Analytical prediction of the geometry of contact ellipses and kinematics in a roller screw versus experimental results

2019 ◽  
Vol 131 ◽  
pp. 115-136 ◽  
Author(s):  
Sebastian Sandu ◽  
Nans Biboulet ◽  
Daniel Nelias ◽  
Folly Abevi
Keyword(s):  
Experimental Results ◽  
Analytical Prediction ◽  
Roller Screw

scholarly journals The Estimation of Angular Misalignments for Ultra Short Baseline Navigation Systems. Part II: Experimental Results

2013 ◽  
Vol 66 (5) ◽  
pp. 773-787 ◽  
Author(s):  
Hsin-Hung Chen
Keyword(s):  
Trial Data ◽  
Experimental Results ◽  
Experimental Result ◽  
Alignment Error ◽  
Navigation Systems ◽  
Analytical Prediction ◽  
Short Baseline ◽  
Sea Trial ◽  
Alignment Errors ◽  
Cross Track

An algorithm of alignment calibration for Ultra Short Baseline (USBL) navigation systems was presented in the companion work (Part I). In this part (Part II) of the paper, this algorithm is tested on the sea trial data collected from USBL line surveys. In particular, the solutions to two practical problems referred to as heading deviation and cross-track error in the USBL line survey are presented. A field experiment running eight line surveys was conducted to collect USBL positioning data. The numerical results for the sea trial data demonstrated that the proposed algorithm could robustly and effectively estimate the alignment errors. Comparisons of the experimental result with the analytical prediction of roll misalignment estimation in Part I is drawn, showing good agreement. The experimental results also show that an inappropriate estimation of roll alignment error will significantly degrade the quality of estimations of heading and pitch alignment errors.

Experimental Measurement of Water Evaporation Rates Into Air and Superheated Steam

1988 ◽  
Vol 110 (1) ◽  
pp. 237-242 ◽  
Author(s):  
M. Haji ◽  
L. C. Chow
Keyword(s):  
Heat Transfer ◽  
Superheated Steam ◽  
Evaporation Rate ◽  
Free Stream ◽  
Experimental Results ◽  
Water Evaporation ◽  
Analytical Prediction ◽  
Conduction Heat Transfer ◽  
Inversion Temperature ◽  
Analytical Results

The rates of evaporation of water from a horizontal water surface into a turbulent stream of hot air or superheated steam at different free-stream mass fluxes and modulated temperatures were experimentally measured. The pressure of the free stream was atmospheric. For steam, the experimental results are mostly within 10 percent of the available analytical results. Two previous experimental results are about 50 percent and 300 percent higher than the analytical results. For air, the measured evaporation rates are consistently higher than the analytical results. An estimate of the conduction heat transfer from the walls of the test section to water was made for several air tests. If the conduction heat transfer were subtracted from the total heat transfer, the measured evaporation rates are actually quite close to the analytical results. The present experiment also confirms the existence of a temperature, called the inversion temperature, below which the water evaporation rate is higher in air than in steam, but above which the opposite is true. The inversion temperature is in good agreement with the analytical prediction. The results for both air and superheated steam show that a certain scaled expression for the evaporation rate is independent of the free-steam mass flux, also in agreement with the analytical prediction.

Prediction of the geometric accuracy attenuation of the slide guide of machine tools with analysis of worn surface

2021 ◽  
pp. 1-31
Author(s):  
Yanqing Tan ◽  
Lianjie Ma ◽  
Han Kong
Keyword(s):  
Prediction Model ◽  
Machine Tool ◽  
Working Conditions ◽  
Length Distribution ◽  
Experimental Results ◽  
Skewed Distribution ◽  
Analytical Prediction ◽  
Geometric Accuracy ◽  
Feed System ◽  
Geometric Precision

Abstract A guide pair is a core part of the feed system in a machine tool. Its geometric accuracy is attenuated due to wear, thus directly affecting its guiding accuracy and the processing accuracy and quality of a machine tool. In this paper, based on the statistical principle, the influences of the surface wear of guideway on its straightness attenuation was explored and an analytical prediction model for the geometric accuracy attenuation of slide guide was established. The reciprocating wear test of slide guide samples was performed with a test bench to explore the attenuation of guideway surface straightness under various machining conditions: isometric feeding, random length distribution feeding (normal distribution, negatively skewed distribution and positively skewed distribution), and feeding-retracting (with unequal reciprocating speeds). The comparison between experimental results and predicted results showed that the prediction model could well predict the precision attenuation of the guideway under stable working conditions. The experimental results also proved that machining workpieces with the same size or machining workpieces with a larger size as possible was beneficial to extend the precision maintaining life of slide guide. The prediction model suggested the quantitative relationship between the precision attenuation of slide guide and the main factors including material properties, surface topography parameters, working conditions, operation parameters and surface friction properties. With this model, the real-time straightness on the guideway surface can be calculated and the geometric precision maintaining life of slide guide can also be predicted.

Analytical prediction of the transition from Mach to regular reflection over cylindrical concave wedges

1985 ◽  
Vol 158 ◽  
pp. 365-380 ◽  
Author(s):  
G. Ben-Dor ◽  
K. Takayama
Keyword(s):  
Mach Reflection ◽  
Wedge Angle ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Experimental Results ◽  
Radius Of Curvature ◽  
Analytical Prediction ◽  
Regular Reflection ◽  
Catch Up ◽  
Good Agreement

Two formulas, based on analytical considerations, which are capable of predicting the wedge angle of transition from Mach to regular reflection over cylindrical concave wedges, are developed. They are derived using Hornung, Oertel & Sandeman's (1979) conclusion that a Mach reflection can exist only if the corner-generated signals can catch up with the incident shock wave. The good agreement between the present models and the experimental results confirm Hornung et al.'s (1979) concept. The predictions of these models are in better agreement with experimental results than the predictions of Itoh, Okazaki & Itaya's (1981) model. The present models are very simple to use and apply but, like Itoh et al.'s (1981) model, they also lack the ability to account for the dependence of the transition angle on the radius of curvature of the cylindrical wedge.

Analytical Study of End-Plate Connection on Cruciform Column Section

2015 ◽  
Vol 74 (4) ◽  
Author(s):  
Boon Cheik Tan ◽  
Poi Ngian Shek ◽  
Mahmood Md Tahir ◽  
Ker Shin Mu
Keyword(s):  
Analytical Study ◽  
Experimental Results ◽  
Analytical Prediction ◽  
Initial Stiffness ◽  
Component Method ◽  
End Plate ◽  
Column Section ◽  
Extended End Plate ◽  
The Moment ◽  
Plate Connection

This paper presents an analytical study on flush end-plate (FEP) and extended end-plate (EEP) connections connected to cruciform column section using component method. The objective of this study is to predict the moment resistance and initial stiffness of FEP and EEP connections on cruciform column section. A series of FEP and EEP connections are tested in laboratory. The connection tests consist of four FEP and four EEP specimens with different configuration. Component method outlined in the publication of Steel Construction Institute and British Constructional Steelwork Association are based on BS5950 and Eurocode 3 (EC3) are used to predict the moment resistance and initial stiffness of the tested specimens. The experimental results are then used to validate the analytical predictions. As compare to the experimental results, all moment resistance of the connections coincide well with analytical predictions. Analytical prediction for initial stiffness using EC3 does not show good agreement with the experimental results. This study shows that the component method can be used to predict the moment resistance of FEP and EEP connections on cruciform column section. Further study need to be carried out for initial stiffness to obtain accurate analytical representation.

scholarly journals Experimental Research on Static Stiffness of the Planetary Roller Screw Mechanism

2020 ◽  
Vol 306 ◽  
pp. 02002
Author(s):  
Ma Shangjun ◽  
Wu Guanyu ◽  
Zhang Jianxin ◽  
Liu Geng
Keyword(s):  
Elastic Deformation ◽  
Experimental Results ◽  
Static Stiffness ◽  
Machining Error ◽  
Analytical Results ◽  
Roller Screw ◽  
Screw Mechanism ◽  
Stiffness Characteristics ◽  
Assembly Error ◽  
Good Agreement

This paper investigates the static stiffness characteristics of the planetary roller screw mechanism (PRSM). Firstly, an analytical model of elastic deformation in the PRSM considering contact deformation, combined deformation of screw shaft and thread deformations is established. Then, an accuracy coefficient is introduced to take into account the effect of machining error and assembly error on elastic deformation. Secondly, the stiffness tests of the PRSM are performed under different loads and nut positions. Lastly, the correctness of the analytical results is verified via the comparison with experimental results. The results show that the analytical results are in good agreement with the experimental results, and the stiffness variations under different loads and nut positions are obtained.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun

1974 ◽  
Vol 32 ◽  
pp. 390-391
Author(s):  
Y. Harada ◽  
T. Goto ◽  
H. Koike ◽  
T. Someya
Keyword(s):  
Field Emission ◽  
Phase Contrast ◽  
Image Formation ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electron Gun ◽  
Scanning Microscopy ◽  
Emission Electron ◽  
Lattice Images

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.

A new dissociation mode for dislocations in silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 346-347
Author(s):  
A. Ourmazd ◽  
G.R. Booker ◽  
C.J. Humphreys
Keyword(s):  
Detailed Examination ◽  
Experimental Results ◽  
Dislocation Network ◽  
Weak Beam ◽  
Phosphorus Doped

A (111) phosphorus-doped Si specimen, thinned to give a TEM foil of thickness ∼ 150nm, contained a dislocation network lying on the (111) plane. The dislocation lines were along the three <211> directions and their total Burgers vectors,ḇt, were of the type , each dislocation being of edge character. TEM examination under proper weak-beam conditions seemed initially to show the standard contrast behaviour for such dislocations, indicating some dislocation segments were undissociated (contrast A), while other segments were dissociated to give two Shockley partials separated by approximately 6nm (contrast B) . A more detailed examination, however, revealed that some segments exhibited a third and anomalous contrast behaviour (contrast C), interpreted here as being due to a new dissociation not previously reported. Experimental results obtained for a dislocation along [211] with for the six <220> type reflections using (g,5g) weak-beam conditions are summarised in the table below, together with the relevant values.

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