How organ-shaping mechanical imbalances are generated is a central question of morphogenesis, with existing paradigms focusing on asymmetric force generation within cells. We show here that organs can be sculpted instead by patterning anisotropic resistance within their extracellular matrix (ECM). Using direct biophysical measurements of elongating Drosophila egg chambers, we document robust me...

The research presented in this thesis addresses the problem of updating an analytical model using a parametric Reference Basis approach. In this method, some parameters are assumed to be accurate (e.g. natural frequencies, mode shapes and mass matrix), while others are adjusted so that the eigenvalue equation is satisfied. Updating is done with the use of principal submatrices, and the method s...

Many studies simulates the machining process by using a single degree of freedom springmass sytem to model the tool stiffness, or the workpiece stiffness, or the unit toolworkpiece stiffness in modelings 2D. Others impose the tool action, or use more or less complex modelings of the efforts applied by the tool taking account the tool geometry. Thus, all these models remain two-dimensional or so...

J.H. van Dieën Spinal segments with altered stiffness causing spinal deformations and low-back pain might be identifiable by comparing stiffness values between adjacent levels, since positive or negative outliers might indicate a clinically relevant condition. The stiffness matrix of a structure can be obtained by parameter estimation techniques such as model updating, which requires the constr...

Finite Element Analysis (FEA) is known to be a highly reliable tool for structural analysis, but this is usually conducted offline. Online use of FEA is usually out of the question because it is highly demanding in terms of computing time. We show in this report how the Cartesian stiffness matrix of robotic structures of a certain class can be computed online with FEA support. The procedure is ...

Fast algorithms for applying finite element mass and stiffness operators to the B-form of polynomials over d-dimensional simplices are derived. These rely on special properties of the Bernstein basis and lead to stiffness matrix algorithms with the same asymptotic complexity as tensor-product techniques in rectangular domains. First, special structure leading to fast application of mass matrice...

Tissue stiffening is a hallmark of fibrotic disorders but has traditionally been regarded as an outcome of fibrosis, not a contributing factor to pathogenesis. In this study, we show that fibrosis induced by bleomycin injury in the murine lung locally increases median tissue stiffness sixfold relative to normal lung parenchyma. Across this pathophysiological stiffness range, cultured lung fibro...