Direct-Ranging Loran Model Identification and Performance Predictions

With the availability of modern data processing techniques and lowcost stable time references, the use of Loran in a direct-ranging mode offers certain potential advantages. In order to generate reliable direct-ranging Loran (DRL) performance projections and system designs, however, accurate system error models are required. This paper first describes the processing of airborne flight data from a DRL receiver to identify models for significant DRL system errors. These models are then used in a Kalman filter covariance simulation to generate performance predictions for an optimally integrated DRL system. Comparisons with conventional hyperbolic Loran are also given. DRL is shown to be capable of substantially improved position accuracy over that of conventional hyperbolic Loran, especially in regions of poor geometry. A stationary ground-align technique for improving DRL performance is also discussed.     

High-Accuracy Sounding Rocket Attitude Estimation Using Star Sensor Data

A three-axis attitude reconstitution scheme for spin stabilized sounding rockets is presented, using star transit pulse intormation from a single slit all solid state star sensor. The method, based on Kalman filtering and smoothing, gives accuracies in the arcminute range and has been successfully tested on four different missions in the Swedish sounding rocket program.     

Communicating bioastronautics research to students, families and the nation

The National Space Biomedical Research Institute (NSBRI) is supporting the National Aeronautics and Space Administration's (NASA) education mission through a comprehensive Education and Public Outreach Program (EPOP) that communicates the excitement and significance of space biology to schools, families, and lay audiences. The EPOP is comprised of eight academic institutions: Baylor College of Medicine, Massachusetts Institute of Technology, Morehouse School of Medicine, Mount Sinai School of Medicine, Texas A&M University, University of Texas Medical Branch Galveston, Rice University, and the University of Washington. This paper describes the programs and products created by the EPOP to promote space life science education in schools and among the general public. To date, these activities have reached thousands of teachers and students around the US and have been rated very highly.     

Application of GFP technique for cytoskeleton visualization onboard the International Space Station

Cytoskeleton recently attracted wide attention of cell and molecular biologists due to its crucial role in gravity sensing and trunsduction. Most of cytoskeletal research is conducted by the means of immunohistochemical reactions, different modifications of which are beneficial for the ground-based experiments. But for the performance onboard the space vehicles, they represent quite complicated technique which requires time and special skills for astronauts. In addition, immunocytochemistry provides only static images of the cytoskeleton arrangement in fixed cells while its localization in living cells is needed for the better understanding of cytoskeletal function. In this connection, we propose a new approach for cytoskeletal visualization onboard the ISS, namely, application of green fluorescent protein (GFP) from Aequorea victoria, which has the unique properties as a marker for protein localization in vivo. The creation of chimerical protein-GFP gene constructs, obtaining the transformed plant cells possessed protein-GFP in their cytoskeletal composition will allow receiving a simple and efficient model for screening of the cytoskeleton functional status in microgravity.     

Autonomic straightening of gravitropically curved cress roots in microgravity.

The typical response of plant organs to gravistimulation is differential growth that leads to organ bending. If the gravitropic stimulus is withdrawn, endogenous compensation of the graviresponse and subsequent straightening occur in some plants. For instance, autonomic straightening of Lepidium roots occurs when gravitropically-curved rootsare rotated on a clinostat (Stankovi et al., 1998a). To determine whether endogenous compensation of the graviresponse also occurs in space, microgravity-grown cress roots were laterally centrifuged in-flight and then returned to microgravity using Biorack hardware on a shuttle mission (STS-81). The cress roots were centrifuged at 4 different g-doses (0.1 x g and 1 x g for 15 or 75 min). All four treatments yielded varying degrees of root curvature. Upon removal from the centrifuge, roots in all four treatments underwent subsequent straightening in microgravity. This straightening resulted from a loss of gravitropic curvature in older regions of the root and the coordinated alignment of new growth. These results show that both microgravity and clinostat rotation on Earth are equivalent in stimulus withdrawal with respect to the induction of endogenous compensation of the curvature. Cress roots are the only plant organ shown to undergo compensation of the curvature in both microgravity and on a clinostat. The compensation of graviresponse in space rules out the hypothesis that the endogenous root straightening ("autotropism") represents a commitment to a pre-stimulus orientation with respect to gravity and instead suggests that there is a default tendency towards axiality following a withdrawal of a g-stimulus.     

On monitoring the bacterial component as an indicator of the state of small man-made ecosystems.

High reproduction rates make the bacterial component of ecosystems a good indicator of the state of the system on the whole. This determines the necessity to develop rapid monitoring of the functional state of the bacterial component of small ecosystems. Information about substrate concentration in the population is indicative of the state of the bacterial culture. Conventional methods of monitoring the concentration of integral substrate in the system take time much longer than the changes in the ecosystem. The paper presents theoretical foundations for the logical sequence "catalase activity--intracellular substrate concentration--estimate of substrate consumed by bacteria" for experimental verification and as a consequence of development of the integral method of monitoring the bacterial population on the basis of determining bacterial catalase activity. Grant numbers: 04-96017, N25.     

Nonlinear eddy viscosity and algebraic stress models for solving complex turbulent flows

Nonlinear eddy viscosity and algebraic stress models are currently providing an invaluable link between the more common linear eddy viscosity turbulence models and the full differential Reynolds stress forms. With the increased popularity has come an abundance of different formulations. The purpose of this review is to provide a cohesive framework for the variety of models proposed and to highlight the various similarities and differences among the models. Their link with differential Reynolds stress models and their improved predictive capability over linear eddy-viscosity models is also highlighted.     

CCD互相关粒子图像测速及其在对抗流流场测量中的应用

在常规自相关粒子图像测速（ＰＩＶ）系统的基础上,发展了一个采用ＣＣＤ像机的互相关粒子图像测速系统。用这一新系统测量了对抗流流场的结果表明,这一技术克服了自相关粒子图像测速技术在测量具有滞止点的流场中的困难。实验说明,与自相关粒子图像测速技术相比,这一技术更快捷有效。     

Fuel mass penalty due to generators and fuel cells as energy source of the all-electric aircraft

The paper presents the results of an assessment of the fuel mass penalty due to generators and fuel cell systems. Based on the simulation tool SysFuel, fuel mass penalties for different mission ranges and fuel cell architectures are calculated and compared to a conventional reference architecture. Different fuel cell architectures using ram air or cabin exhaust air and different options of energy recovery are considered. As a result of the studies, target values are presented for the mass to power ratio of fuel cell systems to achieve fuel mass reductions compared to conventional generator and auxiliary power unit systems.