Congruent Dudeney Dissections of Triangles and Convex Quadrilaterals – All Hinge Points Interior to the Sides of the Polygons

2003 ◽  
pp. 43-63 ◽  
Author(s):  
Jin Akiyama ◽  
Gisaku Nakamura
Keyword(s):  
Hinge Points

scholarly journals Analysis on Force Transmission Characteristics of Two-Legged Shield Support under Impact Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Qing-liang Zeng ◽  
Zhao-sheng Meng ◽  
Li-rong Wan ◽  
Cheng-long Wang
Keyword(s):  
Structural Design ◽  
Load Transfer ◽  
Impact Load ◽  
Force Transmission ◽  
Full Account ◽  
Flexible Bodies ◽  
Powered Support ◽  
Structural Design Optimization ◽  
Hinge Points ◽  
The Impact

To study the load transfer characteristics of a two-legged shield powered support, a numerical simulation model of the support was established using the multibody dynamics software ADAMS. The model took full account of the hydraulic-elastic deformation characteristics of the support, as a series spring-damper system was used to replace the leg and the equilibrium jack. The canopy, goaf shield, lemniscate bars, and equilibrium jack are equivalent to flexible bodies. The setting force of the leg was provided by the preload of the equivalent spring, the static roof load was simulated using a slope signal, and the impact load was simulated using a step signal. Using the model, the impact and excitation effects of each hinge joint of the support were analyzed under different impact load conditions across the canopy. The results show that the location of the impact load affects the force transmissions of all hinge points of the support. Both the impact effect and the excitation effect are at a minimum when the impact force is located near the leg action line. These results are useful for the adaptive control and structural design optimization of the support.

Development of a Global Infrared Land Surface Emissivity Database for Application to Clear Sky Sounding Retrievals from Multispectral Satellite Radiance Measurements

2008 ◽  
Vol 47 (1) ◽  
pp. 108-123 ◽  
Author(s):  
Suzanne W. Seemann ◽  
Eva E. Borbas ◽  
Robert O. Knuteson ◽  
Gordon R. Stephenson ◽  
Hung-Lung Huang
Keyword(s):  
Land Surface ◽  
Atmospheric Temperature ◽  
Surface Emissivity ◽  
Spectral Gaps ◽  
Global Database ◽  
Land Surface Emissivity ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Hinge Points ◽  
Moisture Profiles

Abstract A global database of infrared (IR) land surface emissivity is introduced to support more accurate retrievals of atmospheric properties such as temperature and moisture profiles from multispectral satellite radiance measurements. Emissivity is derived using input from the Moderate Resolution Imaging Spectroradiometer (MODIS) operational land surface emissivity product (MOD11). The baseline fit method, based on a conceptual model developed from laboratory measurements of surface emissivity, is applied to fill in the spectral gaps between the six emissivity wavelengths available in MOD11. The six available MOD11 wavelengths span only three spectral regions (3.8–4, 8.6, and 11–12 μm), while the retrievals of atmospheric temperature and moisture from satellite IR sounder radiances require surface emissivity at higher spectral resolution. Emissivity in the database presented here is available globally at 10 wavelengths (3.6, 4.3, 5.0, 5.8, 7.6, 8.3, 9.3, 10.8, 12.1, and 14.3 μm) with 0.05° spatial resolution. The wavelengths in the database were chosen as hinge points to capture as much of the shape of the higher-resolution emissivity spectra as possible between 3.6 and 14.3 μm. The surface emissivity from this database is applied to the IR regression retrieval of atmospheric moisture profiles using radiances from MODIS, and improvement is shown over retrievals made with the typical assumption of constant emissivity.

scholarly journals Optimization of hinge point in luffing mechanism of aerial working vehicle based on PSO algorithm

2021 ◽  
Vol 233 ◽  
pp. 04034
Author(s):  
Yongjie Xu ◽  
Bangsheng Xing ◽  
Lei Cai
Keyword(s):  
Particle Swarm ◽  
Decisive Role ◽  
Pso Algorithm ◽  
Particle Swarm Algorithm ◽  
Force Analysis ◽  
Construction Machinery ◽  
Hinge Point ◽  
Overall Stability ◽  
Working Principle ◽  
Hinge Points

Luffing mechanism is one of the important parts of aerial working vehicle, which plays a decisive role in the overall stability of boom system, the force of luffing cylinder and the force at each hinge point position. In this paper, the five hinge point luffing mechanism of aerial working vehicle is taken as the research object, and the force of its luffing cylinder under dangerous conditions is optimized. By studying the working principle of the boom system and the force analysis of the luffing mechanism, and then establishing the mechanical model, the objective function was optimized based on particle swarm algorithm and Matlab. The optimization results show that the maximum force on the luffing cylinder decreases by 18.9% with the optimized hinge points, which greatly improves the performance of the whole machine and provides a reference for the application of particle swarm optimization in construction machinery.

scholarly journals Depth Optimization Analysis of Articulated Steering Hinge Position Based on Genetic Algorithm

Algorithms ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 55 ◽  
Author(s):  
Bing-wei Cao ◽  
Xin-hui Liu ◽  
Wei Chen ◽  
Yong Zhang ◽  
Ai-min Li
Keyword(s):  
Genetic Algorithm ◽  
Pressure Fluctuation ◽  
Steering System ◽  
Cylinder Pressure ◽  
Objective Functions ◽  
Pressure Function ◽  
Steering Mechanism ◽  
Hinge Position ◽  
Hinge Points ◽  
Force Difference

Articulated steering is affected by the position of the articulated points of the steering cylinder. When the two steering cylinders turn, there is a stroke difference and arm of force difference. The existence of the above differences causes the pressure fluctuation of the steering system. Firstly, the mathematical model of the steering mechanism is established through theoretical analysis. Then, the coordinates of the hinge points of the steering cylinder are optimized using genetic algorithm (GA) with the stroke difference function and cylinder pressure function as the objective functions. The curves of the stroke difference and the arm of force difference of the steering cylinder are obtained by mathematical modeling, and the correctness of the GA is verified. According to the optimization results, the wheel loader prototype was reconstructed, and the reconstruction verified by corresponding sensors. The experimental curves show that the steering system has no obvious pressure fluctuation. Finally, the arm of force difference and stroke difference curves were analyzed, and it was concluded that the arm of force difference was the main cause of pressure fluctuation. The objective function was improved, and the arm of force function and cylinder pressure function were taken as the objective functions to continue the optimization by GA. The arm of force difference and stroke difference after optimization were reduced, which provides a constructive reference for the design of articulated steering systems in the future.

Fatigue Failure in Nylon Reinforced Tires

1965 ◽  
Vol 38 (4) ◽  
pp. 832-839 ◽  
Author(s):  
Ralph G. Patterson ◽  
Robert K. Anderson
Keyword(s):  
Fatigue Failure ◽  
Strength Loss ◽  
Fatigue Tests ◽  
Fiber Axis ◽  
Principal Mechanism ◽  
Tensile Forces ◽  
Tire Rotation ◽  
Hinge Points ◽  
High Degree ◽  
Fatigue Failures

Abstract The principal mechanism leading to fatigue failure of nylon cord tires is progressive loss of cord strength from filament ruptures that occur at an angle of approximately 25 degrees to the fiber axis. Flexing causes cords to become weaker until residual strength is less than tensile forces in the tire, at which time the remaining filaments break with a blunt-ended tensile rupture. Individual cords in tires have stress environments determined by such factors as cord spacing, uniformity, and stiffness of the immediate flexing region, which appear to influence significantly their fatiguing rate. It is probable that these factors also operate in laboratory in-rubber fatigue tests, so that a high degree of precision in sample preparation and loading conditions is essential for such tests to give reproducible data. Measurement of cord strength loss was found to be a valid and useful means for following the progress of fatigue when it was recognized that cords under opposite sidewalls of tires lost strength at markedly different rates, which were not linearly proportional to test mileage. The direction of tire rotation and the cord angle in a given ply determined which half of the ply lost strength fastest. Strength loss was higher for the half of the cord that led into the load bearing region of the tire as it rotated. This presumably happened because of unsymmetrical stress conditions, but no measurement of cord stress was made. Fatigue failures of tires generally occurred at localized points and resulted from failure of a few cords that lost strength faster than the surrounding cords. The failures occurred in the innermost ply at “hinge points” opposite the end of the flipper fabric in the ply splice.

Selective Accommodation in Great Power Competition and U.S. Grand Strategy

2021 ◽  
pp. 182-210
Author(s):  
Timothy W. Crawford
Keyword(s):  
United States ◽  
Short Circuit ◽  
The United States ◽  
The Other ◽  
Great Power ◽  
Grand Strategy ◽  
Power Politics ◽  
Future Developments ◽  
Great Power Politics ◽  
Hinge Points

This chapter examines a pair of scenarios built around hinge points in current U.S. grand strategy. The scenarios envision surprising departures from current alignment trends and prevailing precepts in U.S. foreign policy. One explores how China might undermine the deepening Indo-American partnership by accommodating India. The other explores how the United States might short-circuit the emerging Russia–China alliance by accommodating Russia. These scenarios show how the book's theoretical constructs may describe and explain future developments. They also illuminate potential changes in great power politics that today's orthodoxies in U.S. grand strategy make hard to imagine, let alone think about carefully. The chapter then concludes with commentary for policy practitioners seeking to make selective accommodation work.

scholarly journals Mechanics of fibroblast locomotion: quantitative analysis of forces and motions at the leading lamellas of fibroblasts.

1990 ◽  
Vol 111 (6) ◽  
pp. 2513-2526 ◽  
Author(s):  
S Felder ◽  
E L Elson
Keyword(s):  
Average Rate ◽  
Substrate Surface ◽  
Two Dimensions ◽  
Video Enhancement ◽  
Differential Interference Contrast Microscopy ◽  
Acceleration And Deceleration ◽  
Chick Embryo Heart ◽  
Hinge Points ◽  
Embryo Heart ◽  
Cell Force

Shapes, motions, and forces developed in lamellipodia and ruffles at the leading edges of primary chick embryo heart fibroblasts were characterized by differential interference contrast microscopy and digital video enhancement techniques. The initial extension of the cell edge to form a thin, planar lamellipodium parallel to the substrate surface was analyzed in two dimensions with temporal and spatial resolution of 3 s and 0.2 micron, respectively. An extension begins and ends with brief, rapid acceleration and deceleration separated by a long period of nearly constant velocity in the range of 4-7 microns/min. Extensions and retractions were initiated randomly over time. As demonstrated by optical sectioning microscopy, the extended lamellipodia formed ruffles by sharply bending upward at hinge points 2-4 microns behind their tips. Surprisingly, ruffles continued to grow in length at the same average rate after bending upward. They maintained a straight shape in vertical cross section, suggesting the ruffles were mechanically stiff. The forces required to bend ruffles of these cells and of BC3H1 cells were measured by pushing a thin quartz fishpole probe against the tip of a ruffle 7-10 microns from its base either toward or away from the center of the cell. Force was determined by measuring the bending of the probe monitored by video microscopy. Typically the probe forced the ruffle to swing rigidly in an arc about an apparent hinge at is base, and ruffles rapidly, and almost completely, recovered their shape when the probe was removed. Hence, ruffles appeared to be relatively stiff and to resist bending with forces more elastic than viscous, unlike the cell body. Ruffles on both types of cells resisted bending with forces of 15-30 mudyn/microns of displacement at their tips when pushed toward or away from the cell center. The significance of the observations for mechanisms of cell locomotion is discussed.

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