Tech Briefs

Quantitative Analysis of a Hybrid Electric Humvee for Fuel Economy Improvement

The Army has acquired several hybrid platforms to assess the applicability of hybrid technology for military missions. These hybrid platforms include both series and parallel hybrid topologies. This work compares a conventional HMMWV (High Mobility Multi-purpose Wheeled Vehicle) M1113 with a series hybrid HMMWV XM1124 in terms of fuel economy improvements over three military drive cycles.

Posted in: Briefs, Physical Sciences, Architecture, Fuel economy, Hybrid electric vehicles, Military vehicles and equipment

Electrochemical Energy Storage Materials

One of the most important requirements in next-generation batteries is to concurrently deliver high energy density and high power density (fast charge-discharge rates). The high power density requirement can be met with enhanced ion and electron transport kinetics in batteries, which in turn requires active materials with high ion diffusion constants and conductive additives or architectures for faster electron transport to respective current collectors. It is well known that nanostructuring the electrode materials would significantly enhance the characteristic time constant for ion diffusion, thereby reducing the intercalation/deintercalation time.

Posted in: Briefs, Materials, Battery cell chemistry, Energy storage systems, Nanotechnology

Solar and Thermal Energy Harvesting Textile Composites for Aerospace Applications

The proposed research focuses on developing novel energy harvesting devices that can be integrated with loadbearing structures in an air vehicle (e.g. a UAV). Several ambient energy sources are available on a UAV: light, heat, and vibration. The amount of energy available from light and heat exceeds that in vibration, so this work focuses on the first two modes of harvesting.

Posted in: Briefs, Materials, Aircraft structures, Solar energy, Heat exchangers, Composite materials, Textiles

Thermo-Elastic Nondestructive Evaluation of Fatigue Damage in PMR-15 Resin

New aircraft are expected to use more composite materials. This drives the need for nondestructive evaluation (NDE) of composite materials. Current aircraft are flown beyond their design lives, and have to be inspected for fatigue and other types of damage. This necessitates a need to understand the NDE signal-material relationship to evaluate the component state.

Posted in: Briefs, Materials, Aircraft structures, Composite materials, Fatigue, Resins, Non-destructive tests

Characterization of Ceramic Composite Materials Using Terahertz Nondestructive Evaluation Techniques

This work describes the use of nondestructive evaluation (NDE) techniques to characterize defects such as rust, voids, etc. in materials, and to analyze and predict strain and stress-induced breakdown. The use of terahertz (THz) imaging as an evaluation tool for novel materials and systems has found much success in recent years. While suggested as a potential NDE tool for use in the field of ceramic and ceramic matrix composite materials, the use of THz spectroscopy and imaging in the examination of the effects of mechanical and thermally induced strain on ceramic composite materials is not well established. In order to assess the effectiveness of THz imaging for use in the analysis of ceramic composite material health, it is necessary to determine if THz spectroscopic imaging can clearly highlight areas of the samples that have been affected by mechanical and thermal stress.

Posted in: Briefs, Materials, Ceramics, Composite materials, Materials properties, Non-destructive tests

High Strain Rate Mechanical Properties of Glassy Polymers

Arange of experimental data has been generated describing the response of glassy polymers to high strain rate loading in compression. Recently, research programs that study the combined effects of temperature and strain rate have made significant steps in providing better understanding of the physics behind the observed response, and also in modeling this response. However, limited data are available in tension, and even more limited are data describing both the compressive and tensile response of the same polymer. In those studies that do examine tensile response, often there are large gaps in the strain rate dependence. These gaps are due to the relative difficulty of performing characterization experiments in tension, especially on polymers and especially at high rates.

Posted in: Briefs, Materials, Materials properties, Polymers, Tensile Strength

Thermal-to-Visible Face Recognition

For nighttime surveillance, acquisition of visible light imagery is impractical due to the lack of illumination. Thermal imaging, which acquires mid-wave infrared or long-wave infrared radiation naturally emitted by the human body, can be utilized in low-light conditions to perform surveillance tasks. Identification of individuals captured by thermal imaging would significantly enhance nighttime intelligence gathering capabilities. However, government watch lists and databases almost exclusively contain visible-light face imagery of individuals of interest. Matching thermal face imagery to the existing databases therefore requires the development of across-modality face recognition algorithms and methods. Due to the large modality gap caused by the wavelength difference between visible and thermal radiation, thermal-to-visible face recognition is a challenging problem.

Posted in: Briefs, Information Technology, Mathematical models, Surveillance, Thermodynamics, Identification, Visibility