Amine-terminated polysulfone as modifier for epoxy resin

The synthesis of carboxyl-terminated poly(ethylene glycol adipate) (CTPA) and amine-terminated poly(amide sulfone) (ATPS) based on the CTPA and 4,4′-diaminodiphenyl sulfone (DDS) is described. The products were characterized by IR and ¹³C-NMR spectroscopic analysis, nonaqueous titration, viscosity measurement, and solubility characteristics. The developed ATPS was incorporated as a modifier into the epoxy matrix and its effect was studied by DSC and DMTA. It was found that ATPS forms a compatible blend with epoxy and imparts flexibility to the epoxy matrix. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:901–907, 1997     

Studies on IPNS based on nitrile rubber and polyalkyl methacrylates

Sequential interpenetrating polymer networks (IPNs) based on nitrile rubber and various types of polyalkyl methacrylates such as poly(n-butyl methacrylate), poly(ethyl methacrylate), and poly(methyl methacrylate) were synthesized. The compositions of the IPNs could be varied by varying the reaction parameters such as swelling time and concentration of crosslinker. The tensile properties of the IPNs show that with increase in bulkiness of the ester group of the acrylates the tensile strength decreases, whereas elongation at break increases because of decreased stiffness of the acrylate phase. The dynamic modulus and loss tangent of the IPNs also show similar trend because of the above reason. All the IPNs were also tested for dynamic properties under multifrequency mode, and with the help of the WLF equation, the behavior of these IPNs in the frequency range of 1–10⁵ Hz were evaluated. The results showed reasonably high tan δ with good storage modulus in the entire frequency range for all the IPNs. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:549–554, 1997     

GaN nanorod Schottky and p-n junction diodes

Conductive atomic force microscopy has been used to characterize single GaN nanorod Schottky and p-n junction diodes. The ideality factor, reverse breakdown voltage, and the Schottky barrier height of individual nanorod diodes were compared to those from conventional thin-film diodes. Large-area contacts, enabling diodes with arrays of GaN nanorods in parallel, were also fabricated and their electrical characteristics investigated. The defect-free nature of the GaN nanorods and enhanced tunneling effects due to nanoscale contacts have been invoked to explain the electrical behavior of the nanorod diodes.     

Synthesis and characterization of AgI-Ag2O-SeO2 glass-nanocomposites embedded with beta-AgI and Ag2SeO3 nanocrystals

Glass-nanocomposites of compositions xAgI - (1 - x)(0.40Ag2O-0.60SeO2) for 0.15 < or = x < or = 0.30 were prepared by quenching the melt of the appropriate mixtures of the chemicals AgI, AgNO3 and SeO2. Differential scanning calorimetry (DSC) was employed to determine the glass transition and crystallization temperatures. The as-prepared samples were heat-treated above glass transition temperature to observe the growth of nanoparticles. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to explore the microstructure of these samples. These studies revealed the presence of beta-AgI and Ag2SeO3 nanocrystals in both the as-prepared and heat-treated samples. The particle size was found to decrease with the increase of AgI content in both cases. The heat-treated samples showed increased tendency of crystallization for the compositions with higher AgI content. The beta-alpha phase transition of AgI crystals was observed at approximately 147-149 degrees C for heat-treated samples. Fourier transform infrared (FTIR) spectra revealed that the basic structure of the glassy network remained invariant to change of AgI content as well as to heat-treatment.     

Solution of facility layout problems with pickup/drop-off locations using random search techniques

Due to non-polynomial hardness, the facility layout problem (FLP) becomes more critical when pickup/drop-off (P/D) locations are considered in the design of an open field layout under a manufacturing environment. This paper proposes an indigenous model of the facility layout problem based on random search techniques and its solution methodology using a genetic algorithm (GA), simulated annealing (SA) and a hybrid algorithm (HA). The paper illustrates the performance of different random search operating parameters in solving the facility layout problem considering P/D locations along the periphery of rectangular machine blocks. The preliminary experiments were carried out on three facility layout test problems having six, eight and ten machines in order to fix the different operating parameters such as crossover operator, crossover rate, initial temperature, temperature reduction factor, number of generations, population size, etc. The results of extensive preliminary experimentation were utilized to solve facility layout problems having 12 and 18 machines and, finally, were compared with the existing procedures in the literature. The experimental tables and related analysis performed via the solution methods by applying GA, SA and HA revealed that random-search-based modeling of FLP considering P/D and its solution as suggested in this paper is worth pursuing.     

Towards automating the discovery of certain innovative design principles through a clustering-based optimization technique

In this article, a methodology is proposed for automatically extracting innovative design principles which make a system or process (subject to conflicting objectives) optimal using its Pareto-optimal dataset. Such ‘higher knowledge’ would not only help designers to execute the system better, but also enable them to predict how changes in one variable would affect other variables if the system has to retain its optimal behaviour. This in turn would help solve other similar systems with different parameter settings easily without the need to perform a fresh optimization task. The proposed methodology uses a clustering-based optimization technique and is capable of discovering hidden functional relationships between the variables, objective and constraint functions and any other function that the designer wishes to include as a ‘basis function’. A number of engineering design problems are considered for which the mathematical structure of these explicit relationships exists and has been revealed by a previous study. A comparison with the multivariate adaptive regression splines (MARS) approach reveals the practicality of the proposed approach due to its ability to find meaningful design principles. The success of this procedure for automated innovization is highly encouraging and indicates its suitability for further development in tackling more complex design scenarios.     

Treatment of Department of Veterans Affairs primary care patients with posttraumatic stress disorder.

Posttraumatic stress disorder (PTSD) is common among Veterans Affairs (VA) primary care patients and may be managed via multiple treatment pathways. Using the Behavioral Model of Health Service Use (Anderson, 1995), this retrospective study based on medical chart review examined factors associated with three types of mental health treatment: intervention by a 1) primary care provider (PCP), 2) primary care-mental health integration (PC-MHI) provider, and 3) specialty mental health (SMH) provider. A second goal was to describe PTSD treatment services for patients not receiving SMH by detailing the content of mental health treatment provided by PCPs and PC-MHI providers. Electronic medical record data for a five year time period for 133 Veterans were randomly selected for review from a population 6,637 primary care patients with PTSD. Results indicated that the evaluated needs of participants (i.e., number of unique medical and psychiatric disorders) were associated with Veterans receiving more intensive services (i.e., SMH). PCPs commonly addressed patients' mental health concerns, but patients often declined referrals for mental health treatment. PC-MHI consultations most often focused on medication management and supportive psychotherapy. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A genetic algorithm based heat transfer analysis of a bloom re‐heating furnace

A heat transfer model, coupled with an optimization scheme has been presented in designing a re‐heating furnace typically used in the integrated steel plants. Numerical solution of the pertinent differential equations were coupled with the optimal settings of the burner and the velocity of the bloom, using biologically inspired genetic algorithms (GAs) and differential evolution (DE), which led to optimized temperature profiles satisfying bloom dropout temperature constraints. The ease of application and efficiency of solution methodology demonstrated in this paper suggest further application of GAs and DE to more complex engineering design problems.     

Experimental performance evaluation of a novel heat exchanger for a solar hot water storage system

The performance of a novel heat exchanger unit (‘Solasyphon’) developed for a solar hot water storage system was experimentally investigated. The ‘Solasyphon’ is a simple ‘bolt-on’ heat exchange unit that can be integrated externally to a traditional single-coil hot water cylinder (HWC) avoiding the costly replacement of an existing HWC with a twin-coil HWC. The installation cost of a ‘Solasyphon’ is lower compared to a traditional HWC thus offers greater cost effectiveness. A data acquisition system was designed to compare the thermal performance of an integrated ‘Solasyphon’ HWC with a traditional twin-coil HWC under controlled simulated conditions. The analysis was based on experimental data collected under various operating conditions including different primary supply temperatures (solar simulated); primary supply patterns and draw off patterns. The results indicated that the ‘Solasyphon’ delivered solar heated water directly to the top of the HWC producing a stratified supply at a useable temperature. Under variable solar conditions the ‘Solasyphon’ would transfer the heat gained by a solar collector to a HWC more efficiently and quickly than a traditional HWC. The ‘Solasyphon’ system can reduce installation costs by 10–40% and has a lower embodied energy content due to less material replacement.     

Comparison of multiobjective evolutionary algorithms: empirical results

In this paper, we provide a systematic comparison of various evolutionary approaches to multiobjective optimization using six carefully chosen test functions. Each test function involves a particular feature that is known to cause difficulty in the evolutionary optimization process, mainly in converging to the Pareto-optimal front (e.g., multimodality and deception). By investigating these different problem features separately, it is possible to predict the kind of problems to which a certain technique is or is not well suited. However, in contrast to what was suspected beforehand, the experimental results indicate a hierarchy of the algorithms under consideration. Furthermore, the emerging effects are evidence that the suggested test functions provide sufficient complexity to compare multiobjective optimizers. Finally, elitism is shown to be an important factor for improving evolutionary multiobjective search.