Engineering

Modeling tether–ballast asteroid diversion systems, including tether mass and elasticity
The risk of an impact between a large asteroid and the Earth has been significant enough to attract the attention of many researchers. This paper focuses on a mitigation technique that involves the use of a long tether and ballast mass to divert an asteroid. When such a tether is modeled as massless and inelastic, results show that the method may be viable for diverting asteroids away from a co...


Multiple spacecraft formation reconfiguration using solar radiation pressure
In this paper the use of solar radiation pressure for spacecraft formation reconfiguration at the L 2 Sun–Earth/Moon collinear libration point is presented. The system consisting of a leader and three follower spacecraft is considered. The leader spacecraft is assumed to be in a fixed halo trajectory and the follower spacecraft position relative to the leader satellite is controlled using two...
Scale-independent description of the rigid-body penetration of spherical projectiles into semi-infinite adobe targets
In impact experiments, the penetration depth of spherical projectiles into semi-infinite adobe targets has been investigated. In total, 20 tests were performed with steel projectiles of diameters 7.5, 10.0 and 13.5 mm in the velocity regime from 240 to 3230 m/s. In addition, 2 single experiments with aluminum and titanium projectiles were conducted at impact velocities of 830 and 920 m/s, respe...


A Numerical Study of Heat and Water Vapor Transfer in MDCT-Based Human Airway Models
A three-dimensional (3D) thermo-fluid model is developed to study regional distributions of temperature and water vapor in three multi-detector row computed-tomography-based human airways with minute ventilations of 6, 15 and 30 L/min. A one-dimensional (1D) model is also solved to provide necessary initial and boundary conditions for the 3D model. Both 3D and 1D predicted temperature distribu...
Behavioral analysis of analogical reasoning in design: Differences among designers with different expertise levels
This paper explores the impacts of the expertise level of designers during analogical reasoning. In study 1, participants were asked to select source examples and explain their selections. It was found that experts were more likely to consider Experience and Esthetics as reasons for their selections. Third-year students were more inclined to draw inspiration from Symbolism, whereas first-year s...


Value of information method for optimization and experimental design using surrogate models
Experimentation is required for modeling empirical functions and optimization. In manufacturing, experiments are costly and time-consuming, thereby limiting the number of function evaluations. This paper describes a value of information method for experimental design and optimization using surrogate modeling. Value of information is defined as the absolute difference between optimal value befor...
Identifying local co-regulation relationships in gene expression data
Identifying interesting relationships between pairs of genes, presented over some of experimental conditions in gene expression data set, is useful for discovering novel functional gene interactions. In this paper, we introduce a new method for id entifying L ocal C o-regulation R elationships (IdLCR). These local relationships describe the behaviors of pairwise genes, which are either up- or d...

Evil green beards: Tag recognition can also be used to withhold cooperation in structured populations
Natural selection works against cooperation unless a specific mechanism is at work. These mechanisms are typically studied in isolation. Here we look at the interaction between two such mechanisms: tag recognition and population structure. If cooperators can recognize each other, and only cooperate among themselves, then they can invade defectors. This is known as the green beard effect. Anothe...
A study of spermatozoan swimming stability near a surface
The swimming stability of spermatozoa with a specified planar beat pattern in the presence of a no-slip flat surface is explored in a modelling study exploiting direct numerical computation via the boundary element method and dynamical systems theory. Parameter sweeps varying the sperm head morphology and flagellar beat pattern wavenumber are conducted and reveal that stable surface swimming is...

How to not get stuck—Negative feedback due to crowding maintains flexibility in ant foraging
Ant foraging is an important model system in the study of adaptive complex systems. Many ants use trail pheromones to recruit nestmates to resources. Differential recruitment depending on resource quality coupled with positive feedback allows ant colonies to make rapid and accurate collective decisions about how best to allocate their work-force. However, ant colonies can become trapped in sub-...
Nonuniform shear warping effect in the analysis of composite beams by BEM
In this paper a general formulation for the nonuniform shear warping analysis of composite beams of arbitrary simply or multiply connected cross section with at least one axis of symmetry, under general boundary conditions is presented. The beam is subjected to the combined action of arbitrarily distributed or concentrated transverse loading passing through the shear center of the cross section...

Nonlinear pre-yield modal properties of timber structures with large-diameter steel dowel connections
In timber structures, the connections are generally flexible in comparison to the members they connect, and so contribute significantly to the dynamic properties of the structure. It is shown here that a widely-used form of connection, the dowel-type connection, exhibits nonlinear stiffness and energy dissipation, even at pre-yield loads, and that this nonlinearity affects the modal properties ...
Seismic performance-based design optimization considering direct economic loss and direct social loss
Seismic performance-based design of a steel structure is performed using a multi-objective optimization that considers both direct economic and social losses. Specified performance objectives are considered as constraints and their variance over the obtained Pareto front is investigated. Optimization objectives are selected as the lifetime cost calculated from the initial construction cost and ...
A locally convergent rotationally invariant particle swarm optimization algorithm
Several well-studied issues in the particle swarm optimization algorithm are outlined and some earlier methods that address these issues are investigated from the theoretical and experimental points of view. These issues are the: stagnation of particles in some points in the search space, inability to change the value of one or more decision variables, poor performance when the swarm size is sm...
Epoxy laminated composites reinforced with polyethyleneimine functionalized carbon fiber fabric: Mechanical and thermal properties
Epoxy (EP) laminated composites reinforced with polyethyleneimine (PEI) functionalized carbon fiber fabric (CFF), which were prepared by pre-depositing polydopamine on the surface of pristine CFF and then further grafting with PEI, were fabricated and their mechanical and thermal properties were investigated in detail. The flexural strength and flexural modulus of PEI-functionalized CFF/EP comp...