Influence of coating on the thermal resistance of a Ni-Based superalloy

In this paper, the influence of M-CrAlY polycrystalline coating on the thermal fatigue behavior of a Nickel-base superalloy has been investigated. A special device using a rotating bending machine and two thermal sources has been used to perform thermo-mechanical tests. The two thermal sources have been set to obtain temperature variations between 750 and 1120 °C in the central part of the specimens, with a frequency of 0.1 Hz. The results showed a deleterious effect of the coating on the fatigue resistance. Numerical simulations have been carried out on SAMCEF to determine the thermo-mechanical field of the so-tested specimens. Calculated thermo-mechanical cycles of critical sites are associated with microstructure evolution and damage by cracking observed on the specimens. Damage mechanisms related to the presence of coating are discussed

Factors Associated with The Use of Antenatal Care in East Sumba, East Nusa Tenggara

Background: Antenatal care (ANC) is very important to pregnant women as it helps prevent mother and child mortality, prevent complications, helps foster a good relationship between the husband and wife, mother and child and father. Good antenatal care includes regular screening which can detect and prevent early complications such as hypertension and pregnancy diabetes; both of which can dramatically affect the fetus. Early detection means regular monitoring and treatment. This study aimed to analyze factors associated with the use of ANC in East Sumba, East Nusa Tenggara. Subjects and Method: This was an cross sectional study conducted in East Sumba, East Nusa Tenggara. A sample of 254 pregnant women were selected for this study by simple random sampling. The dependent variable was use of ANC. The independent variables were being a housewife, receiving husband's support, and social support. The data were collected by questionnaire and analyzed by a multiple logistic regression. Results: The use of ANC was associated with being a housewife (b= 0.88; 95% CI= 1.30 to 4.48; p= 0.005), receiving husband's support (b= 0.72; 95% CI= 0.25 to 0.95; p= 0.035), and social support (b= 1.52; 95% CI= 0.10 to 0.51; p<0.001). Conclusion: The use of ANC is associated with being a housewife, receiving husband's support and social support. Keywords: housewife, husband's support, social support, antenatal care, utilizatio

Hybridization and speciation in angiosperms: a role for pollinator shifts?

The majority of convincingly documented cases of hybridization in angiosperms has involved genetic introgression between the parental species or formation of a hybrid species with increased ploidy; however, homoploid (diploid) hybridization may be just as common. Recent studies, including one in BMC Evolutionary Biology, show that pollinator shifts can play a role in both mechanisms of hybrid speciation

The Effect of Perceived Threat on Hypertension Preventive Behavior in Kupang, East Nusa Tenggara

Background: The prevalence of hypertension has increased annually in Kupang, East Nusa Tenggara. Hypertension is hypothesized to be influenced by behavior and lifestyle. This study aimed to determine the effect of perceived threat on hypertension preventive behavior, using health belief model. Subjects and Method: This was an analytic observational study with a cross-sectional design. This study was conducted in Kupang, East Nusa Tenggara. A sample of 180 study subjects was selected for this study by multistage random sampling. The dependent variable was hypertension preventive behavior. The independent variable was perceived threat. The data were measured by questionnaire and analyzed by path analysis. Results: Hypertension preventive behavior increased with stronger perceived threat (b= 4.07; p= 0.084). Conclusion: Hypertension preventive behavior increases with stronger perceived threat. Keywords: hypertension, preventive behavior, perceived threa

Crack fronts and damage in glass at the nanometer scale

We have studied the low speed fracture regime for different glassy materials with variable but controlled length scales of heterogeneity in a carefully mastered surrounding atmosphere. By using optical and atomic force microscopy (AFM) techniques we tracked in real-time the crack tip propagation at the nanometer scale on a wide velocity range (mm/s - pm/s and below). The influence of the heterogeneities on this velocity is presented and discussed. Our experiments reveal also -for the first time- that the crack progresses through nucleation, growth and coalescence of nanometric damage cavities within the amorphous phase. This may explain the large fluctuations observed in the crack tip velocities for the smallest values. This behaviour is very similar to what is involved, at the micrometric scale, in ductile fracture. The only difference is very likely due to the related length scales (nanometric instead of micrometric). Consequences of such a nano-ductile fracture mode observed at a temperature far below the glass transition temperature in glass is finally discussed.Comment: 12 pages, 8 figures, submitted to Journal of Physics: Condensed Matter; Invited talk at Glass and Optical Materials Division Fall 2002 Meeting, Pittsburgh, Pa, US

CONSIDERATIONS ON THE USE OF ELECTRIC MOTORVIBRATORS AS DRIVE SYSTEMS FOR GRAVITATIONAL SEPARATORS

The cleaning of cereal seeds represent an essential operation of the conditioning chain.Taking into account all considerations, the experts attention has been drawn by the study of phenomena which influence upon the impurities separation process, aiming at a maximum reduction impurities. The paper presents the constructive and functional scheme of an gravitational separator driven by means of non balanced vibration generating systems known under the trade name of electrical motovibrators and also the constructive scheme of these, in view of theirs utilisation with best results for the drive of vibrating sieves. At the end of the paper are presented the advantages of using these types of acting systems for gravitational separators

Serializing the Parallelism in Parallel Communicating Pushdown Automata Systems

We consider parallel communicating pushdown automata systems (PCPA) and define a property called known communication for it. We use this property to prove that the power of a variant of PCPA, called returning centralized parallel communicating pushdown automata (RCPCPA), is equivalent to that of multi-head pushdown automata. The above result presents a new sub-class of returning parallel communicating pushdown automata systems (RPCPA) called simple-RPCPA and we show that it can be written as a finite intersection of multi-head pushdown automata systems

Spiking Neural P Systems: A Short Introduction and New Normal Forms

Spiking neural P systems are a class of P systems inspired from the way the neurons communicate with each other by means of electrical impulses (called \spikes"). In the few years since this model was introduced, many results related to the computing power and e ciency of these computing devices were reported. The present paper quickly surveys the basic ideas of this research area and the basic results, then, as typical proofs about the universality of spiking neural P systems, we present some new normal forms for them. Speci cally, we consider a natural restriction in the architecture of a spiking neural P system, to have neurons of a small number of types (i.e., using a small number of sets of rules). We prove that three types of neurons are su cient in order to generate each recursively enumerable set of numbers as the distance between the rst two spikes emitted by the system; the problem remains open for accepting SN P systems. The paper ends with the complete bibliography of this domain, at the level of April 2009.Ministerio de Educación y Ciencia TIN2006-13452Junta de Andalucía P08-TIC-0420

On the Size Complexity of Non-Returning Context-Free PC Grammar Systems

Improving the previously known best bound, we show that any recursively enumerable language can be generated with a non-returning parallel communicating (PC) grammar system having six context-free components. We also present a non-returning universal PC grammar system generating unary languages, that is, a system where not only the number of components, but also the number of productions and the number of nonterminals are limited by certain constants, and these size parameters do not depend on the generated language