An Investigation into Vertical Bias Effects

ABSTRACT

In three experiments, after exploring a virtual environment (VE), adult participants made spatial judgments about the location of target objects that were higher and lower than their perceived test location within the VE. In Experiment 1, the locations of the target objects were inferred from verbal instructions. The main results were a tendency to judge objects as closer to the horizontal plane than their true locations, and more efficient downward than upward judgments. Both effects generally accord with findings reported by Wilson et al. (2004a Wilson, P. N., Foreman, N., Stanton, D. and Duffy, H. 2004a. Memory for targets in a multilevel simulated environment: Evidence for vertical asymmetry in spatial memory. Memory & Cognition, 32: 283–297. [Crossref] , [Google Scholar], 2004b Wilson, P. N., Foreman, N., Stanton, D. and Duffy, H. 2004b. Memory for targets in a multi-level simulated-environment: A comparison between able-bodied and physically disabled children. British Journal of Psychology, 95: 325–338.  [Google Scholar]). In Experiments 2 and 3, which were closely modeled on the design of the Wilson et al. studies, regression to the horizontal plane was noted but no downward bias was observed. A misperception in the viewing height between the floors and ceilings of the virtual rooms was apparent in both experiments. The results from the present study together with earlier investigations suggest different hierarchical encoding of between-axis and within-axis information.     

Dual-Task Interference in Spatial Reorientation: Linguistic and Nonlinguistic Factors

Abstract

Language has been proposed as a medium that serves to promote spatial orientation through integrating geometric and featural information (Spelke, 2003 Spelke, E. S. 2003. “What makes us smart? Core knowledge and natural language”. In Language in mind: Advances in the study of language and thought, Edited by: Gentner, D. and Goldin-Meadow, S. 277–312. Cambridge, MA: MIT Press..  [Google Scholar]). This proposal has been explored in dual-task experiments where linguistic resources are blocked by verbal shadowing. Although some studies report disruption in using environmental cues for spatial reorientation, findings have not been consistently replicated, and the source of disruption to reorientation by verbal shadowing remains unclear. We examined conditions under which verbal shadowing affects reorientation. Shadowing of meaningful language disrupted healthy adults' use of geometric and featural information to reorient only when task instructions were unclear and when extraneous visual information provided a source of nonlinguistic interference. Reorientation was examined during the shadowing of meaningful prose or nonword syllables and was similar under both concurrent task conditions. These results indicate that language is not necessary for spatial cue integration.     

Similarities in Object and Event Segmentation: A Geometric Approach to Event Path Segmentation

Abstract

Events, like objects, can be decomposed into parts. Path, the spatiotemporal trajectory of an object during an event, is the most commonly labeled event feature across the world's languages, provides important social information, and is increasingly central to theories of general event segmentation. However, little is understood about how adults visually segment paths. We apply theories developed for object segmentation to help understand path segmentation. Overall subjects segmented equivalent object shapes and event paths in similar ways following patterns predicted by Singh and Hoffman's (2001) Singh, M. and Hoffman, D. D. 2001. “Parts-based representations of visual shape and implications for visual cognition.”. In From fragments to objects—Segmentation and grouping in vision Edited by: Shipley, T. F. and Kellman, P. J. 401–459. New York, NY: Elsevier Science..  [Google Scholar] geometric analysis of object parts. There were two notable differences between object and event segmentation: (1) event parsing occurred at points of negative curvature minima and positive curvature maxima as opposed to simply negative curvature minima; and (2) event parsing was more frequent and variable than object parsing. Implications of these results for event perception and categorization are discussed.     

Correlation between oxygen excess density and critical transition temperature in superconducting Bi-2201, Bi-2212 and Bi-2223

It is suggested that oxygen excess in undoped material of the high temperature superconducting bismuth family creates periodic two-dimensional Cu³⁺-ion patches in the copper–oxygen planes. These nanostructures have a size of square and show a strong linear relationship to their critical transition temperatures T_c.     

A Qualitative Calculus for Three-Dimensional Rotations

We have developed a qualitative calculus for three-dimensional directions and rotations. A direction is characterized in terms of the signs of its components relative to an absolute coordinate system. A rotation is characterized in terms of the signs of the components of the associated 3 × 3 rotation matrix.

A system has been implemented that can solve the following problems: 1. Given the signs of direction and rotation matrix P, find the possible signs of the image of under P. Moreover, for each possible sign vector of · P, generate numerical instantiations of and P that yields that result.

2. Given the signs of rotation matrices P and Q, find the possible signs of the composition P · Q. Moreover, for each possible sign matrix for the composition, generate numerical instantiations of P and Q that yield that result.

We have also proved some related complexity and expressivity results. The satisfiability problem for a qualitative rotation constraint network is NP-complete in two dimensions and NP-hard in three dimensions. In three dimensions, any two directions are distinguishable by a qualitative rotation constraint network.     

Quasistatic Microaccelerations onboard the Foton Satellite during Its Flight at High-Altitude Orbits

The level of quasistatic microaccelerations onboard the Foton-M satellite is predicted for its flights in two orbits: the planned orbit with the altitudes in perigee h = 262 km and in apogee h = 304 km and the orbit with h = 262 km and h = 350 km. The prediction is based on mathematical simulation of the satellite motion with respect to its center of mass under the action of gravitational and aerodynamic moments. The model is represented by the system of equations of the satellite rotational motion. Parameters of this system are chosen from the condition of coincidence of the motion of preceding Foton satellites (h 220 km and h 400 km) calculated using this model with the results of determination of actual rotational motion of the Foton-11 and Foton-12 satellites. With the help of the model thus calibrated, a calculation is made of the rotational motion of the Foton-M satellite and of the quasistatic microaccelerations onboard it. As is shown by the results of simulation, the use of the first and the second orbits will result in reductions of microaccelerations by 30% and 60%, respectively.     

Analyzing Qualitative Spatio-Temporal Calculi using Algebraic Geometry

Abstract

Qualitative spatial reasoning is based on calculi which comprise relations and operation tables that encode operations like relation composition. Designing a calculus involves determining these tables and analyzing reasoning properties—a demanding task that is susceptible to errors if performed manually. This paper is concerned with automating computation of operation tables and analysis of qualitative calculi over real-valued domains like the plane ². We present an approach to specify qualitative relations using polynomial equations that allows methods from algebraic geometry to be applied. This paper shows how reasoning with qualitative relations can be posed algebraically and demonstrates algebraic reasoning using Gröbner base analysis. We evaluate this approach and describe our implementation, which is freely available as part of the spatial reasoning toolbox SparQ.     

Characterization of a novel miniature cell culture device

Recent advancements in the field of microfluidics have generated much interest in the advent of a miniaturized cell culture device. In this study, we developed a novel miniature culture system for the continuous long-term cultivation of both anchorage dependent and suspension cells, either prokaryotic or eukaryotic in type, for both 1 g and microgravity applications. The miniature culture system may advance the development of microanalytical remote monitoring tools such as biological sentinels, biosensors, and lab-on-a-chip. Integrating the autonomous miniature culture system with a microanalytical device makes a powerful biological tool. Cells can be cultured long-term, harvested, and released directly into an analytical tool without the need for human interaction through fluid dynamic manipulations. This work characterizes the miniature bioreactor system through numerical and experimental proof of concept studies.     

Chandrayaan-1 mission to the Moon

Chandrayaan-1 is the first Indian planetary exploration mission that will perform remote sensing observation of the Moon to further our understanding about its origin and evolution. Hyper-spectral studies in the 0.4– region using three different imaging spectrometers, coupled with a low energy X-ray spectrometer, a sub-keV atom analyzer, a 3D terrain mapping camera and a laser ranging instrument will provide data on mineralogical and chemical composition and topography of the lunar surface at high spatial resolution. A low energy gamma ray spectrometer and a miniature imaging radar will investigate volatile transport on lunar surface and possible presence of water ice in the polar region. A radiation dose monitor will provide an estimation of energetic particle flux en route to the Moon as well as in lunar orbit. An impact probe carrying a mass spectrometer will also be a part of the spacecraft. The 1 ton class spacecraft will be launched by using a variant of flight proven indigenous Polar Satellite Launch Vehicle (PSLV-XL). The spacecraft will be finally placed in a 100 km circular polar orbit around the Moon with a planned mission life of two years.     

Variations of the magnetopause position versus the level of geomagnetic activity (according to data of the INTERBALL-1 Satellite for 1995–1997)

The variations in the deviation of the observed position of the magnetosphere boundary from its mean position predicted by the Shue at al., 1997 (Sh97) model [7] are studied as a function of the substorm activity level (the AE-index value) and magnetic storm intensity (the value of the corrected D _st ^* index). The results obtained make it possible to state that the amplitude of motion of the magnetospheric boundary on the dayside and in the low-latitude tail is small. It is likely that the position of the boundary is either independent of the AE and D _st ^* indices or this dependence is weak. At the same time, the boundary of the high-latitude tail shifts inward on the average by 1.5R _E with an increase of the AE-index in the case of absence of magnetic storms (contraction of the magnetospheric tail). On the contrary, in the presence of magnetic storms, this boundary shifts outward by up to 3R _E with an increase of the AE-index (inflation of the magnetospheric tail). It is also shown that the boundary of the high-latitude tail moves outward with an increase of the D _st ^* index, both at low substorm activity and in periods of high substorm activity. The amplitude of the outward motion of the high-latitude tail of the magnetosphere is by a factor of two higher for moderate magnetic storms with strong substorms than for moderate magnetic storms with weak substorms.     

Liquid rocket engine test facility engineering challenges

Liquid rocket engines for launch vehicles and space crafts as well as their subsystems need to be verified and qualified during hot-runs. A high test cadence combined with a flexible test team helps to reduce the cost for test verification during development/qualification as well as during acceptance testing for production. Test facility intelligence allows to test subsystems in the same manner as during complete engine system tests and will therefore reduce development time and cost.This paper gives an overview of the maturing of test engineering know how for rocket engine test stands as well as high altitude test stands for small propulsion thrusters at EADS-ST in Ottobrunn and Lampoldshausen and is split into two parts:

• Part 1 gives a historical overview of the EADS-ST test stands at Ottobrunn and Lampoldshausen since the beginning of Rocket propulsion activities in the 1960s.

• Part 2 gives an overview of the actual test capabilities and the test engineering know-how for test stand construction/adaptation and their use during running programs.

Examples of actual realised facility concepts are given to demonstrate cost saving potential for test programs in both cases for development/qualification issues as well as for production purposes.

Families of periodic solutions in three-dimensional restricted three-body problem

Planar orbits of three-dimensional restricted circular three-body problem are considered as a special case of three-dimensional orbits, and the second-order monodromy matrices M (in coordinate z and velocity v _z ) are calculated for them. Semi-trace s of matrix M determines vertical stability of an orbit. If |s| ≤ 1, then transformation of the subspace (z, v _z ) in the neighborhood of solution for the period is reduced to deformation and a rotation through angle φ, cosφ = s. If the angle ? can be rationally expressed through 2π,φ = 2π·p/q, where p and q are integer, then a planar orbit generates the families of three-dimensional periodic solutions that have a period larger by a factor of q (second kind Poincareé periodic solutions). Directions of continuation in the subspace (z, v _z ) are determined by matrix M. If |s| < 1, we have two new families, while only one exists at resonances 1: 1 (s = 1) and 2: 1 (s = ?1). In the course of motion along the family of three-dimensional periodic solutions, a transition is possible from one family of planar solutions to another one, sometimes previously unknown family of planar solutions.     

Manifestations of sudden commencement of a severe magnetic storm of November 20, 2003, in generation of an SC pulse, <Emphasis Type="Italic">P</Emphasis><Subscript>SC</Subscript> pulsations,and spatial modulation of the auroral brightness

The results of investigation of the geomagnetic and auroral response to the commencement of a severe magnetic storm of November 20, 2003, are presented. It is established that the onset of SC led to the brightening of the auroral arc in the dusk sector for 2–3 min with its extent to the east with a velocity of 10–20 km/s and to displacement poleward with a velocity of 1.0 km/s. Furtheron, the fast auroral expansions of short duration (5 min) to the pole up to 2–4°were observed, repeating every 5–10 min during 40 min, which led to the spatial modulation of the brightness of the glow and to generation of P_SC pulsations with similar periods of oscillations. The broadening of aurora poleward had a steplike character, with generation of new arcs poleward of previous ones 5 arcs per 1.5 min. The modulation of brightness of the glow and P_SC were observed against the background of intensification of a two-cell DP2 type current system and were accompanied by multiple turnings of the IMF B_z from south to north and back. It is assumed that the source of P_SC pulsations was a modulation of the intensity of the DP2 ionosphere currents as a result of variations of the magnetosphere convection level.Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 6, 2004, pp. 608–615.Original Russian Text Copyright © 2004 by Baishev, Borisov, Velichko, Solovyev, Yumoto.     

The influence of kinetics of neutral particles on near-surface glow of spacecraft

A technique for calculation of the glow around low-orbit spacecraft is developed, taking into consideration the kinetics of neutral particles. Using this technique, the altitude ranges are determined where molecular processes dominate over ion-electron mechanisms. The influence of the molecular composition of the Earth’s atmosphere on the production of excited radicals NO ₂ ^* near the surface of spacecraft is studied in some detail.     

Advanced technologies available for future solid propellant grains

Significant advances have been made during the last decade in several fields of solid propulsion: the advances have enabled new savings in the motor development phase and recurring costs, because they help limit the number of prototypes and tests.The purpose of the paper is to describe the improvements achieved by SNPE in solid grain technologies, making these technologies available for new developments in more efficient and reliable future SRMs: new energetic molecules, new solid propellants, new processes for grain manufacturing, quick response grain design tools associated with advanced models for grain performance predictions.Using its expertise in chemical synthesis, SNPE develops new molecules to fit new energetic material requirements.Tests based on new propellant formulations have produced good results in the propellant performance/safety behavior ratio. New processes have been developed simultaneously to reduce the manufacturing costs of the new propellants.In addition, the grain design has been optimized by using the latest generation of predictive theoretical tools supported by a large data bank of experimental parameters resulting from over 30 years' experience in solid propulsion:

• Computer-aided method for the preliminary grain design

• Advanced models for SRM operating and performance predictions

Satellite constellation mission analysis and design

The considerable surge in satellite constellations has brought to the fore the imperative need for an efficient constellation design and management plan. To address this emerging need, GMV has studied and tested algorithms for the analysis of the key phases in constellation development. These algorithms provide complete analysis capabilities and outline optimal strategies to deal with the following issues of the constellation life cycle:

• •Constellation orbital design
• •Constellation performance evaluation
• •Launch strategy and constellation set-up
• •Constellation replacement and spare strategy
• •Constellation long-term evolution and end-of-life policy.

This paper presents a comprehensive overview of the algorithms developed to plan and handle a generic constellation. The main effort has been devoted to define a general approach to the problem, so as to allow the characterization of a wide range of possible mission requirements and constraints. A representative Earth observation constellation for fire detection and monitoring (FUEGO) has been considered to assess the effectiveness and the commercial viability of the algorithms and the strategies implemented.     

Application of LB-Planning for Designing the Programs of Trajectory Measurements

The LB-planning is a construction of the dependence between three variables k, m, and , where k is the number of parameters of the linear dynamic system (LDS) under study, m is the specified number of measurements (communication sessions), and (defect) is the maximum value of failure (set of all criterion functions) in a chosen m-point measurement program relative to the optimal program. The problem is reduced to the solution of an extremal problem, which, at m = k + 1, is found rather simply by maximization of the Tchebyshev determinant (TD-planning).     

Ray Based Diffraction Tomography of the Ionosphere and Laboratory Inhomogeneous Plasma

A new procedure for restoration of the plasma inhomogeneities with improved resolution is suggested. The procedure deals with the double weighted Fourier transform (DWFT) of the observed wavefield in coordinates of both receivers = (x, y) and sources ₀ = (x ₀, y ₀) [1]. Phase increments between the sources and receivers, being found from DWFT representation, can be used for extracting information on small perturbations of the dielectric constant ~(, z) in a way similar to traditional radio tomography. The resulting resolution of the method is close to the diffraction limit = h/D in the horizontal direction and z = (h/D)² in the vertical direction, where h is the height of inhomogeneities and D is the length of the ground-based receiving system.