influences of the wood fiber acetylation as well as the compatibilizer mapp on water absorption, thickness swelling and dimensional stability of acetylated wood/ polypropylene composites (wpcs) were the main concerns of this research. wood fibers were acetylated with acetic anhydride without using any catalyst to achieve weight percent gains (wpgs) of 4.5, 7.5 and 17.6%. the acetylated fibers w...

A theoretical study analyzing three-dimensional combustion acoustic instabilities in a liquid propellant rocket engine combustor has been conducted. A linear theory based on Crocco’s pressure sensitive time lag model is used. To apply this theory the combustor is divided into two main components, including the combustion chamber and the converging part of the nozzle. The assumption of concentra...

statement of problem: disinfection of dental impressions is a weak point in the dental hygiene chain. in addition, dental office personnel and dental technicians are endangered by cross-contamination. objectives : this study aimed to investigate the dimensional stability of two color-changing irreversible hydrocolloid materials (ih) after disinfection with glutaraldehyde. materials and methods ...

this paper deals with three-dimensional evaluation of the slopes on the basis of limit analysis. an upper-bound technique of limit analysis is used in this paper to determine either the bearing capacity of a shallow foundation near a slope or the safety factor of the slope. the theorems of limit analysis (upper and lower bound) provide a powerful tool for solving problems in which limit loads n...

fuzzy control systems have had various applications in a wide range of science and engineering in recent years. since an unstable control system is typically useless and potentially dangerous, stability is the most important requirement for any control system (including fuzzy control system). conceptually, there are two types of stability for control systems: lyapunov stability (a special case ...

objective: the aim of this study was to evaluate the dimensional stability of casts made from an alginate impression material poured immediately and stored after specific periods. materials and methods: the common alginate used in iran (super; iralgin, golchai co., tehran, iran) was tested. a master model was mounted on a special device and used to obtain the impressions. these impressions were...

Fuzzy control systems have had various applications in a wide range of science and engineering in recent years. Since an unstable control system is typically useless and potentially dangerous, stability is the most important requirement for any control system (including fuzzy control system). Conceptually, there are two types of stability for control systems: Lyapunov stability (a special case ...

Cryogenic treatment can be used as a supplemental treatment that is performed on some tool steels between quenching and tempering as an effective method for decreasing retained austenite and increasing wear resistance. In this research, the effect of deep cryogenic treatment (DCT) on dimensional stability and mechanical properties of 80CrMo12 5 tool steel was investigated. The martensitic trans...