Abstract: This paper proposes a phasor representation of
electrical networks by using bond graph methodology. A so-called
phasor bond graph is built up by means of two-dimensional bonds,
which represent the complex plane. Impedances or admittances are
used instead of the standard bond graph elements. A procedure to
obtain the steady-state values from a phasor bond graph model is
presented. Besides the presentation of a phasor bond graph library in
SIDOPS code, also an application example is discussed.
Abstract: This study investigated the combined effect of cold rolling and heat treatment on the mechanical properties of Al-Ti alloy. Samples of the alloy are cast in metal mould to obtain 0.94-2.19wt% mixes of titanium. These samples are grouped into untreated (as-cast) and those that are cold rolled to fifty percent reduction, homogenized at 5000C and soaked for one hour. The cold rolled and heat treated samples are normalized (RTn) and quench-tempered (RTq-t) at 1000C. All these samples are subjected to tensile, micro-hardness and microstructural evaluation. Results show remarkable improvement in the mechanical properties of the cold rolled and heat treated samples compared to the as-cast. In particular, the RTq-t samples containing titanium in the range of 1.7-2.2% demonstrates improve tensile strength by 24.7%, yield strength, 28%, elastic modulus, 38.3% and micro-hardness, 20.5%. The Al3Ti phase being the most stable precipitate in the α-Al matrix appears to have been responsible for the significant improvement in the alloy’s mechanical properties. It is concluded that quench and temper heat treatment is an effective method of improving the strength-strain ratio of cold rolled Al-.0.9-2.2%Ti alloy.
Abstract: By means of Sidi-Israeli’s quadrature rules, mechanical quadrature methods (MQMs) for solving the first kind boundary integral equations (BIEs) of steady state Stokes problem are presented. The convergence of numerical solutions by MQMs is proved based on Anselone’s collective compact and asymptotical compact theory, and the asymptotic expansions with the odd powers of the errors are provided, which implies that the accuracy of the approximations by MQMs possesses high accuracy order O (h3). Finally, the numerical examples show the efficiency of our methods.
Abstract: Purpose: To compare attitudes and perceptions of
Israeli native born mothers versus former Soviet Union (FSU)
immigrant mothers regarding the physical health of their infant.
Methodology: cross-sectional design. A convenience sample of 50
participants was recruited by face to face and snowball technique. A
questionnaire was constructed according to the instructions of the
Ministry of Health for the care and treatment of infants. The main
areas explored were: sources of knowledge that the young mother
acquired regarding the care of her infant, ways of caring for the
infant, hygiene and sanitary habits, and the pattern of referral to
health professionals. The last topic relates to emotions mothers might
experience towards their infant.
Results: Mothers from both cultural groups present some similar
caring behaviors, which may express a universal aspect of mothers'
behavior towards their infants. However, immigrant mothers differ
significantly from native born by relying less on their mothers' and
grandmothers' experience, they wean their infants from diapers
earlier, they are stricter about hygiene and sanitary habits and they
tend to consult a physician when their infant has low fever. Native
born and immigrant mothers differ in their expressions of pride and
wonder. Immigrant mothers report of a lesser degree of these
emotions towards their infants than native born mothers.
Conclusion: The theoretical model of socialization and
acculturation of immigrant mothers is employed as an explanatory
model for the current findings Young immigrant mothers undergo a
complex acculturation process and adapt behavioral patterns in
various areas to comply with Israeli norms and values, demonstrating
assimilation. In other areas they adhere to the norms of their original
culture.
Abstract: A bond graph model of an electrical transformer
including the nonlinear saturation is presented. A nonlinear observer for the transformer based on multivariable circle
criterion in the physical domain is proposed. In order to show the saturation and hysteresis effects on the electrical transformer,
simulation results are obtained. Finally, the paper describes that convergence of the estimates to the true states is achieved.
Abstract: Five original strains of entomopathogenic bacteria
with insecticidal activity against mosquito larvae of the genera Aedes,
Culex and Anopheles have been isolated from natural conditions in
Armenia and characterized. According to morphological,
physiological and biochemical parameters, all isolates were identified
as Bacillus thuringiensis spp. israelensis (Bti). High larvicidal
activity has been showed by three strains Bti. These strains can be
recommended for industrial production of bacterial preparations.
Abstract: This study examined the role of driving experience in hazard perception and categorization using traffic scene pictures. Specifically, young-inexperienced, moderately experienced and very experienced (taxi) drivers observed traffic scene pictures while connected to an eye tracking system and were asked to rate the level of hazardousness of each picture and to mention the three most prominent hazards in it. Target pictures included nine, nearly identical, pairs of pictures where one picture in each pair included an actual hazard as an additional element. Altogether, 22 areas of interest (AOIs) were predefined and included 13 potential hazards and 9 actual hazards. Data analysis included both verbal reports and eye scanning patterns of these AOIs. Generally, both experienced and taxi drivers noted a relatively larger number of potential hazards than young inexperienced drivers Thus, by relating to less salient potential hazards, experienced drivers have demonstrated a better situation model of the traffic environment.
Abstract: Nigeria is considered as one of the many countries in
sub-Saharan Africa with a weak economy and gross deficiencies in technology and engineering. Available data from international monitoring and regulatory organizations show that technology is pivotal to determining the economic strengths of nations all over the
world. Education is critical to technology acquisition, development,
dissemination and adaptation. Thus, this paper seeks to critically
assess and discuss issues and challenges facing technological
advancement in Nigeria, particularly in the education sector, and also
proffers solutions to resuscitate the Nigerian education system
towards achieving national technological and economic sustainability
such that Nigeria can compete favourably with other technologicallydriven
economies of the world in the not-too-distant future.