Introducing a Novel Hybrid Machine Learning Model and Developing its Performance in Estimating Water Quality Parameters

Water Resources Management - For the first time, a novel hybrid machine learning model named the least-squares support vector machine-arithmetic optimization algorithm (LSSVM-AOA) was proposed. The...     

Phonon Bottleneck and Auger Recombination Effect on the Perfermance of a Self -assembled Quantum Dot Laser

Silicon - Considering the excited state and the standard rate equations, this study provides a new circuit model for a self-assembled quantum dot laser made by InGaAs/GaAs and investigates the...     

Conventional vs. Temperature-Gradient Transient Liquid Phase Bonding of Stainless Steel 304 Using a Multi-component (Fe–Ni–Mo–B) Filler Metal

Metallurgical and Materials Transactions A - The application of the multi-component Fe-based filler metals (FMs) for transient liquid phase (TLP) bonding of AISI 304 austenitic stainless steel has...     

Characterization,microstructure and corrosion behavior of magnesia refractories produced from recycled refractory aggregates

This paper aims to report the results of some investigations carried out in Iranian steel industries to reuse the spent magnesia graphite refractory bricks in the forms of the new shaped and unshaped magnesia refractories. Economical aspects of recycling and minimizing the environmental effects of spent refractories landfills were the basic goals of this research. The spent MgO–C refractory bricks from electric arc (EAF) and ladle (LF) furnaces were analyzed in terms of microstructural and chemical properties. Different samples were prepared from natural sintered magnesia and 10–30 wt.% of recycled aggregates in the forms of magnesia refractory brick and ramming mix and their physical and mechanical properties were evaluated. Also the slag corrosion behavior and microstructural properties of corroded samples were investigated. The results showed that the addition of up to 30 wt.% of recycled aggregates had no negative effects on the properties of magnesia refractories.     

Experimental Investigation on Flow Boiling Heat Transfer and Pressure Drop of HFC-134a inside a Vertical Helically Coiled Tube

An investigation on flow boiling heat transfer and pressure drop of HFC-134a inside a vertical helically coiled concentric tube-in-tube heat exchanger has been experimentally carried out. The test section is a six-turn helically coiled tube with 5.786-m length, in which refrigerant HFC-134a flowing inside the inner tube is heated by the water flowing in the annulus. The diameter and the pitch of the coil are 305 mm and 45 mm, respectively. The outer diameter of the inner tube and its thickness are respectively 9.52 and 0.62 mm. The inner diameter of the outer tube is 29 mm. The average vapor qualities in test section were varied from 0.1 to 0.8. The tests were conducted with three different mass velocities of 112, 132, and 152 kg/m²-s. Analysis of obtained data showed that increasing of both the vapor qualities and the mass fluxes leads to higher heat transfer coefficients and pressure drops. Also, it was observed that the heat transfer coefficient is enhanced and also the pressure drop is increased when a helically coiled tube is used instead of a straight tube. Based on the present experimental results, a correlation was developed to predict the flow boiling heat transfer coefficient in vertical helically coiled tubes.     

The isomerization kinetics of lactose to lactulose in the presence of sodium hydroxide at constant and variable pH

Lactulose (4-O-β-d-galactopyranosyl-d-fructose) is a synthetic disaccharide. Unique characteristics of lactulose have resulted in its wide use in pharmaceutical and food industries. It is produced by isomerization of lactose in an alkaline medium. The purpose of this work is to investigate the kinetics of lactose to lactulose isomerization in the presence of sodium hydroxide in constant and variable pH condition. The experiments were carried out at three temperatures (50, 60 and 70 °C) and three pH values (10, 10.5 and 11). The effect of different parameters such as temperature, pH and time on the reaction rate, conversion, sugar concentration and maximum conversion of lactose to lactulose were investigated. The experimental results were then used to calculate the rate constants and activation energies. The effects of temperature and pH on rate constants were also investigated. Finally the experimental data were compared to kinetic model predictions.     

A Project Management Training Program

In March 1998, the City of Los Angeles, Bureau of Engineering, completed a nine-month training effort including over 30,000 hours of project management training for over 1,000 employees. This work documents the challenges faced and the solutions formulated during the course of the training. The two separate needs assessments done prior to developing the training program are explained. The development of the course contents for each of the three elements included in the training program—system optimization, project management technical tools, and human relations∕organizational development training—is described. The multiple-level training assessment processes of measuring the instruction, measuring the learning, maintaining the learning, and utilizing the learning are explained and illustrated with examples and results. The lessons learned in managing the training effort, particularly with respect to the logistics of training so many people in such a short amount of time, are documented for managers facing similar large scale training programs.     

Coherent differential absorption lidar measurements of CO2

A differential absorption lidar has been built to measure CO2 concentration in the atmosphere. The transmitter is a pulsed single-frequency Ho:Tm:YLF laser at a 2.05-microm wavelength. A coherent heterodyne receiver was used to achieve sensitive detection, with the additional capability for wind profiling by a Doppler technique. Signal processing includes an algorithm for power measurement of a heterodyne signal. Results show a precision of the CO2 concentration measurement of 1%-2% 1sigma standard deviation over column lengths ranging from 1.2 to 2.8 km by an average of 1000 pulse pairs. A preliminary assessment of instrument sensitivity was made with an 8-h-long measurement set, along with correlative measurements with an in situ sensor, to determine that a CO2 trend could be detected.     

Improved Krill Algorithm for Reservoir Operation

Much of the world is facing water scarcity during one or the other part of the year. Hence, water resources management and optimal operation of water resources system take on added importance these days. This study introduces an improved version of krill algorithm for reservoir operation. The algorithm is based on adding an onlooker search mechanism to avoid being trapped in local optima and then updating its position. The new krill algorithm is tested using a case study for irrigation management. The computation time is 33 s for the new algorithm but is 54, 59, and 60 s for krill algorithm, particle swarm optimization and genetic algorithm, respectively. Also, the improved krill algorithm can meet 97% of irrigation demands and has the lowest value of vulnerability index among genetic algorithm, particle swarm optimization, and simple krill algorithm. Also, the average solution of improved krill algorithm is close to the global solution. Results indicate that the improved krill algorithm has high potential for application in water resource management.     

Application of molecularly imprinted hydrogel for the preparation of lactose‐free milk

BACKGROUND: A variety of lactose imprinted hydrogels were prepared and their binding properties were studied in comparison with blank non‐imprinted hydrogel. Methacrylamide and ethylene glycol dimethacrylate were used as functional monomer and cross‐linker, respectively. Dimethylsulfoxide was also applied as polymerisation solvent. RESULTS: Different template/monomer ratios were studied and the optimised imprinted hydrogel (MIP₂), with a lactose/methacrylamide ratio of 1:8, was selected in a rebinding test. In Scatchard analysis of MIP₂‐lactose interactions, the dissociation constant and maximum binding sites were 0.33 mmol L^?1 and 67.76 µmol g^?1 hydrogel, respectively. The selectivity of MIP₂ for lactose in aqueous media was also evaluated in comparison with different mono‐ and disaccharides. The data showed that the affinity of MIP₂ for lactose is significantly higher than other saccharides. The imprinted hydrogel was finally used as a sorbent for separation of lactose from milk. CONCLUSIONS: The results indicated that MIP₂, as an optimised imprinted hydrogel, can effectively bind lactose and decrease its concentration in milk. Copyright © 2012 Society of Chemical Industry