PSO-DS: a scheduling engine for scientific workflow managers

Cloud computing, an important source of computing power for the scientific community, requires enhanced tools for an efficient use of resources. Current solutions for workflows execution lack frameworks to deeply analyze applications and consider realistic execution times as well as computation costs. In this study, we propose cloud user–provider affiliation (CUPA) to guide workflow’s owners in identifying the required tools to have his/her application running. Additionally, we develop PSO-DS, a specialized scheduling algorithm based on particle swarm optimization. CUPA encompasses the interaction of cloud resources, workflow manager system and scheduling algorithm. Its featured scheduler PSO-DS is capable of converging strategic tasks distribution among resources to efficiently optimize makespan and monetary cost. We compared PSO-DS performance against four well-known scientific workflow schedulers. In a test bed based on VMware vSphere, schedulers mapped five up-to-date benchmarks representing different scientific areas. PSO-DS proved its efficiency by reducing makespan and monetary cost of tested workflows by 75 and 78%, respectively, when compared with other algorithms. CUPA, with the featured PSO-DS, opens the path to develop a full system in which scientific cloud users can run their computationally expensive experiments.     

Multiobjective optimization of an industrial semibatch nylon 6 reactor

Multiobjective Pareto optimal solutions have been generated for three grades of nylon 6 being produced in an industrial semibatch reactor. The optimal operating conditions (called preferred solutions) for these three batches are easy to implement and lead to substantial improvements over current practice. The technique used is quite general and can easily be applied to improve the operation of other industrial polymerization reactors or design better (new) reactors. Good mathematical models, which account for the important physicochemical aspects actually operative in a reactor and which have been tested on industrial data, are a prerequisite for such optimization studies. © 1995 John Wiley & Sons, Inc.     

Compact two-dimensional coarse-positioner for scanning probe microscopes

We report on the design and fabrication of a compact two-dimensional xy-positioner for scanning probe microscopes. This positioner uses three piezoelectric bimorphs in flexing or length-change mode by appropriate selection of electrodes and voltage polarities. One end of these bimorphs is fixed to a rectangular metal frame while on each of the free ends two sapphire disks are fixed which can slide against the polished plates of a platform movable in the xy-plane. For moving the platform by one step, the bimorphs are deformed sequentially in one mode and they are brought back to their undeformed state simultaneously. The motion of the positioner has been tested with an optical microscope and a homemade scanning tunneling microscope.     

Performance modeling in critical engineering systems using RAM analysis

Reliability, availability and maintainability (RAM) analysis of system is helpful in carrying out design modifications, if any, required to achieve minimum failures or to increase mean time between failures (MTBF) and thus to plan maintainability requirements, optimize reliability and maximize equipment availability. To this effect, the paper presents the application of RAM analysis in a process industry. Markovian approach is used to model the system behavior. For carrying out analysis, transition diagrams for various subsystems are drawn and differential equations associated with them are formulated. After obtaining the steady state solution the corresponding values of reliability and maintainability are estimated at different mission times. The computed results are presented to plant personnel for their active consideration. The results proved helpful to them for analyzing the system behavior and thereby to improve the system performance considerably by adopting and practicing suitable maintenance policies/strategies.     

Progress in multimodality imaging: truly simultaneous ultrasound and magnetic resonance imaging

Multimodality medical imaging takes advantage of the strengths of different imaging modalities to provide a more complete picture of the anatomy under investigation. Many complementary modalities have been combined to form such systems and some are gaining use clinically. One combination that has not been developed, in large part due to technical difficulties, is a combined magnetic resonance (MR) and ultrasound (US) imaging system. Such a system offers the potential to combine the strengths of these modalities in a wide range of diagnostic and therapeutic applications. The goal of this study was to evaluate the feasibility of performing simultaneous multimodality US and MR imaging. An US imaging system capable of operation in a clinical MR imager was developed, and methods to perform simultaneous imaging were investigated. Simultaneous imaging was feasible without any mutual interference by either filtering the transmitted and received US signal, or by synchronizing data acquisition between the two imaging systems. Spatial registration between the two modalities was achieved by using a reference phantom with implanted glass beads in orthogonal planes. Excellent agreement was observed between spatial measurements of an object made with both modalities, and the feasibility of using this system in vivo was demonstrated in a rabbit model. Simultaneous US and MR imaging is achievable, and can provide complementary information about an object under investigation. This demonstration of technical feasibility and the development of a prototype system open up the potential to investigate the promising clinical applications of this combined technology.     

Synthesis and characterization of polysiloxanes for controlled release of 2-pyridine aldoxime–chloride

A number of polysiloxanes and their copolymers were synthesized by hydrolytic polycondensation of dialkyl (ary) dichlorosilane or their mixtures in a saturated solution of NaCl in water at low temperature (0–5°C). These polysiloxanes were characterized by intrinsic viscosity, infrared and nuclear magnetic resonance spectroscopy. 2-Pyridine aldoxime–chloride (PAM–Cl) was incorporated into these polysiloxanes, followed by crosslinking with tetraethoxysilane using dibutyltindilaurate as catalyst. The effect of pH on in vitro release rate of PAM–Cl from polysiloxane matrices was investigated in phosphate buffer of pH 3.0, 7.4, and 10.0 at 37°C using an ultraviolet spectrophotometer. Transport parameters like the order of release and diffusion coefficients for these systems (polysiloxane—PAM–Cl) were also calculated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1837–1846, 1998     

An insight into spray pulsed reactor through mathematical modeling of catalytic dehydrogenation of cyclohexane

A mathematical model has been developed to study the impact of nozzle-catalyst distance and bulk gas temperature on the conversion and hydrogen evolution rate in a spray pulse reactor. The effects of reactor configuration and operating parameters on conversion and evolution rate were predicted with more than 90% accuracy. Reactor optimization and sensitivity analysis were carried out and an optimal design of nozzle-catalyst distance 5 cm and bulk gas temperature of 50 °C were proposed. The optimized design was predicted to increase the conversion from approximately 32–74%. The model could be in general used for designing any endothermic heterogeneous catalytic reaction in a spray pulse reactor.     

Guest–host interaction in ferroelectric liquid crystal–nanoparticle composite system

The present paper deals with the characterization of a ferroelectric liquid crystal–nanoparticle (FLC–NP) composite system. The dielectric, electrical and polarization property of the FLC–NP composite system have been studied as a function of temperature and frequency. Ferroelectric Cu-doped ZnO (Cu–ZnO) nanoparticles have been added to the pure ferroelectric liquid crystal (FLC) Felix 17/100. The nanoparticles are bigger in size as compared to FLC molecules; therefore, they distort the existing geometry of FLC matrix and set up an antiparallel correlation with the dipole moments of the host FLC molecules. This antiparallel correlation of guest–host geometry reduces the net ferroelectricity of the composite system and modifies all the physical properties of the pure FLC. The change in properties has been analysed and explained in the light of guest–host interaction.     

Media as Educator,Media as Disruptor: Conceptualizing the Role of Social Context in Media Effects

We document how social contexts serve to refract media effects. We theorized the relationship between media use and individual‐level knowledge (and attitude) would be stronger when community‐level knowledge (and attitude) was low than when it was high. Data come from a national survey (N = 12,608 women and 1,237 men) conducted in Nepal. Knowledge and stigma toward people living with HIV were the 2 dependent variables. Hypotheses were tested 12 times: across the use of 3 media (newspaper, radio, television) × 2 study outcomes (knowledge and attitudes) × 2 genders. Predicted interactions were supported in 9 of the 12 tests. Findings point to the need to take into account the role of community factors in theorizing about media effects.