Controlled clearance piston gauges are used as primary pressure standards at many national metrology institutes. The National Institute of Standards and Technology, in collaboration with the National Physical Laboratory (India), is studying the performance of a new generation of controlled clearance gauges that offer the potential for reduced uncertainties. The gauges are also well suited to in...

A compressed air energy storage (CAES) system that uses a high pressure, isothermal air compressor/expander (C/E) has no carbon emission and is more efficient than a conventional system that uses fossil fuels. To be successful, the compressor/expander must be efficient and has high power density. However, there is a trade-off between efficiency and power density due to heat transfer. Our previo...

background & objectives: the aim of this study was to compare the effectiveness of two stapes prostheses in hearing improvement of patients undergoing stapes surgery for otosclerosis.   materials & methods: in this retrospective and descriptive study, the charts of 291 stapedectomies performed by one surgeon (first author) from 1997 to 2011 in imam khomeini and apadana hospitals of ahva...

Background & objectives: The aim of this study was to compare the effectiveness of two stapes prostheses in hearing improvement of patients undergoing stapes surgery for otosclerosis.   Materials & Methods: In this retrospective and descriptive study, the charts of 291 stapedectomies performed by one surgeon (first author) from 1997 to 2011 in Imam Khomeini and Apadana hospitals of Ahvaz were...

A simplified version of a classical problem in thermodynamics--the adiabatic piston--is discussed in the framework of kinetic theory. We consider the limit of gases whose relaxation time is extremely fast so that the gases contained in the left and right chambers of the piston are always in equilibrium (that is, the molecules are uniformly distributed and their velocities obey the Maxwell-Boltz...

Recent experimentswith 100 terawatt-class, sub-50 femtosecond laser pulses show that electrons self-injected into a laser-driven electron density bubble can be accelerated above 0.5 gigaelectronvolt energy in a sub-centimetrelength rarefied plasma. To reach this energy range, electrons must ultimately outrun the bubble and exit the accelerating phase; this, however, does not ensure high beam qu...

Regular wave-induced behaviour of a floating stationary two-dimensional body with a moonpool is studied. The focus is on resonant piston-mode motion in the moonpool and rigid-body motions. Dedicated two-dimensional experiments have been performed. Two numerical hybrid methods, which have previously been applied to related problems, are further developed. Both numerical methods couple potential ...

Internal combustion engines in now a days is the best available reliable source of power for all domestic, large scale industrial and transportation applications. The major issue arises at the efficiency of these engines. Every attempt made to improve these engines tends to attain the maximum efficiency. The performances of the diesel engines are enhanced by proper design of inlet manifold, exh...

OBJECTIVE This study aimed to compare gas exchange with heliox and oxygen-enriched air during piston-type high-frequency oscillatory ventilation (HFOV). We hypothesized that helium gas would improve both carbon dioxide elimination and arterial oxygenation during piston-type HFOV. METHOD Five rabbits were prepared and ventilated by piston-type HFOV with carrier 50% helium/oxygen (heliox50) or ...