Spectral contents readout of birefringent sensors

The objective of the research performed was to establish the feasibility of using spectral contents analysis to measure accurately, strains and retardation in birefringent sensors, and more generally, on transparent materials

Modeling a Cell Motility on the Surface with a Pit

Living cells respond to outside physical environment in many ways including changing their geometry and location. A cell was modeled as a tensegrity structure that consists of the cytoskeleton, the cellular nucleus and lamellipodia. This model was based on the use of isolated elastic components consisting of a set of continuous compression components and a set of continuous tension components. To investigate the influence of surface topography on cellular movement, several representative cases were designed and simulated. By using internal strain energy as a main criterion to estimate the stability of the cell at various locations, we could show that cells have a tendency to move towards and stay on the sidewall of a pit. They also have a tendency to leave the concave corner. The obtained simulation results were in agreement with the available experimental evidence. Thus, the proposed model and approach may be a valuable tool for understanding the mechanics of a cell motion

Migration of the 3T3 Cell with a Lamellipodium on Various Stiffness Substrates—Tensegrity Model

Changes in mechanical stimuli and the physiological environment are sensed by the cell. Thesechanges influence the cell’s motility patterns. The cell’s directional migration is dependent on the substrate stiffness. To describe such behavior of a cell, a tensegrity model was used. Cells with an extended lamellipodium were modeled. The internal elastic strain energy of a cell attached to the substrates with different stiffnesses was evaluated. The obtained results show that on the stiffer substrate, the elastic strain energy of the cell adherent to this substrate decreases. Therefore, the substrate stiffness is one of the parameters that govern the cell’s directional movement

Validation of Smartphone Sway Analysis for Fall Prevention

Analysis of the balance and sway of the elderly remains a field continuously studied for additional means of assessing the risks of falls. Almost 50% of falls among the elderly lead to serious injuries, and falls are the leading cause of death for the elderly. Thus, the development of a convenient method to assess the risks of falling would be beneficial in helping to diminish these risks. We recorded the sway data by using the widely acceptable force plate and simultaneously compared it to the angular orientation measured by a cell phone’s accelerometer attached to the subject. It was found that the correlation of the average path length and average velocity between the results from the force plate and the phone application were 0.83 and 0.86 respectively. Overall, the direction of the strongest correlation was in the anterior–posterior (AP) direction that is mostly associated with falls. The smart phone application was able to represent the results that were gathered by the force plate, thus opening the door to a simpler way to track sway variables in the elderly without the necessity to come to a doctor’s office

Statics: learning from engineering examples

This textbook introduces and explains the basic concepts on which statics is based utilizing real engineering examples. The authors emphasize the learning process by showing a real problem, analyzing it, simplifying it, and developing a way to solve it. This feature teaches students intuitive thinking in solving real engineering problems using the fundamentals of Newton’s laws. This book also: · Stresses representation of physical reality in ways that allow students to solve problems and obtain meaningful results · Emphasizes identification of important features of the structure that should be included in a model and which features may be omitted · Facilitates students' understanding and mastery of the "flow of thinking" practiced by professional engineers

Digital image correlation based internal friction characterization in granular materials

Based on the realization that Newtonian fluids have the unique property to redirect the forces applied to them in a perpendicular direction, a new apparatus, called the Granular Friction Analyzer (GFA), and the related GFA index, were proposed for characterizing the internal friction and related flow behavior of granular materials under uniaxial compression loading. The calculation of the GFA index is based on the integration of the internal pressure distribution along the cylinder wall, within which the granular material is being uniaxially compressed by a piston. In this paper an optical granular friction analyzer (O-GFA) is presented, where a digital image correlation (DIC) method is utilized to assess the cylinder strains used to calculate the internal pressure distribution. The main advantage of using the DIC method is that the starting point (piston-powder contact point) and the length of the integration considering the edge effects can be defined. By using the DIC full-field, instead of a few points strain measurements, a 2% improvement of the GFA indexʼs accuracy has been achieved and its robustness with respect to the number of points has been demonstrated. Using the parametric error analysis it has been shown that most of the observed total error (7.5%) arises from the DIC-method-based measurements of the strains, which can be improved by higher-resolution cameras and DIC algorithms for the strain evaluation. Additionally, it was shown that the GFA index can be used for determining the well-known Janssen model parameters. The latter was demonstrated experimentally, by testing three SS 316 L granular material samples with different mean particle sizes. The results confirm that the mean particle size regulates the internal friction of granular materials