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arXiv 1005.0445math-phmath.MPphysics.bio-ph
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人体呼吸树的2-adic方法

A 2-adic approach of the human respiratory tree

Frederic Bernicot, Bertrand Maury, Delphine Salort

摘要:

我们在这里提出了一个通用的框架来解决二元树上的跟踪运算符的问题。这项工作的动机是人体支气管树的建模,由于其规律性,可以以自然的方式外推到一个无限的电阻树。在这个无限树的分叉节点处的压力场的空间可以被赋予一个Sobolev空间结构,具有一个半范数,其测量耗散能量的瞬时速率。我们的目的是描述行为的有限能量压力场附近的结束。该方法的核心是2-adic整数环Z_2的端点集的识别。Z_2上的Sobolev空间可以通过Fourier变换以一种非常自然的方式定义,这使我们能够建立精确的迹定理,这些迹定理在形式上与标准Sobolev空间中的迹定理非常相似,具有依赖于阻力增长率的Sobolev正则性,即依赖于树的几何性质。此外,我们展示了一个明确的表达的“通风算子”,它映射到通量的树的末端的压力场,在卷积的形式由Riesz内核的基础上的2-adic距离。

英文摘要:

We propose here a general framework to address the question of trace operators on a dyadic tree. This work is motivated by the modeling of the human bronchial tree which, thanks to its regularity, can be extrapolated in a natural way to an infinite resistive tree. The space of pressure fields at bifurcation nodes of this infinite tree can be endowed with a Sobolev space structure, with a semi-norm which measures the instantaneous rate of dissipated energy. We aim at describing the behaviour of finite energy pressure fields near the end. The core of the present approach is an identification of the set of ends with the ring Z_2 of 2-adic integers. Sobolev spaces over Z_2 can be defined in a very natural way by means of Fourier transform, which allows us to establish precised trace theorems which are formally quite similar to those in standard Sobolev spaces, with a Sobolev regularity which depends on the growth rate of resistances, i.e. on geometrical properties of the tree. Furthermore, we exhibit an explicit expression of the "ventilation operator", which maps pressure fields at the end of the tree onto fluxes, in the form of a convolution by a Riesz kernel based on the 2-adic distance.

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