Missile Defense Agency

In this paper, we studied the application of a radial slot to the propulsion engine to relieve the strain of solid propellant by applying the optimal design concept to the shape and location of the radial slot.The propulsion engine under study was set to be a high-ratio, high-charge propulsion engine that requires the application of radial slots due to its high overall strain.The optimization was performed in conjunction with ABAQUS's 3D structural analysis based on codes written in MATLAB. . , . MATLAB ABAQUS 3 .

Standard plain film medical radiographs often form a valuable line of evidence to identify individuals in large-scale fatality events. While commonly available, chest radiographs present a challenge that their analysis is somewhat more involved and complex than radiographic records of other body regions. For example, chest radiographs concern subtler morphological varieties of smaller anatomical features across a larger number of skeletal elements in contrast to frontal sinus comparisons that concern a large, (often) single, highly variable void within one bone. This does not detract from or discount chest radiographs as useful identification aids, but it does demand additional prerequisite skills in radiographic interpretation to ensure valid conclusions are attained. When subjects deviate from standardized antemortem (AM) radiographic positions and/or the image quality decreases, the complexity of a chest radiograph comparison is elevated. Generally, the current body of forensic radiographic comparison literature infrequently addresses these more complex circumstances. In this paper, we use real-world radiographic comparison reference images from a military DVI repatriation context to illustrate these factors and outline some procedures that enable these complexities to be easily recognized and appropriately addressed at case examination. A report for an exemplar case that concurrently highlights multiple factors is presented. For novices learning radiographic comparison methods, this case review saliently demonstrates: (1) why the AM reference radiograph(s) drive(s) the radiographic comparison procedure; (2) why care should be taken for correct positioning of the cervicothoracic junction in postmortem radiography of chest elements.

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

This paper presents the results from an experimental investigation into changes in regression rate due to varying oxidizer port diameter in axial-injection, end-burning, hybrid rocket motors. This investigation was conducted in an effort to validate derived models which predicted a decreasing oxidizer port diameter would cause an increase in the regression rate. Two parameters were chosen as the independently variable criterion for the experimental test matrix. The first was a variation of port diameter, i.e. area, with a constant number of ports per grain. The second varied the number of ports while holding the grain port area constant. These methods were chosen to assess the effects of port diameter on the burning characteristics, while accounting for the effects of other factors, such as oxidizer velocity and port spacing. Results from these experiments indicate that oxidizer port diameter varies in its regression effects based on the overall grain geometry. For cases where the geometry and exit area are relatively constant, decreasing port diameters tend to increase regression rate; but for cases where increasing the port diameter significantly increases the total port area, the reduction in oxidizer velocity increases regression rate. As such, the experiments demonstrate the proposed model is valid for a subset of axial-injection, end-burning hybrid rocket motor grain designs.

This experimental test campaign continues efforts to investigate the performance and suitability of different materials for use as fuel grains in axial-injection, end-burning hybrid rocket motors. Three different fuel materials were evaluated during the study – Somos WaterClear from Stratasys, Visijet from Shapeways, and Castable Wax from Formlabs – at chamber pressures ranging from 168 kPa to 1780 kPa. These test parameters resulted in regression rates ranging from 0.07 to 7.11 mm/s calculated using a mass-based approach accounting for any grain mass lost due to sideburning. The regression rate of both materials followed a pressure trend for regression rate as seen in the literature for axial-injection, end-burning hybrids. This study also evaluated larger scale fuel grains than those evaluated in previous studies. Overall, the three materials yielded lower regression rates and fuel mass flux values but greater grain integrity than previous tests using ABS plastic. Results from the larger grains will be used to inform future tests as part of an effort to evaluate performance at relevant scales.

All AESS Chapters and IEEE Sections are encouraged to take advantage of the AESS Distinguished Lecturer and Tutorial Program for their regular or special meetings, allowing them to select from an outstanding list of truly distinguished speakers who are experts in the technical fields of the society.The AES Society will pay reasonable speaker's expenses for economy-class travel, lodging, and meals, with the inviting IEEE AES chapter expected to cover 50% of the speaker's expenses.Speaker's expenses involving travel wholly within North America or within the European Union can generally be approved to be covered up to $1000 USD.Expenses involving extensive international travel can be approved to be covered up to $2000 USD.

Detection of targets can be difficult using thermal camera during thermal cross-over periods. Under these conditions, the target takes on the apparent temperature of objects in the foreground or background and becomes undetectable. It is commonly said that the thermal imagery is “washed-out”. When the thermal contrast of an object against its background is zero, many times a polarization contrast of the same object is non-zero. In this paper, we introduce a camera that measures thermal and polarization images in both the mid-wave infrared (MWIR) and long-wave infrared (LWIR). We also show example images and derive a simple equation that explains the conditions under which a polarization signature of an object can be expected.

Trotter and Gleser’s (1958) Asian equations have most frequently been used for stature estimation of Korean skeletal remains. However, limitations or caveats in using those equations have rarely been argued. This study reviews five issues frequently overlooked in applying the equations and interpreting the outcomes. First, Trotter and Gleser (1958) multiply the standard errors by 2 to obtain the 95% prediction interval (PI). However, there is discrepancy between their calculation and actual PIs, and thus correct method for PI calculation is recommended. Secondly, given the uncertainty about the tibia length measurement, there is a possibility that the tibia-related equations yield biased estimates. Thirdly, since a mathematical error was incorporated in the development process of the combined equations, caution should be taken. Fourthly, extrapolation may cause additional unexpected error in applying regression equations. Therefore, it is necessary to check if a target sample falls within the reference sample range prior to using the equations. Lastly, applying Trotter and Gleser’s (1958) equations to female samples should be avoided because they produce highly biased estimates. The issues discussed in this study will contribute to reducing potential errors associated with application of these equations, and eventually enhancing accuracy of the final stature estimates. If errors are anticipated but unavoidable, discussions about the potential errors should be made to minimize misunderstanding about the outcomes.