New Top Land Computing Method for Spiral Bevel Gears

In this study, we present two methods for determining the top land of bevel gears. One of them that can be found in the professional literature is based on the Tredgold's virtual cylindrical gear model and, corresponding to this, deals with a limited accuracy. The alternative method developed by us is based on a mathematical modelling of the manufacturing process and involves in the computing of the top land dimensions theoretically perfect surface models

Rheological Behaviour of Pigment Filled Polymer Dispersions: The influence of electric field

Rheological properties of materials are related to their response to applied stress. The field induced chain formation of a large number of organic and inorganic substances such as starch, aluminium oxide, ferric oxide, carbon black, ion-exchange resins, and polymer powders have been studied mainly in insulating oils. Much less is studied and understood the electrorheological effect of pigments in polymer dispersions. Titanium dioxide is one of the most frequently used surface coatings due to its high-quality and ecologically acceptable properties. In the present paper the authors first review the basic principle of electrorheology, then it is followed by experimental studies on structuring and rheological properties

Improper Supplementation Habits of Folic Acid Intake by Hungarian Pregnant Women: Improper Recommendations

Background: Neural tube defects (NTDs) are some of the most common congenital anomalies. Proper folic acid supplementation is a dominant risk factor, which has been shown to decrease the incidence of NTDs. In Canada, the incidence of neuroblastoma has presented a considerable decrease of 60% as a result of enrichment cereal grain flours with synthetic folic acid. The aim of this study was to investigate the effect of folic acid intake by pregnant women on the incidence of NTDs and neuroblastoma. Methods: Regular folic acid intake has been recommended to pregnant women in Hungary since the eighties of the last century by health visitors eventually raking effect as an official protocol which had been released in 1997. During 2001, 2002 and 2003. folic acid intake habits of pregnant women were evaluated by health visitors, proving to be successful in collecting data front 95.06% of the pregnant women. The incidence of NTDs has been registered by the Hungarian National Centre of Epidemiology, Department of Human Genetics and Teratology. The Pediatric Cancer Registry provided the incidence of neuroblastoma in children. Results: Consistent findings revealed a regular intake of supplementary folic acid products by 68.71% of the pregnant women. Out of these. 93.13% of pregnant women who were taking folic acid, started the supplementation after their 7 weeks of pregnancies, a time designated as the completion period of the development of the neural tube. The dose of folic acid supplementation was evaluated as less than 5 mg/day in 84.75% of the pregnant women. In Hungary, the incidence of NTDs has remained constant, while the incidence of neuroblastoma has shown constant slight increase in spite of the introduction of folic acid supplementation in 1997. Conclusions: Based on our experience, folic acid supplementation was initiated after the recognition of pregnancy and its application in a dose of lower than 5 mg/day neither decreased the incidence of NTDs nor did it have an effect on the neuroblastoma incidence. It is implicated that proper folic acid supplementation, which is started front the conception. can be achieved only with the enrichment of cereal grain flours

History of Gleason Works Spiral Bevel Gear Technology

The paper deals with the history of Gleason Works history in regard for their bevel gear manufacturing technology. In spiral bevel gear technology Gleason is a leading company, with many patterns and research studies in this field. The focus of this paper is to show the development of the technology provided by Gleason over the past more than 100 years