Microwave-assisted synthesis and characterization of tin oxide nanoparticles

Tin oxide nanoplatelets (SnO) and nanoparticles (SnO₂) were prepared by microwave assisted technique with an operating frequency of 2.45 GHz. This technique permits to produce gram quantity of homogeneous nanoparticles in just 10 min. The crystalline size was evaluated from XRD and found to range from 26 to 34 nm. SEM and TEM analyses showed that the nanoparticles present a platelet-like shaped particle or, a pseudo spherical morphology, after calcination at moderate temperature during which the phase transformation from SnO to SnO₂ takes place. Additional FT-IR, density and resistivity measurements were also presented.     

Transforming generate-and-test programs to execute under committed-choice AND-parallelism

This paper concerns the exploitation of user transparent inherent parallelism of pure Prolog programs using program transformation. We describe a novel paradigmenumerate-and-filter for transforming generate-and-test programs for execution under the committed-choice model extended to incorporate multiple solutions based on set enumeration. The paradigm simulates OR-parallelism by stream AND-parallelism integrating OR-parallelism, AND-parallelism, and stream parallelism. Generate-and-test programs are classified into three categories:simple generate-and-test, recursively embedded generate-and-test, and deeply intertwined generate-and-test. The intermediate programs are further transformed to reduce structure copying and metacalls. Algorithms are presented and demonstrated by transforming the representative examples of different classes of generate-and-test programs to Flat Concurrent Prolog equivalents. Statistics show that the techniques are efficient.Funded in part by Cleveland Advanced Manufacturing Program through the State of Ohio as a part of its core research program grant to Center of Automation and Intelligent Systems Research, Case Western Reserve University and NSF equipment grant CDA-8820390 to Kent State University.     

Chronic growth faltering amongst a birth cohort of Indian children begins prior to weaning and is highly prevalent at three years of age

Background  

Poor growth of children in developing countries is a major public health problem associated with mortality, morbidity and developmental delay. We describe growth up to three years of age and investigate factors related to stunting (low height-for-age) at three years of age in a birth cohort from an urban slum.     

Provably good multiprocessor scheduling with resource sharing

We present a 12(1+3R/(4m)) competitive algorithm for scheduling implicit-deadline sporadic tasks on a platform comprising m processors, where a task may request one of R shared resources.     

Parametric sensitivity and runaway in chemical reactors

In certain regions of operating conditions, chemical reactors may exhibit parametric sensitivity; i.e., small changes in one or more of the reactor input parameters lead to much larger changes in the output variables. Since such behaviour leads to deleterious performance, it is of practical interest to identify regions of parametric sensitivity in the reactor parameter space. Until recently, this could be done only to describe thermal runaway, and only for those systems where a temperature profile could be defined. Both of these limitations can be removed by consideringthe generalized criterion for parametric sensitivity, whereby sensitivity ofany output of the model toany input can be treated. Applications of the generalized criterion are discussed, with specific examples including pseudohomogeneous and heterogeneous model tubular reactors, a nonisothermal CSTR, and a polymerization reactor. Dedicated to Dr L K Doraiswamy — Gentleman, Scholar, Friend — on his sixtieth birthday.     

Reliability and MTTF analysis of a non repairable parallel redundant complex system under hardware and human failures

This paper deals with the evaluation of point-wise availability and M.T.T.F., of a two-unit standby redundant electronic equipment, incorporating the concept of human failures. Single service facility is available for the service of constant failure. Using the supplementary variable technique, general equations are set up for deriving the above two measures. In addition, steady state availability is also derived and some important graphs have been sketched in the end.     

Reliability and MTTF evaluation of a repairable complex system under waiting

This paper deals with the reliability and mean time to failure (MTTF) evaluation of a complex system under waiting incorporating the concept of hardware failure and human error. Failure rates of the complex system follow exponential time distributions, whereas repair follows a general repair time distribution. Laplace transforms of various state probabilities have been evaluated and then reliability is obtained by the inversion process. A formula for variance of time to failure has also been developed. A particular case is also given to highlight some important results. Moreover, various plots have been sketched at the end.     

Effect of pulsing on reaction outcome in a gas–liquid catalytic packed-bed reactor

A novel experiment is described for studying the effect of flow regime on reaction outcome for a consecutive-parallel reaction. By taking advantage of the convective nature of disturbances that grow into pulses in gas–liquid packed-bed reactors, it is shown that it is possible to compare reaction behavior for pulsing and trickling at the same flow rates. This contrasts previous studies where effects of regime were found, but at different flow rates. This experiment is accomplished by packing the column with mostly inert particles and confining the catalytically active region either near the inlet, where pulses have not yet formed, or near the end where they have developed. It is found that for the reaction of phenylacetylene to styrene and ethylbenzene over a platinum/alumina catalyst, where pulses are present in the bottom of the reactor but not at the top, about a 15% increase in styrene concentration, as an intermediate, occurs under pulsing conditions.