An Alternate Approach to the Prediction of Polynomial Signals in Noise from Discrete Data

When the problem of predicting the past, present, or future value of a polynomial signal or any of its derivatives is considered, where the signal is in white Gaussian noise, the standard approach has been to minimize mean-square-error with constraints by use of Lagrange multipliers. In this paper an alternate approach is described, using results of Rao and Bhattacharyya from the statistical literature, which reduce the specified prediction problem to a simple one requiring no formal minimizations and no use of Lagrange multipliers. It further has the advantage of yielding the covariances between estimates of the polynomial and its derivates. Useful engineering formulas for smoothing and prediction are developed in the main part of the paper. These include both filter and covariance expressions. A tutorial discussion of the theory is given in two appendixes.     

Investigation of solid propellant combustion instability by means of a T-burner

Experimental investigation of solid propellant combustion instability using variable area T-burner is presented. The test facility is described and theoretical background and formulation related to the specific geometry are given. A number of solid propellants were tested over pressure oscillation frequency range of 350–1000 Hz. Results show complex behavior of the propellant response, and can characterize the different propellants according to their combustion instability level.     

Optimal trajectories for the aeroassisted flight experiment

This paper deals with the determination of optimal trajectories for the aeroassisted flight experiment (AFE). The intent of this experiment is to simulate a GEO-to-LEO transfer, where GEO denotes a geosynchronous Earth orbit and LEO denotes a low Earth orbit. Specifically, the AFE spacecraft is released from the Space Shuttle and is accelerated by means of a solid rocket motor toward Earth, so as to achieve atmospheric entry conditions identical with those of a spacecraft returning from GEO. During the atmospheric pass, the angle of attack is kept constant, and the angle of bank is controlled in such a way that the following conditions are satisfied: (a) the atmospheric velocity depletion is such that, after exiting, the AFE spacecraft first ascends to a specified apogee and then descends to a specified perigee; and (b) the exit orbital plane is identical with the entry orbital plane. The final maneuver, not analyzed here, includes the rendezvous with and the capture by the Space Shuttle. In this paper, the trajectories of an AFE spacecraft are analyzed in a 3D space, employing the full system of 6 ODEs describing the atmospheric pass. The atmospheric entry conditions are given, and the atmospheric exit conditions are adjusted in such a way that requirements (a) and (b) are met, while simultaneously minimizing the total characteristic velocity, hence the propellant consumption required for orbital transfer. Two possible transfers are considered: indirect ascent (IA) to a 178 NM perigee via a 197 NM apogee; and direct ascent (DA) to a 178 NM apogee. For both transfers, two cases are investigated: (i) the bank angle is continuously variable; and (ii) the trajectory is divided into segments along which the bank angle is constant. For case (ii), the following subcases are studied; 2, 3, 4 and 5 segments; because the time duration of each segment is optimized, the above subcases involve 4, 6, 8 and 10 parameters, respectively. It is shown that the optimal trajectories of cases (i) and (ii) coalesce into a single trajectory: a two-subarc trajectory, with the bank angle constant in each subarc (bang-bang control). Specifically, the bank angle is near 180° in the atmospheric entry phase (positive lift projection phase) and is near 0° in the atmospheric exit phase (negative lift projection phase). It is also shown that, during the atmospheric pass, the peak values of the changes of the orbital inclination and the longitude of the ascending node are nearly zero; hence, the peak value of the wedge angle (angle between the instantaneous orbital plane and the initial orbital plane) is nearly zero. This means that the motion of the spacecraft is nearly planar in an inertial space.     

Improving science literacy and education through space life sciences.

The National Space Biomedical Research Institute (NSBRI) encourages open involvement by scientists and the public at large in the Institute's activities. Through its Education and Public Outreach Program, the Institute is supporting national efforts to improve Kindergarten through grade twelve (K-12) and undergraduate education and to communicate knowledge generated by space life science research to lay audiences. Three academic institution Baylor College of Medicine, Morehouse School of Medicine and Texas A&M University are designing, producing, field-testing, and disseminating a comprehensive array of programs and products to achieve this goal. The objectives of the NSBRI Education and Public Outreach program are to: promote systemic change in elementary and secondary science education; attract undergraduate students--especially those from underrepresented groups--to careers in space life sciences, engineering and technology-based fields; increase scientific literacy; and to develop public and private sector partnerships that enhance and expand NSBRI efforts to reach students and families.     

Forecasting of the Total Electron Content at a Single Location

The autocovariance prediction method previously used for the forecast of VI derived ionospheric characteristics has been used for forecast of one of the most important ionospheric—the total electron content (TEC)—at single locations. Quiet and disturbed conditions at different European stations were studied in regard to clarify the forecasting capabilities of the method for determination of the TEC. The accuracies of the method achieved in dependence on the time range of the forecast are demonstrated.     

High magnetic gradient environment causes alterations of cytoskeleton and cytoskeleton-associated genes in human osteoblasts cultured in vitro

The effects of a high magnetic gradient environment (HMGE) on the cytoskeletal architecture and genes associated with the cytoskeleton in osteoblasts (MC3T3-E1 and MG-63 cells) were investigated using confocal microscopy, real-time polymerase chain reaction (PCR) and atomic force microscopy (AFM). The findings showed that, under diamagnetic levitation conditions, the architecture and average height of the cytoskeleton and surface roughness in osteoblasts were dramatically altered. HMGE affects cytoskeleton arrangement and cytoskeleton-associated gene expression.     

回归到朴素的真正艺术 《艺术家》影评

<正>2012年,横扫奥斯卡三大重要奖项的是一批黑马,一部与其他竞争影评显得格格不入的艺术片《艺术家》。这是法国著名导演迈克尔·啥扎纳维希乌斯的大胆尝试,因为《艺术家》是一部默片。《艺术家》以黑白默片的表现形式拍摄,音乐、字卡交代剧情,音效、双关阐述默片与有声片的艺术形式与角色关系,值得玩味。片头衬着传统配乐的字幕图案来呈现演职员名单。以一段     

Analytical synthesis of functional observers

A technique for constructing the observers to evaluate a linear combination of state variables is considered. We propose an algorithm for analytical synthesis of the minimum-order functional observers based on the nondegenerate transformation of the object model in the state space using the matrix canonization technology. The applicability limits of the technique and the conditions of problem solvability are defined.     

Two dimensional simulation of amplitude modulated electron plasma waves

Highly modulated waves near electron plasma frequency with both parallel and perpendicular polarization have been observed near diffusion region at dayside and in the tail region. In this paper, two dimensional Particle-In-Cell (PIC) simulation was performed to study the possible generation mechanism of these modulated electron plasma waves. It is shown that weak beam instability could generate the modulated Langmuir wave and the ambient magnetic field plays an important role in the formation of modulation. When the weak beam has loss cone distribution, highly modulated upper hybrid waves are generated and propagate with large angle to the ambient magnetic field. The properties of these modulated waves are discussed and compared with observations.     

Changes in operational procedures to improve spaceflight experiments in plant biology in the European Modular Cultivation System

The microgravity environment aboard orbiting spacecraft has provided a unique laboratory to explore topics in basic plant biology as well as applied research on the use of plants in bioregenerative life support systems. Our group has utilized the European Modular Cultivation System (EMCS) aboard the International Space Station (ISS) to study plant growth, development, tropisms, and gene expression in a series of spaceflight experiments. The most current project performed on the ISS was termed Seedling Growth-1 (SG-1) which builds on the previous TROPI (for tropisms) experiments performed in 2006 and 2010. Major technical and operational changes in SG-1 (launched in March 2013) compared to the TROPI experiments include: (1) improvements in lighting conditions within the EMCS to optimize the environment for phototropism studies, (2) the use of infrared illumination to provide high-quality images of the seedlings, (3) modifications in procedures used in flight to improve the focus and overall quality of the images, and (4) changes in the atmospheric conditions in the EMCS incubator. In SG-1, a novel red-light-based phototropism in roots and hypocotyls of seedlings that was noted in TROPI was confirmed and now can be more precisely characterized based on the improvements in procedures. The lessons learned from sequential experiments in the TROPI hardware provide insights to other researchers developing space experiments in plant biology.