Measurement Of Inner Diameter Research Articles

Analysis of Friction Factor in Cold Forging by using Ring with Triangular Boss Compression Test

ABSTRACT The ring compression test, a quantitative method to evaluate various conditions of friction at the interface of the dies and work piece by the analysis of diametric (inner) change in the dimension and height of the ring in metal forming. After the compression, it is difficult to measure the inner diameter precisely due to nonuniform deformation. To overcome these difficulties in the conventional ring compression test, an alternative method named RTB-CT is proposed in which two types of geometries of the ring were used one is the ring with the equilateral triangular boss and the other is the ring with isosceles triangular boss. In conventional approach of determination of coefficient of friction of the lubricants, the Ring compression test was used. But, the accuracy of the results through this test was directly linked to the measurements of the different parameters of the compressed ring under the application of the lubricant and due to bulging effect of the ring, the measurement of the inner diameter was difficult. In proposed RTB-CT, this difficulty was overcome by eliminating the measurement of inner diameter of the deformed ring and using a boss on the ring which makes the process of measurement easier and accurate.

Prediction of coefficient of friction by using ring with triangular boss compression test

ABSTRACT Ring compression test is a quantitative method used to evaluate various friction conditions at the interface of tool and work piece, by the analysis of inner diameter variations of the ring in metal forming. But the precise measurement of inner diameter of the ring is very difficult due to non-uniform deformation of the inner hole after the compression. To overcome these difficulties of measurement in conventional ring compression test, an alternative method named ring with triangular boss compression test (RTB-CT) is proposed in which two types of geometries of the ring were used one is ring with equilateral triangular boss and another is ring with isosceles triangular boss. Simulations were carried out for geometries of RTB-CT and results for different friction condition were obtained. The calibration curves for ring with equilateral triangular boss and ring with isosceles triangular boss were separately constructed for above mentioned friction conditions. Finally, this method was experimentally verified in determination of coefficient of friction of various lubricating conditions in the cold forging of aluminium rings. Results showed that the shapes of triangular boss remain same during deformation and the sharp edge of triangular boss makes the measurement of outer diameter is quite easier and precise.

Stiffness Analysis of Reinforced Ureteral Stents Against Radial Compression: In vitro Study.

IntroductionMalignant ureteral obstruction caused by cancer diseases may induce renal failure. Indwelling stent is a popular method to release renal obstruction. But adequate stent placement across an obstructed ureter does not necessarily guarantee renal decompression. The aim of the study was to compare, in vitro, the physical characteristics and stiffness of several commercially available reinforced ureteral stents and identify the physical factors that could lead to the obstruction of the stent.Material and MethodsThe test apparatus used for measurements allowed applying a radial compression force on a segment of the stent to stop a water flow through the lumen of the stent. Some reinforced double-pigtail stents Teleflex Medical, Bard, and Coloplast were evaluated.ResultsThe best physical-stiffness characteristic was obtained with the Teleflex 8F stent (5.4 N mm−2). The best result against the radial compression was obtained with tandem stents. The radial compressive stresses of the Teleflex stents (4.4 to 5.4 N mm−2) were higher than with the other stents used in the study (1.0 to 2.9 N mm−2). Among the reinforced stents selected in the present study, a wider inner diameter helped increase volumetric flow rate but did not affect the stiffness of the stent. The measurement of inner diameter showed heterogeneity along the tube of some stents.ConclusionThe stiffness of the stent appeared to be an important factor to maintain patency with respect to radial compression forces but the inner diameter of the stent and its preservation may be essential parameters to increase the volumetric flow rate. Some reinforced stents tested in the present study confirmed that it is possible to combine stiffness and wide lumen. The use of tandem stents provided the best stiffness against radial compression and the greatest lumen.

On site calibration of inner defect detection based on structured light

A special calibration cylinder is intended to meet the actual requirement of calibration in defect detection system, and a calibration method is proposed based on this calibration the cylinder. The relative measurement method is adopted in the measurement of inner diameter of cylinder. Through processing the structured light image of inner surface of calibrated cylinder, the relationship between the depth of groove in calibrated cylinder and the distance between the displaced pixels of structured light stripes is obtained, which is used in the calculation of groove depth, and the wear of inner diameter of cylinder is obtained. Experiments show that this method can effectively adapt to the detection environment with a small field of view and weak light, and have higher calibration accuracy, and can meet the actual needs of the detection system calibration.

Wall Shear Stress in the Feeding Native Conduit Arteries of Superficial Arteriovenous Malformations of the Lower Face is a Reliable Marker of Disease Progression.

To assess the prognostic value of the wall shear stress (WSS) measured in the feeding native arteries upstream from facial superficial arteriovenous malformations (sAVMs). Reliable prognostic criteria are needed to distinguish progressive from stable sAVMs and thus support the indication for an aggressive or a conservative management to avoid severe facial disfigurement. We prospectively included 25 patients with untreated facial sAVMs, 15 patients with surgically resected sAVMs and 15 controls. All had undergone Doppler ultrasound examination (DUS) with measurements of inner diameters, blood flow velocities, computation of blood flow and WSS of the feeding arteries. Based on the absence or presence of progression in clinical and imaging examinations 6 months after, we discriminated untreated patients as stable or progressive. WSS in the ipsilateral external carotid artery was higher in progressive compared to stable sAVMs (15.8 ± 3.3dynes/cm² vs. 9.6 ± 2.0dynes/cm², mean±SD, p < 0.0001) with a cut-off of 11.5dynes/cm² (sensitivity: 92 %, specificity: 92 %, AUC: 0.955, [95 %CI: 0.789-0.998], p = 0.0001). WSS in the ipsilateral facial artery was also higher in progressive compared to stable sAVMs (50.7 ± 14.5dynes/cm² vs. 25.2 ± 7.1dynes/cm², p < 0.0001) with a cut-off of 34.0dynes/cm² (sensitivity: 100 %, specificity: 92 %, AUC: 0.974, [95 %CI: 0.819-1.000], p = 0.0001). The hemodynamic data of operated patients were not different from those of the control group. WSS measured in the feeding arteries of an sAVM may be a simple reliable criterion to distinguish stable from progressive sAVMs. This value should be considered to guide the therapeutic strategy as well as the long-term follow-up of patients with facial sAVMs.

Precise measurement of inner diameter of mono-capillary optic using X-ray imaging technique.

Mono-capillary optics have been applied to increase the performance of X-ray instruments. However, performance of a mono-capillary optic strongly depends on the shape accuracy, which is determined by the diameters of the inner hollow of the capillary along the axial direction. To precisely determine the inner diameter of the capillary optic used in X-ray imaging technique, which aims to replace the conventional method using a visible microscope. High spatial resolution X-ray images of the mono-capillary optic were obtained by a synchrotron radiation beamline. The inner diameter of the mono-capillary optic was measured and analyzed by the pixel values of the X-ray image. Edge enhancement effect was quite useful in determining the inner diameter, and the accuracy of the diameter determination was less than 1.32 μm. Many images obtained by scanning the mono-capillary optic along the axial direction were combined, and the axial profile, consisting of diameters along the axial direction, was obtained from the combined image. The X-ray imaging method could provide an accurate measurement with slope error of±19 μrad. Applying X-ray imaging technique to determine the inner diameter of a mono-capillary optic can contribute to increasing fabrication accuracy of the mono-capillary optic through a feedback process between the fabrication and measurement of its diameter.

用数字全息层析成像技术测量毛细管的内径及壁厚

The feasibility to measure the inner diameter and wall thickness of a micro-capillary by using digital holographic tomography was explored.As the micro-capillary had an ideal cylindrically symmetric structure,the single reconstructed data under zero incidence angle were used to simulate all measured field data under different angles.A tomography was performed for the micro-capillary by a filtered back-projection algorithm and a Fourier diffraction algorithm respectively to reconstruct the 3-D map of refractive index.According to the 3-D distribution of refractive index,the size of inner diameter and wall thickness of micro-capillary were obtained by the related edge detection algorithm of image processing.Experimental results show that diffraction tomography based on the Rytov approximation can better response the dimensions of the micro-capillary than the filtered back-projection reconstruction algorithm for tiny weakly-diffracting objects under the condition of reasonable light path environment of the hologram recording.It proves that the digital holographic tomography can measure the inner diameter and wall thickness of the micro-capillary exactly and can provide a new way for the nondestructive measurement of tiny weakly-diffracting objects.

A new visual method for inner-diameter of pipe figure components

In order to measure the inner-diameter of pipe figure components rapidly and efficiently, a new high accurate method based on computer vision was introduced. The new visual measurement method was comprised of two phases, which were capturing cloud data of generatrix and processing cloud data of generatrix. The first phase employed the LMS (Laser Multi-spots Scanning) method, which combined the merits of the LSS (Laser Single-spot Scanning) method, the IRLS (Integrated Ringy Laser Section) method, the DRLS (Distributed Ringy Laser Section) method and the DRDL (Distributed Ringy Discrete Laser-spot) method, and overcame the faults of these methods. The second phase introduced the generatrix resample technology and the symmetrical generatrix difference technology. In this paper, the visual measuring arm based on the LMS method was designed in the beginning. Then, according to the optical structure of the visual measuring arm, a 3D real time mathematic model was developed. Lastly, the data processing technology proposed was adopted to process the cloud data of generatrix. The measurement system based on the new method could complete the measurement of inner-diameter of pipe figure components rapidly and efficiently in experiments, demonstrated good stability, and got high precision.

Pulsed remote field technique used for nondestructive inspection of ferromagnetic tube

Remote field eddy current (RFEC) technique is an effective method for measurement of ferromagnetic tube. However, traditional RFEC is unable to differentiate the internal and external defect and the probe has a long length. Pulsed eddy current techniques excite the induction coil with a pulsed waveform and have the richness of frequency harmonics. The wideband excitation is thought to be a potential in providing more information about the flaw. In this paper, pulsed RFEC technique is used to inspect ferromagnetic tube. The finite element analysis and experiment method is used to give a thorough analysis of the influence effect with the variations of the system parameters. Results show that this technique effectively combines the advantages of RFEC and pulsed excitation, which not only acquires more inspection information, including measurements of inner diameter of tubes, internal and external defects, but also reduces the length of probe and power consumption. The agreement between simulation and experiment shows that the present method is correct.

Fetal cardiac output, distribution to the placenta and impact of placental compromise

Intrauterine growth restriction is a common clinical problem, but the underlying hemodynamic changes are not well known. Our aim was to determine the normal distribution of fetal cardiac output to the placenta during the second half of pregnancy, and to assess the changes imposed by growth restriction with various degrees of placental compromise. A cross-sectional study of 212 low-risk pregnancies with a gestational age of 18-41 weeks constituted the reference population. A second group of 64 pregnancies with an estimated fetal weight <or = 2.5(th) percentile constituted the study group. Ultrasound measurements of inner diameters and velocities at the fetal left and right ventricular outlets and intra-abdominal umbilical vein were used to determine combined left and right cardiac output (CCO) and the fraction distributed to the placenta. Placental compromise was graded according to umbilical artery waveform: pulsatility index normal, > 97.5th percentile, or absent/reversed end-diastolic velocity. Regression analysis and Z-score (SD-score) statistics were used to establish normal ranges and to compare groups. During gestational weeks 18-41 the normal CCO/kg was on average 400 mL/min/kg and the fraction directed to the placenta was on average 32%, while after 32 weeks it was 21%. In intrauterine growth restriction the CCO/kg was not significantly different, but the fraction to the placenta was lower (P < 0.001). This effect was more pronounced in severe placental compromise (P < 0.001). Normally, one third of the fetal CCO is distributed to the placenta in most of the second half of pregnancy, and one fifth near term. In placental compromise this fraction is reduced while CCO/kg is maintained at normal levels, signifying an increased recirculation of umbilical blood in the fetal body.

Validation of a Coil Impedance Model for Simultaneous Measurement of Electromagnetic Properties and Inner Diameter of a Conductive Tube

In eddy-current nondestructive testing of conductive tubes such as oil-well casings, the measured tube wall thickness and inner diameter must be compensated for variations of electromagnetic properties of a tube material -magnetic permeability and electrical conductivity. Commercial systems for eddy-current nondestructive testing of oil-well casings incorporate multiple coils and multifrequency excitation for measurement of the inner diameter and the electromagnetic properties. This paper investigates the feasibility of the electromagnetic properties and inner diameter measurement with only one coil excited at one frequency. The authors have derived a coil impedance model and developed an inversion procedure for the determination of tube properties. Measurements have been performed on several tubes made of different materials. In order to validate the model and the optimization algorithm, measurement results were compared with the predictions of the model and finite-element analysis. Applicability of the method has been confirmed for the investigated frequency range (1-50 kHz).

Transducer forin vivo measurement of the inner diameter of arteries in laboratory animals

A transducer permitting the measurement of the instantaneous inner diameter of arteriesin vivo is presented. Instantaneous diameter is related to a potential difference induced in the secondary coil of a miniature transformer. A detailed description is given and the transducer's performance is evaluated. Variation in artery diameter of 0·005 mm can be detected. The maximum force exerted on the artery wall was found to be 4·5×10−2N leading to an estimated distortion error of less than 0·3% for diameters of about 7 mm. The error of the mean diameter measurementin vivo is about 2% in the range from 6 mm to 8 mm. The transducer has a limited range of linearity. Four different sizes cover the range from 3·5 mm to 10 mm. The transducer was successfully used in quantifying the effect of injected contrast media (in dogs).