منابع مشابه
Chemical Models of Collapsing Envelopes
We discuss recent models of chemical evolution in the developing and collapsing protostellar envelopes associated with low-mass star formation. In particular, the effects of depletion of gas-phase molecules onto grain surfaces is considered. We show that during the middle to late evolutionary stages, prior to the formation of a protostar, various species selectively deplete from the gas phase. ...
متن کاملMultiresolution Surface Reconstruction: Edge Collapsing + Simplification Envelopes
Multiresolution surfaces are especially useful for fast rendering, real-time display, and progressive transmission. This paper reviews major surface simplification techniques and multiresolution surface reconstruction approaches. Based on comparison among various approximation algorithms we propose an appropriate measure for surface approximation accuracy and essential concepts for multiresolut...
متن کاملFar-infrared Line Emission from Collapsing Protostellar Envelopes
We present a theoretical model that computes the chemical evolution, thermal balance, and line emission from the collapsing gas of the envelopes that surround protostars. This is the Ðrst attempt to calculate self-consistently the line spectrum from the infalling gas with a model that includes dynamics, chemistry, heating and cooling, and radiative transfer. For the dynamics, we have adopted th...
متن کاملMinimal Collapsing Extensions of Models of ZFC
We present some results concerning extensions of models of ZFC in which cofinalities of cardinals are changed and/or cardinals are collapsed, in particular on minimal such extensions. Our main tools are perfect tree forcing PF(S) and Namba forcing Nm(S). We prove that if N 2 M is an extension such that (i) M k K = I+ > H,, (ii) 1 fl N E M and (iii) N = Mlf] for some cofinal f : oo+ K, then N 2 ...
متن کاملTolerance envelopes of parametric planar part models
We present a framework for modeling parametric variation in planar parts and for efficiently computing approximations of their tolerance envelopes. Part features are specified by algebraic equations defining their position and shape as a function of parameters whose nominal values vary along tolerance intervals. Their tolerance envelopes model perfect form Least and Most Material Conditions (LM...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 2000
ISSN: 0074-1809
DOI: 10.1017/s0074180900164678