The particle size distribution PSD of lunar dust, the 20 m portion of the regolith, was determined as an initial step in the study of the possible toxicological effects it may have on the human respiratory and pulmonary systems. Utilizing scanning electron microscopy, PSDs were determined for Apollo 11 10084 and 17 70051 dust samples, as well as lunar dust simulant JSC-1Avf. The novel methodolo...

Aesthetic and ethical issues of building design are presented here to encourage meaningful discussion among today’s archi­ tectural engineering students and practitioners. The evaluative aesthetic ideas of scale, simplicity, and surprise are applied to two important structures designed by Fazlur R. Khan. Khan’s profound understanding of load flow in his buildings influenced his aesthetic ideas....

This paper describes the development of new air-coupled ultrawideband ground-penetrating radar (GPR) for highway pavement and bridge deck inspections that can achieve high spatial resolution and high inspection performance while operating on vehicles driving at regular highway speeds. Themajor design features include dual-frequency band operation, 8 gigasamples per second high-speed real-time d...

Basic experiments were conducted on a large-size broad-crested weir with a rounded corner. Detailed free-surface, velocity, and pressure measurements were performed for a range of flow conditions. The results showed the rapid flow distribution at the upstream end of the weir and next to the weir brink at large flow rates. The flow properties above the crest were analyzed taking into account the...

This paper describes a model for the spatial variation of the elastic modulus of parallel strand lumber PSL that is based on bending experiments and also describes a validated stochastic computational model that incorporates orthotropic elasticity and uncertainty in strand geometry and material properties. The PSL exhibits significant variability both within members and between members, but thi...

The Muskingum model is the most widely used method for flood routing in hydrologic engineering. However, the application of the model still suffers from a lack of an efficient method for parameter estimation. Particle swarm optimization PSO is applied to the parameter estimation for the nonlinear Muskingum model. PSO does not need any initial guess of each parameter and thus avoids the subjecti...

In this paper, by combining the geographic information systems ~GIS! spatial analysis function and a hydrologic analysis and modeling tool with a column-based three-dimensional ~3D! slope stability analysis model, a new GIS grid-based 3D deterministic model has been developed for slope stability analysis. Assuming the initial slip as the lower half of an ellipsoid, the identification of the 3D ...

A problem exists in that the classifications used by the Federal Emergency Management Agency ~FEMA! for weather-related disasters do not always allow analysts to clearly link declared disasters to their ultimate meteorological cause. This research focuses on those disasters related to flooding resulting from tropical cyclones. Neither FEMA nor the states that request federal disaster aid distin...

Hydrogels have a large number of potential applications in microelectromechanical technology as sensors and actuators. In this paper we try to understand the physics of dissolvable hydrogels and investigate the various parameters controlling the dissolution process. Hydrogels, crosslinked via disulfide bonds, when immersed in a solution containing the disulfide cleaving agent can break covalent...

To investigate their adequacy as energy dissipating elements during earthquakes, this paper reports on cyclic inelastic tests executed to determine the maximum strength and ductility of four concrete-filled circular steel piers joined to a foundation detail proposed to develop the full composite strength at the base of these columns. Column diameters considered were 324 and 406 mm, with D/t rat...