibility of significantly improving the life and reliability of thermal barrier coatings. However, prior research reveals that progress has been somewhat limited because of the oxidative instability exhibited by some metal-ceramic composite microstructures. The present study addresses some of the materials criteria and research issues associated with preparing chemically stable, yet mechanically durable, graded metal-ceramic microstructures for realistic application environments.     

MIMO decision feedback equalization from an H/sup /spl infin// perspective

We approach the multiple input multiple output (MIMO) decision feedback equalization (DFE) problem in digital communications from an H/sup /spl infin// estimation point of view. Using the standard (and simplifying) assumption that all previous decisions are correct, we obtain an explicit parameterization of all H/sup /spl infin// optimal DFEs. In particular, we show that, under the above assumption, minimum mean square error (MMSE) DFEs are H/sup /spl infin// optimal. The H/sup /spl infin// approach also suggests a method for dealing with errors in previous decisions.     

Analysis and Optimization Study of Antenna Selection in Dual Hop Relay Networks over Weibull Fading Channels

Field experiments show that Weibull distribution can be considered as the most suitable distribution to model weak to high signal power levels in indoor and outdoor environments. Recently, Exponentiated Weibull which is a special case of Weibull fading, have been widely adopted in free-space optical communication systems to model weak and high levels of turbulence effects. Motivated from the increasing use of Weibull distribution, this paper studies the popular dual-hop amplify-and-forward relay network with joint transmit and receive antenna selection where closed form ergodic capacity, symbol error rate and outage probability expressions are derived for Weibull fading channels. With the help of high SNR analysis, diversity gain, array gain and optimum relay location are obtained. Finally, theoretical findings are validated by simulation results.     

Integrating UAHPL-DA systems with VLSI design tools to support VLSIDA courses

A complete operational environment established with the help of state-of-the-art tools, to support courses in design automation (DA) of VLSI circuits, is described. It was accomplished with the integration of two systems: (1) a DA system which automatically produces VLSI layouts of digital systems modeled in Universal Hardware Programming Language (UAHPL); and (2) a set of VLSI tools, which in addition to several other functions can be used for simulation and verification of layout designs. Compared with other approaches, the integrated DA system provides a very simple user interface, fast turnaround time, no restriction on the final structure of the layout, and simulation and verification of all phases of design. The new environment, called UAHPL-based VLSI DA, is excellent for teaching and research at universities     

Cuckoo search based resource optimization of datacenters

With advancements in virtualization technology, datacenters are often faced with the challenge of managing large numbers of virtual machine (VM) requests. Due to this large amount of VM requests, it has become practically impossible to search all possible VM placements in order to find a solution that best optimizes certain design objectives. As a result, managers of datacenters have resorted to the employment of heuristic optimization algorithms for VM placement. In this paper, we employ the cuckoo search optimization (CSO) algorithm to solve the VM placement problem of datacenters. Firstly, we use the CSO to optimize the datacenter for the minimization of the number of physical machines used for placement. Secondly, we implement a multiobjective CSO algorithm to simultaneously optimize the power consumption and resource wastage of the datacenter. Simulation results show that both CSO algorithms outperform the reordered grouping genetic algorithm (RGGA), the grouping genetic algorithm (GGA), improved least-loaded (ILL) and improved FFD (IFFD) methods of VM placement.     

Image noise level estimation based on higher-order statistics

Multimedia Tools and Applications - Noise level estimation is a required step for many preprocessing algorithms in computer vision such as image denoising. In this paper, a model-based technique...     

Setting and hardening of borogypsum-Portland cement clinker-fly ash blends. Studies on effects of molasses on properties of mortar containing borogypsum

The present work describes a study of setting and hardening of blends of borogypsum, fly ash, and Portland cement clinker (PC). The possibility of using borogypsum instead of natural gypsum in fly ash-cement matrix has been investigated through several tests. In addition, the effects of molasses on the setting times of cement and strength of the mortar were also studied. The setting times of the cement were retarded when the natural gypsum was replaced by borogypsum. Molasses exhibited a rather significant retarding effect when used in combination with borogypsum in cement. The inclusion of molasses to the system at a level of 0.1% resulted in a reduction in early strength of the mortar. However, it significantly enhanced the strength of the mortar after 7 days of curing age. In general, the cement prepared with borogypsum was found to have similar strength properties to those obtained with natural gypsum, and inclusion of molasses into the system significantly increased the strength of the sample after 7 days of curing age.     

High-pressure phase behavior in polyethylene/n-butane binary and polyethylene/n-butane/CO2 ternary systems

Solubility of polyethylene molecular weight standards (M_w = 2150, 16,400, 108,000, and 420,000 and M_w/M_n = 1.14, 1.16, 1.32, and 2.66, respectively) has been studied in near- and supercritical n-butane and n-butane/CO₂ mixtures at pressures up to 70 MPa. For each polyethylene/solvent system at selected compositions, demixing pressures have been determined using a high-pressure variable-volume view-cell at temperatures up to 200°C. Solutions in pure n-butane are found to display LCST (lower critical solution temperature)-type behavior. The behavior of the solutions in n-butane/CO₂ mixtures are observed to change from the LCST to the UCST (upper critical solution temperature) with increasing CO₂ content in the binary solvent. Sanchez–Lacombe theory has been used to model these systems. The predictions correctly describe the nature of the phase diagrams for both binary and ternary systems and the calculations are in reasonable agreement with experimental data. © 1994 John Wiley & Sons, Inc.