We present a simplified model of planetary accretion based on conservation of mass, conservation of momentum, and angular-momentum-deficit stability. Within the limitations of this model, we show how the organization of generic planetary systems may be derived from the knowledge of their initial mass distribution. Comparisons with our Solar System and the upsilon-Andromedae planetary system are...

Background: For an effective treatment planning in brachytherapy, it is necessary to know the accurate source dosimetric information such as air kerma strength, exposure rate constant, dose rate constant and redial dose distribution. The usual method to determine these factors is thermo luminescent dosimeter (TLD) dosimetry. Nowadays, another more accurate method is known to be the Monte Carlo ...

today air conditioning systems have been considered by all people as one of welfarerequirements in buildings and closed environments. since a considerable part of energy lossoccurs in ordinary modern systems, new strategies and solutions are developed in the field inorder to save amount of energy consumption and observe environmental considerations. fuzzycontrol is one of these methods which pr...

air pollution is an example of a negative externality; it imposes harmful effects and costs on people other than polluters. in controlling air pollution, efficiency argument implies that, there is a rolefor the government to play. studies show that taxation of fuels can be a powerful indirect instrumentfor controlling air polluticn because of the association between fuels use and emissions. in ...