scholarly journals Research for Space Interception Simulation under Nonlinear Time-Varied Similarity

2020 ◽  
Vol 38 (4) ◽  
pp. 715-722
Author(s):  
Xiaodong Lu ◽  
Tao Cui ◽  
Jiayao Gu
Keyword(s):  
Dimensional Analysis ◽  
High Speed ◽  
Uniform Motion ◽  
Simulation Algorithm ◽  
Large Magnitude ◽  
Small Magnitude ◽  
Whole Process ◽  
Scale Factors ◽  
Reference Motion ◽  
Spatio Temporal

A nonlinear time-varied similarity(NTVS) simulation algorithm is proposed to solve the problem that the process of space interception is intractable to simulate with high precision in limited platform under the linear constant similarity(LCS). Firstly, the similarity criterions based on the dimensional analysis are given in the simulation of the interception motion at high-speed, and the disadvantage of LCS is analyzed. Then, the reference motion is introduced to establish a time-varied spatio-temporal transform system which scale factors are self-adaptive with time, and the method is proved to satisfy the similarity consistency. Finally the way that linear separation and independent mapping solve the problem that the large magnitude uniform motion in approaching directions and small magnitude overload motion in lateral directions are simulated in a limited ground platform. The results show that the NTVS can simulate the whole process of interception and perform better in accuracy comparing with that via LCS.

scholarly journals Perceiving numerosity does not cause automatic shifts of spatial attention

2021 ◽  
Author(s):  
Michele Pellegrino ◽  
Mario Pinto ◽  
Fabio Marson ◽  
Stefano Lasaponara ◽  
Fabrizio Doricchi
Keyword(s):  
Spatial Attention ◽  
Colour Change ◽  
Simultaneous Presentation ◽  
Variable Delay ◽  
Large Magnitude ◽  
Small Magnitude ◽  
Spatial Component ◽  
Speed Up ◽  
The Right

AbstractIt is debated whether the representation of numbers is endowed with a directional-spatial component so that perceiving small-magnitude numbers triggers leftward shifts of attention and perceiving large-magnitude numbers rightward shifts. Contrary to initial findings, recent investigations have demonstrated that centrally presented small-magnitude and large-magnitude Arabic numbers do not cause leftward and rightward shifts of attention, respectively. Here we verified whether perceiving small or large non-symbolic numerosities (i.e., clouds of dots) drives attention to the left or the right side of space, respectively. In experiment 1, participants were presented with central small (1, 2) vs large-numerosity (8, 9) clouds of dots followed by an imperative target in the left or right side of space. In experiment 2, a central cloud of dots (i.e., five dots) was followed by the simultaneous presentation of two identical dot-clouds, one on the left and one on the right side of space. Lateral clouds were both lower (1, 2) or higher in numerosity (8, 9) than the central cloud. After a variable delay, one of the two lateral clouds turned red and participants had to signal the colour change through a unimanual response. We found that (a) in Experiment 1, the small vs large numerosity of the central cloud of dots did not speed up the detection of left vs right targets, respectively, (b) in Experiment 2, the detection of colour change was not faster in the left side of space when lateral clouds were smaller in numerosity than the central reference and in the right side when clouds were larger in numerosity. These findings show that perceiving non-symbolic numerosity does not cause automatic shifts of spatial attention and suggests no inherent association between the representation of numerosity and that of directional space.

Are Firms with Negative Book Equity in Financial Distress?

2015 ◽  
Vol 18 (03) ◽  
pp. 1550016 ◽  
Author(s):  
Tze Chuan Chewie ANG
Keyword(s):  
Failure Rate ◽  
Financial Distress ◽  
Operating Performance ◽  
Large Magnitude ◽  
Small Magnitude ◽  
First Report ◽  
Distress Risk ◽  
Financial Characteristics ◽  
And Control ◽  
Negative Earnings

This study examines whether negative book equity (BE) firms are in financial distress by analyzing their operating performance, financial characteristics, distress risk, and survivability when they first report negative BE. Firms with small magnitude of negative BE (SNBE firms) suffer from persistent negative earnings and financial distress, while firms with large magnitude of negative BE (LNBE firms) experience a temporary non-distress related earnings shock. LNBE firms report consecutive years of negative BE, but have lower distress risk and failure rate than both SNBE and control firms. However, all negative BE stocks have abysmal returns subsequent to their first report of negative BE.

Transonic Hull: Theory, Validation, Breakthroughs and Applications to Ships

2015 ◽  
Author(s):  
Alberto A. Calderon ◽  
Brian Maskew
Keyword(s):  
High Speed ◽  
Feasibility Studies ◽  
Hydrodynamic Characteristics ◽  
Large Magnitude ◽  
Transverse Waves ◽  
Triangular Shape ◽  
Bow Wave ◽  
Linear Drag ◽  
Speed Function ◽  
Displacement Regime

Froude laws are inductive therefore not universally applicable. The relation between Froude and Kelvin, and Froude and Wigley are made explicit. Transonic Hull (TH) has hydrodynamic characteristics not predictable by Froude’s laws. In Transonic Hydrofield (THF) Theory TH’s 3-D triangular shape induces a submerged current - subduction effect - that replaces and substantially precludes bow wave, reducing or eliminating wave making drag growth. TH’s ability to transverse waves without diminishing their energy eliminates slam. TH’s unprecedented breakthroughs with large magnitude are: substantially no bow or stern wave; full displacement regime and near zero pitch independent of speed; linear drag-speed function with greatly reduced wave making (residual) drag; accelerations in a sea that decrease with increasing speed; no slam at any speed and sea conditions. CFD studies of TH-900 vs. Fastship and TH-4022 vs. Axe Bow 4103 shows reduction of drag from 20% to 37% with gains of weight/drag from 33% to 59%. Gains originate from much smaller residual drag. Pre-feasibility studies demonstrate that TH’s triangular waterplanes houses same contents and payloads as conventional vessels provided TH has larger length and beam. TH-1200 Strategic Lift with full payload and range has exceptional high L/D at high speed in Von-Karman-Gabrielli chart.

The Mechanics and Thermodynamics of Steady One-Dimensional Gas Flow

1947 ◽  
Vol 14 (4) ◽  
pp. A317-A336 ◽  
Author(s):  
Ascher H. Shapiro ◽  
W. R. Hawthorne
Keyword(s):  
Heat Transfer ◽  
Dimensional Analysis ◽  
High Speed ◽  
Gas Flow ◽  
Gas Injection ◽  
Wall Friction ◽  
Analytical Treatment ◽  
Area Change ◽  
One Dimensional ◽  
Recent Developments

Abstract Recent developments in the fields of propulsion, flow machinery, and high-speed flight have emphasized the need for an improved understanding of the characteristics of compressible flow. A one-dimensional analysis for flow without shocks is presented which takes into account the simultaneous effects of area change, wall friction, drag of internal bodies, external heat exchange, chemical reaction, change of phase, injection of gases, and changes in molecular weight and specific heat. The method of selecting independent and dependent variables, and the organization of the working equations, leads, it is believed, to a better understanding of the influence of the foregoing effects, and also simplifies greatly the analytical treatment of particular problems. Examples are given first of several simple types of flow, including (a) area change only; (b) heat transfer only; (c) wall friction only; and (d) gas injection only. In addition, examples of flow with combined effects are given, including (a) simultaneous friction and area change; (b) simultaneous friction and heat transfer; and (c) simultaneous liquid injection and evaporation. A one-dimensional analysis for flow through a discontinuity is presented, allowing for energy, shock, drag, and gas-injection effects, and for changes in gas properties. This analysis is applicable to such processes as: (a) the adiabatic normal shock; (b) combustion; (c) moisture condensation shocks; and (d) steady explosion waves.

Spatio-Temporal Development of Supercavitation Over an Impulsively Launched Projectile

2006 ◽  
Author(s):  
C. J. Weiland ◽  
P. P. Vlachos
Keyword(s):  
High Speed ◽  
Temporal Development ◽  
Two Phase ◽  
Time Resolved ◽  
Gas Gun ◽  
Supercavitating Flow ◽  
Image Velocimetry ◽  
Spatio Temporal ◽  
Asymmetric Vortices ◽  
First Time

Supercavitation inception and formation was studied over blunt projectiles. The projectiles were fired using a gas gun method. In this method, projectiles are launched under the action of expanding detonation gases. Both qualitative and quantitative optical flow diagnostics using high speed digital imaging were used to analyze the spatio-temporal development of the supercavitating flow. For the first time, quantification of the supercavitation was achieved using Time Resolved Digital Particle Image Velocimetry (TRDPIV) detailing the two phase flow field surrounding the translating projectiles and the gas vapor bubble. Experimental results indicate that the supercavity forms at the aft end of the projectile and travels forward along the direction of projectile travel. The impulsive start of the projectile generates two asymmetric vortices which are shed from the blunt nose of the projectile. The vortices interact with the moving cavity and subsequently deform. This interaction is believed to directly contribute to the instabilities in the flight path.

Analysis on Effect of Tunnel Crossing Underneath Foundation of Tall Buildings on Anti-Seismic Mortar Anchor in Weathered Rock Area

2012 ◽  
Vol 446-449 ◽  
pp. 2581-2589
Author(s):  
Xiao Bei Shi ◽  
Kai Wei ◽  
Bing Long Wang ◽  
Da Wei Huang
Keyword(s):  
High Speed ◽  
Failure Process ◽  
Tall Buildings ◽  
Element Model ◽  
Tunnel Excavation ◽  
High Speed Railway ◽  
Weathered Rock ◽  
Whole Process ◽  
Influence Area ◽  
Before And After

Depending on a project of constructing a tunnel of high-speed railway which crosses underneath the foundation of tall buildings in weathered rock area, the paper analyzes the failure process and its law of anti-seismic mortar anchors under the foundation of tall buildings by simulating the whole process of construction with finite element model. Then the coverage scope, influence rules and extent of tunnel excavation on the anti-pulling effect and stability of mortar anchors are analyzed according to the changes of lateral pressure and axial force of anti-seismic mortar anchors before and after construction. The results show that the influence area can be divided into three parts， of which the main area where the anti-seismic mortar anchors are badly affected is on the top of the tunnel and extends horizontally to a certain range. Finally, the paper gives an applicable method to estimate the area where the anti-seismic mortar anchors should be strengthened by grouting, which also applies to the similar projects in weathered rock area.

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