Dose equivalent, absorbed dose and charge spectrum investigation in low Earth orbit.

Particle intensity, dose equivalent and absorbed dose have been measured on board the space shuttle Endeavour during STS-108 in December 2001 by Dublin Institute for Advanced Studies (DIAS). The dose estimates are based on very accurate measurements of recoils produced in CR-39 by cosmic ray primary and secondary protons and heavier nuclei and by secondary neutrons. The corresponding LET spectra were used to determine dose equivalent and absorbed dose values. Estimates of the total flux of Z > or = 2 nuclei have been undertaken and a preliminary charge spectrum was measured. Some comparisons are made with preliminary data obtained on STS-105 (ISS Expedition) and other missions using CR-39 detectors.     

Protection by WR-2721 and WR-151327 against late effects of gamma rays and neutrons.

Two thiophosphoroate compounds WR-2721 and WR-151327 were assessed for their ability to modify the deleterious effects (life shortening and carcinogenesis) of fission-spectrum neutrons (kerma-weighted mean energy of 0.85 MeV) or gamma rays on B6CF1 hybrid mice. Male and female mice, 200 of each sex per experimental group, were irradiated individually at 110 days of age. Radioprotectors (400 mg/kg of WR-2721 or 580 mg/kg of WR-151327) were administered intraperitoneally 30 min prior to irradiation. Neutron doses were 10 cGy or 40 cGy and gamma ray doses were 206 cGy or 417 cGy. Animals were housed five to a cage; cage locations in the holding rooms were randomized by computer. Animals were checked daily and all deceased animals were necropsied. WR-2721 afforded protection against both neutron- and gamma-ray-induced carcinogenesis and subsequent life shortening. Cumulative survival curves for unirradiated mice of either sex were unaffectecd by protectors. WR-2721 protected irradiated groups against life shortening by approximately 10 cGy of neutrons or 100 cGy of gamma rays. WR-151327 was as effective as WR-2721 against neutron irradiation.     

A large flat panel multifunction display for military and spaceapplications

A flat panel multifunction display (MFD) that offers the size and reliability benefits of liquid crystal display technology while achieving near-CRT display quality is presented. Display generation algorithms that provide exceptional display quality are being implemented in custom VLSI components to minimize MFD size. A high-performance processor converts user-specified display lists to graphics commands used by these components, resulting in high-speed updates of two-dimensional and three-dimensional images. The MFD uses the MIL-STD-1553B data bus for compatibility with virtually all avionics systems. The MFD can generate displays directly from display lists received from the MIL-STD-1553B bus. Complex formats can be stored in the MFD and displayed using parameters from the data bus. The MFD also accepts direct video input and performs special processing on this input to enhance image quality     

Safety testing of lithium ion batteries for navy devices

Lithium ion battery technology is being introduced into power supplies used by our armed forces for a variety of applications. In many cases, the same cells and design parameters that support commercial battery packs are being used in military battery packs. This approach is expected to result in a major decrease in the total life cycle cost of the equipment these batteries support. On June 13, 1991, NAVSEA issued INST9310.1B1, which states that all lithium battery powered equipment must undergo safety evaluation and approval prior to fleet use. This safety program governs a process whereby approvals are issued for lithium batteries to be used in specific equipment on ground facilities, surface combatants, air combatants, and/or submarines. The Naval Ordnance Safety and Security Activity (NOSSA) manages the program. The chief technical advisors are Code 644 at NSWC Carderock Division and Code 609A at NSWC Crane Division. This paper describes three battery designs that incorporate lithium ion technology, and the results of battery safety tests conducted in accordance with navy requirements.     

Chromosome instability of HPRT-mutant subclones induced by ionising radiation of various LET.

The induction of HPRT-mutations and survival of Chinese hamster cells (line B11ii-FAF28, clone 431) were studied after irradiation by 4He and 12C-ions of various LET (20-360 keV/micrometers), produced by the U-200 heavy ion accelerator. The RBE increases with LET up to the maximum at 100-200 keV/micrometers and then decreases. Cytogenetic analysis was performed on the HPRT-mutant subclones selected from unirradiated Chinese hamster V-79 cells and from HPRT-mutant subclones that arose after exposure to gamma-rays, 1 GeV protons and 14N-ions (LET-77 keV/micrometers), produced by the synchrophasotron and the U-400M heavy ion accelerator. Slow growing mutant subclones were observed. The cytogenetic properties of individual clones were highly heterogeneous and chromosome instability was observed in both spontaneous and radiation-induced mutants. Chromosome instability was highest among spontaneous mutants and decreased with increasing LET.     

Analysis of radiation risk from alpha particle component of solar particle events.

The solar particle events (SPE) will contain a primary alpha particle component, representing a possible increase in the potential risk to astronauts during an SPE over the often studied proton component. We discuss the physical interactions of alpha particles important in describing the transport of these particles through spacecraft and body shielding. Models of light ion reactions are presented and their effects on energy and linear energy transfer (LET) spectra in shielding discussed. We present predictions of particle spectra, dose, and dose equivalent in organs of interest for SPE spectra typical of those occurring in recent solar cycles. The large events of solar cycle 19 are found to have substantial increase in biological risk from alpha particles, including a large increase in secondary neutron production from alpha particle breakup.     

An energy management system to improve electric vehicle range andperformance

An electric vehicle (EV) energy management system (EMS) developed to accurately predict and extend the usable driving range and the life of the battery pack is discussed. The EMS monitors and records battery state of charge, vehicle performance, power consumption of key components, and driver's actions. Convenient drive inputs in conjunction with memorized energy consumption profiles allow accurate prediction of driving range and selection of appropriate recharging profiles. EV range extension is accomplished by identifying inefficient use of energy, resulting in EMS modification of energy usage by offending subsystems or EMS suggestion to the driver of improved driving habits or vehicle use. Factors affecting the accuracy of range prediction and the amount of range extension are described     

Distributed flight control system using fiber distributed datainterface (FDDI)

The design of fault-tolerant distributed control systems is discussed. The application described is a generic flight control system (FCS) for a fighter aircraft. The system is designed for high redundancy and expandability to meet various requirements. The communication network is based on the fiber distributed data interface (FDDI), which provides a high level of electromagnetic interference resistance and reliability. The choice of fiber optic media also provides an extremely high bandwidth and tremendous growth capability for future communications needs. This study is not specific to FDDI or flight control systems. The methods and configurations presented should be applicable to many real-time control implementations     

MEMS Electronically Steerable Antennas for Fire Control Radars

Large apertures are of great benefit to applications that are prime powered limited as is found on aerostat and other airborne platforms. Electronically scanned array antennas are often proposed for these applications. However, increasing the aperture area with conventional array technology is met with prohibitive cost, weight, and prime power increases because of the dense spacing of phase shifters and/or active T/R modules. This discusses the recent development of RF MEMS (Microelectromechanical System) switch technology and the use of these switches in a Radanttrade lens configuration for arrays of approximately 10 m² at X-band. A proof-of-concept 0.4 m² MEMS Electronically Steerable Antenna (ESA) containing 25,000 MEMS switches has been successfully designed, fabricated, and tested. The 0.4 m² MEMS ESA was then integrated with an AN/APG-67 radar system to form the MEMS Demonstration Radar System. The MEMS Demonstration Radar System successfully detected both airborne and ground moving targets during a series of extensive radar demonstrations. This is believed to be the first large scale employment of MEMS switches in a scanning antenna and radar system. The low-cost, lightweight, and low power technology demonstrated can enable weight and power constrained platforms with electronic steering.     

Voting fusion adaptation for landmine detection

This paper presents a voting fusion application for use with a remotely controlled multisensor vehicle platform for antitank landmine detection. Data from three landmine detection sensors mounted at the front of the vehicle enhance the probability of detection and, when combined via data fusion, limit the false alarm density to practical levels. The performance of the voting fusion scheme presented in this paper is contrasted with a heuristic data fusion approach developed by General Dynamics Canada.