In this paper the ratcheting behavior of four pairs of stainless steel elbows is studied under conditions of steady internal pressure and dynamic conditions that induced out-of-plane external moments at frequencies ty...In this paper the ratcheting behavior of four pairs of stainless steel elbows is studied under conditions of steady internal pressure and dynamic conditions that induced out-of-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear kinematic hardening model has been used to evaluate ratcheting behavior of the piping elbows under mentioned loading condition. Material parameters have been obtained from several stabilized cycles of specimens that are subjected to symmetric strain cycles. The direction of maximum strain is at about 45° between the hoop and axial directions. The results show that the direction of highest ratcheting is along the hoop direction rather than the direction of maximum principal strain. Also, the initial rate of ratcheting is large and then it decreases with the increasing cycles. Also, the FE method gives over estimated values compared with the experimental data.展开更多
Experimental data on the pressure drop across different types of elbow for non-Newtonian pseudoplastic liquid flow in laminar condition have been presented. A generalized correlation has been developed for predicting ...Experimental data on the pressure drop across different types of elbow for non-Newtonian pseudoplastic liquid flow in laminar condition have been presented. A generalized correlation has been developed for predicting the frictional pressure drop across the elbows in the horizontal plane.展开更多
The present study demonstrates the comparison of erosion rate of critical pipeline parts, namely elbow and T-junction which face the maximum erosion in a pipeline and may cause an early damage and failure of the syste...The present study demonstrates the comparison of erosion rate of critical pipeline parts, namely elbow and T-junction which face the maximum erosion in a pipeline and may cause an early damage and failure of the system. CFD （computational fluid dynamics） with an Eulerian-Lagrangian approach coupled with an approved erosion model is applied to visualize the 3-D flow behavior of slurry flow in both parts and to predict the erosion rate and the location of erosion at the internal surfaces. The analysis of slurry erosion is performed in five steps; geometry and grid generation, grid study/refinement, fluid flow solution, solid particles tracking and finally, the erosion calculation. In previous publications in literature considering transportation of gas-solid flows in pipe parts, the application ofT-junctions instead of elbows for specified conditions in order to reduce the erosion is recommended. In this article, it is approved that for liquid-solid flows, the Stokes number is reasonably smaller than the values for gas-solid flows. This causes the solid particles tightly couple to the fluid phase and to travel more closely with the fluid streamlines. The effects of important influencing parameters such as feed flow velocity, solid concentration, particle size and shape are investigated in detail in current work. It was found that for liquid-solid flows, the erosion of T-junction for all of the mentioned influencing parameters, due to its geometrical specifications and Stokes number variation in comparison with gas-solid flows, is reasonably higher than erosion of elbow. Due to these findings, in contrary to the gas-solid mixture flows, application of T-junction instead of elbow for liquid-solid flow transportation is not recommended.展开更多
Sulfur particles carried by high-speed flow impact pipelines,which may cause equipment malfunctions and even failure.This paper investigates the scouring effect of mist gas containing sulfur particles on elbows in hig...Sulfur particles carried by high-speed flow impact pipelines,which may cause equipment malfunctions and even failure.This paper investigates the scouring effect of mist gas containing sulfur particles on elbows in highly sour gas fields.The multiphase-flow hydrodynamic model of the 90elbow was established by using the computational fluid dynamics(CFD)method.The scouring effects of the gasliquid mist fluid with the water-liquid fraction of 20%and particles with the diameter of 0.01 e0.05mm on elbows were explored within the flow velocity range of 0e20 m/s.In addition,the influences of secondary collision,mean curvature radius to diameter(R/D)ratio,inertial force,drag force,and Stokes number on trajectories of sulfur particles were studied.Moreover,the influences of hydrodynamic parameters of multiphase flow on corrosion inhibitor film were analyzed with the wall shear stress as the reference value.Serious erosion mainly occurred in the extrados of elbow as well as the junction between downstream pipeline and the intrados of elbow,the maximum erosion area occurs at 61.9.When the incident position of the particle was far away from the top of the inlet plane,the probability of secondary collision became smaller.Furthermore,the erosion rate decreased with the rise in the R/D radio.The maximum erosion rate of elbow increased with the increase in the Stoke number.The maximum erosion rate reached 0.428 mm/a at 0.05mm particle diameter and 20 m/s fluid velocity.The wall shear stress increased with the increase in fluid velocity and mass flow rate of particle,the fitting function of the wall shear stress curve was the Fourier type.The results indicated that highvelocity particles had a serious erosion effect on elbows and affected the stability of the corrosion inhibitor film.The erosion effect could be retarded by controlling the velocity and diameter of particles.The results provided technical supports for the safe production in highly sour gas fields.展开更多
The details of the shock propagated through the right angled multiple elbows (mainly double elbow and fourfold elbow) are investigated by the numerical study. Computations were carried out by solving the two-dimension...The details of the shock propagated through the right angled multiple elbows (mainly double elbow and fourfold elbow) are investigated by the numerical study. Computations were carried out by solving the two-dimensional compressible Navier-Stokes equations by using the total variation diminishing (TVD) scheme. Computations were performed for six types of elbow (two types of double elbow and four types of fourfold elbow) and two incident shock Mach numbers (Ms=1.5, 2.3). The effects of the direction and number of the bends in the stabilizing, merging and attenuating processes of the shock are numerically explored by various diagrams such as pressure contours, pressure distributions on the walls and time histories of the pressure contours, and the strength of the shock front at the location of about 20 times the length for each type of elbows was displayed.展开更多
Based on the demands of compact heat exchangers and micro cooling channels applied for aviation thermal protection on aero-engines,the elbow localflow resistance charac-teristics for supercritical pressure aviation fu...Based on the demands of compact heat exchangers and micro cooling channels applied for aviation thermal protection on aero-engines,the elbow localflow resistance charac-teristics for supercritical pressure aviation fuel RP-3flowing in adiabatic horizontal serpentine tubes with the inner diameter of 1.8 mm and the massflux of 1179 kg/(m^(2)·s)were experimen-tally studied.The long-short-tube method was used to obtain the elbow pressure drop from the total serpentine tube pressure drop,and the effects of system pressures(P/Pc=1.72-2.58)and geometry parameters including bend numbers(n=5-11),bend diameters(D/d=16.7-27.8),and bend distances(L/d=20-60)on elbow pressure drops and local resistance co-efficients are analyzed on the basis of the thermal physical property variation.The results show that both the increase in the elbow pressure drop and the decrease in the local resistance coef-ficient with temperatures speed up at the near pseudo-critical temperature region of T>0.85Tpc.And the growth of the elbow local pressure drop could be inhibited by the increase of system pressures,while the local resistance coefficient is slightly affected by pressures.The influence of bend diameters on the local resistance coefficient is mild when D/d is larger than 22.2 in the premise of fully developedflow in straight tubes.Furthermore,a piecewise empir-ical correlation considering the bend diameter and physical property ratio is developed to pre-dict the elbow pressure drop of the serpentine tube and optimize the layout of the cooling tube system on aero-engines.展开更多
In the practice of pipeline transport of oil,oil products and gas to perform turns of trunk and field pipelines in vertical and horizontal planes are used bends of various designs such as:elbows with bending radius of...In the practice of pipeline transport of oil,oil products and gas to perform turns of trunk and field pipelines in vertical and horizontal planes are used bends of various designs such as:elbows with bending radius of 1.0DN or 1.5DN and standardized angles of 30°,45°,60°,90°;induction bends with bending angles from 1°to 90°;cold bends with bending angles depending on the nominal diameter DN.展开更多
BACKGROUND Radial head fractures constitute approximately one-third of all elbow fractures,significantly impacting the young and active population.While open reduction and internal fixation is the preferred treatment ...BACKGROUND Radial head fractures constitute approximately one-third of all elbow fractures,significantly impacting the young and active population.While open reduction and internal fixation is the preferred treatment for displaced fractures,its high complication rate in comminuted fractures has led to the increasing use of radial head arthroplasty(RHA).RHA provides improved functional outcomes with fewer complications,yet its long-term efficacy remains a topic of debate.AIM To evaluate the functional outcomes of patients undergoing RHA with a modular metallic prosthesis for comminuted Mason type III and IV radial head fractures.METHODS A prospective and retrospective hospital-based study was conducted at Dayanand Medical College and Hospital,Ludhiana over 32 months(January 2021-August 2023).A total of 26 patients with Mason type III and IV fractures were included,with six retrospective and 20 prospective cases.Functional outcomes were assessed using the Mayo Elbow Performance Score(MEPS),elbow range of motion,pain via Visual Analog Scale,and activities of daily living at immediate postoperative,three-month,and six-month follow-ups.RESULTS MEPS at 6 months follow up for 4 cases(15.38%)had good scores,and 22 cases(84.62%)had excellent scores,with a mean±SD of 97.31±6.67.Comparisons showed significant improvement from immediate post-operative to 3 months(P<0.0001),from immediate post-operative to 6 months(P<0.0001),and between 3 months and 6 months(P<0.0001).None of the patients had elbow instability after radial head replacement and 22 cases(84.62%)had no complications,while 3 cases(11.54%)had a stiff elbow,and 1 case(3.85%)had heterotopic ossification.CONCLUSION RHA is an effective treatment for comminuted radial head fractures,providing stable elbow function with minimal complications.展开更多
BACKGROUND Supracondylar humeral fractures(SCHF)are the second most common fractures in childhood and can lead to short-and long-term complications.Despite their prevalence,the anatomical factors that predispose child...BACKGROUND Supracondylar humeral fractures(SCHF)are the second most common fractures in childhood and can lead to short-and long-term complications.Despite their prevalence,the anatomical factors that predispose children to SCHF remain unclear.This study aimed to determine whether there are significant morpho-logical differences in the elbow by comparing the radiographic angular measure-ments of the contralateral elbows of patients with SCHF to those of patients with distal radius fractures(DRF)and a healthy control group.We sought to explore if these morphological variations contribute to the occurrence of SCHF.Radiographs of 78 SCHF patients were analyzed for angular measurements of the contralateral elbow.Two control groups were used:98 healthy children and 40 patients with DRF.Angular measurements included Baumann angle(BA),hu-meroulnar angle(HUA),humerus metaphysis-diaphysis angle(HMDA),humerus shaft-condylar angle(HSCA),and lateral capitellohumeral angle.Only BA,HUA,and HMDA were measured in the DRF group.Statistical analysis was performed to compare differences among groups.RESULTS Significant differences were found in elbow measurements between SCHF and control groups(P<0.05).However,the mean values for all groups fell within the ranges described in the literature.CONCLUSION While statistically significant differences were found in elbow morphology between SCHF patients and controls,these differences don't translate into clinically meaningful morphological deviations.展开更多
Gas-liquid flow(GLF),especially slug and annular flows in oil and gas gathering and transportation pipelines,become particularly complex inside elbows and can easily exacerbate pipeline corrosion and damage.In thisstu...Gas-liquid flow(GLF),especially slug and annular flows in oil and gas gathering and transportation pipelines,become particularly complex inside elbows and can easily exacerbate pipeline corrosion and damage.In thisstudy,FLUENT was used to conduct 3D simulations of slug and annular flow in elbows for different velocitiesto assess the ensuing changes in terms of pressure.In particular,the multifluid VOF(Volume of Fraction)modelwas chosen.The results indicate that under both slug and annular flow conditions,the pressure inside the elbow islower than the outside.As the superficial velocity of liquid and gas increase,the pressure and liquid flow velocityat different positions of the elbow also increase,while the secondary flow weakens.Under annular flow conditions,the liquid film on the outer side of the elbow is thicker than that on the inner side,and the liquid velocityin the main liquid film zone is the lowest.展开更多
Elbow dislocations are rare injuries in children due to the resistance of the capsuloligamentous structures. Anterior dislocation is very rare and its combination with an olecranon fracture is unusual. The authors rep...Elbow dislocations are rare injuries in children due to the resistance of the capsuloligamentous structures. Anterior dislocation is very rare and its combination with an olecranon fracture is unusual. The authors report a case of this lesion in a 7-year-old child managed nonoperatively.展开更多
BACKGROUND Accurate surgical fixation of intra-articular distal humerus fractures require olecranon osteotomy.Repair of osteotomy is achieved with a variety of techniques but no consensus has been achieved regarding t...BACKGROUND Accurate surgical fixation of intra-articular distal humerus fractures require olecranon osteotomy.Repair of osteotomy is achieved with a variety of techniques but no consensus has been achieved regarding the optimum technique for fixing the olecranon osteotomy.In this retrospective study,we compared the functional and radiological outcome of the two commonly used techniques of fixing olecranon osteotomy after fixing distal humerus intra-articular fractures.We hypothesized that olecranon osteotomy fixed with 6.5 mm cancellous intramedullary screw alone yielded better radiological and functional outcome than fixation with cerclage wire over cancellous screw applied in figure of eight as tension band wiring(TBW).AIM To determine the radiological and functional outcome of olecranon osteotomy fixation with cancellous screw alone vs cancellous screw combined with cerclage wiring applied as TBW.METHODS This retrospective study was conducted in Lady Reading Hospital Peshawar Pakistan.Intra-articular distal humerus fractures fulfilling the inclusion criteria and operated during 2023 to 2025 were included.Olecranon osteotomy fixation with 6.5 mm cancellous screw alone was labelled as group A while cerclage wire over cancellous screw in figure of eight as TBW were labelled as group B.The demographics,radiological and functional outcome in both groups were compared at one year using Mayo Elbow Performance Score and Quick Disabilities of the Arm,Shoulder,and Hand Score.RESULTS We included 32 patients in this study.The mean age of group A patients was 34±5.5 years while group B had a mean age of 34±6.2 years.Radiological union of olecranon osteotomy was achieved in all cases in both groups.Functional outcome however was significantly better in group A than in group B(P<0.05).The Mayo Elbow Performance Score was excellent in 14(87.5%)and good in 2(12.5%)patients in group A while 7(43.47%)patients had excellent outcome,5(31.25%)good and 4(25%)had fair outcome in group B.The mean Quick Disabilities of the Arm,Shoulder,and Hand Score was 24.5±2.1 and 78.1±12.1 in group A and B respectively(P<0.05).CONCLUSION Similar radiological union was achieved in all patients of olecranon osteotomy treated with intramedullary screw alone and intramedullary screw with TBW.Functional outcome however was significantly better in intramedullary screw alone than in intramedullary screw with TBW.展开更多
Wiedemann-Steiner syndrome(OMIM#605130)is a rare congenital malformation syndrome characterized by hypertrichosis cubiti associated with short stature;consistent facial features,including long eyelashes,thick or arche...Wiedemann-Steiner syndrome(OMIM#605130)is a rare congenital malformation syndrome characterized by hypertrichosis cubiti associated with short stature;consistent facial features,including long eyelashes,thick or arched eyebrows with a lateral flare,wide nasal bridge,and downslanting and vertically narrow palpebral fissures;mild to moderate intellectual disability;behavioral difficulties;and hypertrichosis on the back.It is caused by heterozygous pathogenic variants in KMT2A.This gene has an established role in histone methylation,which explains the overlap of Wiedemann-Steiner syndrome with other chromatinopathies,a heterogeneous group of syndromic conditions that share a common trigger:The disruption of one of the genes involved in chromatin modification,leading to dysfunction of the epigenetic machinery.展开更多
Prof. FANG Jian-qiao is good at clinical and basic study on acupuncture analgesia. The therapeutic efficacy in treating tennis elbow of Prof. Fang is significant,＂needling painful point＂ on the basis of clarifying c...Prof. FANG Jian-qiao is good at clinical and basic study on acupuncture analgesia. The therapeutic efficacy in treating tennis elbow of Prof. Fang is significant,＂needling painful point＂ on the basis of clarifying causes and pathogenesis of this disease in TCM and western medicine,treat this disease by using encircling needling in combina on with warm needling moxibus on,and it is convenient,safe and eff ec ve. The encircling needling in combina on with warm needling moxibus on has obvious advantages in trea ng external humeral epicondyli s.展开更多
A loop system was used to investigate the effect of flow velocity on corrosion behavior of AZ91 D magnesium alloy at an elbow of loop system based on array electrode technology by polarization, computational fluid dyn...A loop system was used to investigate the effect of flow velocity on corrosion behavior of AZ91 D magnesium alloy at an elbow of loop system based on array electrode technology by polarization, computational fluid dynamics(CFD) simulation and surface analysis. The experimental results showed that the corrosion rate increased with increasing flow velocity, and a critical flow velocity could exist in the corrosion of AZ91 D magnesium alloy. When flow velocity exceeded the critical flow velocity, fluid hydrodynamics was dominant in the corrosion of AZ91 D magnesium alloy. On the contrary, the electrochemical factors were dominant.展开更多
dwindle(动词)该词的意思是“收缩；缩小；逐渐减少，逐渐削弱”。英语的释义是to decrease or shrink；to become less。没有人相信笨手笨脚的人竟然敢去偷窃，然而，在《亨利王四世上篇》(The First Part of King Henry IV)中，Falst...dwindle(动词)该词的意思是“收缩；缩小；逐渐减少，逐渐削弱”。英语的释义是to decrease or shrink；to become less。没有人相信笨手笨脚的人竟然敢去偷窃，然而，在《亨利王四世上篇》(The First Part of King Henry IV)中，Falstaff爵士竟然这么做了。展开更多
Standard reducer bends have structural functions of both bend and reducer pipe at the same time. However, there is a lack of strength design method in the current codes. In order to develop the strength design method ...Standard reducer bends have structural functions of both bend and reducer pipe at the same time. However, there is a lack of strength design method in the current codes. In order to develop the strength design method of the reducer bends subjected to internal pressure, analytical formulas are re-examined. Finite element analysis and stress measurements of the reducer bend are carried out. It is found that it is not appropriate to analyze the reducer bends by using thin membrane theory. The formula derived directly from circumferential stress formula of reducer bends under internal pressure is conservative, which is further verified by the finite element analysis results and it can thus be applied to piping design.展开更多
7075 aluminum alloy was used to obtain elbow parts by complex thixoextrusion and the microstructure evolution and mechanical properties during this process were studied by SEM,TEM and other analytical methods.The resu...7075 aluminum alloy was used to obtain elbow parts by complex thixoextrusion and the microstructure evolution and mechanical properties during this process were studied by SEM,TEM and other analytical methods.The results show that different parts in 7075 aluminum alloy show quite different microstructures.The microstructure of the thin walls formed by back-extrusion is stratified,and the bottom of the parts formed by angular extrusion is obviously deformed.Shear forces contribute to the crushing of grains and the coarse second phase.The main strengthening phases in the material areηphase and E phase,whose amounts greatly decrease during heating to semi-solid and thixoextrusion.After heat treatment,they can precipitate evenly to improve the mechanical properties of the material.The average tensile strength of whole part after thixoextrusion and heat treatment is 485.49 MPa,while the average elongation is 5.49%.展开更多
Coronal shear fractures of distal humerus involving the capitellum and the trochlea are rare injuries with articular complexity, and are technically challenging for management. With better understanding of the anatomy...Coronal shear fractures of distal humerus involving the capitellum and the trochlea are rare injuries with articular complexity, and are technically challenging for management. With better understanding of the anatomy and imaging advancements, the complex nature of these fractures is well appreciated now. These fractures involve metaphysealcomminution of lateral column and associated intraarticular injuries are common. Previously, closed reduction and excision were the accepted treatment but now preference is for open reduction and internal fixation with an aim to provide stable and congruent joint with early range of motion of joint. Various approaches including extensile lateral, anterolateral and posterior approaches have been described depending on the fracture pattern and complexity. Good to excellent outcome have been reported with internal fixations and poor results are noted in articular comminution with associated articular injuries. Various implants including headleass compression screws, minifragment screws, bioabsorbable implants and column plating are advocated for reconstruction of these complex fractures. Inspite of articular fragments being free of soft tissue attachments the rate of osteonecrosis and osteoarthritis is reported very less after internal fixation. This article summarizes the diagnostic and treatment strategies for these rare fractures and recommendations for management.展开更多
文摘In this paper the ratcheting behavior of four pairs of stainless steel elbows is studied under conditions of steady internal pressure and dynamic conditions that induced out-of-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear kinematic hardening model has been used to evaluate ratcheting behavior of the piping elbows under mentioned loading condition. Material parameters have been obtained from several stabilized cycles of specimens that are subjected to symmetric strain cycles. The direction of maximum strain is at about 45° between the hoop and axial directions. The results show that the direction of highest ratcheting is along the hoop direction rather than the direction of maximum principal strain. Also, the initial rate of ratcheting is large and then it decreases with the increasing cycles. Also, the FE method gives over estimated values compared with the experimental data.
文摘Experimental data on the pressure drop across different types of elbow for non-Newtonian pseudoplastic liquid flow in laminar condition have been presented. A generalized correlation has been developed for predicting the frictional pressure drop across the elbows in the horizontal plane.
文摘The present study demonstrates the comparison of erosion rate of critical pipeline parts, namely elbow and T-junction which face the maximum erosion in a pipeline and may cause an early damage and failure of the system. CFD （computational fluid dynamics） with an Eulerian-Lagrangian approach coupled with an approved erosion model is applied to visualize the 3-D flow behavior of slurry flow in both parts and to predict the erosion rate and the location of erosion at the internal surfaces. The analysis of slurry erosion is performed in five steps; geometry and grid generation, grid study/refinement, fluid flow solution, solid particles tracking and finally, the erosion calculation. In previous publications in literature considering transportation of gas-solid flows in pipe parts, the application ofT-junctions instead of elbows for specified conditions in order to reduce the erosion is recommended. In this article, it is approved that for liquid-solid flows, the Stokes number is reasonably smaller than the values for gas-solid flows. This causes the solid particles tightly couple to the fluid phase and to travel more closely with the fluid streamlines. The effects of important influencing parameters such as feed flow velocity, solid concentration, particle size and shape are investigated in detail in current work. It was found that for liquid-solid flows, the erosion of T-junction for all of the mentioned influencing parameters, due to its geometrical specifications and Stokes number variation in comparison with gas-solid flows, is reasonably higher than erosion of elbow. Due to these findings, in contrary to the gas-solid mixture flows, application of T-junction instead of elbow for liquid-solid flow transportation is not recommended.
基金The authors acknowledge the support from the National Natural Science Foundation Project of China(No.51374177)the Supporting Program of Youth Backbone Teachers of Southwest Petroleum University.
文摘Sulfur particles carried by high-speed flow impact pipelines,which may cause equipment malfunctions and even failure.This paper investigates the scouring effect of mist gas containing sulfur particles on elbows in highly sour gas fields.The multiphase-flow hydrodynamic model of the 90elbow was established by using the computational fluid dynamics(CFD)method.The scouring effects of the gasliquid mist fluid with the water-liquid fraction of 20%and particles with the diameter of 0.01 e0.05mm on elbows were explored within the flow velocity range of 0e20 m/s.In addition,the influences of secondary collision,mean curvature radius to diameter(R/D)ratio,inertial force,drag force,and Stokes number on trajectories of sulfur particles were studied.Moreover,the influences of hydrodynamic parameters of multiphase flow on corrosion inhibitor film were analyzed with the wall shear stress as the reference value.Serious erosion mainly occurred in the extrados of elbow as well as the junction between downstream pipeline and the intrados of elbow,the maximum erosion area occurs at 61.9.When the incident position of the particle was far away from the top of the inlet plane,the probability of secondary collision became smaller.Furthermore,the erosion rate decreased with the rise in the R/D radio.The maximum erosion rate of elbow increased with the increase in the Stoke number.The maximum erosion rate reached 0.428 mm/a at 0.05mm particle diameter and 20 m/s fluid velocity.The wall shear stress increased with the increase in fluid velocity and mass flow rate of particle,the fitting function of the wall shear stress curve was the Fourier type.The results indicated that highvelocity particles had a serious erosion effect on elbows and affected the stability of the corrosion inhibitor film.The erosion effect could be retarded by controlling the velocity and diameter of particles.The results provided technical supports for the safe production in highly sour gas fields.
文摘The details of the shock propagated through the right angled multiple elbows (mainly double elbow and fourfold elbow) are investigated by the numerical study. Computations were carried out by solving the two-dimensional compressible Navier-Stokes equations by using the total variation diminishing (TVD) scheme. Computations were performed for six types of elbow (two types of double elbow and four types of fourfold elbow) and two incident shock Mach numbers (Ms=1.5, 2.3). The effects of the direction and number of the bends in the stabilizing, merging and attenuating processes of the shock are numerically explored by various diagrams such as pressure contours, pressure distributions on the walls and time histories of the pressure contours, and the strength of the shock front at the location of about 20 times the length for each type of elbows was displayed.
基金Fundamental Research Funds for the Central Universities (No.501XTCX2023146001 and 501QYZX2023146001)the National Major Science and Technology Projects of China (Nos.J2019-III-0021-0065 and J2019-III-0015-0059)the Science Center for Gas Turbine Project (No.P2022-C-II-005-001).
文摘Based on the demands of compact heat exchangers and micro cooling channels applied for aviation thermal protection on aero-engines,the elbow localflow resistance charac-teristics for supercritical pressure aviation fuel RP-3flowing in adiabatic horizontal serpentine tubes with the inner diameter of 1.8 mm and the massflux of 1179 kg/(m^(2)·s)were experimen-tally studied.The long-short-tube method was used to obtain the elbow pressure drop from the total serpentine tube pressure drop,and the effects of system pressures(P/Pc=1.72-2.58)and geometry parameters including bend numbers(n=5-11),bend diameters(D/d=16.7-27.8),and bend distances(L/d=20-60)on elbow pressure drops and local resistance co-efficients are analyzed on the basis of the thermal physical property variation.The results show that both the increase in the elbow pressure drop and the decrease in the local resistance coef-ficient with temperatures speed up at the near pseudo-critical temperature region of T>0.85Tpc.And the growth of the elbow local pressure drop could be inhibited by the increase of system pressures,while the local resistance coefficient is slightly affected by pressures.The influence of bend diameters on the local resistance coefficient is mild when D/d is larger than 22.2 in the premise of fully developedflow in straight tubes.Furthermore,a piecewise empir-ical correlation considering the bend diameter and physical property ratio is developed to pre-dict the elbow pressure drop of the serpentine tube and optimize the layout of the cooling tube system on aero-engines.
文摘In the practice of pipeline transport of oil,oil products and gas to perform turns of trunk and field pipelines in vertical and horizontal planes are used bends of various designs such as:elbows with bending radius of 1.0DN or 1.5DN and standardized angles of 30°,45°,60°,90°;induction bends with bending angles from 1°to 90°;cold bends with bending angles depending on the nominal diameter DN.
文摘BACKGROUND Radial head fractures constitute approximately one-third of all elbow fractures,significantly impacting the young and active population.While open reduction and internal fixation is the preferred treatment for displaced fractures,its high complication rate in comminuted fractures has led to the increasing use of radial head arthroplasty(RHA).RHA provides improved functional outcomes with fewer complications,yet its long-term efficacy remains a topic of debate.AIM To evaluate the functional outcomes of patients undergoing RHA with a modular metallic prosthesis for comminuted Mason type III and IV radial head fractures.METHODS A prospective and retrospective hospital-based study was conducted at Dayanand Medical College and Hospital,Ludhiana over 32 months(January 2021-August 2023).A total of 26 patients with Mason type III and IV fractures were included,with six retrospective and 20 prospective cases.Functional outcomes were assessed using the Mayo Elbow Performance Score(MEPS),elbow range of motion,pain via Visual Analog Scale,and activities of daily living at immediate postoperative,three-month,and six-month follow-ups.RESULTS MEPS at 6 months follow up for 4 cases(15.38%)had good scores,and 22 cases(84.62%)had excellent scores,with a mean±SD of 97.31±6.67.Comparisons showed significant improvement from immediate post-operative to 3 months(P<0.0001),from immediate post-operative to 6 months(P<0.0001),and between 3 months and 6 months(P<0.0001).None of the patients had elbow instability after radial head replacement and 22 cases(84.62%)had no complications,while 3 cases(11.54%)had a stiff elbow,and 1 case(3.85%)had heterotopic ossification.CONCLUSION RHA is an effective treatment for comminuted radial head fractures,providing stable elbow function with minimal complications.
文摘BACKGROUND Supracondylar humeral fractures(SCHF)are the second most common fractures in childhood and can lead to short-and long-term complications.Despite their prevalence,the anatomical factors that predispose children to SCHF remain unclear.This study aimed to determine whether there are significant morpho-logical differences in the elbow by comparing the radiographic angular measure-ments of the contralateral elbows of patients with SCHF to those of patients with distal radius fractures(DRF)and a healthy control group.We sought to explore if these morphological variations contribute to the occurrence of SCHF.Radiographs of 78 SCHF patients were analyzed for angular measurements of the contralateral elbow.Two control groups were used:98 healthy children and 40 patients with DRF.Angular measurements included Baumann angle(BA),hu-meroulnar angle(HUA),humerus metaphysis-diaphysis angle(HMDA),humerus shaft-condylar angle(HSCA),and lateral capitellohumeral angle.Only BA,HUA,and HMDA were measured in the DRF group.Statistical analysis was performed to compare differences among groups.RESULTS Significant differences were found in elbow measurements between SCHF and control groups(P<0.05).However,the mean values for all groups fell within the ranges described in the literature.CONCLUSION While statistically significant differences were found in elbow morphology between SCHF patients and controls,these differences don't translate into clinically meaningful morphological deviations.
基金supported by the Ministry of Industry and Information Technology High Tech Ship Special Project(Grant No.CBG3N21-2-6).
文摘Gas-liquid flow(GLF),especially slug and annular flows in oil and gas gathering and transportation pipelines,become particularly complex inside elbows and can easily exacerbate pipeline corrosion and damage.In thisstudy,FLUENT was used to conduct 3D simulations of slug and annular flow in elbows for different velocitiesto assess the ensuing changes in terms of pressure.In particular,the multifluid VOF(Volume of Fraction)modelwas chosen.The results indicate that under both slug and annular flow conditions,the pressure inside the elbow islower than the outside.As the superficial velocity of liquid and gas increase,the pressure and liquid flow velocityat different positions of the elbow also increase,while the secondary flow weakens.Under annular flow conditions,the liquid film on the outer side of the elbow is thicker than that on the inner side,and the liquid velocityin the main liquid film zone is the lowest.
文摘Elbow dislocations are rare injuries in children due to the resistance of the capsuloligamentous structures. Anterior dislocation is very rare and its combination with an olecranon fracture is unusual. The authors report a case of this lesion in a 7-year-old child managed nonoperatively.
文摘BACKGROUND Accurate surgical fixation of intra-articular distal humerus fractures require olecranon osteotomy.Repair of osteotomy is achieved with a variety of techniques but no consensus has been achieved regarding the optimum technique for fixing the olecranon osteotomy.In this retrospective study,we compared the functional and radiological outcome of the two commonly used techniques of fixing olecranon osteotomy after fixing distal humerus intra-articular fractures.We hypothesized that olecranon osteotomy fixed with 6.5 mm cancellous intramedullary screw alone yielded better radiological and functional outcome than fixation with cerclage wire over cancellous screw applied in figure of eight as tension band wiring(TBW).AIM To determine the radiological and functional outcome of olecranon osteotomy fixation with cancellous screw alone vs cancellous screw combined with cerclage wiring applied as TBW.METHODS This retrospective study was conducted in Lady Reading Hospital Peshawar Pakistan.Intra-articular distal humerus fractures fulfilling the inclusion criteria and operated during 2023 to 2025 were included.Olecranon osteotomy fixation with 6.5 mm cancellous screw alone was labelled as group A while cerclage wire over cancellous screw in figure of eight as TBW were labelled as group B.The demographics,radiological and functional outcome in both groups were compared at one year using Mayo Elbow Performance Score and Quick Disabilities of the Arm,Shoulder,and Hand Score.RESULTS We included 32 patients in this study.The mean age of group A patients was 34±5.5 years while group B had a mean age of 34±6.2 years.Radiological union of olecranon osteotomy was achieved in all cases in both groups.Functional outcome however was significantly better in group A than in group B(P<0.05).The Mayo Elbow Performance Score was excellent in 14(87.5%)and good in 2(12.5%)patients in group A while 7(43.47%)patients had excellent outcome,5(31.25%)good and 4(25%)had fair outcome in group B.The mean Quick Disabilities of the Arm,Shoulder,and Hand Score was 24.5±2.1 and 78.1±12.1 in group A and B respectively(P<0.05).CONCLUSION Similar radiological union was achieved in all patients of olecranon osteotomy treated with intramedullary screw alone and intramedullary screw with TBW.Functional outcome however was significantly better in intramedullary screw alone than in intramedullary screw with TBW.
文摘Wiedemann-Steiner syndrome(OMIM#605130)is a rare congenital malformation syndrome characterized by hypertrichosis cubiti associated with short stature;consistent facial features,including long eyelashes,thick or arched eyebrows with a lateral flare,wide nasal bridge,and downslanting and vertically narrow palpebral fissures;mild to moderate intellectual disability;behavioral difficulties;and hypertrichosis on the back.It is caused by heterozygous pathogenic variants in KMT2A.This gene has an established role in histone methylation,which explains the overlap of Wiedemann-Steiner syndrome with other chromatinopathies,a heterogeneous group of syndromic conditions that share a common trigger:The disruption of one of the genes involved in chromatin modification,leading to dysfunction of the epigenetic machinery.
基金Supported by a construc on project of inheritance studio of TCM of old Chinese medicine experts:GZS 2012014a na onal construc on project of inheritance studio of TCM of old Chinese medicine experts in 2013
文摘Prof. FANG Jian-qiao is good at clinical and basic study on acupuncture analgesia. The therapeutic efficacy in treating tennis elbow of Prof. Fang is significant,＂needling painful point＂ on the basis of clarifying causes and pathogenesis of this disease in TCM and western medicine,treat this disease by using encircling needling in combina on with warm needling moxibus on,and it is convenient,safe and eff ec ve. The encircling needling in combina on with warm needling moxibus on has obvious advantages in trea ng external humeral epicondyli s.
基金Project(51401151)supported by the National Natural Science Foundation of ChinaProjects(2015T80792,2012M511207)supported by the Postdoctoral Science Foundation of China
文摘A loop system was used to investigate the effect of flow velocity on corrosion behavior of AZ91 D magnesium alloy at an elbow of loop system based on array electrode technology by polarization, computational fluid dynamics(CFD) simulation and surface analysis. The experimental results showed that the corrosion rate increased with increasing flow velocity, and a critical flow velocity could exist in the corrosion of AZ91 D magnesium alloy. When flow velocity exceeded the critical flow velocity, fluid hydrodynamics was dominant in the corrosion of AZ91 D magnesium alloy. On the contrary, the electrochemical factors were dominant.
文摘dwindle(动词)该词的意思是“收缩；缩小；逐渐减少，逐渐削弱”。英语的释义是to decrease or shrink；to become less。没有人相信笨手笨脚的人竟然敢去偷窃，然而，在《亨利王四世上篇》(The First Part of King Henry IV)中，Falstaff爵士竟然这么做了。
文摘Standard reducer bends have structural functions of both bend and reducer pipe at the same time. However, there is a lack of strength design method in the current codes. In order to develop the strength design method of the reducer bends subjected to internal pressure, analytical formulas are re-examined. Finite element analysis and stress measurements of the reducer bend are carried out. It is found that it is not appropriate to analyze the reducer bends by using thin membrane theory. The formula derived directly from circumferential stress formula of reducer bends under internal pressure is conservative, which is further verified by the finite element analysis results and it can thus be applied to piping design.
文摘7075 aluminum alloy was used to obtain elbow parts by complex thixoextrusion and the microstructure evolution and mechanical properties during this process were studied by SEM,TEM and other analytical methods.The results show that different parts in 7075 aluminum alloy show quite different microstructures.The microstructure of the thin walls formed by back-extrusion is stratified,and the bottom of the parts formed by angular extrusion is obviously deformed.Shear forces contribute to the crushing of grains and the coarse second phase.The main strengthening phases in the material areηphase and E phase,whose amounts greatly decrease during heating to semi-solid and thixoextrusion.After heat treatment,they can precipitate evenly to improve the mechanical properties of the material.The average tensile strength of whole part after thixoextrusion and heat treatment is 485.49 MPa,while the average elongation is 5.49%.
文摘Coronal shear fractures of distal humerus involving the capitellum and the trochlea are rare injuries with articular complexity, and are technically challenging for management. With better understanding of the anatomy and imaging advancements, the complex nature of these fractures is well appreciated now. These fractures involve metaphysealcomminution of lateral column and associated intraarticular injuries are common. Previously, closed reduction and excision were the accepted treatment but now preference is for open reduction and internal fixation with an aim to provide stable and congruent joint with early range of motion of joint. Various approaches including extensile lateral, anterolateral and posterior approaches have been described depending on the fracture pattern and complexity. Good to excellent outcome have been reported with internal fixations and poor results are noted in articular comminution with associated articular injuries. Various implants including headleass compression screws, minifragment screws, bioabsorbable implants and column plating are advocated for reconstruction of these complex fractures. Inspite of articular fragments being free of soft tissue attachments the rate of osteonecrosis and osteoarthritis is reported very less after internal fixation. This article summarizes the diagnostic and treatment strategies for these rare fractures and recommendations for management.
