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[en] As the flame width of the conventional combustor is narrow, it reduces the quality of the products to be heated by heating them partially. A wide flame combustor can heat the heating region uniformly with fewer combustors. An impinging jet combustor was set up to generate the wide flame and oxygen was used as the oxidizer to increase the radiation heat flux. The results show that a stable oxygen fuel wide flame can be generated using the impinging jets method. The oxygen fuel wide flame changed to a diffusion flame, wide flame, and split flame, respectively, with increasing oxygen inlet velocity. In particular, the oxygen fuel wide flame was found to be highly stable with a wide flame region with the following parameters: fuel 1.0 l/min, oxygen 1.2 l/min, h 0, w 4, and impinging angle 50°.
[en] Between 2004 July 5 and July 7, two intriguing fast coronal mass ejection (CME)-streamer interaction events were recorded by the Large Angle and Spectrometric Coronagraph. At the beginning of the events, the streamer was pushed aside from its equilibrium position upon the impact of the rapidly outgoing and expanding ejecta; then, the streamer structure, mainly the bright streamer belt, exhibited elegant large-scale sinusoidal wavelike motions. The motions were apparently driven by the restoring magnetic forces resulting from the CME impingement, suggestive of magnetohydrodynamic kink mode propagating outward along the plasma sheet of the streamer. The mode is supported collectively by the streamer-plasma sheet structure and is therefore named 'streamer wave' in the present study. With the white light coronagraph data, we show that the streamer wave has a period of about 1 hr, a wavelength varying from 2 to 4 solar radii, an amplitude of about a few tens of solar radii, and a propagating phase speed in the range 300-500 km s-1. We also find that there is a tendency for the phase speed to decline with increasing heliocentric distance. These observations provide good examples of large-scale wave phenomena carried by coronal structures and have significance in developing seismological techniques for diagnosing plasma and magnetic parameters in the outer corona.
[en] The article gives an overview of the pain syndrome of the ventral compartment shoulder joint and a detailed description of the etiopathogenesis of subcoracoid impingement. One of the factors causing subcoracoid impingement is the reduction of the subcoracoid space when the distance is smaller than 11 mm. Other morphological manifestations of subcoracoid impingement include the subsequent tendinopathy of the m. subscapularis tendon, abnormal filling of the subcoracoid bursa, and primary morphological differences in the configuration of the caracide tip and tuberculum minus humeri. The authors describe the technique of examination of the shoulder joint by means of indirect MR arthrography, which they consider an optimal imaging method for the examination of the shoulder joint. (author)
[en] Soft-tissue and osseous impingement syndromes can be an important cause of chronic ankle pain, particularly in the professional athlete. The classification of ankle impingement syndromes is based to their anatomical location around the tibiotalar joint. The most important impingement syndromes are anterolateral, anterior and posterior impingement with more recent studies describing posteromedial and anteromedial impingement. Usually conventional radiography is the first imaging technique to be performed as it allows assessment of potential bone abnormalities, particularly in anterior and posterior joint compartments. Computed tomography (CT) only plays a role in the assessment of the posterior impingement. Magnetic resonance (MR) imaging is regarded as the modality of choice as it is able to demonstrate both osseous and soft tissue changes, such as bone marrow edema, capsular and ligametous thickening, and localized synovitis. (orig.)
[en] When a liquid droplet impacts on a solid surface, it recoils to the center of that surface after reaching its maximum spreading diameter. The mechanism of droplet recoiling is not fully understood. To simulate this recoiling of a droplet, a particle method is a good choice because it does not require grids for simulating fluid motions, and can easily handle a large deformation of fluid. In this study, the coupled method of rigid body dynamics and the moving particle semi-implicit (MPS) method (Park and Jeun, 2012) was used to calculate three-dimensional droplet impingement. Also, the previous surface tension model for MPS (Nomura et al., 2001) was revised to get a more realistic surface tension force. A two-step calculation was performed. In the first step, a MPS calculation was performed with particles that were considered to have no mass or volume. In the second step, rigid body dynamics came into the calculation and considered the diameters of particles being slightly lesser than the initial distance between particles. In this study, the calculated results were compared with the measured data (Kim and Chun, 2000) and the recoiling lengths of droplets for the various initial impingement speeds were estimated
[en] The validations on DRAWTHREE-LDI are made through the comparisons of results calculated with those measured in feedwater heater vent lines at an actual power plant. In DRAWTHREE-LDI, pipe wall thinning rates are evaluated by the procedure composed of six steps. Comparison of calculated results by DRAWTHREE-LDI is made with those measured in feedwater heater vent lines at an actual power plant. Most calculated results agreed with those measured within a factor of two which is the target in the development of DRAWTHREE-LDI. (author)
[en] The diagnosis of shoulder impingement is primarily a clinical one. Imaging has a role in assisting clinicians in developing a treatment strategy by identifying and characterizing the cause of shoulder impingement. In this review, the relevant anatomy, cause/pathomechanics, clinical features, and magnetic resonance imaging (MRI) findings of the different types of impingement syndromes are presented
[en] The present study aimed to assess the reliability of intra and inter-examiner subacromial impingement index (SII) measures obtained from radiographs. Thirty-six individuals were enrolled and divided into two groups: control group, composed of 18 volunteers in good general health without shoulder problems, and a group of 18 patients with subacromial impingement syndrome (SIS). Radiographic images were taken with the dominant upper limb in neutral rotation, while the volunteers held their arm at 90 of abduction in the frontal plane. The beam of radiation at 30 craniocaudal inclination was used to provide an antero-posterior image view. Three blinded examiners each performed three measurements from the subacromial space (SS) and the anatomical neck of the humerus (NH). The SII was calculated as the ratio of the SS and the NH measures. The mean values of SII were compared using t-tests. The intra-class correlation coefficient (ICC) was used to assess intra- and inter-examiner reliability of the measures. The mean values of SII were greater for the control group (0.12) than for the SIS group (0.08; p = 0.0071). SII measurements showed excellent intra (0.96-0.99) and inter-examiner reliability (0.94) for both the control and SIS group. The results of this study show the potential use of the SII; a greater mean value for the control group compared to the SIS group and excellent reliability for intra- and inter-examiner measurement. Validation studies of the index should be conducted to correlate the index with clinical findings from subacromial impingement syndrome. (orig.)
[en] To determine if overhead-throwing athletes with internal impingement pain and internal rotation deficit have thickening of the posterior inferior labrocapsular complex on MR arthrogram images. This study was approved and a waiver of consent granted by our institutional review board. Twenty-six overhead-throwing athletes with internal impingement pain and internal rotation deficit, and 26 controls who had undergone MR arthrograms, were retrospectively examined. The MR studies were combined and read in a blind fashion. On an axial image through the posteroinferior glenoid rim, the readers measured the labral length, capsule-labrum length, and the posterior recess angle. A t-test was used to determine statistical significance. The mean labral length was 4.9 mm [standard deviation (SD) 1.4 mm] for the controls, and 6.4 mm (SD 1.6 mm) for the athletes (P = 0.001). The mean capsule-labrum length was 5.4 mm (SD 2.1 mm) for the controls, and 8.8 mm (SD 2.9 mm) for the athletes (P < 0.001). The mean posterior recess angle measured 65 (SD 27 ) for the controls and 94 (SD 38 ) for the athletes (P = 0.002). Overhead-throwing athletes with internal impingement pain and internal rotation deficit tend to have a thicker labrum and a shallower capsular recess in the posterior inferior shoulder joint than do non-overhead-throwing athletes. In many, the posteroinferior capsule is also thickened. These MR findings should alert the radiologist to closely inspect the posterior cuff and posterosuperior labrum for the tears associated with internal impingement. (orig.)
[en] Aim: To assess the relationship between the severity of full-thickness supraspinatus tendon tears and the development of subcoracoid impingement. Materials and methods: Fifty-one magnetic resonance imaging (MRI) shoulder examination reports with full-thickness supraspinatus tears were retrospectively identified and reviewed by two dedicated musculoskeletal radiologists. The appearances of the rotator cuff muscles, biceps tendon and the lesser tubercle were recorded. The acromio-humeral distance and the axial coraco-humeral distance were measured. The data were recorded and analysed electronically. Results: The kappa values for inter-observer agreement were: 0.91 for acromio-humeral distance and 0.85 for coraco-humeral distance measurements. Twenty-six patients had significant retraction of the supraspinatus tendon, 85% (22 cases) of this group had imaging evidence of tear or tendonopathy of the subscapularis tendon. Twenty-five patients had no significant retraction of the supraspinatus, 56% (14 cases) of this group had imaging evidence of a subscapularis tear or tendonopathy. The acromio-humeral distance was significantly less in patients with supraspinatus tears and retraction (p < 0.05). The subscapularis tendon was significantly more likely to be abnormal if the supraspinatus was retracted than if no retraction was present (p < 0.05). There were no significant differences in coraco-humeral distances between the groups. Conclusion: Subscapularis tendon signal and structural changes are frequently associated with full-thickness supraspinatus tendon tears, particularly if the supraspinatus is significantly retracted. In this static MRI series, the data do not support the occurrence of classical subcoracoid impingement as an aetiology; however, they may support the possibility of a dynamic mechanism, to which future studies could be directed