Showing papers by "General Dynamics published in 2013"

Comparison of novel hemostatic dressings with QuikClot combat gauze in a standardized swine model of uncontrolled hemorrhage.

Abstract: BACKGROUNDUncontrolled hemorrhage is the leading cause of preventable death on the battlefield. The development, testing, and application of novel hemostatic dressings may lead to a reduction of prehospital mortality through enhanced point-of-injury hemostatic control. This study aimed to determine

Understanding the Group Size Effect in Electronic Brainstorming

Abstract: A number of studies on electronic brainstorming have found that large electronic groups can facilitate the number of ideas generated relative to control groups of similar numbers of solitary perfor...

Computational Prediction of Structures and Optical Excitations for Nanoscale Ultrasmall ZnS and CdSe Clusters.

Abstract: Small semiconductor nanoclusters are important for understanding the initial formation and growth of quantum dots and also for application, for example in the tunability provided by size. However, electronic structures and effects of capping ligands have not been systematically characterized. Thus, ground and excited state calculations using coupled-cluster methods were carried out to provide benchmarks for evaluating the applicability of density functional theory (DFT) and time-dependent DFT (TDDFT) with different functionals for the ground and excited states, respectively. Our computed data suggests that the popular B3LYP functional does not deliver optimal results for the ground and excited state. While the PBE0 functional was found to provide a good description for both the ground and excited states for small bare (ZnS)n and bare and ligated (CdSe)n clusters, the results for the hydrated (ZnS)n clusters were found to deteriorate significantly. However, the errors appear to decrease with increasing clu...

Nanosecond pulsed electric field thresholds for nanopore formation in neural cells.

Abstract: d General Dynamics Information Technology, Naval Medical Research Unit-San Antonio, Fort Sam Houston, Texas 78234 Abstract. The persistent influx of ions through nanopores created upon cellular exposure to nanosecond pulse electric fields (nsPEF) could be used to modulate neuronal function. One ion, calcium (Ca 2þ ), is important to action potential firing and regulates many ion channels. However, uncontrolled hyper-excitability of neurons leads to Ca 2þ overload and neurodegeneration. Thus, to prevent unintended consequences of nsPEF-induced neural stimu- lation, knowledge of optimum exposure parameters is required. We determined the relationship between nsPEF exposure parameters (pulse width and amplitude) and nanopore formation in two cell types: rodent neuroblastoma (NG108) and mouse primary hippocampal neurons (PHN). We identified thresholds for nanoporation using Annexin V and FM1-43, to detect changes in membrane asymmetry, and through Ca 2þ influx using Calcium Green. The ED50 for a single 600 ns pulse, necessary to cause uptake of extracellular Ca 2þ , was 1.76 kV∕cm for NG108 and 0.84 kV∕cm for PHN. At 16.2 kV∕cm, the ED50 for pulse width was 95 ns for both cell lines. Cadmium, a nonspecific Ca 2þ channel blocker, failed to prevent Ca 2þ uptake suggesting that observed influx is likely due to nanoporation. These data demonstrate that moderate amplitude single nsPEF exposures result in rapid Ca 2þ influx that may be capable of controllably modulating neurological function. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution

User-Defined Material Model for Progressive Failure Analysis

Abstract: An overview of different types of composite material system architectures and a brief review of progressive failure material modeling methods used for structural analysis including failure initiation and material degradation are presented. Different failure initiation criteria and material degradation models are described that define progressive failure formulations. These progressive failure formulations are implemented in a user-defined material model (or UMAT) for use with the ABAQUS/Standard1 nonlinear finite element analysis tool. The failure initiation criteria include the maximum stress criteria, maximum strain criteria, the Tsai-Wu failure polynomial, and the Hashin criteria. The material degradation model is based on the ply-discounting approach where the local material constitutive coefficients are degraded. Applications and extensions of the progressive failure analysis material model address two-dimensional plate and shell finite elements and three-dimensional solid finite elements. Implementation details and use of the UMAT subroutine are described in the present paper. Parametric studies for composite structures are discussed to illustrate the features of the progressive failure modeling methods that have been implemented.

Using a portable terahertz spectrometer to measure the optical properties of in vivo human skin.

Abstract: Terahertz (THz) time-domain spectroscopy systems permit the measurement of a tissue's hydration level. This feature makes THz spectrometers excellent tools for the noninvasive assessment of skin; however, current systems are large, heavy and not ideal for clinical settings. We previously demonstrated that a portable, compact THz spectrometer permitted measurement of porcine skin optical properties that were comparable to those collected with conventional systems. In order to move toward human use of this system, the goal for this study was to measure the absorption coefficient (μa) and index of refraction (n) of human subjects in vivo. Spectra were collected from 0.1 to 2 THz, and measurements were made from skin at three sites: the palm, ventral and dorsal forearm. Additionally, we used a multiprobe adapter system to measure each subject's skin hydration levels, transepidermal water loss, and melanin concentration. Our results suggest that the measured optical properties varied considerably for skin tissues that exhibited dissimilar hydration levels. These data provide a framework for using compact THz spectrometers for clinical applications.

Exciplex formation in blended spin-cast films of fluorene-linked dyes and bisphthalimide quenchers.

Abstract: Spin-cast films of dyes (donor−π–donor, donor−π–acceptor, and acceptor−π–acceptor type, where the donor is Ph2N–, the acceptor is 2-benzothiazoyl, and the π-linker is 9,9-diethylfluorene) blended with nonconjugated bisphthalimides were prepared. Upon visible-light excitation of the dyes, quenching of the excited state occurs by exciplex formation between dye and bisphthalimide molecules or, in some cases, by excimer formation or aggregation-induced emission between two dye molecules. The extent of exciplex formation is dependent on the driving force, which can be calculated using the energy difference between the lowest unoccupied molecular orbitals (LUMOs) of the dyes and bisphthalimides. The results show that complete exciplex formation occurs when this driving force is greater than 0.57 eV whereas partial exciplex formation occurs when the driving force is between 0.28 and 0.57 eV. The exciplex emission energies can also be predicted by calculating the difference between the LUMO level of the bisphthal...

Communication Units and Methods for Relay-Assisted Uplink Communication

Abstract: A relay device for supporting uplink communication between a terminal device and a base station is described. The relay device comprises at least one receiver arranged to receive a downlink message from the base station; a control processor, operably coupled to the at least one receiver and arranged to determine from the downlink message information identifying an uplink control resource to be used by the terminal device; and a transmitter, operably coupled to the control processor and arranged to relay received periodic uplink control channel messages on the identified uplink control resource from the terminal device to the base station.

Apparatus and Methods for Relay-Assisted Uplink Communication

Abstract: A terminal device is arranged to communicate with a base station via a relay device in a wireless communications system. The terminal device comprises: a transmitter arranged to transmit a first access request message to the base station wherein the access request message comprises one from a set of access preambles that indicate relay device uplink assistance is required; a receiver arranged to receive an access request grant response from the base station; and a control processor operably coupled to the transmitter and receiver and arranged to: process the access request grant response; extract transmit power control information therefrom for transmissions to the relay device; map a first power level indicated in the transmit power control information to a second power level associated with a transmission via the relay device; and generate and transmit a transmission to the relay device at the mapped transmit second power level.

Common world model for unmanned systems

Abstract: The Robotic Collaborative Technology Alliance (RCTA) seeks to provide adaptive robot capabilities which move beyond traditional metric algorithms to include cognitive capabilities. Key to this effort is the Common World Model, which moves beyond the state-of-the-art by representing the world using metric, semantic, and symbolic information. It joins these layers of information to define objects in the world. These objects may be reasoned upon jointly using traditional geometric, symbolic cognitive algorithms and new computational nodes formed by the combination of these disciplines. The Common World Model must understand how these objects relate to each other. Our world model includes the concept of Self-Information about the robot. By encoding current capability, component status, task execution state, and histories we track information which enables the robot to reason and adapt its performance using Meta-Cognition and Machine Learning principles. The world model includes models of how aspects of the environment behave, which enable prediction of future world states. To manage complexity, we adopted a phased implementation approach to the world model. We discuss the design of “Phase 1” of this world model, and interfaces by tracing perception data through the system from the source to the meta-cognitive layers provided by ACT-R and SS-RICS. We close with lessons learned from implementation and how the design relates to Open Architecture.

TIGR: the tactical ground reporting system

Abstract: The Tactical Ground Reporting System (TIGR) is a cloud-based application that facilitates collaboration and information sharing at the patrol level. DARPA began development efforts in 2005, and introduced the system to a single brigade in Iraq at the beginning of 2007. Its use spread to all Army units in Iraq and Afghanistan, as well as Kuwait, the Philippines, South Korea, and the Horn of Africa, and it has proven to be an indispensable tool for counterinsurgency operations. The system enables collection and dissemination of fine-grained information on people, places, and events, and offers a media-rich view of the battlefield with digital photos, videos, and high-resolution geospatial imagery. In 2011 TIGR transitioned to the Army and is now managed by the Project Manager for the Joint Battle Command-Platform (PM JBC-P), where it has expanded to include vehicle-based systems and other on-themove operational scenarios. Despite the richness of its multimedia content, TIGR has successfully operated for years in multiple theaters of war with minimal impact on low-bandwidth tactical networks. This article describes the TIGR system and how it has evolved, as well as the challenges of designing and deploying a distributed system for disadvantaged networks, and the unique data dissemination architecture that has made TIGR such a success.

Standardizing Medicare payment information to support examining geographic variation in costs.

Abstract: Objectives Examination of efficiency in health care requires that cost information be normalized. Medicare payments include both geographic and policy-based facility type differentials (e.g., wage index and disproportionate share hospital), which can bias cost comparisons of hospitals and averages across geographic areas. Standardizing payment information to remove the area- and policy-based payment differentials should normalize much of the observed geographic variability in payments, allowing for a more accurate comparison of resource use between providers and across geographic regions. Use of standardized payments will ensure that observed payment variation is due to differences in practice patterns and service use, rather than Medicare payment differences over which the providers have no control. This paper describes a method for standardizing claim payments, and demonstrates the difference in actual versus standardized payments by geographic region.

Electromagnetic modeling and measurements of the 104 cm rod and biconical antenna for radiated emissions testing below 30 MHz

Abstract: The purpose of this paper is to identify the optimum approach to grounding of the 104 cm rod antenna counterpoise in a radiated emissions test setup when testing below 30 MHz. Electromagnetic modeling is used to analyze various grounding approaches and empirical results are included to substantiate the analysis. Results of the analysis and measurements reveal a complete floating of the counterpoise to be the optimum approach for obtaining accurate measurements. Commercially available fiber optic isolators are demonstrated as an easy way to achieve isolation of the counterpoise. Additional results are included for the biconical antenna in the frequency range of 20 to 30 MHz.

Tasklettes – a Fine Grained Parallelism for Ada on Multicores

Abstract: The widespread use of multi-CPU computers is challenging programming languages, which need to adapt to be able to express potential parallelism at the language level. In this paper we propose a new model for fine grained parallelism in Ada, putting forward a syntax based on aspects, and the corresponding semantics to integrate this model with the existing Ada tasking capabilities. We also propose a standard interface and show how it can be extended by the user or library writers to implement their own parallelization strategies.

Accounting for unobservable exposure time bias when using Medicare prescription drug data.

Abstract: OBJECTIVE To describe the prevalence and correlates of unobservable medication exposure time, and to recommend approaches for minimizing bias, in studies using Medicare Part D data.. SAMPLE 179,065 Medicare patients hospitalized for an AMI in 2007 or 2008. METHODS We compared two methods for creating medication exposure observation periods using acute care discharge vs. post-acute care discharge dates. We examined options for increasing cohort sizes by requiring different thresholds for observable days, or by using as a covariate, in the observation period. We calculated the extent and health status correlates of unobserved Medicare Part D exposure time and examined its association with receipt of beta-blockers. RESULTS 39% of patients had unobservable time during the 30 day exposure assessment period following acute care; they were significantly older, had more comorbidity and longer acute care stays, had worse 1-year survival, and were significantly less likely to be classified as beta-blocker users. Using the alternative exposure assessment window, only 29% of the sample had unobservable time, and differences between groups were less pronounced. Significant gains in sample size can be obtained by restricting or controlling for the number of observable days required in the exposure assessment period. CONCLUSIONS Unobservable exposure time is common among Medicare Part D beneficiaries, and they are often in worse health. To retain patients with unobservable exposure time, we recommend stratifying patients on receipt of post-acute facility-based care, calculating and using observable days as a covariate and, when appropriate, using the discharge date from contiguous post-acute facility care for beginning the exposure assessment period.

Apparatus and Methods for Semi-Persistent Scheduling

Abstract: A base station for supporting communications with a terminal device in a wireless communications system is described. The base station comprises a dynamic scheduler module; a semi-persistent scheduler, SPS, module, a receiver arranged to receive at least one data packet; and a compressor module arranged to compress the received at least one data packet prior to transmission to the terminal device. A control processor is operably coupled to the compressor module and arranged to determine a compression state of the compressor module and based thereon select one of the dynamic scheduler module and semi persistent scheduler module to allocate resource for communicating with the terminal device. A transmitter is arranged to transmit the compressed at least one data packet to the terminal device on the allocated resource.

Wing Velocity Control System for Testing Body Motion Control Methods for Flapping Wing MAVs

Abstract: This work is focused on testing the viability of split-cycle constant-period frequency modulation for controlling a flapping wing micro air vehicle. By varying the velocities of the upstroke and downstroke portions of a flapping wings’ motion, non-zero cycle-averaged drag can be generated. This results in the ability to control the roll and horizontal translation of the vehicle by varying the split-cycle parameter. In this paper, a flapping wing prototype is developed for testing the split-cycle technique. A fuselage, wings, motor control electronics, and motor control software are created to allow wireless control of the motion of the flapping wing vehicle. The complete vehicle is then placed on an air table for experimental testing. The air table provides the lift equal to weight condition and constrains the pitch and yaw degrees of freedom while allowing for roll rotation and horizontal translation. In this way, testing of the degrees of freedom which can be manipulated via split-cycle, namely roll and horizontal translation, can be performed. The air table tests reveal that split-cycle can be used to control these two degrees of freedom.

Stags Example Problems Manual

Abstract: This document summarizes the STructural Analysis of General Shells (STAGS) development effort, STAGS performance for selected demonstration problems, and STAGS application problems illustrating selected advanced features available in the STAGS Version 5.0. Each problem is discussed including selected background information and reference solutions when available. The modeling and solution approach for each problem is described and illustrated. Numerical results are presented and compared with reference solutions, test data, and/or results obtained from mesh refinement studies. These solutions provide an indication of the overall capabilities of the STAGS nonlinear finite element analysis tool and provide users with representative cases, including input files, to explore these capabilities that may then be tailored to other applications.

Apparatus and Methods for Supporting Control Plane Data

Abstract: A wireless communications system supports control plane data and comprises: a first mobility management entity, MME; at least one second mobility management entity, MME; and a terminal device; wherein both the first MME and the at least one second MME are allocated to interoperate to support control plane data for the terminal device

Apparatus and Methods for Key Generation

Abstract: A method for key generation at a terminal device supporting at least two communication modes of operation is described. The method comprises, at a terminal device comprising a key derivation function: receiving at least one input parameter from a first wireless communication system; generating a first key in the key derivation function using the received at least one input parameter and at least one first locally stored input parameter in order to transmit in a first mode of operation on the first wireless communication system; and generating a second key in the key derivation function solely using at least one second locally stored input parameter in order to transmit in a second mode of operation on a second wireless communication system; wherein the at least one second locally stored input parameter is arranged to enable the second key to be used as the first key.

Effects of a TASER ® conducted energy weapon on the circulating red-blood-cell population and other factors in Sus scrofa

Abstract: In previous studies hematocrit has been consistently increased in an anesthetized animal model after exposures to TASER® conducted energy weapons (CEWs). In the present study we analyzed changes in blood cell counts and red blood cell membrane proteins following two 30-s applications of a TASER C2 device (which is designed for civilian use). Hematocrit increased significantly from 33.2 ± 2.4 (mean ± SD) to 42.8 ± 4.6 % immediately after CEW exposure of eleven pigs (Sus scrofa). Red blood cell count increased significantly from 6.10 ± 0.55 × 1012/L to 7.45 ± 0.94 × 1012/L, and mean corpuscular volume increased significantly from 54.5 ± 2.4 fl to 57.8 ± 2.6 fl. Mean corpuscular hemoglobin concentration decreased significantly from 20.5 ± 0.7 to 18.5 ± 0.6 mM. Thirty protein spots (from two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis, selected for detailed comparison) exhibited greater densities 30-min post-exposure compared with pre-exposure values. A greater number of echinocytes were observed following CEW exposure. On the basis of these results it appears that, during the strong muscle contractions produced by TASER CEWs, a specific population of red blood cells (RBCs) may be released from the spleen or other reservoirs within the body. The total time of CEW exposure in the present study was relatively long compared with exposures in common law-enforcement scenarios. Despite statistically significant changes in red blood cell counts (and other measures directly related to RBCs), the alterations were short-lived. The transient nature of the changes would be likely to counteract any potentially detrimental effects.

Spin-stabilized non-lethal projectile with a shear-thinning fluid

Abstract: A non-lethal projectile having a shear-thinning fluid within an interior cavity. The shear-thinning fluid having a greater apparent viscosity at low shear rates to spin-stabilize the non-lethal projectile during flight and a lower apparent viscosity at a high shear rate corresponding with the shear-thinning fluid shearing against the frangible cap upon the non-lethal projectile striking the target, with the low viscosity of the shear-thinning fluid allowing proper dispersal upon impact with the target. The shear-thinning fluid can comprise a marking media and be in the form of an emulsion with less than about 50% liquid by volume to effectively disperse upon impact with the target.

Maximum Likelihood Joint Tracking and Association in Strong Clutter

Abstract: We have developed a maximum likelihood formulation for a joint detection, tracking and association problem An efficient non-combinatorial algorithm for this problem is developed in case of strong clutter for radar data By using an iterative procedure of the dynamic logic process "from vague-to-crisp" explained in the paper, the new tracker overcomes the combinatorial complexity of tracking in highly-cluttered scenarios and results in an orders-of-magnitude improvement in signal- to-clutter ratio

Development of a Flapping Wing Mechanism that Can Produce Lift Greater than Weight

Abstract: This work is focused on testing multiple versions of flapping wing mechanisms to improve the lift generating capabilities of the mechanisms. Three mechanisms are considered in this work, a traditional four bar linkage version, a four bar mechanism which used ball joints, and a four bar mechanism with a sector and output gear for amplified motion. The traditional four bar version has a wing stroke amplitude of about 55 while the other two mechanisms have an amplitude of nearly 90. The criteria for comparison is the lift force generating capacity of each mechanism. For each mechanism, the forward kinematics are derived for use in a table lookup so that symmetric and asymmetric flapping can be achieved as desired.

The challenges of applying service orientation to the U.S. Army's live training software product line

Abstract: Live Training Transformation (LT2) is the product line strategy put in place by the United States Army Program Executive Office for Simulation, Training and Instrumentation (PEO STRI). The purpose of the LT2 product line is to provide a common set of core assets including architectures, software components, standards and processes that form the basis of all Army Live Training systems. As products consuming LT2 core assets evolve to meet the latest requirements of the military live training community, changes to the core product line architecture must also be made. Based on thorough analysis of the LT2 core capabilities and user trends toward web-enabled and mobile computing technologies, a Service Oriented Architecture (SOA) strategy was identified and adopted as the objective architecture for the evolving LT2 product line. Future success of the LT2 product line now depends on the alignment of product line engineering concepts with the business and technical benefits of SOA, and to ensure that systematic reuse continues to provide substantial return-on-investment for the Army. This paper addresses the challenges of adopting SOA into an existing software product line, the unique circumstances of the LT2 SOA environment, and present a set of analysis and design considerations for the product line engineering community.

Temporal gene expression kinetics for human keratinocytes exposed to hyperthermic stress.

Abstract: The gene expression kinetics for human cells exposed to hyperthermic stress are not well characterized. In this study, we identified and characterized the genes that are differentially expressed in human epidermal keratinocyte (HEK) cells exposed to hyperthermic stress. In order to obtain temporal gene expression kinetics, we exposed HEK cells to a heat stress protocol (44 °C for 40 min) and used messenger RNA (mRNA) microarrays at 0 h, 4 h and 24 h post-exposure. Bioinformatics software was employed to characterize the chief biological processes and canonical pathways associated with these heat stress genes. The data shows that the genes encoding for heat shock proteins (HSPs) that function to prevent further protein denaturation and aggregation, such as HSP40, HSP70 and HSP105, exhibit maximal expression immediately after exposure to hyperthermic stress. In contrast, the smaller HSPs, such as HSP10 and HSP27, which function in mitochondrial protein biogenesis and cellular adaptation, exhibit maximal expression during the “recovery phase”, roughly 24 h post-exposure. These data suggest that the temporal expression kinetics for each particular HSP appears to correlate with the cellular function that is required at each time point. In summary, these data provide additional insight regarding the expression kinetics of genes that are triggered in HEK cells exposed to hyperthermic stress.

Apparatus and methods for accessing a data network

Abstract: A packet data network gateway, P-GW, is located in a second network for supporting control plane data in a wireless communications system that additionally comprises a first network having a first packet data network gateway, P-GW, operably couplable to the P-GW and a serving gateway, S-GW. The P-GW comprises a processor arranged to determine an operational status of at least one of: a backhaul link, first P-GW. In response to the processor determining that both of the backhaul link and the first P-GW are available, the processor is arranged to perform at least one of: trigger deferred signalling between the first network and at least one of a mobility management entity, MME, the S-GW; trigger user plane handling, monitor and build terminal device context information for a plurality of terminal devices being served with user plane data by the backhaul link of the second network.

Apparatus and methods for device to device communications

Abstract: A terminal device for communicating in a cellular system is described. The terminal device comprises: at least one first transceiver arranged to communicate with a plurality of communication units; and at least one first signal processor, operably coupled to the at least one first transceiver and arranged to: communicate with a first communication unit in the cellular system in a first mode of operation when the terminal device is located within a coverage range of the at least one base station; and facilitate in a second mode of operation direct communications between at least one other terminal device and the first communication unit when the at least one other terminal device is located outside of the coverage range of the at least one base station.

Methods and apparatus for sharing a service between multiple virtual machines

Abstract: Methods and apparatus for sharing a physical device and/or service between multiple virtual and/or physical machines are disclosed. In an embodiment, a hypervisor grants permission to a first virtual machine to access a physical device via the hypervisor. For example, the hypervisor may grant permission to a first virtual machine to access a physical audio device. A second virtual machine then accesses the physical device via the hypervisor and the first virtual machine using a virtual services network stack. For example, the second virtual machine may play music on the audio device via the first virtual machine. In another embodiment, a first physical machine is granted permission to access and/or is connected to a physical device (e.g., an audio device) via a communication channel. A second physical machine then accesses the physical device (e.g., plays music) via the communication channel and the first physical machine using the virtual services network stack.

Pressure vessel with safety features

Abstract: A vessel, such as a rocket motor tube, comprised of an insert, and a joint that allows the insert to decouple from the vessel to relieve pressure when subjected to excessive temperatures and/or a predetermined temperature or temperature range.