Simulations of blasts in an urban environment were performed using Loci/BLAST, a fulleatured fluid dynamics simulation code, and analyzed. A two-structure urban environment blast case was used to perform a mesh refinement study. Results show that mesh spacing on and around the structure must be 12.5 cm or less to resolve fluid dynamic features sufficiently to yield accurate results. The effects of confinement were illustrated by analyzing a blast initiated from the same location with and without the presence of a neighboring structure. Analysis of extreme pressures and impulses on showed that confinement can increase blast loading by more than 200 percent.

No description available.

The goal of this thesis is to advance knowledge about the balance of forces acting on granular materials in the interior of the blast furnace and on the walls. Using the principles of fluid and granular flows, a mathematical model is developed and used to generate new knowledge about the influence of process parameters, under control of the blast furnace operator, on the granular stress at the level of the gas inlet and the walls. The mathematical model developed is validated under ambient conditions by comparing predictions with experimental data obtained from physical scale models of the blast furnace. Comparison of the wall gas pressure profile from a commercial blast furnace with results from the mathematical model developed, indicate that gas temperature is an important factor in estimating the magnitude of the external force exerted by gas flow on granular materials. Results also show that the vertical stress acting on the upper boundary of the coke bed in the hearth can be altered by changing variables which are under the operator’s control. These variables include the gas properties (mass flow rate and pressure) and the properties of the granular column (bulk density of granular materials and cohesive zone location). Information generated in this thesis can be used by blast furnace operators for guidance in controlling the vertical stress at the upper boundary of the coke bed in the hearth and for defining the force at this boundary for subsequent studies of hearth region. / Thesis / Doctor of Philosophy (PhD)

The high frequency response of a circular ring of rectangular cross section interior to a conical shell excited by a blast wave is examined. The ring supports a rigidly attached mass during excitation. It is hypothesized that the response is a function of the four excitation parameters which characterize the loading. These are: peak reflected pressure; characteristic time (pulse duration); wave engulfment time; and circumferential distribution. These parameters are varied over a range of interest in an effort to ascertain the structural sensitivity to such perturbations. A series of tests sponsored by the Department of the Army and the Martin Marietta Corporation were conducted by the Stanford Research Institute on the missile. Data acquired during these tests will be used to verify and support the hypothesis. In addition analytic correlation is presented based on parametric studies performed on a simple two degree of freedom ring model excited by a local pressure forcing function. The experimental data indicated a linear dependence of the structural response on variations in pressure, duration and engulfment. The analytic results indicated higher sensitivities by comparison, but supported the experimental results in general.

In this thesis, we evaluate the performance of multi-user detectors over an uplink using AWGN, Rayleigh flat fading single-input single-output (SISO) and multiple-input multiple-output (MIMO) channel models. First, we review the performance of three multiuser receivers; the decorrelator, the MMSE receiver and the multistage parallel interference cancellation receiver in an AWGN and Rayleigh flat fading SISO channel. Next, the V-BLAST algorithm is reviewed and the error propagation of this algorithm is investigated. Then, the V-BLAST algorithm is combined with multiuser receivers to achieve high channel capacity while sharing the spectral resources over a MIMO channel. A bias reduction technique is considered for multistage parallel interference cancellation receiver on both SISO and MIMO channel. Finally, the effect of channel estimation error and timing delay estimation error is evaluated for MIMO systems with multiple users. / Master of Science

Combat-related blast injuries are occurring more frequently with the increased use of improvised explosive devices in current military conflicts. Though much research has focused on how the body responds to the relatively low loading rates associated with blunt trauma, little is known regarding the response of the body to the higher loading rates associated with blast trauma. While soldiers are surviving once-lethal blast events due to enhanced protective equipment, injuries such as those to the eye and face that were once considered inconsequential, can now be detrimental to long-term healthcare costs and quality of life. Although it is suggested primary blast overpressure (i.e., the shock wave) can cause severe eye injuries, there remains few empirical data in the literature that confirms this. Adding to this, there are currently no testing standards to assess the effectiveness of personal protective equipment during blast exposure. Expanding upon traditional research techniques within the field of injury biomechanics, the research in this dissertation focuses specifically on developing experimental and physical models of the eye, face, and orbit for blast overpressure exposure. Foremost, a porcine eye model is used to quantify eye injury risk from blast overpressure exposure. Subsequently, these biomechanical data are used to develop a physical model of the eye that can be used in lieu of cadaver specimens for blunt and blast loading. Lastly, military spectacles and goggles are examined for effectiveness at protecting the eye during blast exposure. Combined with detailed computer-aided design geometries, these data can be used to validate computational models of the eye, orbit, and face to blast loading. Results from these tests support one theory that shock waves may enter the skull through the orbit, alluding to future work that is essential to more fully understanding the physiological response of the brain and ocular motor system to blast exposure. Ultimately, the experimental methods and analysis techniques disseminated herein serve as a framework for future experimental work related to blast and other high-rate loading scenarios. / Ph. D.

This thesis presents a damage model developed for the rapid prediction of the vulnerability of a ship concept design to AIREX weapon effects. The model uses simplified physics-based and empirical equations, threat charge size, geometry of the design, and the structure of the design as inputs. The damage volumes are customized to the design being assessed instead using of a single volume defined only by the threat charge size as in previous damage ellipsoid methods. This methodology is validated against a range of charge sizes and a library of notional threats is created. The model uses a randomized hit distribution that is generated using notional threat targeting and the geometry of the design. A Preliminary Arrangement and Vulnerability (PAandV) model is updated with this methodology and used to calculate an Overall Measure of Vulnerability (OMOV) by determining equipment failures and calculating the resulting loss of mission capabilities. A selection of baseline designs from a large design space search in a Concept and Requirements Exploration (CandRE) are assessed using this methodology. / Master of Science

No description available.

This thesis describes the simulation of ERDC’s Blast Load Simulator (BLS) using MSU’s Loci/BLAST. The BLS was created to replicate waveforms found in blast scenarios. Loci/BLAST is an explicit, unstructured CFD code that specializes in moving waveforms. ERDC conducted various tests, and a grid for each scenario was created using the SolidMesh tool. Each grid was simulated, and the results were displayed as time history plots and spatial plots. Simulations were also performed that compared 2D and 3D grids and determined the effect of the grate and striker components. There was a strong correlation between the experimental and simulation results for each case, demonstrating that Loci/BLAST is fully capable of modeling the BLS waveforms. A 2D grid produced results comparable to those on a full 3D grid. The grate and striker were critical in the simulation because they significantly affected the waveform.

In order to examine the feasibility of assessing blast event conditions from bone and to distinguish blast trauma from aircraft crash trauma, this study attempts to determine if the observations made in clinical research are mirrored in skeletal remains of individuals who died in blast events. Research was conducted by assessing the frequency of different forms of trauma and their comparison to aircraft crash trauma, the directionality of trauma, and open-air versus enclosed blast trauma. Data consisted of historic and forensic anthropology reports of individuals who died from blast events and aircraft crashes from the Defense POW/MIA Accounting Agency (DPAA). The results indicate a difference in the projectile/comminuted trauma between aircraft crash trauma and blast events, and that directionality is present in blast event fractures but should be used judiciously to determine blast direction. A sample of one open-air blast individual precluded assessment of enclosed versus open-air blast events.