Line Displacement Research Articles

Numerical investigation of flow erosion and flow induced displacement of gas well relief line

High-pressure particle-laden gas flow should be discharged through relief line of gas well timely to ensure safe test and exploitation. Erosion and vibration usually take place on the bend in relief lines, bringing a potential safety hazard to field operation. The majority of this paper investigates the factors affecting the erosion of bend and displacement of relief line in the downstream of bend using the computational fluid dynamics (CFD) methodology. A three-dimensional elbow pipe is selected as computational domain in this investigation. The kinematics and trajectory of discrete solid particles and liquid droplets are described by discrete phase model (DPM) while the hydrodynamic characteristics of continuous phase are obtained based on Reynolds-Averaged-Navier-Stokes (RANS) equations. An empirical erosion model is employed to predict the erosion rate of bend, and a fluid–structure interaction (FSI) model is adopted to calculate the displacement of relief line. The effects of types of multiphase flow (such as gas–solid two-phase flow and gas–liquid–solid three-phase flow), inlet flow rate and pipe diameter on erosion and displacement are discussed. The results show that large displacement and severe erosion present with large inlet flow rate in minor diameter pipe. The increase in liquid droplet content has less effect on flow erosion than that by the same increase in sand particle content.

DYNAMICAL FIELD LINE CONNECTIVITY IN MAGNETIC TURBULENCE

Point-to-point magnetic connectivity has a stochastic character whenever magnetic fluctuations cause a field line random walk, but this can also change due to dynamical activity. Comparing the instantaneous magnetic connectivity from the same point at two different times, we provide a nonperturbative analytic theory for the ensemble average perpendicular displacement of the magnetic field line, given the power spectrum of magnetic fluctuations. For simplicity, the theory is developed in the context of transverse turbulence, and is numerically evaluated for the noisy reduced MHD model. Our formalism accounts for the dynamical decorrelation of magnetic fluctuations due to wave propagation, local nonlinear distortion, random sweeping, and convection by a bulk wind flow relative to the observer. The diffusion coefficient DX of the time-differenced displacement becomes twice the usual field line diffusion coefficient Dx at large time displacement t or large distance z along the mean field (corresponding to a pair of uncorrelated random walks), though for a low Kubo number (in the quasilinear regime) it can oscillate at intermediate values of t and z. At high Kubo number the dynamical decorrelation decays mainly from the nonlinear term and DX tends monotonically toward 2Dx with increasing t and z. The formalism and results presented here are relevant to a variety of astrophysical processes, such as electron transport and heating patterns in coronal loops and the solar transition region, changing magnetic connection to particle sources near the Sun or at a planetary bow shock, and thickening of coronal hole boundaries.

Fuzzy multi-objective optimization for movement performance of deep-notch elliptical flexure hinges.

Compared with commonly used flexure hinges, deep-notch elliptical flexure hinges are more suitable for flexible mechanisms with high precise transmission requirements. The rotation stiffness model of deep-notch elliptical flexure hinges was built first, and the compliance matrix was analyzed and solved by using Newton-Cotes quadrature formula to simplify the calculation of compliance coefficients; on the other hand, the fuzzy multi-objective optimization model with distribution was constructed, and a detailed example was given out to validate the effectiveness of the fuzzy optimization. The experiment results show that the desired angular displacement α(z) around the z axis is increased by 30.13%; while the undesired α(y) that around the y axis is decreased by 15.74% in experiment. The line displacements of Δ(y) and Δ(z) along the Y and Z axes are decreased by 18.15% and 47.69%, respectively. All the optimization data show that after the fuzzy optimization, the rotation capacity of z axis has been raised, and the motion capacity of the undesired directions has been restrained, so that the movement precision and the performance of the deep-notch elliptical flexure hinge can be improved, which is more suitable for the optical waveguide packaging positioning platform with high precision transmission.

Imaging observation of the femoral neck anteversion in patients with developmental dysplasia of the hip

To observe the distribution law and study the factors related to the femoral neck anteversion angle among the patients with developmental dysplasia of the hip of Hartofilakidis type I. Among the patients with hip dysplasia of Hartofilakidis type I who was admitted to Department of Orthopaedic Surgery, the First Affiliated Hospital of People's Liberation Army General Hospital from June 2010 to June 2013, a total of 340 hips (25 male and 161 female) were included in the study. The average age was 28.3 years, ranging from 13.5 to 49.9 years. The observation index included: femoral neck anteversion angle, lateral center-edge angle, acetabular index angle, lateral displacement of the femoral head, superior displacement of the femoral head, continuity of Shenton's line and Calve's line. The correlation between different factors was analyzed, and the factor closest to femoral neck anteversion angle was analyzed further by regression analysis. Among the patients of developmental dysplasia of the hip of Hartofilakidis type I, the femoral neck anteversion angle increased, with an average of 28°±13°. Correlation and regression analysis showed significant negative correlation with treatment age (r=-0.158, P=0.003; t=-6.892, P=0.000); positive correlation with gender (r=0.332, P=0.000; t=-4.376, P=0.000); significant positive correlation with lateral displacement of the femoral head (r=0.092, P=0.000; t=3.766, P=0.000); significant negative correlation with central-edge angle (r=-0.122, P=0.024; t=2.031, P=0.043). The femoral neck anteversion angle showed correlation with acetabular index angle, continuity of Calve's line and superior displacement of the femoral head in correlation analysis, not in regression analysis, however, it did not show correlation with side and continuity of Shenton's line. Among the patients of developmental dysplasia of the hip of Hartofilakidis type I, the increasing of the femoral neck anteversion angle may not only lead to early onset and therefore early treatment of pain in the hip joint but also the lateral displacement of the femoral head that requires immediate medical attention.

Estimation of J-resistance Curves for CT Specimen Based on Unloading Compliance Method and CMOD Data

Abstract The unloading compliance method is one of the most widely used methods in laboratory testing for J-resistance estimation. A specimen configuration including compact tension (CT) is recommended by almost all the standard test procedures for evaluating fracture toughness, such as ASTM E1820-11, ISO 12135-2002, and GB/T 21143-2007. In the unloading compliance method, key techniques including instantaneous crack size measurement, correction of specimen rotation, and J-integral computation can be used for a CT specimen when using load line displacement (LLD) but not when using crack mouth opening displacement (CMOD) from those standard test procedures. However, a CT specimen with CMOD measurement is also used for J-resistance estimation under certain severe environments because of the convenience of measuring displacement. This study proposes a simplified linear formula for crack size calculation for a CT specimen with CMOD data, discusses the rotation correction in detail based on the equivalence of work, and develops reasonable incremental expressions for J-integral computation and a CMOD-to-LLD conversion equation. By measuring the LLD and CMOD data of a CT specimen simultaneously, we carried out experiments on J-resistance curve estimation for four different types of materials. According to the developed procedure of the unloading compliance method in this study, J-resistance curves for all materials determined from LLD and CMOD data of the CT specimen are clearly exhibited.

Evaluation on Dynamic Responses of Transmission Lines Subjected to Wind Excitations

The evaluation on dynamic responses of transmission lines subjected to wind excitations is actively carried out in this study. A transmission tower-line system constructed in the southern coastal areas of China is taken as example to examine the wind induced response of the transmission lines. The structural model is established based on finite element approach by using commercial package. The displacement, velocity and acceleration responses of the transmission lines are computed to explore structural performance. The made observations indicate that the transmission lines vibrant substantially when subjected to strong winds. It is obvious that the dynamic responses of the ground wire are smaller than those of the wire and the responses in the long span are much larger than those in the short span.

Influence of loading rate on fracture behaviour of extra deep drawn steel sheets

AbstractFracture tests of extra deep drawn steel sheet were carried out at ambient temperature to investigate the effect of loading rate on fracture toughness. To determine fracture limits, fracture tests and finite‐element cohesive zone model simulation tool are used. Fracture tests are conducted at various loading rates (0.1–2.5 mm min−1). An alternative constant traction separation law is used to account for maximum load and large load line displacements. Experimental findings, as well as cohesive zone model, show that the loading rate has no significant effect on fracture toughness till 0.4 mm min−1; however, there is a sharp decrease in fracture toughness beyond 0.4 mm min−1.

Size independent fracture energy evaluation for plain cement concrete

AbstractThe present work deals with the investigation of a robust analytical scheme to assess the size‐independent fracture energy of concrete. The study involves the numerical modelling of three‐point bend (TPB) concrete beams that are geometrically similar, having constant length to depth ratio with varying range of notch to depth (a/W) ratios. The unique nonlinear behaviour of concrete 1material is incorporated through fracture energy‐based strain‐softening model in the finite‐element numerical simulation. The International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM) fracture energy values are evaluated through numerical simulation of several set of experimentally observed load‐load line displacement response. The RILEM fracture energy values associated with geometrically similar beams have been utilised to develop a methodology for assessment of the size‐independent fracture energy of concrete. The numerically predicted and experimentally evaluated size‐independent fracture energy using the RILEM fracture energy values are found to be in close agreement.

HFQ forming of AA6082 tailor welded blanks

An advanced forming technology, solution Heat treatment, Forming and in-die Quenching (HFQ ® ), has been employed to form AA6082 tailor welded blanks (TWBs). In comparison with conventional stamping of TWBs, the mechanical properties and formability of AA6082 laser TWBs could be improved under the HFQ forming condition. The TWB was divided into three physical zones, i.e. base metal, heat affected zone (HAZ) and weld zone, based on the hardness distribution. It was found that the degraded hardness of the weldment can be restored after HFQ forming. TWBs of AA6082 with different thickness ratios of 2 (2-1mm), 1.3 (2-1.5mm) and 1 (1.5-1.5mm) were used to study the TWB thickness ratio effects on the forming behaviour. Hemispherical punch dome tests on the TWBs with varying thickness ratios demonstrated different formabilities, and indicated increased displacement of the weld line with increasing thickness ratio. Finite element (FE) modelling was adopted to analyse the weld line movement and strain distributions during HFQ forming. HFQ ® is a registered trademark of Impression Technologies Ltd.

J resistance curve behaviour of S355NL structural steel using the unloading compliance technique

Room temperature toughness measurements performed on 32mm thick flat surface and side grooved C(T) specimens of the S355NL structural steel are presented. As expected, stable ductile crack growth was observed during the tests and toughness characterization based on resistance curve (R curve) concepts was therefore used. The unloading compliance technique was chosen to estimate stable crack growth during the tests, and accurate load line displacement measurements were performed using a clip gage. Stress intensity factor and compliance calibrations as a function of crack length/width ratio, published by ASTM, were used to derive the J R-curve. The R-curve for the flat surface specimen is higher than for the grooved specimen. The estimated J at initiation of stable crack propagation is also higher for the flat surface specimen, although difference between the flat and grooved specimens is very small. Generally, a drop in fracture toughness was observed for the grooved specimens, as expected given its higher triaxiality. As an additional comparison of the two types of specimens, the maximum load J0,max value was obtained using the actuator displacement record. The maximum load measurements proved to be rather similar in both types of specimen.

På sporet av senmesolittiske døderiter

The first part of the paper discusses the dating of the rock art site Ausevik in Flora, Sogn og Fjordane, and evaluates previous suggestions from the last appsoximately years, based primarily on stylistic comparisons and to some extent shore line displacements. On the basis of new evidence from excavations at the site it is argued that the rock art should be dated to the Late Mesolithic, and that its iconography, use and expression is simultaneous with the more renown Vingen site a short distance further north. This opens for a much better understanding of the similarities of images and the organisation and expression of the narratives at the two sites. In the second part of the paper it is argued that both these sites are related to mortuary practices at the term of the Late Mesolithic period in Western Norway. It seems also to address important ideological issues in the relation between animal images and what seem to be representations of skeletons. The iconography also hints at reasons why cemeteries or graves have not been found in any numbers. The practise in Western Norway might have been of another tradition.

Change in collateral ligament length and tibiofemoral movement following joint line variation in TKA.

The primary intent of total knee arthroplasty is the restoration of normal knee kinematics, with ligamentous constraint being a key influential factor. Displacement of the joint line may lead to alterations in ligament attachment sites relative to knee flexion axis and variance of ligamentous constraints on tibiofemoral movement. This study aimed to investigate collaterals strains and tibiofemoral kinematics with different joint line levels. A previously validated knee model was employed to analyse the change in length of the collateral ligaments and tibiofemoral motion during knee flexion. The models shifted the joint line by 3 and 5mm both proximally and distally from the anatomical level. The data were captured from full extension to flexion 135°. The elevated joint line revealed a relative increase in distance between ligament attachments for both collateral ligaments in comparison with the anatomical model. Also, tibiofemoral movement decreased with an elevation in the joint line. Conversely, lowering the joint line led to a significant decrease in distance between ligament attachments, but greater tibiofemoral motion. Elevation of the joint line would strengthen the capacity of collateral ligaments for knee motion constraint, whereas a distally shifted joint line might have the advantage of improving tibiofemoral movement by slackening the collaterals. It implies that surgeons can appropriately change the joint line position in accordance with patient's requirement or collateral tensions. A lowered joint line level may improve knee kinematics, whereas joint line elevation could be useful to maintain knee stability. V.

Effect of Specimen Thickness and Punch Diameter in Evaluation of Small Punch Test Parameters Toward Characterization of Mechanical Properties of Cr–Mo Steels

Abstract Small punch tests on circular specimens were conducted using hemispherical tipped punches on Chromium–Molybdenum (Cr–Mo) steels of varying thermal histories. Combinations of punch diameters and sample thicknesses were used to obtain load–load line displacement (LLD) responses of these steels. Characteristic load, displacement, and energy values at transition points on LLD curves were identified and their dependency on punch diameter and sample thicknesses were studied. From the studies, sample thicknesses in the range of 0.4 to 0.5 mm and a punch tip diameter of more than 1.7 mm have been suggested to be used for the application of the SPT test procedure in the assessment of mechanical properties of in-service Cr–Mo steel components.

Analysis of image distortion on projection electron microscope image

Distortion of image obtained from a projection electron microscope (PEM) was investigated using an upgraded Monte Carlo simulation assembled with electron imaging optics (EO) data. A simulated PEM image distortion was reconstructed by the imaging on the image-plane through the EO. The image distortion was created by a local field effect (Type II). The displacement of lines, contrast degradation, and changes in the line widths were simultaneously observed. In the case of a negative charge condition, these image degradations were enhanced by an increased gradient of the electric field produced by a local charge and an extraction voltage. The image distortion and the associated image degradation were improved by applying a 7.5-times higher extraction voltage.

The Influence of the Punch Speed on the Welding Line Movement during Deep Drawing in Case of Tailor Welding Blanks

The work presented in this paper refers to numerical simulation related to deep drawing of three parts having different geometry, as follows: square shape, cylindrical shape and semispherical shape. The current paper is trying to prove out the important role of the punch speed on the welding line displacement during the forming process. The punch speed influence is testes for the fallowing values: 100, 300, 600, 800 and 1000 mm/s. The punch stroke is 25 mm, which is the safe drawing depth for all three selected shapes. The parts are made from tailor welded blanks, having the welding line positioned as axis of symmetry. It must be mentioned that both materials from the welded structure are having the same thickness (1mm). The Dynaform 5.8.1 software is used to simulate the forming process. The part obtained after each simulation is analyzed and measured to quantify the displacement of the welding line. The welding line behave differently for each tested punch speed and also for each part shape. All the parameters are maintained fixed except the punch speed. The obtained results for those three shapes were compared to realise the behaviour of the tailor welded blanks during deep drawing process. In the final part of this paper conclusions regarding the influence of the punch speed and of the part shape on the welding line movements are presented.

Characterization of concrete specimen fracture response: 2D numerical study

The reported investigations undertaken so far on concrete fracture involve limited tests on laboratory size concrete specimens and provide a basic understanding of the fracture phenomenon, but the precise quantification of fracture parameters is still elusive. Therefore purely an experimental approach is not preferably a practicable solution, rather it is important to invoke the systematic computational approach for evaluating the load-crack mouth opening displacement and load–load line displacement responses to characterize the concrete fracture phenomenon.While performing the numerical study of concrete components using finite element method, mesh sensitivity is an extremely important issue which is investigated in this paper, through detailed analysis of geometrically similar three point bend (TPB) beams having constant length to depth ratio. The finite element modeling of the TPB concrete beams performed by incorporating the fracture energy based softening model predicted the results that are found to be mesh insensitive.In the present finite element analysis, the performance of triangular elements is investigated and observed to be superior over the quadrilateral elements. This has been concluded based on the completeness of interpolation function and discretization technique, which is illustrated by simulating a number of benchmark problems of TPB concrete specimens.The efficient analytical procedures to predict the parameters required to characterize the concrete fracture phenomenon are explored. The simulation of TPB specimen yields the parameters, such as maximum load, vertical displacement at maximum load, load vs. load line displacement and load vs. crack mouth opening displacement responses which are required for epitomizing the concrete fracture behavior. The numerically observed response is found to be in excellent agreement in most of the cases with the reported literature.

Elastic and Inelastic Responses of C(T) Specimens With Discontinuous Cracks

This paper investigates elastic and elastic–plastic responses of a plane strain compact tension specimen containing a discontinuous crack using two-dimensional (2D) finite element analyses. Discontinuous cracking is represented by modeling two (main and sub) cracks with the distance between them systematically varied. The finite element predictions show that the presence of subcracks has minimal effect on the elastic compliance and potential difference but significantly influences the plastic limit loads and load line displacements (LLDs). The evaluation of the elastic and elastic–plastic behavior of the J-integrals evaluated using different contours for discontinuous cracks are also examined and explained.

Superior vena cava (SVC) filters placed over central lines – analysis of line trapping and difficulties with line retrieval: an in-vitro experimental study

Placement of superior vena cava (SVC) filters has been shown to be both safe and effective in preventing symptomatic pulmonary embolism in patients with upper extremity deep venous thrombosis that have contraindications to anticoagulation therapy. In many patients, existing central lines pose a challenge to SVC filter placement due to the theoretical risk of line displacement and/or entrapment. To assess the risk of catheter entrapment by filter legs during SVC filter deployment and the risk of subsequent filter migration during catheter removal. A model was created by placing a 22 mm vascular graft inside a plastic tube and submerged in a warm saline bath. Five types of filters were deployed under fluoroscopic guidance over different types of central lines of varying calibers (5-14 Fr). Each filter was deployed five times over each type of central line. The positioning of the legs of the filters in relationship to the central lines was studied by fluoroscopic and direct inspection. The lines were then removed under fluoroscopic guidance noting any line trapping, migration, and/or tilting of the filters. Movement of the lines during filter expansion was commonly seen after deployment of all filters with varying frequencies. During line removal slight resistance was encountered with the Celect filter (10%) and the Option filter (5%), while significant resistance was only encountered when using the OptEase filter (20%). Filter migration was only observed when the OptEase filter was deployed over large (>10 Fr) caliber lines (10%). When SVC filters are placed over existing central lines, the risk of catheter entrapment is very low in this in-vitro model. Filter migration during line retrieval was only observed when the OptEase filter was placed over >10 Fr caliber lines.

Modelos de estratégia de busca: será o passeio de Lévy a solução?

In nature, many organisms must cope with the problem of finding mates, food and shelter. The strategy of search that drives an organism can reveal important aspects of its behavior; models have been proposed to address this problem. Levy walk is the most discussed model and it has some empirical support. Our aim was to compare straight line displacements against Levy walk and Brownian motion in terms of survival and probability of reward. Our results show that straight line displacements have better performance in all environments we created. We discuss that straight line movements should be considered more probable as a search strategy considering the arguments that support Levy walk, however, it is not seen like a strategy.

CONSTRAINING SUB-PARSEC BINARY SUPERMASSIVE BLACK HOLES IN QUASARS WITH MULTI-EPOCH SPECTROSCOPY. II. THE POPULATION WITH KINEMATICALLY OFFSET BROAD BALMER EMISSION LINES

A small fraction of quasars have long been known to show bulk velocity offsets in the broad Balmer lines with respect to the systemic redshift of the host galaxy. Models to explain these offsets usually invoke broad-line region gas kinematics/asymmetry around single black holes (BHs), orbital motion of massive (~sub-pc) binary black holes (BBHs), or recoil BHs, but single-epoch spectra are unable to distinguish between these scenarios. The line-of-sight (LOS) radial velocity (RV) shifts from long-term spectroscopic monitoring can be used to test the BBH hypothesis. We have selected a sample of 399 quasars with offset broad H-beta lines from the SDSS DR7 quasar catalog, and have conducted second-epoch optical spectroscopy for 50 of them. Combined with the existing SDSS spectra, the new observations enable us to constrain the LOS RV shifts of broad H-beta lines with a rest-frame baseline of a few years to nearly a decade. Using cross-correlation analysis, we detect significant (99% confidence) radial accelerations in the broad H-beta lines in 24 of the 50 objects. We suggest that 9 of the 24 detections are sub-pc BBH candidates, which show consistent velocity shifts independently measured from a second broad line (either H-alpha or Mg II) without significant changes in the broad-line profiles. Combining the results on the general quasar population studied in Paper I, we find a tentative anti-correlation between the velocity offset in the first-epoch spectrum and the average acceleration between two epochs, which could be explained by orbital phase modulation when the time separation between two epochs is a non-negligible fraction of the orbital period of the motion causing the line displacement. We discuss the implications of our results for the identification of sub-pc BBH candidates in offset-line quasars and for the constraints on their frequency and orbital parameters. [Abridged]