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Sample records for inversion recovery stir

  1. Study of the fast inversion recovery pulse sequence. With reference to fast fluid attenuated inversion recovery and fast short TI inversion recovery pulse sequence

    International Nuclear Information System (INIS)

    Tsuchihashi, Toshio; Maki, Toshio; Suzuki, Takeshi

    1997-01-01

    The fast inversion recovery (fast IR) pulse sequence was evaluated. We compared the fast fluid attenuated inversion recovery (fast FLAIR) pulse sequence in which inversion time (TI) was established as equal to the water null point for the purpose of the water-suppressed T 2 -weighted image, with the fast short TI inversion recovery (fast STIR) pulse sequence in which TI was established as equal to the fat null point for purpose of fat suppression. In the fast FLAIR pulse sequence, the water null point was increased by making TR longer. In the FLAIR pulse sequence, the longitudinal magnetization contrast is determined by TI. If TI is increased, T 2 -weighted contrast improves in the same way as increasing TR for the SE pulse sequence. Therefore, images should be taken with long TR and long TI, which are longer than TR and longer than the water null point. On the other hand, the fat null point is not affected by TR in the fast STIR pulse sequence. However, effective TE was affected by variation of the null point. This increased in proportion to the increase in effective TE. Our evaluation indicated that the fast STIR pulse sequence can control the extensive signals from fat in a short time. (author)

  2. Fat suppression with short inversion time inversion-recovery and chemical-shift selective saturation: a dual STIR-CHESS combination prepulse for turbo spin echo pulse sequences.

    Science.gov (United States)

    Tanabe, Koji; Nishikawa, Keiichi; Sano, Tsukasa; Sakai, Osamu; Jara, Hernán

    2010-05-01

    To test a newly developed fat suppression magnetic resonance imaging (MRI) prepulse that synergistically uses the principles of fat suppression via inversion recovery (STIR) and spectral fat saturation (CHESS), relative to pure CHESS and STIR. This new technique is termed dual fat suppression (Dual-FS). To determine if Dual-FS could be chemically specific for fat, the phantom consisted of the fat-mimicking NiCl(2) aqueous solution, porcine fat, porcine muscle, and water was imaged with the three fat-suppression techniques. For Dual-FS and STIR, several inversion times were used. Signal intensities of each image obtained with each technique were compared. To determine if Dual-FS could be robust to magnetic field inhomogeneities, the phantom consisting of different NiCl(2) aqueous solutions, porcine fat, porcine muscle, and water was imaged with Dual-FS and CHESS at the several off-resonance frequencies. To compare fat suppression efficiency in vivo, 10 volunteer subjects were also imaged with the three fat-suppression techniques. Dual-FS could suppress fat sufficiently within the inversion time of 110-140 msec, thus enabling differentiation between fat and fat-mimicking aqueous structures. Dual-FS was as robust to magnetic field inhomogeneities as STIR and less vulnerable than CHESS. The same results for fat suppression were obtained in volunteers. The Dual-FS-STIR-CHESS is an alternative and promising fat suppression technique for turbo spin echo MRI. Copyright 2010 Wiley-Liss, Inc.

  3. Short TI inversion-recovery MR imaging of chest wall malignancies

    International Nuclear Information System (INIS)

    Dubinsky, T.J.; Porter, B.A.; Olson, D.O.

    1987-01-01

    Short-T1 inversion-recovery (STIR) sequences have greater constant, less motion sensitivity, and require shorter imaging times than conventional T2-weighted spin-echo (SE) sequences and are therefore particularly useful for staging chest wall malignancies. MR studies of 49 patients with possible chest wall malignancies were reviewed. Images were produced at 0.15 T with a variety of SE sequences. Forty-five also had STIR (repetition time, 1,400 - 2,100; echo time, 36 or 40; inversion time, 100 or 125). MR studies indicated chest wall involvement in 39 of 49 patients; 12 had obvious rib encasement, the most definitive finding. IN 13, lesions detected on STIR were either not visible or seen only in retrospect on T1 SE images. In five of five, STIR was clearly superior to T2 SE for delineation of tumor margins. The authors have discontinued using T2 SE sequences for chest neoplasms in favor of the higher contrast and sensitivity of STIR

  4. Comparison of diffusion-weighted images using short inversion time inversion recovery or chemical shift selective pulse as fat suppression in patients with breast cancer

    International Nuclear Information System (INIS)

    Kazama, Toshiki; Nasu, Katsuhiro; Kuroki, Yoshifumi; Nawano, Shigeru; Ito, Hisao

    2009-01-01

    Fat suppression is essential for diffusion-weighted imaging (DWI) in the body. However, the chemical shift selective (CHESS) pulse often fails to suppress fat signals in the breast. The purpose of this study was to compare DWI using CHESS and DWI using short inversion time inversion recovery (STIR) in terms of fat suppression and the apparent diffusion coefficient (ADC) value. DWI using STIR, DWI using CHESS, and contrast-enhanced T1-weighted images were obtained in 32 patients with breast carcinoma. Uniformity of fat suppression, ADC, signal intensity, and visualization of the breast tumors were evaluated. In 44% (14/32) of patients there was insufficient fat suppression in the breasts on DWI using CHESS, whereas 0% was observed on DWI using STIR (P<0.0001). The ADCs obtained for DWI using STIR were 4.3% lower than those obtained for DWI using CHESS (P<0.02); there was a strong correlation of the ADC measurement (r=0.93, P<0.001). DWI using STIR may be excellent for fat suppression; and the ADC obtained in this sequence was well correlated with that obtained with DWI using CHESS. DWI using STIR may be useful when the fat suppression technique in DWI using CHESS does not work well. (author)

  5. Magnetic resonance imaging of pelvic entheses - a systematic comparison between short tau inversion recovery (STIR) and T1-weighted, contrast-enhanced, fat-saturated sequences

    International Nuclear Information System (INIS)

    Klang, Eyal; Aharoni, Dvora; Rimon, Uri; Eshed, Iris; Hermann, Kay-Geert; Herman, Amir; Shazar, Nachshon

    2014-01-01

    To assess the contribution of contrast material in detecting and evaluating enthesitis of pelvic entheses by MRI. Sixty-seven hip or pelvic 1.5-T MRIs (30:37 male:female, mean age: 53 years) were retrospectively evaluated for the presence of hamstring and gluteus medius (GM) enthesitis by two readers (a resident and an experienced radiologist). Short tau inversion recovery (STIR) and T1-weighted pre- and post-contrast (T1+Gd) images were evaluated by each reader at two sessions. A consensus reading of two senior radiologists was regarded as the gold standard. Clinical data was retrieved from patients' referral form and medical files. Cohen's kappa was used for intra- and inter-observer agreement calculation. Diagnostic properties were calculated against the gold standard reading. A total of 228 entheses were evaluated. Gold standard analysis diagnosed 83 (36 %) enthesitis lesions. Intra-reader reliability for the experienced reader was significantly (p = 0.0001) higher in the T1+Gd images compared to the STIR images (hamstring: k = 0.84/0.45, GM: k = 0.84/0.47). Sensitivity and specificity increased from 0.74/0.8 to 0.87/0.9 in the STIR images and T1+Gd sequences. Intra-reader reliability for the inexperienced reader was lower (p > 0.05). Evidence showing that contrast material improves the reliability, sensitivity, and specificity of detecting enthesitis supports its use in this setting. (orig.)

  6. Demonstration of the postcommissural fibres of the fornix in short-inversion time inversion-recovery imaging on a high-field system

    Energy Technology Data Exchange (ETDEWEB)

    Saeki, N.; Kansaku, K.; Higuchi, Y.; Yamaura, A. [Dept. of Neurological Surgery, Chiba University School of Medicine (Japan); Kawano, K.; Iijima, T. [Electrotechnical Lab., Tsukuba (Japan); Inoue, N. [GE Yokagawa Medical Systems, Tokyo (Japan)

    2001-07-01

    Short-inversion time inversion-recovery (STIR) imaging using a 3 tesla system was assessed to reveal the postcommissural fibres (PF) of the fornix, which have rarely been highlighted neuroradiologically in the clinical setting. We studied 27 normal subjects. Sequence parameters were TR/TE/TI 8000/52/150 ms. STIR was expected to take advantage of the high signal-to-noise ratio of a high-field system, due to the long repetition time. PF were identifiable in axial and coronal slices in all cases. They were bordered anteriorly and superiorly by the anterior commissure and posteriorly and inferiorly by the mamillary body. Behind the anterior commissure, they ran in an arch-shaped posterior and inferior course in the hypothalamic nuclei and joined the mamillary body anterolaterally. They usually extended through three 3-mm slices (with 1 mm interslice gap) in anteroposterior and vertical dimensions. Little variation was observed in their course or size. Demonstration of the PF would provide a more detailed correlation of human neuroanatomy to hypothalamic function and individualised understanding of hypothalamic pathology and influence therapy. (orig.)

  7. Demonstration of the postcommissural fibres of the fornix in short-inversion time inversion-recovery imaging on a high-field system

    International Nuclear Information System (INIS)

    Saeki, N.; Kansaku, K.; Higuchi, Y.; Yamaura, A.; Kawano, K.; Iijima, T.; Inoue, N.

    2001-01-01

    Short-inversion time inversion-recovery (STIR) imaging using a 3 tesla system was assessed to reveal the postcommissural fibres (PF) of the fornix, which have rarely been highlighted neuroradiologically in the clinical setting. We studied 27 normal subjects. Sequence parameters were TR/TE/TI 8000/52/150 ms. STIR was expected to take advantage of the high signal-to-noise ratio of a high-field system, due to the long repetition time. PF were identifiable in axial and coronal slices in all cases. They were bordered anteriorly and superiorly by the anterior commissure and posteriorly and inferiorly by the mamillary body. Behind the anterior commissure, they ran in an arch-shaped posterior and inferior course in the hypothalamic nuclei and joined the mamillary body anterolaterally. They usually extended through three 3-mm slices (with 1 mm interslice gap) in anteroposterior and vertical dimensions. Little variation was observed in their course or size. Demonstration of the PF would provide a more detailed correlation of human neuroanatomy to hypothalamic function and individualised understanding of hypothalamic pathology and influence therapy. (orig.)

  8. Inverse Thermal Analysis of Ti-6Al-4V Friction Stir Welds Using Numerical-Analytical Basis Functions with Pseudo-Advection

    Science.gov (United States)

    Lambrakos, S. G.

    2018-04-01

    Inverse thermal analysis of Ti-6Al-4V friction stir welds is presented that demonstrates application of a methodology using numerical-analytical basis functions and temperature-field constraint conditions. This analysis provides parametric representation of friction-stir-weld temperature histories that can be adopted as input data to computational procedures for prediction of solid-state phase transformations and mechanical response. These parameterized temperature histories can be used for inverse thermal analysis of friction stir welds having process conditions similar those considered here. Case studies are presented for inverse thermal analysis of friction stir welds that use three-dimensional constraint conditions on calculated temperature fields, which are associated with experimentally measured transformation boundaries and weld-stir-zone cross sections.

  9. MRI in multiple sclerosis of the spinal cord: evaluation of fast short-tan inversion-recovery and spin-echo sequences

    International Nuclear Information System (INIS)

    Dietemann, J.L.; Thibaut-Menard, A.; Neugroschl, C.; Gillis, C.; Abu Eid, M.; Bogorin, A.; Warter, J.M.; Tranchant, C.

    2000-01-01

    We compared the sensitivity of T2-weighted spin-echo (FSE) and fast short-tau inversion-recovery (fSTIR) sequences in detection of multiple sclerosis of the spinal cord in 100 consecutive patients with clinically confirmed multiple sclerosis (MS); 86 patients underwent also brain MRI. In all, 310 focal lesions were detected on fSTIR and 212 on T2-weighted FSE, spinal cord lesions were seen better on fSTIR images, with a higher contrast between the lesion and the normal spinal cord. In 24 patients in whom cord plaques were shown with both sequences, the cranial study was normal or inconclusive. Assessment of spinal plaques can be particularly important when MRI of the brain is inconclusive, and in there situations fSTIR can be helpful. (orig.)

  10. Usefulness of combined fat- and fluid-suppressed SPIR-FLAIR images in optic neurits : Comparison with fat-suppressed SPIR or STIR images

    International Nuclear Information System (INIS)

    Kim, Hye Yeon; Son, Seok Hyun; Eun, Choong Ki; Han, Sang Suk

    2001-01-01

    To compare the usefulness of combined fat- and fluid-suppressed selective partial inversion recovery-fluid attenuated inversion recovery(SPIR-FLAIR) images in the detection of high signal intensity of the optic nerve in optic neuritis with that of fat-suppressed selective partial inversion recovery(SPIR) or short inversion time inversion recovery(STIR) images. Two radiologists independently analyzed randomly mixed MR images of 16 lesions in 14 patients (M:F=7:7; mean age, 40 years) in whom optic neuritis had been clinically diagnosed. All subjects underwent both SPIR-FLAIR and fat-suppressed SPIR or STIR imaging, in a blind fashion. In order to evaluate the optic nerve, coronal images perpendicular to its long axis were obtained. The detection rate of high signal intensity of the optic nerve, the radiologists preferred imaging sequences, and intersubject consistency of detection were evaluated. 'High signal intensity' was defined as the subjective visual evaluation of increased signal intensity compared with that of the contralateral optic nerve or that of white matter. The mean detection rate of high signal intensity of the optic nerve was 90% for combined fat- and fluid-suppressed SPIR-FLAIR images, and 59% for fat-suppressed SPIR or STIR images. In all cases in which the signal intensity observed on SPIR-FLAIR images was normal, that on fat-suppressed SPIR or STIR images was also normal. The radiologists preferred the contrast properties of SPIR-FLAIR to those of fat-suppressed SPIR or STIR images. In the diagnosis of optic neuritis using MRI, combined fat- and fluid-suppressed SPIR-FLAIR images were more useful for the detection of high signal intensity of the optic nerve than fat-suppressed SPIR or STIR images. For the evaluation of optic neuritis, combined fat- and fluid-suppressed SPIR-FLAIR imaging is superior to fat-suppressed SPIR or STIR imaging

  11. Serial quantitative MR assessment of optic neuritis in a case of neuromyelitis optica, using gadolinium-'enhanced' STIR imaging

    International Nuclear Information System (INIS)

    Barkhof, F.; Scheltens, P.; Valk, J.; Waalewijn, C.; Uitdehaag, B.M.J.; Polman, C.H.

    1991-01-01

    A patient is presented with neuromyelitis optica. MR imaging, using a short inversion time inversion recovery (STIR) technique, clearly depicted the lesion in the left optic nerve. Subsequent serial STIR imaging, with and without Gadolinium-DTPA, allowed quantitative assessment of changes parallel to improved optic nerve function. STIR imaging is a sensitive technique to demonstrate optic nerve lesions, and enables quantitative assessment to be made of the effect of (steroid) medication. (orig.)

  12. Serial quantitative MR assessment of optic neuritis in a case of neuromyelitis optica, using gadolinium-'enhanced' STIR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Barkhof, F.; Scheltens, P.; Valk, J. (Vrije Univ., Amsterdam (Netherlands). Dept. of Diagnostic Radiology); Waalewijn, C.; Uitdehaag, B.M.J.; Polman, C.H. (Vrije Univ., Amsterdam (Netherlands). Dept. of Neurology)

    1991-02-01

    A patient is presented with neuromyelitis optica. MR imaging, using a short inversion time inversion recovery (STIR) technique, clearly depicted the lesion in the left optic nerve. Subsequent serial STIR imaging, with and without Gadolinium-DTPA, allowed quantitative assessment of changes parallel to improved optic nerve function. STIR imaging is a sensitive technique to demonstrate optic nerve lesions, and enables quantitative assessment to be made of the effect of (steroid) medication. (orig.).

  13. MRI assessment of bone marrow oedema in the sacroiliac joints of patients with spondyloarthritis: is the SPAIR T2w technique comparable to STIR?

    Energy Technology Data Exchange (ETDEWEB)

    Faeda Dalto, Vitor; Nogueira-Barbosa, Marcello Henrique [University of Sao Paulo, Division of Radiology, Department of Internal Medicine, Ribeirao Preto Medical School, Ribeirao Preto, SP (Brazil); Assad, Rodrigo Luppino [University of Sao Paulo, Division of Clinical Imunology, Department of Internal Medicine, Ribeirao Preto Medical School, Ribeirao Preto, SP (Brazil); Crema, Michel Daoud [Hopital Saint-Antoine, Universite Paris VI, Service de Radiologie, Paris (France); Boston University School of Medicine, Department of Radiology, Quantitative Imaging Center, Boston, MA (United States); Hospital do Coracao (HCor) e Teleimagem, Departamento de Radiologia, Sao Paulo, SP (Brazil); Louzada-Junior, Paulo [University of Sao Paulo, Department of Internal Medicine, Ribeirao Preto Medical School, Ribeirao Preto, SP (Brazil)

    2017-09-15

    To compare short tau inversion-recovery (STIR) with another fat saturation method in the assessment of sacroiliac joint inflammation. This prospective cross-sectional study comprised 76 spondyloarthritis (SpA) patients who underwent magnetic resonance imaging of the sacroiliac joints in a 1.5-T scanner, using STIR, spectral attenuated inversion recovery (SPAIR) T2w and spectral presaturation with inversion recovery (SPIR) T1w post-contrast sequences. Two independent readers (R1 and R2) assessed the images using the Spondyloarthritis Research Consortium of Canada (SPARCC) score. We assessed agreement of the SPARCC scores for SPAIR T2w and STIR with that for T1 SPIR post-contrast (reference standard) using the St. Laurent coefficient. We evaluated each sequence using the concordance correlation coefficient (CCC). We observed a strong agreement between STIR and SPAIR T2w sequences. Lin's CCC was 0.94 for R1 and 0.84 for R2 for STIR and 0.94 for R1 and 0.84 for R2 for SPAIR. The interobserver evaluation revealed a good CCC of 0.79 for SPAIR and 0.78 for STIR. STIR technique and SPAIR T2w sequence showed high agreement in the evaluation of sacroiliac joint subchondral bone marrow oedema in patients with SpA. SPAIR T2w may be an alternative to the STIR sequence for this purpose. (orig.)

  14. MRI assessment of bone marrow oedema in the sacroiliac joints of patients with spondyloarthritis: is the SPAIR T2w technique comparable to STIR?

    International Nuclear Information System (INIS)

    Faeda Dalto, Vitor; Nogueira-Barbosa, Marcello Henrique; Assad, Rodrigo Luppino; Crema, Michel Daoud; Louzada-Junior, Paulo

    2017-01-01

    To compare short tau inversion-recovery (STIR) with another fat saturation method in the assessment of sacroiliac joint inflammation. This prospective cross-sectional study comprised 76 spondyloarthritis (SpA) patients who underwent magnetic resonance imaging of the sacroiliac joints in a 1.5-T scanner, using STIR, spectral attenuated inversion recovery (SPAIR) T2w and spectral presaturation with inversion recovery (SPIR) T1w post-contrast sequences. Two independent readers (R1 and R2) assessed the images using the Spondyloarthritis Research Consortium of Canada (SPARCC) score. We assessed agreement of the SPARCC scores for SPAIR T2w and STIR with that for T1 SPIR post-contrast (reference standard) using the St. Laurent coefficient. We evaluated each sequence using the concordance correlation coefficient (CCC). We observed a strong agreement between STIR and SPAIR T2w sequences. Lin's CCC was 0.94 for R1 and 0.84 for R2 for STIR and 0.94 for R1 and 0.84 for R2 for SPAIR. The interobserver evaluation revealed a good CCC of 0.79 for SPAIR and 0.78 for STIR. STIR technique and SPAIR T2w sequence showed high agreement in the evaluation of sacroiliac joint subchondral bone marrow oedema in patients with SpA. SPAIR T2w may be an alternative to the STIR sequence for this purpose. (orig.)

  15. Detection and characterization with short TI inversion recovery MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Komata, Kaori (Nippon Medical School, Tokyo (Japan))

    1994-10-01

    Short TI inversion recovery magnetic resonance imaging (STIR-MRI) with spin echo (SE) T1- and T2-weighted images of the pelvis was investigated to evaluate its usefulness in detecting and characterizing endometriosis. Thirty-one women suspected of having the disease were studied in detail. MR findings with and without STIR-MRI were correlated with the results of laparotomy (27 women) and laparoscopy (4 women). Surgery revealed endometriosis in 29 women (17 ovarian chocolate cysts, 22 intestinal adhesions, 14 cul-de-sac obliterations and 12 adenomyosis). The other two women did not have endometriosis (uterine prolapse in one and submucosal leiomyoma in one). An ovarian chocolate cyst was diagnosed when a T1-elongated lesion showed shading, loculus or a low intensity rim on SE MR images, and a low intensity rim on STIR-MRI. Only 12 of the 17 chocolate cysts and neither of the two hemorrhagic corpus lutein cysts were correctly diagnosed on SE MR images, whereas 18 of these 19 cysts were correctly diagnosed because of the low intensity rim on STIR-MRI. In the pathological analysis, the rim was found to be a fibrous capsule and there were many macrophages which phagocytized hemosiderin. For the assessment of ovarian chocolate cysts, accuracy improved from 63.2% to 94.7%. As for the adhesion between the intestine and the uterus, specificity improved from 61.9% to 90.5% and accuracy improved from 67.7% to 93.5% when STRI-MRI was used. For the assessment of the cul-de-sac obliteration, accuracy improved from 67.7% to 83.8% although [chi][sup 2] analysis showed no significance. The major factors for the improved accuracy with STIR-MRI are the decrease of the motion artifact owing to the suppression of the fat signal, decreased chemical shift artifact and accurate differentiation of fat from hemorrhagic component. Therefore, STIR-MRI is a useful and reliable procedure and should be used together with SE T1-, T2-weighted images for the assessment of endometriosis. (author).

  16. Detection and characterization with short TI inversion recovery MR imaging

    International Nuclear Information System (INIS)

    Komata, Kaori

    1994-01-01

    Short TI inversion recovery magnetic resonance imaging (STIR-MRI) with spin echo (SE) T1- and T2-weighted images of the pelvis was investigated to evaluate its usefulness in detecting and characterizing endometriosis. Thirty-one women suspected of having the disease were studied in detail. MR findings with and without STIR-MRI were correlated with the results of laparotomy (27 women) and laparoscopy (4 women). Surgery revealed endometriosis in 29 women (17 ovarian chocolate cysts, 22 intestinal adhesions, 14 cul-de-sac obliterations and 12 adenomyosis). The other two women did not have endometriosis (uterine prolapse in one and submucosal leiomyoma in one). An ovarian chocolate cyst was diagnosed when a T1-elongated lesion showed shading, loculus or a low intensity rim on SE MR images, and a low intensity rim on STIR-MRI. Only 12 of the 17 chocolate cysts and neither of the two hemorrhagic corpus lutein cysts were correctly diagnosed on SE MR images, whereas 18 of these 19 cysts were correctly diagnosed because of the low intensity rim on STIR-MRI. In the pathological analysis, the rim was found to be a fibrous capsule and there were many macrophages which phagocytized hemosiderin. For the assessment of ovarian chocolate cysts, accuracy improved from 63.2% to 94.7%. As for the adhesion between the intestine and the uterus, specificity improved from 61.9% to 90.5% and accuracy improved from 67.7% to 93.5% when STRI-MRI was used. For the assessment of the cul-de-sac obliteration, accuracy improved from 67.7% to 83.8% although χ 2 analysis showed no significance. The major factors for the improved accuracy with STIR-MRI are the decrease of the motion artifact owing to the suppression of the fat signal, decreased chemical shift artifact and accurate differentiation of fat from hemorrhagic component. Therefore, STIR-MRI is a useful and reliable procedure and should be used together with SE T1-, T2-weighted images for the assessment of endometriosis. (author)

  17. Cardiovascular Magnetic Resonance T2-STIR Imaging is Unable to Discriminate Between Intramyocardial Haemorrhage and Microvascular Obstruction

    DEFF Research Database (Denmark)

    Søvsø Szocska Hansen, Esben; Pedersen, Steen Fjord; Pedersen, Steen Bønløkke

    2015-01-01

    Recent studies have used cardiovascular magnetic resonance (CMR) and T2-weighted short tau inversion recovery (T2-STIR) imaging to detect intramyocardial haemorrhage (IMH) as a measure of ischemic/reperfusion injury. We investigated the ability of T2-STIR to differentiate between microvascular...

  18. Low-field STIR imaging of avascular necrosis, marrow edema, and infarction

    International Nuclear Information System (INIS)

    Porter, B.A.; Schwartz, A.N.; Olson, D.O.

    1987-01-01

    Based on 12 months experience with low-field (0.15-T) short-T1 inversion recovery (STIR) imaging, the authors replaced T2-weighted spin echo (T2SE) images with STIR for avascular necrosis (AVN). With STIR (repetition time 1,600 echo time 36, inversion time 100, 2 Avg, 256 x 128), fat is black and edema or joint fluid is bright white; 14 contiguous images take less than 7 minutes and have much greater contrast than T1 or T2 SE images. MR examinations of 36 patients with suspected AVN, marrow edema, or infarction were reviewed. AVN was equally well diagnosed with T1 SE and STIR in 16 of 16 patients. However, small effusions and the extent of marrow edema or infarction were better delineated on STIR. Joints with effusions were almost always symptomatic. Asymptomatic AVN was detected and confirmed by pressure measurements. AVN or asymptomatic marrow infarction was detected in four of six renal transplant patients. Serial STIR imaging may allow clinical monitoring of AVN. STIR improves detection of effusion, permits shorter imaging time, and can replace T2SE for AVN

  19. STIR imaging of lymphadenopathy: Advantages over conventional spin-echo techniques

    International Nuclear Information System (INIS)

    Porter, B.A.; Neumann, E.B.; Olson, D.O.; Nyberg, D.A.; Teefy, S.A.; Shields, A.F.

    1987-01-01

    Spin-echo (SE) imaging of lymphadenopathy has been limited by the high signal of surrounding fat. With short TI Inversion Recovery (STIR), fat is cancelled (black), T1 and T2 contrast are additive, and pathologic nodes are white. STIR images (repetition time, 1,400 - 2,400; echo time, 36 or 40; inversion time, 100 or 125) of 69 patients with malignant adenopathy were compared with T1-weighted spin-echo (T1 SE) or intermediate SE and some T2 SE sequences at 0.15 T. Signal-intensity measurements of nodes versus adjacent tissues were used as a measure of contrast. Ratios of these values ranged from 2.5- to more than 17-fold greater for STIR versus T1 or intermediate SE sequences and to more than 40:1 for STIR versus T2 SE images. Some nodes detected on STIR were only identifiable in retrospection CT or T1 SE. In two cases, STIR detected minimally enlarged nodes not detected on CT; biopsy confirmed malignancy. Normal nodes have lower signal than malignant nodes; inflammatory nodes may mimic neoplasm. The authors replaced T2 SE with a combination of T1 SE and STIR, shortening imaging time and enhancing detection of lymphadenopathy

  20. Optic nerve injury demonstrated by MRI with STIR sequences

    International Nuclear Information System (INIS)

    Takehara, S.; Tanaka, T.; Uemura, K.; Shinohara, Y.; Yamamoto, T.; Tokuyama, T.; Satoh, A.

    1994-01-01

    We studied nine patients with optic nerve injury associated with closed head trauma by magnetic resonance imaging (MRI) with short inversion time inversion recovery (STIR) sequences on 11 occasions from 4 days to 14 years after the injury: three studies were within 17 days and eight over 4 months to 14 years. MRI revealed abnormal high signal in 10 of the 11 injured nerves. MRI 4 days after the injury showed no abnormality. (orig.)

  1. MRI assessment of bone marrow oedema in the sacroiliac joints of patients with spondyloarthritis: is the SPAIR T2w technique comparable to STIR?

    Science.gov (United States)

    Dalto, Vitor Faeda; Assad, Rodrigo Luppino; Crema, Michel Daoud; Louzada-Junior, Paulo; Nogueira-Barbosa, Marcello Henrique

    2017-09-01

    To compare short tau inversion-recovery (STIR) with another fat saturation method in the assessment of sacroiliac joint inflammation. This prospective cross-sectional study comprised 76 spondyloarthritis (SpA) patients who underwent magnetic resonance imaging of the sacroiliac joints in a 1.5-T scanner, using STIR, spectral attenuated inversion recovery (SPAIR) T2w and spectral presaturation with inversion recovery (SPIR) T1w post-contrast sequences. Two independent readers (R1 and R2) assessed the images using the Spondyloarthritis Research Consortium of Canada (SPARCC) score. We assessed agreement of the SPARCC scores for SPAIR T2w and STIR with that for T1 SPIR post-contrast (reference standard) using the St. Laurent coefficient. We evaluated each sequence using the concordance correlation coefficient (CCC). We observed a strong agreement between STIR and SPAIR T2w sequences. Lin's CCC was 0.94 for R1 and 0.84 for R2 for STIR and 0.94 for R1 and 0.84 for R2 for SPAIR. The interobserver evaluation revealed a good CCC of 0.79 for SPAIR and 0.78 for STIR. STIR technique and SPAIR T2w sequence showed high agreement in the evaluation of sacroiliac joint subchondral bone marrow oedema in patients with SpA. SPAIR T2w may be an alternative to the STIR sequence for this purpose. • There are no studies evaluating which fat saturation technique should be used. • SPAIR T2w may be an alternative to STIR for sacroiliac joint evaluation. • The study will lead to changes in guidelines for spondyloarthritis.

  2. The role of the STIR sequence in magnetic resonance imaging examination of bone tumours

    International Nuclear Information System (INIS)

    Golfieri, R.; Baddeley, H.; Pringle, J.S.; Souhami, R.

    1990-01-01

    Sixty patients with primary bone tumours were evaluated with magnetic resonance imaging (MRI) at 0.5 T with both conventional spin-echo (SE) and short inversion time inversion recovery (STIR) sequences. The STIR sequence with T 1 of 120-130 ms in all cases suppressed the high signal from fatty bone marrow, giving a clear depiction of tumour extent, in both its intramedullary and soft-tissue components, and is superior to conventional SE images. The high sensitivity (100% of our cases) of this technique is counterbalanced by its lack of specificity: on STIR sequences both tumour and peritumorous oedema give an increase of signal intensity, limiting assessment of tumour extent. Peritumoral oedema, only present in this series in malignant neoplasms, may however be differentiated on the basis of the configuration of the abnormal areas, and by comparing STIR images with short repetition time/echo time sequence results. (author)

  3. Mesencephalic substantia nigra and Parkinson's disease: spin-echo and inversion-recovery MRI evaluation

    International Nuclear Information System (INIS)

    Michaux, Ruben P.

    2004-01-01

    Objective: To comparatively assess the images of the mesencephalic substantia nigra (mSN) obtained with FSE (PD and T2) and IR (STIR; T1; WMS and GMS) sequences in patients with Parkinson's disease (PKD) and normal volunteers. Methods: We studied 8 normal volunteers (N group) and 8 patients (PKD groups) of similar age, both men and women, with a clinical diagnosis of PKD. We obtained axial oblique images of the mesencephalon with FSE PD and T2 sequences; Inversion-Recovery (IR) with a short inversion time (STIR); T1 weighted (IR-T1 phase reconstruction) with white matter signal suppression (IR-WMS) and gray matter signal suppression (IR-GMS). Average values were measured for: a) normalized signal intensity; b) thickness; and c) area of the mSN in each sequence and group. A statistical analysis of the values obtained for each of the variables was performed for both groups (Student and Welch correlation tests), comparing the results of the intra an inter-group sequences. A p value 0.05). Images obtained with IR-WMS and GMS sequences showed significant differences between the three variables assessed, particularly thickness and area (p<0.01), and also showed a posterolateral-anteromedial gradient in the mSN alteration in patients with PKD or recent onset and chronic evolution. Conclusions: The T2 weighted FSE sequences are not useful for the assessment of mSN, whereas PD, STIR and IR-T1 sequences allow to delineate it more accurately, without morphological differences (thickness and area), or signal intensity differences among the groups assessed. The WMS and GMS sequences showed statistically significant differences in the assessment of thickness, area and the signal intensity of the mSN, and may hence be useful for diagnosis. (author)

  4. An Inversion Recovery NMR Kinetics Experiment

    OpenAIRE

    Williams, Travis J.; Kershaw, Allan D.; Li, Vincent; Wu, Xinping

    2011-01-01

    A convenient laboratory experiment is described in which NMR magnetization transfer by inversion recovery is used to measure the kinetics and thermochemistry of amide bond rotation. The experiment utilizes Varian spectrometers with the VNMRJ 2.3 software, but can be easily adapted to any NMR platform. The procedures and sample data sets in this article will enable instructors to use inversion recovery as a laboratory activity in applied NMR classes and provide research students with a conveni...

  5. Magnetic resonance imaging of lipoma and liposarcoma: potential of short tau inversion recovery as a technique of fat suppression

    International Nuclear Information System (INIS)

    Pang, A.K.K.; Hughes, T.

    2000-01-01

    The present limited retrospective study was performed to assess MR imaging of lipomatous tumours of the musculoskeletal system and to evaluate the potential of the T2 short tau inversion-recovery (STIR) technique for differentiating lipomas from liposarcomas. Magnetic resonance imaging of 12 patients with lipomatous tumours of the musculoskeletal system (eight benign lipomas, three well differentiated liposarcomas and one myxoid liposarcoma) were reviewed. Benign lipomas were usually superficial and showed homogeneity on T1- and T2-weighted spin echo sequences. Full suppression at T2-STIR was readily demonstrated. In contrast the liposarcomas in the present series were all deep-seated. Two well-differentiated liposarcomas showed homogeneity at long and short relaxation time (TR) but failed to show complete suppression at T2-STIR. One case of well-differentiated liposarcoma (dedifferentiated liposarcoma) and one of myxoid liposarcoma showed mild and moderate heterogeneity at T1 and T2, respectively and posed no difficulty in being diagnosed correctly. In conclusion, short and long TR in combination with T2 STIR show promise in differentiating benign from malignant lipomatous tumours of the musculoskeletal system, when taken in combination with the position of the tumour. Copyright (1999) Blackwell Science Pty Ltd

  6. MR STIR imaging versus spin-echo imaging of the breast

    International Nuclear Information System (INIS)

    Zobel, B.B.; Tella, S.; Patrizio, G.; Confalone, D.; D'Archivio, C.; Passariello, R.

    1989-01-01

    A valid tissue characterization of human breast diseases with conventional spin-echo (SE) sequences has not been achieved yet. In spite of experimental works showing that fibroadenomas have a small but significant difference in T1 relaxation time, T1- and T2-weighted SE sequences are not always able to differentiate them. We tried to solve the problem employing two different short T1 inversion-recovery (STIR) sequences with T1 values adequate to nullify the signal of glandular and fatty tissues. This paper reports on twenty-five nodules, including cysts, fibroadenomas, phylloids, and adenocarcinomas, examined with both STIR sequences performed on a superconductive 0.5-T unit

  7. Spin-echo and STIR MR imaging of sports-related muscle injuries at 1.5 T

    International Nuclear Information System (INIS)

    Greco, A.; McNamara, M.T.; Escher, R.M.B.; Trifilio, G.; Parienti, J.

    1990-01-01

    This paper assesses the value of T2-weighted and short T1 inversion recovery (Stir 1,800,170,27) sequences in the MR diagnosis and follow-up of muscle strain injuries. Fifty-six athletes with clinically diagnosed traumatic muscular damage were studied at 1.5 T with SE T1-weighted, double T2-weighted, and STIR techniques. Images were evaluated in order to detect the presence of muscle tear with associated edema, muscle hemorrhage (focal or diffuse), and perimuscular hemorrhage. The relative conspicuity of muscle injuries on T2-weighted and STIR images was assessed. All acute and subacute muscle injuries were detected on both SE T2-weighted and STIR images, muscle edema and subacute hemorrhage appearing hyperintense to normal muscle. Acute hemorrhage could appear hypointense on T2-weighted images but was always hyperintense on STIR images

  8. Magnetic resonance separation imaging using a divided inversion recovery technique (DIRT).

    Science.gov (United States)

    Goldfarb, James W

    2010-04-01

    The divided inversion recovery technique is an MRI separation method based on tissue T(1) relaxation differences. When tissue T(1) relaxation times are longer than the time between inversion pulses in a segmented inversion recovery pulse sequence, longitudinal magnetization does not pass through the null point. Prior to additional inversion pulses, longitudinal magnetization may have an opposite polarity. Spatial displacement of tissues in inversion recovery balanced steady-state free-precession imaging has been shown to be due to this magnetization phase change resulting from incomplete magnetization recovery. In this paper, it is shown how this phase change can be used to provide image separation. A pulse sequence parameter, the time between inversion pulses (T180), can be adjusted to provide water-fat or fluid separation. Example water-fat and fluid separation images of the head, heart, and abdomen are presented. The water-fat separation performance was investigated by comparing image intensities in short-axis divided inversion recovery technique images of the heart. Fat, blood, and fluid signal was suppressed to the background noise level. Additionally, the separation performance was not affected by main magnetic field inhomogeneities.

  9. Phase sensitive reconstruction of T1-weighted inversion recovery in the evaluation of the cervical cord lesions in multiple Sclerosis; is it similarly eligible in 1.5 T magnet fields?

    Science.gov (United States)

    Shayganfar, A; Sarrami, A H; Fathi, S; Shaygannejad, V; Shamsian, S

    2018-04-22

    In primary studies with 3 T Magnets, phase sensitive reconstruction of T1-weighted inversion recovery (PSIR) have showed ability to depict the cervical multiple sclerosis (MS) lesions some of which may not be detected by short tau inversion recovery (STIR). Regarding to more availability of 1.5 T MRI, this study was designed to evaluate the eligibility of PSIR in 1.5 T for detection of spinal cord MS lesions. In a study between September 2016 till March 2017 the patients with proven diagnosis of MS enrolled to the study. The standard protocol (sagittal STIR and T2W FSE and axial T2W FSE) as well as sagittal PSIR sequences were performed using a 1.5 T magnet. The images were studied and the lesions were localized and recorded as sharp or faint on each sequence. Of 25 patients (22 females and 3 males, with mean age of 33.5 ± 9.8 years and mean disease duration of 5.4 ± 3.9 years) 69 lesions in STIR, 53 lesions in T2W FSE, 47 lesions in Magnitude reconstruction of PSIR (Magnitude), and 30 lesions in phase sensitive (real) reconstruction PSIR were detected. A Wilcoxon signed-rank test showed STIR has a statistically significant higher detection rate of the plaques rather than other three sequences. (STIR and T2W FSE, Z = -4.000, p definition of the plaques rather than other three sequences. This study shows that in the setting of a 1.5 T magnet field, STIR significantly has a superiority over both of the PSIR reconstructions (i.e. real and magnitude) for the detection as well as the boundary definition of the cervical cord lesions of MS. These results have a good relevance to clinical practice by using MRI scanners and sequences routinely available, however, it is discrepant with other reports performed by 3 T Magnet fields. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Additional merit of coronal STIR imaging for MR imaging of lumbar spine

    Directory of Open Access Journals (Sweden)

    Ranjana Gupta

    2015-01-01

    Full Text Available Introduction: Back pain is a common clinical problem and is the frequent complaint for referral of lumbar spine magnetic resonance imaging (MRI. Coronal short tau inversion recovery sequence (STIR can provide diagnostically significant information in small percentage of patients. Materials and Methods: MRI examinations of a total of 350 patients were retrospectively included in the study. MR sequences were evaluated in two settings. One radiologist evaluated sagittal and axial images only, while another radiologist evaluated all sequences, including coronal STIR sequence. After recording the diagnoses, we compared the MRI findings in two subsets of patients to evaluate additional merit of coronal STIR imaging. Results: With addition of coronal STIR imaging, significant findings were observed in 24 subjects (6.8%. Twenty-one of these subjects were considered to be normal on other sequences and in three subjects diagnosis was changed with the addition of coronal STIR. Additional diagnoses on STIR included sacroiliitis, sacroiliac joint degenerative disease, sacral stress/insufficiency fracture/Looser′s zones, muscular sprain and atypical appendicitis. Conclusion: Coronal STIR imaging can provide additional diagnoses in a small percentage of patients presenting for lumbar spine MRI for back pain. Therefore, it should be included in the routine protocol for MR imaging of lumbar spine.

  11. The value of STIR sequence in the characterization of mediastinal lymph nodes

    Directory of Open Access Journals (Sweden)

    Aylin Okur

    2013-12-01

    Full Text Available INTRODUCTION: To investigate availability of Short Time Inversion Recovery Turbo Spin Echo Magnetic Resonance imaging (STIR TSE MRI in the detection of mediastinal lymph nodes and in the distinguishing malign and benign lymph nodes detected in cases with pulmonary lesions. METHODS: Overall, 46 patients having mediastinal lymph nodes with confirmed or suspected lung cancer were included to the study. All patients underwent STIR TSE MR imaging before mediastinoscopy. Lymph nodes were assessed by signal characteristics on STIR TSE MRI. The results of histopathological evaluation and STIR TSE MRI were compared after mediastinoscopy. As data were qualitative, distributions were expressed as percentage and chi-square test was used to determine the difference between variables. RESULTS: Overall, 92 lymph nodes were analyzed. When a comparison was made between malign and benign lymph nodes, a significant difference was found between STIR MRI signal properties of lymph nodes and lymph node size. The specificity, sensitivity, positive predictive value and negative predictive value of STIR TSE MRI were estimated as 75.0%, 75.0%, 61.5% and 83.3%, respectively. DISCUSSION AND CONCLUSION: Although the negative predictive value is high in STIR TSE MRI, it has a low positive predictive value. Thus, the case may directly undergo surgery without performing mediastinoscopy when no malign lymph node is detected in STIR TSE MRI, while mediastinoscopy is warranted when a malign lymph node is detected.

  12. Evaluation of an integrated continuous stirred microbial electrochemical reactor: Wastewater treatment, energy recovery and microbial community.

    Science.gov (United States)

    Wang, Haiman; Qu, Youpeng; Li, Da; Zhou, Xiangtong; Feng, Yujie

    2015-11-01

    A continuous stirred microbial electrochemical reactor (CSMER) was developed by integrating anaerobic digestion (AD) and microbial electrochemical system (MES). The system was capable of treating high strength artificial wastewater and simultaneously recovering electric and methane energy. Maximum power density of 583±9, 562±7, 533±10 and 572±6 mW m(-2) were obtained by each cell in a four-independent circuit mode operation at an OLR of 12 kg COD m(-3) d(-1). COD removal and energy recovery efficiency were 87.1% and 32.1%, which were 1.6 and 2.5 times higher than that of a continuous stirred tank reactor (CSTR). Larger amount of Deltaproteobacteria (5.3%) and hydrogenotrophic methanogens (47%) can account for the better performance of CSMER, since syntrophic associations among them provided more degradation pathways compared to the CSTR. Results demonstrate the CSMER holds great promise for efficient wastewater treatment and energy recovery. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Non-contrast-enhanced hepatic MR angiography: Do two-dimensional parallel imaging and short tau inversion recovery methods shorten acquisition time without image quality deterioration?

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Kotaro, E-mail: kotaro@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Isoda, Hiroyoshi, E-mail: sayuki@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Okada, Tomohisa, E-mail: tomokada@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Kamae, Toshikazu, E-mail: toshi13@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Arizono, Shigeki, E-mail: arizono@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Hirokawa, Yuusuke, E-mail: yuusuke@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Shibata, Toshiya, E-mail: ksj@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Togashi, Kaori, E-mail: ktogashi@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan)

    2011-01-15

    Objective: To study whether shortening the acquisition time for selective hepatic artery visualization is feasible without image quality deterioration by adopting two-dimensional (2D) parallel imaging (PI) and short tau inversion recovery (STIR) methods. Materials and methods: Twenty-four healthy volunteers were enrolled. 3D true steady-state free-precession imaging with a time spatial labeling inversion pulse was conducted using 1D or 2D-PI and fat suppression by chemical shift selective (CHESS) or STIR methods. Three groups of different scan conditions were assigned and compared: group A (1D-PI factor 2 and CHESS), group B (2D-PI factor 2 x 2 and CHESS), and group C (2D-PI factor 2 x 2 and STIR). The artery-to-liver contrast was quantified, and the quality of artery visualization and overall image quality were scored. Results: The mean scan time was 9.5 {+-} 1.0 min (mean {+-} standard deviation), 5.9 {+-} 0.8 min, and 5.8 {+-} 0.5 min in groups A, B, and C, respectively, and was significantly shorter in groups B and C than in group A (P < 0.01). The artery-to-liver contrast was significantly better in group C than in groups A and B (P < 0.01). The scores for artery visualization and overall image quality were worse in group B than in groups A and C. The differences were statistically significant (P < 0.05) regarding the arterial branches of segments 4 and 8. Between group A and group C, which had similar scores, there were no statistically significant differences. Conclusion: Shortening the acquisition time for selective hepatic artery visualization was feasible without deterioration of the image quality by the combination of 2D-PI and STIR methods. It will facilitate using non-contrast-enhanced MRA in clinical practice.

  14. Non-contrast-enhanced hepatic MR angiography: Do two-dimensional parallel imaging and short tau inversion recovery methods shorten acquisition time without image quality deterioration?

    International Nuclear Information System (INIS)

    Shimada, Kotaro; Isoda, Hiroyoshi; Okada, Tomohisa; Kamae, Toshikazu; Arizono, Shigeki; Hirokawa, Yuusuke; Shibata, Toshiya; Togashi, Kaori

    2011-01-01

    Objective: To study whether shortening the acquisition time for selective hepatic artery visualization is feasible without image quality deterioration by adopting two-dimensional (2D) parallel imaging (PI) and short tau inversion recovery (STIR) methods. Materials and methods: Twenty-four healthy volunteers were enrolled. 3D true steady-state free-precession imaging with a time spatial labeling inversion pulse was conducted using 1D or 2D-PI and fat suppression by chemical shift selective (CHESS) or STIR methods. Three groups of different scan conditions were assigned and compared: group A (1D-PI factor 2 and CHESS), group B (2D-PI factor 2 x 2 and CHESS), and group C (2D-PI factor 2 x 2 and STIR). The artery-to-liver contrast was quantified, and the quality of artery visualization and overall image quality were scored. Results: The mean scan time was 9.5 ± 1.0 min (mean ± standard deviation), 5.9 ± 0.8 min, and 5.8 ± 0.5 min in groups A, B, and C, respectively, and was significantly shorter in groups B and C than in group A (P < 0.01). The artery-to-liver contrast was significantly better in group C than in groups A and B (P < 0.01). The scores for artery visualization and overall image quality were worse in group B than in groups A and C. The differences were statistically significant (P < 0.05) regarding the arterial branches of segments 4 and 8. Between group A and group C, which had similar scores, there were no statistically significant differences. Conclusion: Shortening the acquisition time for selective hepatic artery visualization was feasible without deterioration of the image quality by the combination of 2D-PI and STIR methods. It will facilitate using non-contrast-enhanced MRA in clinical practice.

  15. Use of limited MR protocol (coronal STIR) in the evaluation of patients with hip pain

    International Nuclear Information System (INIS)

    Khoury, N.J.; Birjawi, G.A.; Hourani, M.H.; Chaaya, M.

    2003-01-01

    To assess the role of a limited MR protocol (coronal STIR) as the initial part of the MR examination in patients with hip pain. Eighty-five patients presenting with hip pain, and normal radiographs of the pelvis, and who underwent our full MR protocol for hips were included retrospectively in the study. The full protocol consists of coronal T1-weighted and short tau inversion-recovery (STIR), and axial T2-weighted sequences. Ninety-three MR examinations were performed. Two radiologists interpreted the STIR (limited) examinations and the full studies separately, masked to each other's findings and to the final diagnosis. Comparison between the two protocols was then undertaken. For both readers, all normal MR examinations on the coronal STIR limited protocol were normal on the full protocol, with an interobserver reliability of 0.96. The STIR protocol was able to detect the presence or absence of an abnormality in 100% of cases (sensitivity). The STIR-only protocol provided a specific diagnosis in only 65% of cases (specificity). A normal coronal STIR study of the hips in patients with hip pain and normal radiographs precludes the need for further pelvic MR sequences. Any abnormality detected on this limited protocol should be further assessed by additional MR sequences. (orig.)

  16. Extent of myocardium at risk for left anterior descending artery, right coronary artery, and left circumflex artery occlusion depicted by contrast-enhanced steady state free precession and T2-weighted short tau inversion recovery magnetic resonance imaging

    DEFF Research Database (Denmark)

    Nordlund, David; Heiberg, Einar; Carlsson, Marcus

    2016-01-01

    Background - Contrast-enhanced steady state free precession (CE-SSFP) and T2-weighted short tau inversion recovery (T2-STIR) have been clinically validated to estimate myocardium at risk (MaR) by cardiovascular magnetic resonance while using myocardial perfusion single-photon emission computed...... tomography as reference standard. Myocardial perfusion single-photon emission computed tomography has been used to describe the coronary perfusion territories during myocardial ischemia. Compared with myocardial perfusion single-photon emission computed tomography, cardiovascular magnetic resonance offers...... to show the main coronary perfusion territories using CE-SSFP and T2-STIR. The good agreement between CE-SSFP and T2-STIR from this study and myocardial perfusion single-photon emission computed tomography from previous studies indicates that these 3 methods depict MaR accurately in individual patients...

  17. Triangular fibrocartilage lesions: comparison STIR sequence versus arthroscopy findings

    International Nuclear Information System (INIS)

    Wang Zhi; Meng; Xianghong; Wang Linsen; Suo Yongmei

    2013-01-01

    Objective: To explore the diagnostic value of short TI inversion recovery (STIR) sequence in evaluating triangular fibrocartilage (TFC) lesions, and to compare the findings with the arthroscopy findings. Materials and Methods: Wrist joint MR examination using STIR sequence and arthroscopy were performed in 56 patients with TFC lesions. The parameters of STIR sequence were: TR: 1164 ms, TE: 16 ms, and TI: 90 ms. The sensibility, specificity, positive predictive value, negative predictive value, and accuracy in the diagnosis of TFC lesions with STIR sequence were calculated, using arthroscopy as the standard. Results: (1) STIR manifested 10 patients with normal TFC; 6 with small edema or mucous degeneration in the body portion but not involving joint surface edge; 6 with horizontal avulsion in the body portion, but not involving joint surface edge; 6 with avulsion involving joint surface edge; 11 with perforation in central portion; 6 with avulsion in radial attached end; 5 with avulsion in ulnar attached end; 3 with avulsion in both radial and ulnar attached ends; 3 with irregular shape and thin on the whole TFC. (2) Arthroscopy manifested 21 patients with normal TFC; 8 with avulsion involving joint surface edge; 10 with perforation in central portion; 7 with avulsion in radial attached end; 5 with avulsion in ulnar attached end; 2 with avulsion in both radial and ulnar attached ends; 3 with irregular shape on the whole TFC. Using STIR sequence, the sensibility, specificity, positive predictive value, negative predictive value. and accuracy were 85.7%, 23.8%, 65.2%, 50%, and 62.5%, respectively, in detection of TFC lesions, with arthroscopy as the standard. Conclusion: STIR sequence has high diagnostic value in detection of TFC lesions. (authors)

  18. The value of fat-suppressed T2 or STIR sequences in distinguishing lipoma from well-differentiated liposarcoma

    Energy Technology Data Exchange (ETDEWEB)

    Galant, J. [Servicio de Radiodiagnostico, Hospital Universitario San Juan de Alicante, Ctra. Nacional 332 Alicante-Valencia s/n, 03550 San Juan de Alicante (Spain); Resonancia Magnetica del Sureste, Murcia (Spain); Marti-Bonmati, L. [Department of Radiology, Hospital Universitario Dr. Peset, Valencia (Spain); Saez, F. [Department of Radiology, Hospital Cruces de Baracaldo, Vizcaya (Spain); Soler, R. [Department of Radiology, Hospital Juan Canalejo, A Coruna (Spain); Alcala-Santaella, R. [Department of Traumatology, Hospital Universitario San Juan de Alicante, Ctra. Nacional 332 Alicante-Valencia s/n, 03550 San Juan de Alicante (Spain); Navarro, M. [Servicio de Radiodiagnostico, Hospital Universitario San Juan de Alicante, Ctra. Nacional 332 Alicante-Valencia s/n, 03550 San Juan de Alicante (Spain)

    2003-02-01

    The objective of this study was to evaluate the diagnostic value of fat-suppressed T2-weighted (FS-T2) images or short tau inversion recovery (STIR) imaging in distinguishing lipoma from lipoma-like subtype of well-differentiated liposarcoma. Spin-echo T1-weighted and STIR or fat-suppression T2-weighted sequences were performed in 60 lipomas and 32 lipoma-like well-differentiated liposarcomas, histologically proven, looking for thick septa or nodules in T1-weighted images and linear, nodular, or amorphous hyperintensities on FS-T2/STIR sequences. Fourteen lipomas (23.3%) showed thick septa and/or nodules on T1, whereas on FS-T2 or STIR sequences only seven (11.7%) displayed hyperintense nodules and/or septa. All well-differentiated liposarcomas contained these signs on FS-T2 or STIR sequences. The presence of hyperintense septa or nodules in a predominantly lipomatous tumor on FS-T2/STIR sequences helps to differentiate malignant tumors from lipomas. Employing the presence of hyperintense nodules and/or septa as criteria of malignancy specificity was 76.6% and sensitivity 100%. Overdiagnoses of well-differentiated liposarcoma can occur due to the presence of non-lipomatous areas within lipomas. (orig.)

  19. The value of fat-suppressed T2 or STIR sequences in distinguishing lipoma from well-differentiated liposarcoma

    International Nuclear Information System (INIS)

    Galant, J.; Marti-Bonmati, L.; Saez, F.; Soler, R.; Alcala-Santaella, R.; Navarro, M.

    2003-01-01

    The objective of this study was to evaluate the diagnostic value of fat-suppressed T2-weighted (FS-T2) images or short tau inversion recovery (STIR) imaging in distinguishing lipoma from lipoma-like subtype of well-differentiated liposarcoma. Spin-echo T1-weighted and STIR or fat-suppression T2-weighted sequences were performed in 60 lipomas and 32 lipoma-like well-differentiated liposarcomas, histologically proven, looking for thick septa or nodules in T1-weighted images and linear, nodular, or amorphous hyperintensities on FS-T2/STIR sequences. Fourteen lipomas (23.3%) showed thick septa and/or nodules on T1, whereas on FS-T2 or STIR sequences only seven (11.7%) displayed hyperintense nodules and/or septa. All well-differentiated liposarcomas contained these signs on FS-T2 or STIR sequences. The presence of hyperintense septa or nodules in a predominantly lipomatous tumor on FS-T2/STIR sequences helps to differentiate malignant tumors from lipomas. Employing the presence of hyperintense nodules and/or septa as criteria of malignancy specificity was 76.6% and sensitivity 100%. Overdiagnoses of well-differentiated liposarcoma can occur due to the presence of non-lipomatous areas within lipomas. (orig.)

  20. An Inversion Recovery NMR Kinetics Experiment

    Science.gov (United States)

    Williams, Travis J.; Kershaw, Allan D.; Li, Vincent; Wu, Xinping

    2011-01-01

    A convenient laboratory experiment is described in which NMR magnetization transfer by inversion recovery is used to measure the kinetics and thermochemistry of amide bond rotation. The experiment utilizes Varian spectrometers with the VNMRJ 2.3 software, but can be easily adapted to any NMR platform. The procedures and sample data sets in this…

  1. Evaluation of T2-weighted versus short-tau inversion recovery sagittal sequences in the identification and localization of canine intervertebral disc extrusion with low-field magnetic resonance imaging.

    Science.gov (United States)

    Housley, Daniel; Caine, Abby; Cherubini, Giunio; Taeymans, Olivier

    2017-07-01

    Sagittal T2-weighted sequences (T2-SAG) are the foundation of spinal protocols when screening for the presence of intervertebral disc extrusion. We often utilize sagittal short-tau inversion recovery sequences (STIR-SAG) as an adjunctive screening series, and experience suggests that this combined approach provides superior detection rates. We hypothesized that STIR-SAG would provide higher sensitivity than T2-SAG in the identification and localization of intervertebral disc extrusion. We further hypothesized that the parallel evaluation of paired T2-SAG and STIR-SAG series would provide a higher sensitivity than could be achieved with either independent sagittal series when viewed in isolation. This retrospective diagnostic accuracy study blindly reviewed T2-SAG and STIR-SAG sequences from dogs (n = 110) with surgically confirmed intervertebral disc extrusion. A consensus between two radiologists found no significant difference in sensitivity between T2-SAG and STIR-SAG during the identification of intervertebral disc extrusion (T2-SAG: 92.7%, STIR-SAG: 94.5%, P = 0.752). Nevertheless, STIR-SAG accurately identified intervertebral disc extrusion in 66.7% of cases where the evaluation of T2-SAG in isolation had provided a false negative diagnosis. Additionally, one radiologist found that the parallel evaluation of paired T2-SAG and STIR-SAG series provided a significantly higher sensitivity than T2-SAG in isolation, during the identification of intervertebral disc extrusion (T2-SAG: 78.2%, paired T2-SAG, and STIR-SAG: 90.9%, P = 0.017). A similar nonsignificant trend was observed when the consensus of both radiologists was taken into consideration (T2-SAG: 92.7%, paired T2-SAG, and STIR-SAG = 97.3%, P = 0.392). We therefore conclude that STIR-SAG is capable of identifying intervertebral disc extrusion that is inconspicuous in T2-SAG, and that STIR-SAG should be considered a useful adjunctive sequence during preliminary sagittal screening for intervertebral disc

  2. Cardiovascular MR T2-STIR imaging does not discriminate between intramyocardial haemorrhage and microvascular obstruction during the subacute phase of a reperfused myocardial infarction

    DEFF Research Database (Denmark)

    Hansen, Esben Søvsø Szocska; Pedersen, Steen Fjord; Pedersen, Steen Bønløkke

    2016-01-01

    ) and T2 weighted short tau inversion recovery (T2-STIR) imaging have been used to detect IMH and to explore its clinical importance. IMH is typically identified within the area-at-risk as a hypointense signal core on T2-STIR images. Because MVO will also appear as a hypointense signal core, T2-STIR...... imaging may not be an optimal method for assessing IMH. In this study, we sought to investigate the ability of T2-STIR to discriminate between MVO with IMH in a porcine myocardial ischaemia-reperfusion model that expressed MVO with and without IMH. METHOD: MVO with and without IMH (defined from both...... MVO in all hearts. CMR and pathology showed that IMH was present in 6 of 13 (46%) infarcts. The sensitivity and specificity of T2-STIR hypointense signal core for identification of IMH was 100% and 29%, respectively. T2-values between hypointense signal core in the pigs with and without IMH were...

  3. Object analysis of bone marrow MR imaging using double echo STIR sequence in hematological diseases

    Energy Technology Data Exchange (ETDEWEB)

    Mizuno, Hitomi [Saitama Medical School, Moroyama (Japan)

    1995-07-01

    The bone marrow of 84 patients with hematological disorders was investigated using short inversion time inversion recovery sequence (STIR) on an 1.5 Tesla superconducting MRI system. Double echo times of 20 and 100 msec were applied to research the signal characteristics of the lesion and carry out quantitative analysis of the receiver operating characteristic curve (ROC). The hematological diseases included 19 cases of myelodysplastic syndrome (MDS), 18 of multiple myeloma (MM), 18 of chronic myelocytic leukemia (CML), 9 of aplastic anemia (AA), 8 of acute myelocytic leukemia (AML), 3 of chronic lymphocytic leukemia (CLL), 3 of myelofibrosis, and 3 others. Using STIR with double echo times, bone marrow showed high signal intensity (SI) on short TE and low SI on long TE in MDS and CML; high SI on short and long TE in myelofibrosis and CLL; high SI on short TE and high to moderately high SI on long TE in MM; and low SI on short and long TE in AA. Quantitative analysis of 33 patients showed high sensitivity and specificity in AA (81% and 94%, respectively) and moderate sensitivity and high specificity in MM (61%, 88%). CML and MDS were similar with low sensitivities (40%, 41%) and high specificities (80%, 78%). Differential diagnosis between CML and MDS was difficult using STIR with the double echo time method. (author).

  4. Bone marrow changes on STIR MR images of asymptomatic feet and ankles

    International Nuclear Information System (INIS)

    Zubler, Veronika; Mengiardi, Bernard; Pfirrmann, Christian W.A.; Duc, Sylvain R.; Schmid, Marius R.; Hodler, Juerg; Zanetti, Marco

    2007-01-01

    The purpose of this study was to evaluate the prevalence, pattern and size of bone marrow changes on short-tau inversion recovery (STIR) magnetic resonance (MR) images of asymptomatic feet and ankles. In 78 asymptomatic volunteers (41 women, 37 men; median age 47 years; range 23-83 years) sagittal STIR MR images of hindfoot and midfoot were reviewed for various patterns of high signal changes in bone marrow. The size of these bone marrow changes was measured, and signal intensity was rated semi-quantitatively using a scale from 0 (=normal) to 10 (=fluid-like). Fifty percent (39/78) of all volunteers had at least one bone marrow change. Thirty-six percent (28/78) of all volunteers had edema-like changes, 26% (20/78) had necrosis-like changes, and 5% (4/78) had cyst-like changes. The long diameters of all changes varied between 4 mm and 16 mm (median 7.5 mm). The median signal intensity for all changes was 5.0 (range 1-10). Bone marrow changes on STIR MR images are commonly detected in asymptomatic feet and ankles. However, such changes tend to be small (<1 cm) or subtle. (orig.)

  5. Muscle MRI STIR signal intensity and atrophy are correlated to focal lower limb neuropathy severity.

    Science.gov (United States)

    Deroide, N; Bousson, V; Mambre, L; Vicaut, E; Laredo, J D; Kubis, Nathalie

    2015-03-01

    The objective is to determine if muscle MRI is useful for assessing neuropathy severity. Clinical, MRI and electromyography (EMG) examinations were performed in 17 patients with focal lower limb neuropathies. MRI Short Tau Inversion Recovery (STIR) signal intensity, amyotrophy, and muscle fatty infiltration measured after T1-weighted image acquisition, EMG spontaneous activity (SA), and maximal voluntary contraction (MVC) were graded using semiquantitative scores and quantitative scores for STIR signal intensity and were correlated to the Medical Research Council (MRC) score for testing muscle strength. Within this population, subgroups were selected according to severity (mild versus severe), duration (subacute versus chronic), and topography (distal versus proximal) of the neuropathy. EMG SA and MVC MRI amyotrophy and quantitative scoring of muscle STIR intensity were correlated with the MRC score. Moreover, MRI amyotrophy was significantly increased in severe, chronic, and proximal neuropathies along with fatty infiltration in chronic lesions. Muscle MRI atrophy and quantitative evaluation of signal intensity were correlated to MRC score in our study. Semiquantitative evaluation of muscle STIR signal was sensitive enough for detection of topography of the nerve lesion but was not suitable to assess severity. Muscle MRI could support EMG in chronic and proximal neuropathy, which showed poor sensitivity in these patients.

  6. Muscle MRI STIR signal intensity and atrophy are correlated to focal lower limb neuropathy severity

    Energy Technology Data Exchange (ETDEWEB)

    Deroide, N.; Mambre, L.; Kubis, Nathalie [Service de Physiologie Clinique-Explorations Fonctionnelles, AP-HP, Hopital Lariboisiere, Paris (France); Universite Paris Diderot, Sorbonne Paris Cite France, Paris (France); Bousson, V.; Laredo, J.D. [Universite Paris Diderot, Sorbonne Paris Cite France, Paris (France); Radiologie Osteo-articulaire, AP-HP, Hopital Lariboisiere, Paris (France); Vicaut, E. [Universite Paris Diderot, Sorbonne Paris Cite France, Paris (France); URC, AP-HP, Hopital Lariboisiere, Paris (France)

    2014-09-26

    The objective is to determine if muscle MRI is useful for assessing neuropathy severity. Clinical, MRI and electromyography (EMG) examinations were performed in 17 patients with focal lower limb neuropathies. MRI Short Tau Inversion Recovery (STIR) signal intensity, amyotrophy, and muscle fatty infiltration measured after T1-weighted image acquisition, EMG spontaneous activity (SA), and maximal voluntary contraction (MVC) were graded using semiquantitative scores and quantitative scores for STIR signal intensity and were correlated to the Medical Research Council (MRC) score for testing muscle strength. Within this population, subgroups were selected according to severity (mild versus severe), duration (subacute versus chronic), and topography (distal versus proximal) of the neuropathy. EMG SA and MVC MRI amyotrophy and quantitative scoring of muscle STIR intensity were correlated with the MRC score. Moreover, MRI amyotrophy was significantly increased in severe, chronic, and proximal neuropathies along with fatty infiltration in chronic lesions. Muscle MRI atrophy and quantitative evaluation of signal intensity were correlated to MRC score in our study. Semiquantitative evaluation of muscle STIR signal was sensitive enough for detection of topography of the nerve lesion but was not suitable to assess severity. Muscle MRI could support EMG in chronic and proximal neuropathy, which showed poor sensitivity in these patients. (orig.)

  7. Three dimensional sampling perfection with application-optimized contrasts by using different flip angle evolutions-short time of the inversion recovery sequence for the post-ganglionic segments of the brachial plexus

    International Nuclear Information System (INIS)

    Fu Naiqi; Zhou Hongyu; Zheng Zhuozhao; Zhao Qiang

    2013-01-01

    Objective: To evaluate the contrast-enhanced 3D sampling perfection with application-optimized contrasts by using different flip angle evolutions-short TI inversion recovery sequence (SPACE-STIR) for the imaging of the post-ganglionic segments of the brachial plexus. Methods: Forty-three patients with suspected brachial plexus lesions were examined with 3D SPACE-STIR and contrast-enhanced 3D SPACE-STIR prospectively. Signal-to-noise ratios (SNR), contrast-to-noise ratios (CNR), and the conspicuousness of roots, trunks,divisions and cords of the brachial plexus of the two 3D sequences were retrospectively compared. Statistical analysis was performed by using student t-test and Wilcoxon rank sum test. Results: Compared with 3D SPACE-STIR, contrast-enhanced 3D SPACE-STIR provided the similar SNRs (left, 37.41 ± 7.34 vs 36.27 ± 7.66, t = 1.574, P = 0.123, right, 43.85 ± 9.56 vs 42.34 ± 9.74, t = 1.937, P = 0.073), but significantly higher nerve-to-muscle CNRs (left, 24.01 ± 6.31 vs 26.39 ± 6.95, right, 29.31 ± 7.84 vs 31.77 ± 8.85, t = -3.278, -3.278, both P < 0.01) and nerve-to-lymph gland CNRs(left, -0.84 ± 10.51 vs 15.35 ± 8.02, right, -8.47 ± 10.85 vs 19.30 ± 10.35, t = -15.984, -15.651, both P < 0.01). The conspicuousness of roots and trunks on contrast-enhanced 3D SPACE-STIR was significantly better than that on 3D SPACE-STIR (Z = -3.606, -4.472, P < 0.01), while the conspicuousness of divisions and cords was similar(Z = -1.732, -1.414, P = 0.083, 0.157). The signal intensity of neoplastic lesions on contrast-enhanced 3D SPACE-STIR tended to decrease rapidly, thus the lesion conspicuousness was worse than that on 3D SPACE-STIR. Conclusions: Contrast-enhanced 3D SPACE-STIR has obvious advantages in displaying normal brachial plexus and revealing non-neoplastic lesions of the brachial plexus, but may be insufficient for the diagnosis of neoplastic lesions of the brachial plexus. (authors)

  8. Ultra-high-speed inversion recovery echo planar MR imaging

    International Nuclear Information System (INIS)

    Stehling, M.K.; Ordidge, R.J.; Coxon, R.; Chapman, B.; Houseman, A.M.; Guifoyle, D.; Blamire, A.; Gibbs, P.; Mansfield, P.

    1988-01-01

    Fast two-dimensional FT MR imaging techniques such as fast low-angle shot do not allow inversion recovery (IR). Rapid repetition of low-angle pulses is incompatible with a 180 0 inversion pulse. Echo planar imaging (EPI) can be applied in conjunction with IR, because after preparation of the spin system, a complete image is acquired. Data acquisition in less than 100 msec and real-time display allows interactive optimization of inversion time (4.0-9,000 msec) with little time penalty. The authors have applied IR EPI to the study of the brain, liver, and kidneys in normal volunteers and patients. Technical details are presented, and the applications of this first ultra-high-speed IR technique will be shown

  9. Quantitative Magnetization Transfer Imaging in Human Brain at 3 T via Selective Inversion Recovery

    OpenAIRE

    Dortch, Richard D.; Li, Ke; Gochberg, Daniel F.; Welch, E. Brian; Dula, Adrienne N.; Tamhane, Ashish A.; Gore, John C.; Smith, Seth A.

    2011-01-01

    Quantitative magnetization transfer imaging yields indices describing the interactions between free water protons and immobile, macromolecular protons—including the macromolecular to free pool size ratio (PSR) and the rate of magnetization transfer between pools kmf. This study describes the first implementation of the selective inversion recovery quantitative magnetization transfer method on a clinical 3.0-T scanner in human brain in vivo. Selective inversion recovery data were acquired at 1...

  10. Comparison of STIR turbo SE imaging and diffusion-weighted imaging of the lung: capability for detection and subtype classification of pulmonary adenocarcinomas

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, Hisanobu; Ohno, Yoshiharu; Onishi, Yumiko; Matsumoto, Keiko; Nogami, Munenobu; Takenaka, Daisuke; Sugimura, Kazuro [Kobe University Graduate School of Medicine, Department of Radiology, Kobe, Hyogo (Japan); Aoyama, Nobukazu [Kobe University Hospital, Division of Radiology, Kobe (Japan); Nishio, Wataru [Kobe University Graduate School of Medicine, Division of Cardiovascular, Thoracic and Pediatric Surgery, Kobe (Japan); Ohbayashi, Chiho [Hyogo Cancer Center, Division of Pathology, Akashi (Japan)

    2010-04-15

    The aim of the study was to evaluate the diagnostic performance of diffusion-weighted imaging (DWI) for detection and subtype classification in pulmonary adenocarcinomas through comparison with short TI inversion recovery turbo spin-echo imaging sequence (STIR). Thirty-two patients (mean age, 65.2 years) with 33 adenocarcinomas (mean diameter, 27.6 mm) were enrolled in this study. The detection rates of both sequences were compared. The ADC values on DWI and the contrast ratio (CR) between cancer and muscle on STIR were measured and those were compared across subtype classifications. Finally, ROC-based positive tests were performed to differentiate subtype classifications, and differentiation capabilities were compared. The DWI detection rate [85% (28/33)] was significantly lower than that of STIR [100% (33/33), P < 0.05]. The ADC values showed no significant difference regarding subtype classification; however, the CRs of bronchio-alveolar carcinomas (BACs) were significantly lower than those of other types (P < 0.05). When threshold values for differentiating BACs from others were adapted, the sensitivity and accuracy of DWI were significantly lower than those of STIR (P < 0.05). For differentiating adenocarcinomas with mixed subtypes from those with no BA component, there were no significant differences between the two sequences. STIR is more sensitive for detection and subtype classification than DWI. (orig.)

  11. Numerical Simulation of Mechanical Property of Post Friction Stir Weld Artificial Ageing of Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    WAN Zhenyu

    2017-08-01

    Full Text Available KWN model was used to establish the precipitation evolution model of friction stir welding of Al-Mg-Si alloy. The yield strength was divided into three parts:the contribution from grain size, the contribution from solid solution and the contribution from the precipitations. Based on this model, the yield strength and hardness of friction stir weld was predicted. The effect of post weld artificial ageing on mechanical properties of friction stir weld was further investigated. The results indicate that longer holding time can be beneficial to the recovery of mechanical properties in the stirring zone. Higher temperature can lead to quick recovery of mechanical properties in the stirring zone, but when the holding temperature is higher than 200℃, longer holding time can lead the base metal softened, which is harmful to the service of friction stir welds. The mechanical property in the heat affected zone cannot be improved by post weld artificial ageing.

  12. Comparison of a conventional cardiac-triggered dual spin-echo and a fast STIR sequence in detection of spinal cord lesions in multiple sclerosis

    International Nuclear Information System (INIS)

    Bot, J.C.J.; Barkhof, F.; Lycklama a Nijeholt, G.J.; Bergers, E.; Castelijns, J.A.; Polman, C.H.; Ader, H.J.

    2000-01-01

    The current optimal imaging protocol in spinal cord MR imaging in patients with multiple sclerosis includes a long TR conventional spin-echo (CSE) sequence, requiring long acquisition times. Using short tau inversion recovery fast spin-echo (fast STIR) sequences both acquisition time can be shortened and sensitivity in the detection of multiple sclerosis (MS) abnormalities can be increased. This study compares both sequences for the potential to detect both focal and diffuse spinal abnormalities. Spinal cords of 5 volunteers and 20 MS patients were studied at 1.0 T. Magnetic resonance imaging included cardiac-gated sagittal dual-echo CSE and a cardiac-gated fast STIR sequence. Images were scored regarding number, size, and location of focal lesions, diffuse abnormalities and presence/hindrance of artifacts by two experienced radiologists. Examinations were scored as being definitely normal, indeterminate, or definitely abnormal. Interobserver agreement regarding focal lesions was higher for CSE (κ=0.67) than for fast STIR (κ=0.57) but did not differ significantly. Of all focal lesions scored in consensus, 47 % were scored on both sequences, 31 % were only detected by fast STIR, and 22 % only by dual-echo CSE (n. s.). Interobserver agreement for diffuse abnormalities was lower with fast STIR (κ=0.48) than dual-echo CSE (κ=0.65; n. s.). After consensus, fast STIR showed in 10 patients diffuse abnormalities and dual-echo CSE in 3. After consensus, in 19 of 20 patients dual-echo CSE scans were considered as definitely abnormal compared with 17 for fast STIR. The fast STIR sequence is a useful adjunct to dual-echo CSE in detecting focal abnormalities and is helpful in detecting diffuse MS abnormalities in the spinal cord. Due to the frequent occurrence of artifacts and the lower observer concordance, fast STIR cannot be used alone. (orig.)

  13. Consensus recommendations for MS cortical lesion scoring using double inversion recovery MRI

    DEFF Research Database (Denmark)

    Geurts, J J G; Roosendaal, S D; Calabrese, M

    2011-01-01

    Different double inversion recovery (DIR) sequences are currently used in multiple sclerosis (MS) research centers to visualize cortical lesions, making it difficult to compare published data. This study aimed to formulate consensus recommendations for scoring cortical lesions in patients with MS...

  14. Fat suppression at 2D MR imaging of the hands: Dixon method versus CHESS technique and STIR sequence.

    Science.gov (United States)

    Kirchgesner, Thomas; Perlepe, Vasiliki; Michoux, Nicolas; Larbi, Ahmed; Vande Berg, Bruno

    2017-04-01

    To compare the effectiveness of fat suppression and the signal-to-noise ratio (SNR) of the Dixon method with those of the CHESS (Chemical Shift-Selective) technique and STIR (Short Tau Inversion Recovery) sequence in hands of normal subjects at 2D MR imaging. 14 healthy volunteers (mean age of 29.4 years) consented to have both hands prospectively imaged with SE T1 Dixon, T1 CHESS, T2 Dixon, T2 CHESS and STIR sequences in a 1.5T MR scanner. Three radiologists scored the effectiveness of fat suppression in bone marrow (EFS BM ) and soft tissues (EFS ST ) in 20 joints per subject. One radiologist measured the SNR in 10 bones per subject. Statistical analysis used two-way ANOVA with random effects, paired t-test and observed agreement to assess differences in effectiveness of fat suppression, differences in SNR and inter-observer agreement. EFS BM was statistically significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for T2 CHESS (pCHESS and for T2 Dixon than for STIR (pCHESS (pCHESS technique at 2D T1-weighted MR imaging of the hands. At T2-weighted MR imaging, fat suppression is more effective with the Dixon method while SNR is higher with the CHESS technique. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Fast STIR (Short TI Inversion Recovery) imaging of the spine. The assessment of the role for the depiction of intramedullary spinal cord lesions and the usefulness of the additional transverse images

    International Nuclear Information System (INIS)

    Okumura, Ryosuke; Kan, Tomoko; Hirose, Tomohiro; Hara, Tadashi; Shibata, Toyomichi; Ueno, Makoto; Takagi, Takehisa; Kohno, Shigene

    2002-01-01

    It is known that the fast STIR images of the spine achieve more excellent lesion contrast than the usual fast spin echo (FSE) T2-weighted images, because the elongation of T1 and T2 relaxation time of the lesion additively contribute to the contrast. The fast STIR images showed advantages in the depiction of acute and chronic lesion of multiple sclerosis and tolerable disadvantages in the depiction of other lesions, such as spondylotic myelopathy or syringomyelia. Transverse images showed less usefulness than sagittal images except for their superior gray-to-white matter contrast. Fast STIR imaging can replace FSE T2-weighted imaging in the study of restricted patients' population. (author)

  16. A study on microstructure and strain-hardening rate of friction stir welded Al-Mg-Si alloys using a weak beam technique

    International Nuclear Information System (INIS)

    Sukedai, E; Yokoyama, T

    2012-01-01

    Mechanical properties of a friction stir welded Al-Mg-Si (6061-T6Al) alloy are evaluated by a tensile test. It is found that the strain-hardening rate is higher than that of a base material. In order to investigate the origin, TEM observations have been performed about 4 kinds of materials; base- and friction stir welded-materials, and both materials deformed to 5 % strain by tension. There are not so large differences about dislocation density, size and density of precipitates and crystal defects between the base material and the friction stir welded-materials, but a significant decrease of grain-size in the friction stir welded-materials is recognized. These results suggest a dynamic recovery occurs during FSW process, and it is speculated that the recovery leads to the differences of yield stress and strain-hardening rate between both materials.

  17. MR analysis of sternal bone marrow using STIR in hematologic diseases

    Energy Technology Data Exchange (ETDEWEB)

    Kozawa, Eito [Saitama Medical School, Moroyama (Japan)

    1998-12-01

    The magnetic resonance (MR) signal intensity pattern of sternal bone marrow was examined in 21 normal volunteers and 10 patients with aplastic anemia (n=4), multiple myeloma (2), AML (2), gammaglobulinemia (1) and MDS (1) using a sagittal STIR sequence. Double Echo STIR images (TR/TI/TE/NEX=2000/180/20, 100/1) were obtained with a CP body array coil. Craniocaudal phase-encoding with a handmade positioning device effectively avoided overlapping artifacts due to cardiac pulsation. In the normal volunteers, age showed a significant inverse correlation with the calculated SIR (signal intensity ratio of bone marrow relative to subcutaneous fat) using STIR with short TE. The SIR in the sternal body was significantly higher than that in the manubrium (p<0.05). Knowledge of the sternal bone marrow distribution according to age is useful for evaluating hematologic diseases. The proposed method provided high spatial resolution and an excellent bone marrow signal, and may be useful for determining site for aspiration. (author)

  18. Ultrasonic Stir Welding

    Science.gov (United States)

    Nabors, Sammy

    2015-01-01

    NASA Marshall Space Flight Center (MSFC) developed Ultrasonic Stir Welding (USW) to join large pieces of very high-strength metals such as titanium and Inconel. USW, a solid-state weld process, improves current thermal stir welding processes by adding high-power ultrasonic (HPU) energy at 20 kHz frequency. The addition of ultrasonic energy significantly reduces axial, frictional, and shear forces; increases travel rates; and reduces wear on the stir rod, which results in extended stir rod life. The USW process decouples the heating, stirring, and forging elements found in the friction stir welding process allowing for independent control of each process element and, ultimately, greater process control and repeatability. Because of the independent control of USW process elements, closed-loop temperature control can be integrated into the system so that a constant weld nugget temperature can be maintained during welding.

  19. Solid state crack repair by friction stir processing in 304L stainless steel

    Institute of Scientific and Technical Information of China (English)

    C.Gunter; M.P.Miles; F.C.Liu; T.W Nelson

    2018-01-01

    Friction stir processing (FSP) was investigated as a method of repairing cracks in 12mm thick 304L stainless steel plate.Healing feasibility was demonstrated by processing a tapered crack using a PCBN/WRe tool with a 25 mm diameter shoulder and a pin length of 6.4 mm.The experiment showed that it was possible to heal a crack that begins narrow and then progressively grows up to a width of 2 mm.Bead on plate experiments were used to find the best parameters for creating a consolidated stir zone with the least amount of hardness difference compared to the base metal.Grain refinement in some specimens resulted in much higher stir zone hardness,compared to base metal.A plot of grain size versus microhardness showed a very strong inverse correlation between grain size and hardness,as expected from the HallPetch relationship.Corrosion testing was carried out in order to evaluate the effect of FSP on potential sensitization of the stir zone.After 1000h of intermittent immersion in 3.5% saline solution at room temperature it was found that no corrosion products formed on the base material controls or on any of the friction stir processed specimens.

  20. Recovery of Forest Canopy Parameters by Inversion of Multispectral LiDAR Data

    Directory of Open Access Journals (Sweden)

    Andrew Wallace

    2012-02-01

    Full Text Available We describe the use of Bayesian inference techniques, notably Markov chain Monte Carlo (MCMC and reversible jump MCMC (RJMCMC methods, to recover forest structural and biochemical parameters from multispectral LiDAR (Light Detection and Ranging data. We use a variable dimension, multi-layered model to represent a forest canopy or tree, and discuss the recovery of structure and depth profiles that relate to photochemical properties. We first demonstrate how simple vegetation indices such as the Normalized Differential Vegetation Index (NDVI, which relates to canopy biomass and light absorption, and Photochemical Reflectance Index (PRI which is a measure of vegetation light use efficiency, can be measured from multispectral data. We further describe and demonstrate our layered approach on single wavelength real data, and on simulated multispectral data derived from real, rather than simulated, data sets. This evaluation shows successful recovery of a subset of parameters, as the complete recovery problem is ill-posed with the available data. We conclude that the approach has promise, and suggest future developments to address the current difficulties in parameter inversion.

  1. Multi-vendor, multicentre comparison of contrast-enhanced SSFP and T2-STIR CMR for determining myocardium at risk in ST-elevation myocardial infarction

    Science.gov (United States)

    Nordlund, David; Klug, Gert; Heiberg, Einar; Koul, Sasha; Larsen, Terje H.; Hoffmann, Pavel; Metzler, Bernhard; Erlinge, David; Atar, Dan; Aletras, Anthony H.; Carlsson, Marcus; Engblom, Henrik; Arheden, Håkan

    2016-01-01

    Aims Myocardial salvage, determined by cardiac magnetic resonance imaging (CMR), is used as end point in cardioprotection trials. To calculate myocardial salvage, infarct size is related to myocardium at risk (MaR), which can be assessed by T2-short tau inversion recovery (T2-STIR) and contrast-enhanced steady-state free precession magnetic resonance imaging (CE-SSFP). We aimed to determine how T2-STIR and CE-SSFP perform in determining MaR when applied in multicentre, multi-vendor settings. Methods and results A total of 215 patients from 17 centres were included after percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction. CMR was performed within 1–8 days. These patients participated in the MITOCARE or CHILL-MI cardioprotection trials. Additionally, 8 patients from a previous study, imaged 1 day post-CMR, were included. Late gadolinium enhancement, T2-STIR, and CE-SSFP images were acquired on 1.5T MR scanners (Philips, Siemens, or GE). In 65% of the patients, T2-STIR was of diagnostic quality compared with 97% for CE-SSFP. In diagnostic quality images, there was no difference in MaR by T2-STIR and CE-SSFP (bias: 0.02 ± 6%, P = 0.96, r2 = 0.71, P < 0.001), or between treatment and control arms. No change in size or quality of MaR nor ability to identify culprit artery was seen over the first week after the acute event (P = 0.44). Conclusion In diagnostic quality images, T2-STIR and CE-SSFP provide similar estimates of MaR, were constant over the first week, and were not affected by treatment. CE-SSFP had a higher degree of diagnostic quality images compared with T2 imaging for sequences from two out of three vendors. Therefore, CE-SSFP is currently more suitable for implementation in multicentre, multi-vendor clinical trials. PMID:27002140

  2. Biodenitrification of gaseous diffusion plant aqueous wastes: stirred bed reactor

    International Nuclear Information System (INIS)

    Holland, M.E.

    1980-01-01

    Approximately 30 kilograms of nitrates per day are discarded in the raffinates (acid wastes) of the Portsmouth Gaseous Diffusion Plant's X-705 Uranium Recovery and Decontamination Facility. A biodenitrification process employing continuous-flow, stirred-bed reactors has been successfully used to remove nitrates from similar acid wastes at the Oak Ridge Y-12 Plant. Laboratory studies have been made at Portsmouth to characterize the X-705 raffinates and to test the stirred-bed biodenitrification process on such raffinates. Raffinates which had been previously characterized were pumped through continuous-flow, stirred-bed, laboratory-scale reactors. Tests were conducted over a period of 146 days and involved variations in composition, mixing requirements, and the fate of several metal ions in the raffinates. Tests results show that 20 weight percent nitrates were reduced to a target nitrate effluent concentration of 100 μg/ml with a 99.64 percent efficiency. However, the average denitrification rate achieved was only 33% of that demonstrated with the Y-12 stirred-bed system. These low rates were probably due to the toxic effects of heavy metal ions on the denitrifying bacteria. Also, most of the uranium in the raffinate feed remained in the biomass and calcite, which collected in the reactor. This could cause criticality problems. For these reasons, it was decided not to make use of the stirred-bed bioreactor at Portsmouth. Instead, the biodenitrification installation now planned will use fluidized bed columns whose performance will be the subject of a subsequent report

  3. Effect of friction stirring on microstructure in equal channel angular pressed aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Y.S.; Urata, M.; Kokawa, H.; Ikeda, K. [Dept. of Materials Processing, Graduate School of Engineering, Tohoku Univ., Aoba-yama, Sendai (Japan)

    2003-07-01

    Friction stir welding (FSW) was applied to equal channel angular (ECA) pressed aluminum (Al) alloys with high strength and toughness, and the effect of FSW on microstructure and the hardness profile in ECA-pressed alloys was examined. In the weld of ECA-pressed Al alloy 1050 and 5083, the stir zone had roughly the same hardness as the ECA-pressed material, while the hardness was slightly reduced in the thermo-mechanically affected zone (TMAZ). The reduction of hardness in the TMAZ was due to dynamic recovery of dislocation cells of the ECA-pressed material. The addition of Zr to Al suppressed the reduction of hardness in the TMAZ. Consequently, friction stir (FS) weld of Al-Zr alloy retained the hardness of the ECA-pressed material throughout the weld. (orig.)

  4. Clinical usefulness of fluid-attenuated inversion recovery (FLAIR) sequences in intracranial lesions focusing on emergent cases

    Energy Technology Data Exchange (ETDEWEB)

    Kuramochi, Masashi; Niitsu, Mamoru; Itai, Yuji [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine; Wada, Mitsuyoshi

    1997-06-01

    Fluid-Attenuated Inversion Recovery (FLAIR) Pulse Sequences with inversion times of 1700 ms and echo times of 110 ms were used to demonstrate the brain of cerebrovascular disease (CVD) and brain trauma. The long inversion times and long echo times nulls the signal from cerebrospinal fluid and produces heavy T{sub 2} weighting images. We compared FLAIR Pulse Sequences with T{sub 2} weighted image Pulse Sequences for signal intensities of CVD and trauma. FLAIR Pulse Sequences is useful to detect at the periphery of the cerebral hemispheres, but infratentorial small infarctions often cannot be detected for its iso-intensity and slight intensity changes. In all patient of traumatic-subarachnoid hemorrhage (t-SAH) can be definitely detected high signal intensity of the cerebral hemispheres. (author)

  5. In-syringe-stirring: A novel approach for magnetic stirring-assisted dispersive liquid–liquid microextraction

    International Nuclear Information System (INIS)

    Horstkotte, Burkhard; Suárez, Ruth; Solich, Petr; Cerdà, Víctor

    2013-01-01

    Graphical abstract: -- Highlights: •We propose a new automatic magnetic stirring assisted dispersive liquid–liquid microextraction. •It allows the extraction of aluminum from seawater and freshwater samples within less than 4 min. •The method was applicable to the natural samples. -- Abstract: For the first time, the use of a magnetic stirrer within the syringe of an automated syringe pump and the resulting possible analytical applications are described. A simple instrumentation following roughly the one from sequential injection analyzer systems is used in combination with an adaptor, which is placed onto the barrel of a glass syringe. Swirling around the longitudinal axis of the syringe and holding two strong neodymium magnets, it causes a rotating magnetic field and serves as driver for a magnetic stirring bar placed inside of the syringe. In a first study it was shown that this approach leads to a sealed but also automatically adaptable reaction vessel, the syringe, in which rapid and homogeneous mixing of sample with the required reagents within short time can be carried out. In a second study in-a-syringe magnetic stirring-assisted dispersive liquid–liquid microextraction (MSA-DLLME) was demonstrated by the application of the analyzer system to fluorimetric determination of aluminum in seawater samples using lumogallion. A linear working range up to 1.1 μmol L −1 and a limit of detection of 6.1 nmol L −1 were found. An average recovery of 106.0% was achieved for coastal seawaters with a reproducibility of 4.4%. The procedure lasted 210 s including syringe cleaning and only 150 μL of hexanol and 4.1 mL of sample were required

  6. A comparative analysis of double inversion recovery TFE and TSE sequences on carotid artery wall imaging

    International Nuclear Information System (INIS)

    Chen Jun; Di Yujin; Bu Chunqing; Zhang Yanfeng; Li Shuhua

    2012-01-01

    Objective: To analyze the characteristics of double inversion recovery (DIR) turbo field echo (TFE) and turbo spin echo (TSE) sequences and explore the value of double inversion recovery TFE sequence on carotid artery wall imaging. Patients and methods: 56 patients (32 males and 24 females, aged 31–76 years with a mean age of 53 years) were performed with DIR TFE and DIR TSE T1 weighted imaging (T1WI) sequences on carotid artery bifurcations. Image quality acquired by different techniques were evaluated and scored by two physicians. Whether there is significant difference is determined by SPSS 11.0 software. Paired-samples t test was used for statistics. Results: There was no significant difference in the image quality scores between two sequences (t = 0.880, P = 0.383 > 0.05). Conclusions: DIR TFE sequence has short scanning time and high spatial resolution. DIR TFE sequence can be used as the preferred sequence for screening carotid atherosclerotic plaque compared with DIR TSE sequence.

  7. Fat suppression at 2D MR imaging of the hands: Dixon method versus CHESS technique and STIR sequence

    International Nuclear Information System (INIS)

    Kirchgesner, Thomas; Perlepe, Vasiliki; Michoux, Nicolas; Larbi, Ahmed; Vande Berg, Bruno

    2017-01-01

    Highlights: • Dixon yields effective fat suppression at 2D MRI of the hands. • CHESS fat suppression is less effective especially in the coronal plane. • SNR is higher with Dixon than with CHESS at T1-weighted MR imaging. • SNR is higher with CHESS than with Dixon and STIR at T2-weighted MR imaging. - Abstract: Objective: To compare the effectiveness of fat suppression and the signal-to-noise ratio (SNR) of the Dixon method with those of the CHESS (Chemical Shift-Selective) technique and STIR (Short Tau Inversion Recovery) sequence in hands of normal subjects at 2D MR imaging. Material and methods: 14 healthy volunteers (mean age of 29.4 years) consented to have both hands prospectively imaged with SE T1 Dixon, T1 CHESS, T2 Dixon, T2 CHESS and STIR sequences in a 1.5T MR scanner. Three radiologists scored the effectiveness of fat suppression in bone marrow (EFS BM ) and soft tissues (EFS ST ) in 20 joints per subject. One radiologist measured the SNR in 10 bones per subject. Statistical analysis used two-way ANOVA with random effects, paired t-test and observed agreement to assess differences in effectiveness of fat suppression, differences in SNR and inter-observer agreement. Results: EFS BM was statistically significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for T2 CHESS (p < 0.0001). EFS BM was significantly higher for T2 Dixon than for STIR in the coronal plane (p = 0.0020). The SNR was significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for STIR (p < 0.0001). The SNR was significantly lower for T2 Dixon than for T2 CHESS (p < 0.0001). Conclusion: The Dixon method yields more effective fat suppression and higher SNR than the CHESS technique at 2D T1-weighted MR imaging of the hands. At T2-weighted MR imaging, fat suppression is more effective with the Dixon method while SNR is higher with the CHESS technique.

  8. Fat suppression at 2D MR imaging of the hands: Dixon method versus CHESS technique and STIR sequence

    Energy Technology Data Exchange (ETDEWEB)

    Kirchgesner, Thomas, E-mail: Thomas.Kirchgesner@uclouvain.be; Perlepe, Vasiliki, E-mail: Vasiliki.Perlepe@uclouvain.be; Michoux, Nicolas, E-mail: Nicolas.Michoux@uclouvain.be; Larbi, Ahmed, E-mail: Ahmed.Larbi@chu-nimes.fr; Vande Berg, Bruno, E-mail: Bruno.VandeBerg@uclouvain.be

    2017-04-15

    Highlights: • Dixon yields effective fat suppression at 2D MRI of the hands. • CHESS fat suppression is less effective especially in the coronal plane. • SNR is higher with Dixon than with CHESS at T1-weighted MR imaging. • SNR is higher with CHESS than with Dixon and STIR at T2-weighted MR imaging. - Abstract: Objective: To compare the effectiveness of fat suppression and the signal-to-noise ratio (SNR) of the Dixon method with those of the CHESS (Chemical Shift-Selective) technique and STIR (Short Tau Inversion Recovery) sequence in hands of normal subjects at 2D MR imaging. Material and methods: 14 healthy volunteers (mean age of 29.4 years) consented to have both hands prospectively imaged with SE T1 Dixon, T1 CHESS, T2 Dixon, T2 CHESS and STIR sequences in a 1.5T MR scanner. Three radiologists scored the effectiveness of fat suppression in bone marrow (EFS{sup BM}) and soft tissues (EFS{sup ST}) in 20 joints per subject. One radiologist measured the SNR in 10 bones per subject. Statistical analysis used two-way ANOVA with random effects, paired t-test and observed agreement to assess differences in effectiveness of fat suppression, differences in SNR and inter-observer agreement. Results: EFS{sup BM} was statistically significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for T2 CHESS (p < 0.0001). EFS{sup BM} was significantly higher for T2 Dixon than for STIR in the coronal plane (p = 0.0020). The SNR was significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for STIR (p < 0.0001). The SNR was significantly lower for T2 Dixon than for T2 CHESS (p < 0.0001). Conclusion: The Dixon method yields more effective fat suppression and higher SNR than the CHESS technique at 2D T1-weighted MR imaging of the hands. At T2-weighted MR imaging, fat suppression is more effective with the Dixon method while SNR is higher with the CHESS technique.

  9. Friction Stir Welding (FSW) of Aged CuCrZr Alloy Plates

    Science.gov (United States)

    Jha, Kaushal; Kumar, Santosh; Nachiket, K.; Bhanumurthy, K.; Dey, G. K.

    2018-01-01

    Friction Stir Welding (FSW) of Cu-0.80Cr-0.10Zr (in wt pct) alloy under aged condition was performed to study the effects of process parameters on microstructure and properties of the joint. FSW was performed over a wide range of process parameters, like tool-rotation speed (from 800 to 1200 rpm) and tool-travel speed (from 40 to 100 mm/min), and the resulting thermal cycles were recorded on both sides (advancing and retreating) of the joint. The joints were characterized for their microstructure and tensile properties. The welding process resulted in a sound and defect-free weld joint, over the entire range of the process parameters used in this study. Microstructure of the stir zone showed fine and equiaxed grains, the scale of which varied with FSW process parameters. Grain size in the stir zone showed direct correlation with tool rotation and inverse correlation with tool-travel speed. Tensile strength of the weld joints was ranging from 225 to 260 MPa, which is substantially lower than that of the parent metal under aged condition ( 400 MPa), but superior to that of the parent material under annealed condition ( 220 MPa). Lower strength of the FSW joint than that of the parent material under aged condition can be attributed to dissolution of the precipitates in the stir zone and TMAZ. These results are presented and discussed in this paper.

  10. Numerical Simulation of Tension Properties for Al-Cu Alloy Friction Stir-Welded Joints with GTN Damage Model

    Science.gov (United States)

    Sun, Guo-Qin; Sun, Feng-Yang; Cao, Fang-Li; Chen, Shu-Jun; Barkey, Mark E.

    2015-11-01

    The numerical simulation of tensile fracture behavior on Al-Cu alloy friction stir-welded joint was performed with the Gurson-Tvergaard-Needleman (GTN) damage model. The parameters of the GTN model were studied in each region of the friction stir-welded joint by means of inverse identification. Based on the obtained parameters, the finite element model of the welded joint was built to predict the fracture behavior and tension properties. Good agreement can be found between the numerical and experimental results in the location of the tensile fracture and the mechanical properties.

  11. MSVAT-SPACE-STIR and SEMAC-STIR for Reduction of Metallic Artifacts in 3T Head and Neck MRI.

    Science.gov (United States)

    Hilgenfeld, T; Prager, M; Schwindling, F S; Nittka, M; Rammelsberg, P; Bendszus, M; Heiland, S; Juerchott, A

    2018-05-24

    The incidence of metallic dental restorations and implants is increasing, and head and neck MR imaging is becoming challenging regarding artifacts. Our aim was to evaluate whether multiple-slab acquisition with view angle tilting gradient based on a sampling perfection with application-optimized contrasts by using different flip angle evolution (MSVAT-SPACE)-STIR and slice-encoding for metal artifact correction (SEMAC)-STIR are beneficial regarding artifact suppression compared with the SPACE-STIR and TSE-STIR in vitro and in vivo. At 3T, 3D artifacts of 2 dental implants, supporting different single crowns, were evaluated. Image quality was evaluated quantitatively (normalized signal-to-noise ratio) and qualitatively (2 reads by 2 blinded radiologists). Feasibility was tested in vivo in 5 volunteers and 5 patients, respectively. Maximum achievable resolution and the normalized signal-to-noise ratio of MSVAT-SPACE-STIR were higher compared with SEMAC-STIR. Performance in terms of artifact correction was dependent on the material composition. For highly paramagnetic materials, SEMAC-STIR was superior to MSVAT-SPACE-STIR (27.8% smaller artifact volume) and TSE-STIR (93.2% less slice distortion). However, MSVAT-SPACE-STIR reduced the artifact size compared with SPACE-STIR by 71.5%. For low-paramagnetic materials, MSVAT-SPACE-STIR performed as well as SEMAC-STIR. Furthermore, MSVAT-SPACE-STIR decreased artifact volume by 69.5% compared with SPACE-STIR. The image quality of all sequences did not differ systematically. In vivo results were comparable with in vitro results. Regarding susceptibility artifacts and acquisition time, MSVAT-SPACE-STIR might be advantageous over SPACE-STIR for high-resolution and isotropic head and neck imaging. Only for materials with high-susceptibility differences to soft tissue, the use of SEMAC-STIR might be beneficial. Within limited acquisition times, SEMAC-STIR cannot exploit its full advantage over TSE-STIR regarding artifact

  12. Influence of crosstalk on the fast fluid attenuated inversion recovery pulse sequence

    International Nuclear Information System (INIS)

    Urata, Tohru; Nonoshita, Koji; Miyazaki, Takayuki; Arima, Akira

    2000-01-01

    The influence of crosstalk on the fast fluid attenuated inversion recovery (fast FLAIR) pulse sequence was studied. On multislice fast FLAIR images, the water null point was shortened in comparison with that on single slice images owing to the crosstalk received from adjacent slices. That influence became greater with decreases in the slice gap and increases in the number of slices. The timing of crosstalk in each slice varied according to excitation order. The process of recovery of longitudinal magnetization changed according to differences in timing; thus, it was possible that the water null point changed in each slice. In brain images with thinner slice gaps, the signal intensity of CSF is increased by the effect of crosstalk. In order to eliminate changes in the water null point caused by crosstalk on fast FLAIR, the multislice sequence requires a sequence with interleaving based on the premise that slice gaps are set for more than 100% of slice thickness. (author)

  13. Influence of crosstalk on the fast fluid attenuated inversion recovery pulse sequence

    Energy Technology Data Exchange (ETDEWEB)

    Urata, Tohru; Nonoshita, Koji; Miyazaki, Takayuki; Arima, Akira [Funabashi Municipal Medical Center, Chiba (Japan)

    2000-04-01

    The influence of crosstalk on the fast fluid attenuated inversion recovery (fast FLAIR) pulse sequence was studied. On multislice fast FLAIR images, the water null point was shortened in comparison with that on single slice images owing to the crosstalk received from adjacent slices. That influence became greater with decreases in the slice gap and increases in the number of slices. The timing of crosstalk in each slice varied according to excitation order. The process of recovery of longitudinal magnetization changed according to differences in timing; thus, it was possible that the water null point changed in each slice. In brain images with thinner slice gaps, the signal intensity of CSF is increased by the effect of crosstalk. In order to eliminate changes in the water null point caused by crosstalk on fast FLAIR, the multislice sequence requires a sequence with interleaving based on the premise that slice gaps are set for more than 100% of slice thickness. (author)

  14. Nonequilibrium chemical instabilities in continuous flow stirred tank reactors: The effect of stirring

    International Nuclear Information System (INIS)

    Horsthemke, W.; Hannon, L.

    1984-01-01

    We present a stochastic model for stirred chemical reactors. In the limiting case of practical interest, i.e., fast stirring, we solve for the characteristic function in steady state and derive expressions for the stationary moments through a perturbation expansion. Moments are explicitly calculated for a generic model of bistable behavior. We find that stirring decreases the area of the bistable region essentially by changing the point of transition from the high reaction rate state to the low reaction rate state. This is in remarkable agreement with the experimental findings of Roux, et al. Our results indicate that stirring should not be considered simply as an ''enhanced diffusion'' process and that nucleation plays only a minor role in transitions between multiple steady states in a continuous flow stirred tank reactor (CSTR)

  15. Stir zone microstructure of commercial purity titanium friction stir welded using pcBN tool

    International Nuclear Information System (INIS)

    Zhang Yu; Sato, Yutaka S.; Kokawa, Hiroyuki; Park, Seung Hwan C.; Hirano, Satoshi

    2008-01-01

    In the present study, friction stir welding was applied to commercial purity titanium using a polycrystalline cubic boron nitride tool, and microstructure and hardness in the weld were examined. Additionally, the microstructural evolution during friction stir welding was also discussed. The stir zone consisted of fine equiaxed α grains surrounded by serrate grain boundaries, which were produced through the β → α allotropic transformation during the cooling cycle of friction stir welding. The fine α grains caused higher hardness than that in the base material. A lath-shaped α grain structure containing Ti borides and tool debris was observed in the surface region of the stir zone, whose hardness was the highest in the weld

  16. Inversion recovery RARE: Clinical application of T2-weighted CSF-suppressed rapid sequence

    International Nuclear Information System (INIS)

    Goetz, G.F.; Hennig, J.; Ziyeh, S.

    1995-01-01

    Inversion-Recovery RARE is a strongly T 2 -weighted fast sequence in which the CSF appears dark. This sequence was used in more than 100 patients. Retrospective analysis of 80 patients with cerebrovascular and inflammatory disease was carried out. The IR-RARE sequence proved to be particularly suitable for identifying small lesions in the neighbourhood of the subarachnoid space. We illustrate the typical contrast provided by this sequence, and describe its characteristics, exemplifying the advantages it offers for the diagnosis of multiple sclerosis, cerebral microangiopathy and brain infarction. (orig.) [de

  17. Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction.

    Science.gov (United States)

    Chisvert, Alberto; Benedé, Juan L; Anderson, Jared L; Pierson, Stephen A; Salvador, Amparo

    2017-08-29

    With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67-791), limits of detection (low ng L -1 ), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87-113%, 91-117% and 89-115% for river, sea and swimming pool water samples, respectively). Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Molecularly imprinted polymeric stir bar: Preparation and application for the determination of naftopidil in plasma and urine samples.

    Science.gov (United States)

    Peng, Jun; Xiao, Deli; He, Hua; Zhao, Hongyan; Wang, Cuixia; Shi, Tian; Shi, Kexin

    2016-01-01

    In this study, molecularly imprinting technology and stir bar absorption technology were combined to develop a microextraction approach based on a molecularly imprinted polymeric stir bar. The molecularly imprinted polymer stir bar has a high performance, is specific, economical, and simple to prepare. The obtained naftopidil-imprinted polymer-coated bars could simultaneously agitate and adsorb naftopidil in the sample solution. The ratio of template/monomer/cross-linker and conditions of template removal were optimized to prepare a stir bar with highly efficient adsorption. Fourier transform infrared spectroscopy, scanning electron microscopy, selectivity, and extraction capacity experiments showed that the molecularly imprinted polymer stir bar was prepared successfully. To utilize the molecularly imprinted polymer stir bar for the determination of naftopidil in complex body fluid matrices, the extraction time, stirring speed, eluent, and elution time were optimized. The limits of detection of naftopidil in plasma and urine sample were 7.5 and 4.0 ng/mL, respectively, and the recoveries were in the range of 90-112%. The within-run precision and between-run precision were acceptable (relative standard deviation bar based microextraction with high-performance liquid chromatography was a convenient, rapid, efficient, and specific method for the precise determination of trace naftopidil in clinical analysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo sequence: improvement of the image quality of oxygen-enhanced MRI

    International Nuclear Information System (INIS)

    Ohno, Yoshiharu; Hatabu, Hiroto; Higashino, Takanori; Kawamitsu, Hideaki; Watanabe, Hirokazu; Takenaka, Daisuke; Cauteren, Marc van; Sugimura, Kazuro

    2004-01-01

    Purpose: The purpose of the study presented here was to determine the improvement in image quality of oxygen-enhanced magnetic resonance (MR) subtraction imaging obtained with a centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo (c-IR-HASTE) sequence compared with that obtained with a conventional sequentially reordered inversion recovery single-shot HASTE (s-IR-HASTE) sequence for pulmonary imaging. Materials and methods: Oxygen-enhanced MR imaging using a 1.5 T whole body scanner was performed on 12 healthy, non-smoking volunteers. Oxygen-enhanced MR images were obtained with the coronal two-dimensional (2D) c-IR-HASTE sequence and 2D s-IR-HASTE sequence combined with respiratory triggering. For a 256x256 matrix, 132 phase-encoding steps were acquired including four steps for phase correction. Inter-echo spacing for each sequence was 4.0 ms. The effective echo time (TE) for c-IR-HASTE was 4.0 ms, and 16 ms for s-IR-HASTE. The inversion time (TI) was 900 ms. To determine the improvement in oxygen-enhanced MR subtraction imaging by c-IR-HASTE, CNRs of subtraction image, overall image quality, and image degradation of the c-IR-HASTE and s-IR-HASTE techniques were statistically compared. Results: CNR, overall image quality, and image degradation of c-IR-HASTE images showed significant improvement compared to those s-IR-HASTE images (P<0.05). Conclusion: Centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo (c-IR-HASTE) sequence enhanced the signal from the lung and improved the image quality of oxygen-enhanced MR subtraction imaging

  20. Evaluation of stir-bar sorptive extraction coupled with thermal desorption GC-MS for the detection of leachables from polymer single use systems to drugs.

    Science.gov (United States)

    Scherer, Nicole; Marcseková, Klaudia; Posset, Tobias; Winter, Gerhard

    2018-04-15

    Stir-bar Sorptive Extraction (SBSE) in combination with thermal desorption and gas chromatography-mass spectrometry (TD-GC-MS) is widely accepted as the gold-standard analysis method for trace amounts of organic substances, including leachables in aqueous matrices. Meanwhile, as far as pharmaceutical quality control in protein-based parenteral drugs is concerned, the use of SBSE analysis remains unexplored. Previous studies reported a strong influence of the matrix on the method's recovery. The scope of the present work was to fill in the unexplored territory in a threefold manner 1) by quantifying the effects that various matrices commonly found in pharmaceutical processing have on the recovery, 2) by comparing between different coating materials for stir bar (namely between polydimethylsiloxane (PDMS) material and ethylene-glycol (EG)-PDMS), and 3) by proposing a preparation step for stir-bar to mitigate inhibitory effects. The current study shows no inhibition of SBSE by protein matrices (p > 0.15). Further the influence of various drug matrices on the recovery of leachables with a log K o/w  ≥ 3.6 is negligible (-3.9 to 3.8%). In contrast, the inhibition effect caused by an alkaline media led to a recovery decrease of -42.9%. For leachables with a log K o/w   0.992). On average, the conventional PDMS coating resulted in a 28-fold higher signal-to-noise ratio compared to EG-PDMS. Furthermore, a broader range of leachables was detectable with the PDSM coating. Preceding stir-bar preparation consisting of a simple soaking step improved the enrichment by 14%, effectively lowering the limit of detection. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Processing of spent nickelcatalyst for fat recovery

    Directory of Open Access Journals (Sweden)

    NASIR Mohammad Ibraim

    2001-01-01

    Full Text Available Spent nickel catalyst (SNC has the potential of insulting the quality of the environment in a number of ways. Its disposal has a pollution effect. Optimum recovery of fat from SNC, could save the environment and reduce the oil loss. Hexane has been the solvent of choice for oil extraction. Alternative solvents considered to have been safer have been evaluated. Hexane, isopropanol, ethanol and heptane were examined using soxhlet extraction. While hexane is more efficient in oil recovery from SNC, isopropanol proved to be very good in clear separation of oil from waste material and also provides high solvent recovery compared to other solvents. Isopropanol extraction with chill separation of miscella into lower oil-rich phase, and an upper, solvent-rich recyclable phase save mush energy of vaporization for distilling. An aqueous extraction process with immiscible solvent assisted was tested. Solvent like hexane added to SNC, and water added later with continuous stirring. The mixture was stirred for about 30 minutes, prior to centrifugation. Aqueous process extracted less amount of oil compared to solvent extraction.

  2. Iterative algorithms for the input and state recovery from the approximate inverse of strictly proper multivariable systems

    Science.gov (United States)

    Chen, Liwen; Xu, Qiang

    2018-02-01

    This paper proposes new iterative algorithms for the unknown input and state recovery from the system outputs using an approximate inverse of the strictly proper linear time-invariant (LTI) multivariable system. One of the unique advantages from previous system inverse algorithms is that the output differentiation is not required. The approximate system inverse is stable due to the systematic optimal design of a dummy feedthrough D matrix in the state-space model via the feedback stabilization. The optimal design procedure avoids trial and error to identify such a D matrix which saves tremendous amount of efforts. From the derived and proved convergence criteria, such an optimal D matrix also guarantees the convergence of algorithms. Illustrative examples show significant improvement of the reference input signal tracking by the algorithms and optimal D design over non-iterative counterparts on controllable or stabilizable LTI systems, respectively. Case studies of two Boeing-767 aircraft aerodynamic models further demonstrate the capability of the proposed methods.

  3. Pesticide residue determination in surface waters by stir bar sorptive extraction and liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Giordano, A; Fernández-Franzón, M; Ruiz, M J; Font, G; Picó, Y

    2009-03-01

    In this stir bar sorptive extraction (SBSE) method, 16 pesticides were extracted from surface water samples by sorption onto 1 mm polydimethylsiloxane layer coated on a 10-mm-length stir bar magnet. After liquid desorption of the analytes with 1 ml of methanol, the detection was performed on a liquid chromatography-tandem mass spectrometry with a triple quadrupole (QqQ) analyzer using selected reaction monitoring mode via electrospray ionization. Parameters affecting SBSE operation, including sample volume, salt addition, extraction time, stirring rate, and desorption conditions, have been evaluated. The optimized SBSE method required two 50 ml aliquots of surface water samples, one aliquot was added of 30% NaCl and stirred at 900 rpm during 1 h for testing five pesticides with log K(o/w) 3. The method was validated in spiked surface water samples at limits of quantifications (LOQs) and ten times the LOQs showing recoveries Albufera Lake and surrounding channels, showing that SBSE is a powerful tool for routine control analysis of pesticide residues in surface water.

  4. Myocardial viability: comparison of free-breathing navigator-echo-gated three-dimensional inversion-recovery gradient-echo MR and standard multiple breath-hold two-dimensional inversion-recovery gradient-echo MR

    International Nuclear Information System (INIS)

    Kim, Jin Hee; Seo, Joon Beom; Do, Kyung Hyun; Yang, Dong Hyun; Lee, Soo Hyun; Ko, Sung Min; Heo, Jeong Nam; Lim, Tae Hwan

    2004-01-01

    To compare a free-breathing, navigator-echo-gated, three-dimensional, inversion-recovery, gradient-echo, MR pulse sequence (3D-MRI) with standard, multiple breath-hold, two-dimensional, inversion-recovery, gradient-echo MR (2D-MRI) for the evaluation of delayed hyperenhancement of nonviable myocardium in patients with chronic ischemic heart disease. Ten patients with chronic ischemic heart disease were enrolled in this study. MRI was performed on a 1.5-T system. 3D-MRI was obtained in the short axis plane at 10 minutes after the administration of Gd-DTPA (0.2 mmol/kg, 4 cc/sec). Prospective gating of the acquisition based on the navigator echo was applied. 2D-MRI was performed immediately after finishing 3D-MRI. The area of total and hyperenhanced myocardium measured on both image sets was compared with paired Student t-test and Bland-Altman method. By using a 60-segment model, the transmural extent and segment width of the hyperenhanced area were recorded by 3-scale grading method. The agreement between the two sequences was evaluated with kappa statistics. We also evaluated the agreement of hyperenhancement among the three portions (apical, middle and basal portion) of the left ventricle with kappa statistics. The two sequences showed good agreement for the measured area of total and hyperenhanced myocardium on paired t-test (ρ = 0.11 and ρ = 0.34, respectively). No systematic bias was shown on Bland-Altman analysis. Good agreement was found for the segmental width (Κ = 0.674) and transmural extent (Κ = 0.615) of hyperenhancement on the segmented analysis. However, the agreement of the transmural extent of hyperenhancement in the apical segments was relatively poor compared with that in the middle or basal portions. This study showed good agreement between 3D-MRI and 2D-MRI in evaluation of non-viable myocardium. Therefore, 3D-MRI may be useful in the assessment of myocardial viability in patients with dyspnea and children because it allows free

  5. Fluid-attenuated inversion recovery vascular hyperintensities in predicting cerebral hyperperfusion after intracranial arterial stenting

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Chih-Cheng; Chen, David Yen-Ting; Tseng, Ying-Chi; Lee, Kun-Yu; Chiang, Chen-Hua; Chen, Chi-Jen [Taipei Medical University, Department of Radiology, Shuang-Ho Hospital, New Taipei City (China); Taipei Medical University, School of Medicine, College of Medicine, Taipei (China); Yan, Feng-Xian [Taipei Medical University, Department of Radiology, Shuang-Ho Hospital, New Taipei City (China)

    2017-08-15

    No reliable imaging sign predicting cerebral hyperperfusion after intracranial arterial stenting (IAS) had been described in the literature. This study evaluated the effect of fluid-attenuated inversion recovery vascular hyperintensities (FVHs), also called hyperintense vessel sign on T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) MR images, in predicting significant increase in cerebral blood flow (CBF) defined by arterial spin labeling (ASL) after IAS. We reviewed ASL CBF images and T2-FLAIR MR images before (D0), 1 day after (D1), and 3 days after (D3) IAS of 16 patients. T1-weighted MR images were used as cerebral maps for calculating CBF. The changes in CBF values after IAS were calculated in and compared among stenting and nonstenting vascular territories. An increase more than 50% of CBF was considered as hyperperfusion. The effect of FVHs in predicting hyperperfusion was calculated. The D1 CBF value was significantly higher than the D0 CBF value in stenting vascular, contralateral anterior cerebral artery, contralateral middle cerebral artery, and contralateral posterior cerebral artery (PCA) territories (all P <.05). The D1 and D3 CBF values were significantly higher than the D0 CBF value in overall vascular (P <.001), overall nonstenting vascular (P <.001), and ipsilateral PCA (P <.05) territories. The rate of more than 50% increases in CBF was significantly higher in patients who exhibited asymmetric FVHs than in those who did not exhibit these findings. FVHs could be a critical predictor of a significant increase in CBF after IAS. (orig.)

  6. Fluid-attenuated inversion recovery vascular hyperintensities in predicting cerebral hyperperfusion after intracranial arterial stenting

    International Nuclear Information System (INIS)

    Wan, Chih-Cheng; Chen, David Yen-Ting; Tseng, Ying-Chi; Lee, Kun-Yu; Chiang, Chen-Hua; Chen, Chi-Jen; Yan, Feng-Xian

    2017-01-01

    No reliable imaging sign predicting cerebral hyperperfusion after intracranial arterial stenting (IAS) had been described in the literature. This study evaluated the effect of fluid-attenuated inversion recovery vascular hyperintensities (FVHs), also called hyperintense vessel sign on T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) MR images, in predicting significant increase in cerebral blood flow (CBF) defined by arterial spin labeling (ASL) after IAS. We reviewed ASL CBF images and T2-FLAIR MR images before (D0), 1 day after (D1), and 3 days after (D3) IAS of 16 patients. T1-weighted MR images were used as cerebral maps for calculating CBF. The changes in CBF values after IAS were calculated in and compared among stenting and nonstenting vascular territories. An increase more than 50% of CBF was considered as hyperperfusion. The effect of FVHs in predicting hyperperfusion was calculated. The D1 CBF value was significantly higher than the D0 CBF value in stenting vascular, contralateral anterior cerebral artery, contralateral middle cerebral artery, and contralateral posterior cerebral artery (PCA) territories (all P <.05). The D1 and D3 CBF values were significantly higher than the D0 CBF value in overall vascular (P <.001), overall nonstenting vascular (P <.001), and ipsilateral PCA (P <.05) territories. The rate of more than 50% increases in CBF was significantly higher in patients who exhibited asymmetric FVHs than in those who did not exhibit these findings. FVHs could be a critical predictor of a significant increase in CBF after IAS. (orig.)

  7. High-Powered, Ultrasonically Assisted Thermal Stir Welding

    Science.gov (United States)

    Ding, Robert

    2013-01-01

    This method is a solid-state weld process capable of joining metallic alloys without melting. The weld workpieces to be joined by thermal stir welding (TSW) are drawn, by heavy forces, between containment plates past the TSW stir tool that then causes joining of the weld workpiece. TSW is similar to friction stir welding (FSW) in that material is heated into a plastic state (not melted) and stirred using a stir rod. The FSW pin tool is an integrated geometrical structure consisting of a large-diameter shoulder, and a smaller-diameter stir pin protruding from the shoulder. When the pin is plunged into a weld workpiece, the shoulder spins on the surface of the weld workpiece, thus inducing frictional heat into the part. The pin stirs the fraying surfaces of the weld joint, thus joining the weld workpiece into one structure. The shoulder and stir pin of the FSW pin tool must rotate together at a desired rotational speed. The induced frictional energy control and stir pin control of the pin tool cannot be de-coupled. The two work as one integrated unit. TSW, on the other hand, de-couples the heating and stirring of FSW, and allows for independent control of each process element. A uniquely designed induction coil heats the weld workpiece to a desired temperature, and once heated, the part moves into a stir rod whose RPM is also independently controlled. As the weld workpiece moves into the stir rod, the piece is positioned, or sandwiched, between upper and lower containment plates. The plate squeezes together, thus compressing the upper and lower surfaces of the weld workpiece. This compressive force, also called consolidation force, consolidates the plastic material within the weld nugget material as it is being stirred by the stir rod. The stir rod is positioned through the center of the top containment plate and protrudes midway through the opposite lower containment plate where it is mechanically captured. The upper and lower containment plates are separated by a

  8. Fast spine echo and fast fluid attenuated inversion recovery sequences in multiple sclerosis

    International Nuclear Information System (INIS)

    Paolillo, Andrea; Giugni, Elisabetta; Bozzao, Alessandro; Bastianello, Stefano

    1997-01-01

    Fast spin echo (FSE) and fast fluid attenuated inversion recovery (fast-FLAIR) sequences, were compared with conventional spin echo (CSE) in quantitating multiple sclerosis (MS) lesion burden. For each sequence, the total number and volume of MS lesions were calculated in 38 remitting multiple sclerosis patients using a semiautomated lesion detection program. Conventional spin echo, fast spin echo, and fast fluid attenuated inversion recovery image were reported on randomly and at different times by two expert observers. Interobserver differences, the time needed to quantitative multiple sclerosis lesions and lesion signal intensity (contrast-to-noise ratio and overall contrast) were considered. The lesions were classified by site into infratentorial, white matter and cortical/subcortical. A total of 2970 lesions with a volume of 961.7 cm 3 was calculated on conventional spin echo images. Fast spin echo images depicted fewer (16.6%; p < .005) and smaller (24.9%; p < .0001) lesions and the differences were statistically significant. Despite an overall nonsignificant reduction for fast-FLAIR images (-5% and 4.8% for lesion number and volume, respectively), significantly lower values (lesion number: p < 0.1; volume: p < .04)were observed for infratentorial lesions, while significantly higher values were seen for cortical/subcortical lesions (lesion number: p < .01; volume: p < .02). A higher lesion/white matter contrast (p < .002), a significant time saving for lesion burden quantitation (p < .05) and very low interobserver variability were found in favor of fast-FLAIR. Our data suggest that, despite the limitations regarding infratentorial lesions, fast-FLAIR sequences are indicated in R studies because of their good identification of cortical/subcortical lesions, almost complete interobserver agreement, higher contrast-to-noise ratio and limited time needed for semiautomated quantitation

  9. Tissue Border Enhancement by inversion recovery MRI at 7.0 Tesla

    International Nuclear Information System (INIS)

    Costagli, Mauro; Tiberi, Gianluigi; Kelley, Douglas A.C.; Symms, Mark R.; Biagi, Laura; Tosetti, Michela; Stara, Riccardo; Cosottini, Mirco; Maggioni, Eleonora; Barba, Carmen; Guerrini, Renzo

    2014-01-01

    This contribution presents a magnetic resonance imaging (MRI) acquisition technique named Tissue Border Enhancement (TBE), whose purpose is to produce images with enhanced visualization of borders between two tissues of interest without any post-processing. The technique is based on an inversion recovery sequence that employs an appropriate inversion time to produce images where the interface between two tissues of interest is hypo-intense; therefore, tissue borders are clearly represented by dark lines. This effect is achieved by setting imaging parameters such that two neighboring tissues of interest have magnetization with equal magnitude but opposite sign; therefore, the voxels containing a mixture of each tissue (that is, the tissue interface) possess minimal net signal. The technique was implemented on a 7.0 T MRI system. This approach can assist the definition of tissue borders, such as that between cortical gray matter and white matter; therefore, it could facilitate segmentation procedures, which are often challenging on ultra-high-field systems due to inhomogeneous radiofrequency distribution. TBE allows delineating the contours of structural abnormalities, and its capabilities were demonstrated with patients with focal cortical dysplasia, gray matter heterotopia, and polymicrogyria. This technique provides a new type of image contrast and has several possible applications in basic neuroscience, neurogenetic research, and clinical practice, as it could improve the detection power of MRI in the characterization of cortical malformations, enhance the contour of small anatomical structures of interest, and facilitate cortical segmentation. (orig.)

  10. Tissue Border Enhancement by inversion recovery MRI at 7.0 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Costagli, Mauro; Tiberi, Gianluigi [Imago7 Foundation, Pisa (Italy); IRCCS Stella Maris, Pisa (Italy); Kelley, Douglas A.C. [GE Healthcare Technologies, San Francisco, CA (United States); Symms, Mark R. [GE Applied Science Laboratory, Pisa (Italy); Biagi, Laura; Tosetti, Michela [IRCCS Stella Maris, Pisa (Italy); Stara, Riccardo; Cosottini, Mirco [Imago7 Foundation, Pisa (Italy); University of Pisa, Pisa (Italy); Maggioni, Eleonora [IRCCS Scientific Institute E. Medea, Bosisio Parini, Lecco (Italy); Politecnico di Milano, Milan (Italy); Barba, Carmen [Children' s Hospital A. Meyer - University of Florence, Neuroscience Department, Florence (Italy); Guerrini, Renzo [IRCCS Stella Maris, Pisa (Italy); Children' s Hospital A. Meyer - University of Florence, Neuroscience Department, Florence (Italy)

    2014-07-15

    This contribution presents a magnetic resonance imaging (MRI) acquisition technique named Tissue Border Enhancement (TBE), whose purpose is to produce images with enhanced visualization of borders between two tissues of interest without any post-processing. The technique is based on an inversion recovery sequence that employs an appropriate inversion time to produce images where the interface between two tissues of interest is hypo-intense; therefore, tissue borders are clearly represented by dark lines. This effect is achieved by setting imaging parameters such that two neighboring tissues of interest have magnetization with equal magnitude but opposite sign; therefore, the voxels containing a mixture of each tissue (that is, the tissue interface) possess minimal net signal. The technique was implemented on a 7.0 T MRI system. This approach can assist the definition of tissue borders, such as that between cortical gray matter and white matter; therefore, it could facilitate segmentation procedures, which are often challenging on ultra-high-field systems due to inhomogeneous radiofrequency distribution. TBE allows delineating the contours of structural abnormalities, and its capabilities were demonstrated with patients with focal cortical dysplasia, gray matter heterotopia, and polymicrogyria. This technique provides a new type of image contrast and has several possible applications in basic neuroscience, neurogenetic research, and clinical practice, as it could improve the detection power of MRI in the characterization of cortical malformations, enhance the contour of small anatomical structures of interest, and facilitate cortical segmentation. (orig.)

  11. Optimization of selective inversion recovery magnetization transfer imaging for macromolecular content mapping in the human brain.

    Science.gov (United States)

    Dortch, Richard D; Bagnato, Francesca; Gochberg, Daniel F; Gore, John C; Smith, Seth A

    2018-03-24

    To optimize a selective inversion recovery (SIR) sequence for macromolecular content mapping in the human brain at 3.0T. SIR is a quantitative method for measuring magnetization transfer (qMT) that uses a low-power, on-resonance inversion pulse. This results in a biexponential recovery of free water signal that can be sampled at various inversion/predelay times (t I/ t D ) to estimate a subset of qMT parameters, including the macromolecular-to-free pool-size-ratio (PSR), the R 1 of free water (R 1f ), and the rate of MT exchange (k mf ). The adoption of SIR has been limited by long acquisition times (≈4 min/slice). Here, we use Cramér-Rao lower bound theory and data reduction strategies to select optimal t I /t D combinations to reduce imaging times. The schemes were experimentally validated in phantoms, and tested in healthy volunteers (N = 4) and a multiple sclerosis patient. Two optimal sampling schemes were determined: (i) a 5-point scheme (k mf estimated) and (ii) a 4-point scheme (k mf assumed). In phantoms, the 5/4-point schemes yielded parameter estimates with similar SNRs as our previous 16-point scheme, but with 4.1/6.1-fold shorter scan times. Pair-wise comparisons between schemes did not detect significant differences for any scheme/parameter. In humans, parameter values were consistent with published values, and similar levels of precision were obtained from all schemes. Furthermore, fixing k mf reduced the sensitivity of PSR to partial-volume averaging, yielding more consistent estimates throughout the brain. qMT parameters can be robustly estimated in ≤1 min/slice (without independent measures of ΔB 0 , B1+, and T 1 ) when optimized t I -t D combinations are selected. © 2018 International Society for Magnetic Resonance in Medicine.

  12. Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction

    International Nuclear Information System (INIS)

    Chisvert, Alberto; Benedé, Juan L.; Anderson, Jared L.; Pierson, Stephen A.; Salvador, Amparo

    2017-01-01

    With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67–791), limits of detection (low ng L −1 ), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87–113%, 91–117% and 89–115% for river, sea and swimming pool water samples, respectively). - Highlights: • A new microextraction method combining the

  13. Molecularly imprinted polymers based stir bar sorptive extraction for determination of cefaclor and cefalexin in environmental water.

    Science.gov (United States)

    Peng, Jun; Liu, Donghao; Shi, Tian; Tian, Huairu; Hui, Xuanhong; He, Hua

    2017-07-01

    Although stir bar sportive extraction was thought to be a highly efficiency and simple pretreatment approach, its wide application was limited by low selectivity, short service life, and relatively high cost. In order to improve the performance of the stir bar, molecular imprinted polymers and magnetic carbon nanotubes were combined in the present study. In addition, two monomers were utilized to intensify the selectivity of molecularly imprinted polymers. Fourier transform infrared spectroscopy, scanning electron microscopy, and selectivity experiments showed that the molecularly imprinted polymeric stir bar was successfully prepared. Then micro-extraction based on the obtained stir bar was coupled with HPLC for determination of trace cefaclor and cefalexin in environmental water. This approach had the advantages of stir bar sportive extraction, high selectivity of molecular imprinted polymers, and high sorption efficiency of carbon nanotubes. To utilize this pretreatment approach, pH, extraction time, stirring speed, elution solvent, and elution time were optimized. The LOD and LOQ of cefaclor were found to be 3.5 ng · mL -1 and 12.0 ng · mL -1 , respectively; the LOD and LOQ of cefalexin were found to be 3.0 ng · mL -1 and 10.0 ng · mL -1 , respectively. The recoveries of cefaclor and cefalexin were 86.5 ~ 98.6%. The within-run precision and between-run precision were acceptable (relative standard deviation bar did not decrease dramatically. This demonstrated that the molecularly imprinted polymeric stir bar based micro-extraction was a convenient, efficient, low-cost, and a specific method for enrichment of cefaclor and cefalexin in environmental samples.

  14. MR imaging of the orbit and eye using inversion recovery sequences

    International Nuclear Information System (INIS)

    Smith, F.W.; Parekh, S.; Forrester, J.; Redpath, T.W.

    1986-01-01

    Most centers performing MR imaging use spin-echo sequences to produce images; however, there are many advantages to using short TI inversion-recovery sequences for examination of the orbits. By selecting a TI similar to the relaxation time of any structure, the signal from this can be suppressed, thereby enhancing the signal from other structures. Using a sequence of TR = 1,000 msec and TI of less than 200 msec, the signal from fat is suppressed, improving image quality adjacent to the surface coil and providing better contrast between orbital structures and fat. The use of this short TI sequence for the examination of the eye in patients with opaque lenses is an accurate method of diagnosis since the sequence enhances the signal from both long T1 and T2 lesions. Eighty-five patients with orbital or ocular pathology have been studied, and the results demonstrate the usefulness of this technique for diagnosis

  15. An improved hollow fiber solvent-stir bar microextraction for the preconcentration of anabolic steroids in biological matrix with determination by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Liu, Wei; Zhang, Lan; Fan, Liangbiao; Lin, Zian; Cai, Yimin; Wei, Zhenyi; Chen, Guonan

    2012-04-13

    In this paper, a convenient and self-assembled hollow fiber solvent-stir bar microextraction (HF-SSBME) device was developed, which could stir by itself. In the extraction process, the proposed device made the solvent "bar" not floating at the sample solution and exposing to air while organic solvents outside hollow fiber always wrapped with donor phase solvent, which reduced the vaporization of organic solvents. This design could improve the precisions and recoveries of experiments. For evaluating the device, seven anabolic steroids (prasterone, 5α-androstane-3α, 17β-diol, methandriol, 19-norandrostenediol, androstenediol, methyltestosterone and methandienone) were used as model analytes and extraction conditions such as type and volume of organic solvents, agitation speed, extraction time, extraction temperature and salt addition were studied in detail. Under the optimum conditions (15 μL toluene, 40 °C, stirring at 750 rpm for 30 min with 1.5 g sodium chloride addition in 20.0 mL donor phase), the linear ranges of anabolic steroids were 0.25-200 ng mL(-1) with gas chromatography-mass spectrometry. The limits of detection were lower than 0.10 ng mL(-1). The recoveries and precisions in spiked urine and hair samples were between 73.97-93.56% and 2.18-4.47% (n=5). HF-SSBME method combined the intrinsical merits of hollow fiber with the superiority of the proposed self-stirring device which can be developed to two-phase, three-phase and in situ derivatization modes with wide prospect of application. Besides, the pedestal of this proposed device can be converted to fix stir bar in stir bar sorptive extraction (SBSE) method. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Characterization of friction stir welded joint of low nickel austenitic stainless steel and modified ferritic stainless steel

    Science.gov (United States)

    Mondal, Mounarik; Das, Hrishikesh; Ahn, Eun Yeong; Hong, Sung Tae; Kim, Moon-Jo; Han, Heung Nam; Pal, Tapan Kumar

    2017-09-01

    Friction stir welding (FSW) of dissimilar stainless steels, low nickel austenitic stainless steel and 409M ferritic stainless steel, is experimentally investigated. Process responses during FSW and the microstructures of the resultant dissimilar joints are evaluated. Material flow in the stir zone is investigated in detail by elemental mapping. Elemental mapping of the dissimilar joints clearly indicates that the material flow pattern during FSW depends on the process parameter combination. Dynamic recrystallization and recovery are also observed in the dissimilar joints. Among the two different stainless steels selected in the present study, the ferritic stainless steels shows more severe dynamic recrystallization, resulting in a very fine microstructure, probably due to the higher stacking fault energy.

  17. Chemical shift-selective snapshot FLASH MR imaging in combination with inversion-recovery T1 contrast at different field strengths

    International Nuclear Information System (INIS)

    Matthaei, D.; Haase, A.; Henrich, D.; Duhmke, E.

    1991-01-01

    With fast MR imaging, chemical shift contract becomes available to the clinician in seconds. The purpose of this paper is to evaluate the combination of chemical shift selective (CHESS) MR imaging using the snapshot FLASH MR method with the inversion-recovery technique and to obtain information concerning the signal-to-noise and chemical shift with the presaturation method at different field strengths. Investigations with volunteers and experimental animals were done at 2 and 3 T (whole body) and in a 4.7-T animal image. For the inversion-recovery experiments, saturation was done before every snapshot FLASH image. With increasing field strength due to signal-to-noise and chemical shift advantages, the method performs better. Increasing T1 values are also important at high field strengths. The combined technique is useful only for T1 water images with fat saturation. It also allows fast quantification of T1 in water-containing organs and pathologic processes. At high field strengths, fast CHESS and T1 imaging promise fast quantitative information. This is a possible argument for clinical high-field-strength MR imagining along with MR spectroscopy

  18. Characterization and optimization of the visualization performance of continuous flow overhauser DNP hyperpolarized water MRI: Inversion recovery approach.

    Science.gov (United States)

    Terekhov, Maxim; Krummenacker, Jan; Denysenkov, Vasyl; Gerz, Kathrin; Prisner, Thomas; Schreiber, Laura Maria

    2016-03-01

    Overhauser dynamic nuclear polarization (DNP) allows the production of liquid hyperpolarized substrate inside the MRI magnet bore as well as its administration in continuous flow mode to acquire MR images with enhanced signal-to-noise ratio. We implemented inversion recovery preparation in order to improve contrast-to-noise ratio and to quantify the overall imaging performance of Overhauser DNP-enhanced MRI. The negative enhancement created by DNP in combination with inversion recovery (IR) preparation allows canceling selectively the signal originated from Boltzmann magnetization and visualizing only hyperpolarized fluid. The theoretical model describing gain of MR image intensity produced by steady-state continuous flow DNP hyperpolarized magnetization was established and proved experimentally. A precise quantification of signal originated purely from DNP hyperpolarization was achieved. A temperature effect on longitudinal relaxation had to be taken into account to fit experimental results with numerical prediction. Using properly adjusted IR preparation, the complete zeroing of thermal background magnetization was achieved, providing an essential increase of contrast-to-noise ratio of DNP-hyperpolarized water images. To quantify and optimize the steady-state conditions for MRI with continuous flow DNP, an approach similar to that incorporating transient-state thermal magnetization equilibrium in spoiled fast field echo imaging sequences can be used. © 2015 Wiley Periodicals, Inc.

  19. Microstructure characterization of the stir zone of submerged friction stir processed aluminum alloy 2219

    International Nuclear Information System (INIS)

    Feng, Xiuli; Liu, Huijie; Lippold, John C.

    2013-01-01

    Aluminum alloy 2219-T6 was friction stir processed using a novel submerged processing technique to facilitate cooling. Processing was conducted at a constant tool traverse speed of 200 mm/min and spindle rotation speeds in the range from 600 to 800 rpm. The microstructural characteristics of the base metal and processed zone, including grain structure and precipitation behavior, were studied using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness maps were constructed on polished cross sections of as-processed samples. The effect of tool rotation speed on the microstructure and hardness of the stir zone was investigated. The average grain size of the stir zone was much smaller than that of the base metal, but the hardness was also lower due to the formation of equilibrium θ precipitates from the base metal θ′ precipitates. Stir zone hardness was found to decrease with increasing rotation speed (heat input). The effect of processing conditions on strength (hardness) was rationalized based on the competition between grain refinement strengthening and softening due to precipitate overaging. - Highlights: • SZ grain size (∼ 1 μm) is reduced by over one order of magnitude relative to the BM. • Hardness in the SZ is lower than that of the precipitation strengthened BM. • Metastable θ′ in the base metal transforms to equilibrium θ in the stir zone. • Softening in the SZ results from a decrease of precipitation strengthening

  20. Microstructure characterization of the stir zone of submerged friction stir processed aluminum alloy 2219

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xiuli, E-mail: feng.97@osu.edu [Welding Engineering Program, Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43221 (United States); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Liu, Huijie, E-mail: liuhj@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Lippold, John C., E-mail: lippold.1@osu.edu [Welding Engineering Program, Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43221 (United States)

    2013-08-15

    Aluminum alloy 2219-T6 was friction stir processed using a novel submerged processing technique to facilitate cooling. Processing was conducted at a constant tool traverse speed of 200 mm/min and spindle rotation speeds in the range from 600 to 800 rpm. The microstructural characteristics of the base metal and processed zone, including grain structure and precipitation behavior, were studied using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness maps were constructed on polished cross sections of as-processed samples. The effect of tool rotation speed on the microstructure and hardness of the stir zone was investigated. The average grain size of the stir zone was much smaller than that of the base metal, but the hardness was also lower due to the formation of equilibrium θ precipitates from the base metal θ′ precipitates. Stir zone hardness was found to decrease with increasing rotation speed (heat input). The effect of processing conditions on strength (hardness) was rationalized based on the competition between grain refinement strengthening and softening due to precipitate overaging. - Highlights: • SZ grain size (∼ 1 μm) is reduced by over one order of magnitude relative to the BM. • Hardness in the SZ is lower than that of the precipitation strengthened BM. • Metastable θ′ in the base metal transforms to equilibrium θ in the stir zone. • Softening in the SZ results from a decrease of precipitation strengthening.

  1. OPTIMIZATION OF STIRRING SPEED AND STIRRING TIME TOWARD NANOPARTICLE SIZE OF CHITOSAN-SIAM CITRUS PEEL (Citrus nobilis L.var Microcarpa 70% ETHANOL EXTRACT

    Directory of Open Access Journals (Sweden)

    Wintari Taurina

    2017-04-01

    Full Text Available Siam citrus peel (Citrus nobilis L. var. Microcarpa is a plant derived from Sambas Regency, West Kalimantan Province. Bioavailability of herbal active compounds can be enhanced by formulating extract into nanoparticle. The polymer used was chitosan with crosslinker Na-TPP. Stirring speed and stirring time play an important role to produce small particle size in forming nanoparticle using ionic gelation method. Enhancement of stirring speed and stirring time could reduce particle size. Nanoparticles were prepared using ionic gelation method by mixing Na-TPP, extract and chitosan (1:1:6 with varying the stirring speed 500 rpm, 1000 rpm, 1500 rpm and stirring time 1 hrs, 2 hrs, 3 hrs. The particle size of nanoparticle was found to be 85.3 nm at 1000 rpm of stirring speed and 3 hrs of stirring times, with polidispersity index 0.287, zeta potential +32.37 mV and entrapment efficiency 87.12 %.

  2. Friction-Stir-Welded and Spin-Formed End Domes for Cryogenic Tanks

    Science.gov (United States)

    Hales, S. J.; Tayon, W. A.; Domack, M. S.

    2012-01-01

    Manufacturing of single-piece end domes for cryogenic tanks employing spin forming of tailored, friction-stir-welded blanks of Al-Li alloy 2195 plate offers cost and reliability benefits. The introduction of plastic deformation into a friction stir weld is a unique feature of the proposed manufacturing route. This investigation addressed abnormal grain growth [AGG] within the friction stir weldments during postfabrication processing of a prototype dome. The phenomenon of AGG was observed during the solution heat treatment [SHT] phase of T8 tempering and is a major concern for meeting specifications. Such abrupt microstructural transitions can be detrimental to notch-sensitive mechanical properties, such as ductility and/or fracture toughness. If the issue of AGG cannot be resolved, then the acceptance of this approach as a viable manufacturing route may be in jeopardy. The innovative approach adopted in this investigation was the insertion of a stand-alone, Intermediate Annealing Treatment [IAT] between the spin forming and T8 processing operations. A simple, recovery annealing step was deemed to be the most readily-scalable solution when fabricating thin-walled, ellipsoidal domes. The research effort culminated in the development of an effective IAT, which resulted in a significant decrease in AGG following SHT. The processing philosophy adopted in designing the IAT is outlined and the microstructural reasons for success are discussed. The analytical results presented are consistent with promoting continuous grain growth during the IAT, thereby suppressing AGG during the SHT.

  3. Trace determination of volatile polycyclic aromatic hydrocarbons in natural waters by magnetic ionic liquid-based stir bar dispersive liquid microextraction.

    Science.gov (United States)

    Benedé, Juan L; Anderson, Jared L; Chisvert, Alberto

    2018-01-01

    In this work, a novel hybrid approach called stir bar dispersive liquid microextraction (SBDLME) that combines the advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) has been employed for the accurate and sensitive determination of ten polycyclic aromatic hydrocarbons (PAHs) in natural water samples. The extraction is carried out using a neodymium stir bar magnetically coated with a magnetic ionic liquid (MIL) as extraction device, in such a way that the MIL is dispersed into the solution at high stirring rates. Once the stirring is ceased, the MIL is magnetically retrieved onto the stir bar, and subsequently subjected to thermal desorption (TD) coupled to a gas chromatography-mass spectrometry (GC-MS) system. The main parameters involved in TD, as well as in the extraction step affecting the extraction efficiency (i.e., MIL amount, extraction time and ionic strength) were evaluated. Under the optimized conditions, the method was successfully validated showing good linearity, limits of detection and quantification in the low ng L -1 level, good intra- and inter-day repeatability (RSD < 13%) and good enrichment factors (18 - 717). This sensitive analytical method was applied to the determination of trace amounts of PAHs in three natural water samples (river, tap and rainwater) with satisfactory relative recovery values (84-115%), highlighting that the matrices under consideration do not affect the extraction process. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Mechanism for Self-Reacted Friction Stir Welding

    Science.gov (United States)

    Venable, Richard; Bucher, Joseph

    2004-01-01

    A mechanism has been designed to apply the loads (the stirring and the resection forces and torques) in self-reacted friction stir welding. This mechanism differs somewhat from mechanisms used in conventional friction stir welding, as described below. The tooling needed to apply the large reaction loads in conventional friction stir welding can be complex. Self-reacted friction stir welding has become popular in the solid-state welding community as a means of reducing the complexity of tooling and to reduce costs. The main problems inherent in self-reacted friction stir welding originate in the high stresses encountered by the pin-and-shoulder assembly that produces the weld. The design of the present mechanism solves the problems. The mechanism includes a redesigned pin-and-shoulder assembly. The welding torque is transmitted into the welding pin by a square pin that fits into a square bushing with set-screws. The opposite or back shoulder is held in place by a Woodruff key and high-strength nut on a threaded shaft. The Woodruff key reacts the torque, while the nut reacts the tensile load on the shaft.

  5. Development of a carbon-nanoparticle-coated stirrer for stir bar sorptive extraction by a simple carbon deposition in flame.

    Science.gov (United States)

    Feng, Juanjuan; Sun, Min; Bu, Yanan; Luo, Chuannan

    2016-03-01

    Stir bar sorptive extraction is an environmentally friendly microextraction technique based on a stir bar with various sorbents. A commercial stirrer is a good support, but it has not been used in stir bar sorptive extraction due to difficult modification. A stirrer was modified with carbon nanoparticles by a simple carbon deposition process in flame and characterized by scanning electron microscopy and energy-dispersive X-ray spectrometry. A three-dimensional porous coating was formed with carbon nanoparticles. In combination with high-performance liquid chromatography, the stir bar was evaluated using five polycyclic aromatic hydrocarbons as model analytes. Conditions including extraction time and temperature, ionic strength, and desorption solvent were investigated by a factor-by-factor optimization method. The established method exhibited good linearity (0.01-10 μg/L) and low limits of quantification (0.01 μg/L). It was applied to detect model analytes in environmental water samples. No analyte was detected in river water, and five analytes were quantified in rain water. The recoveries of five analytes in two samples with spiked at 2 μg/L were in the range of 92.2-106% and 93.4-108%, respectively. The results indicated that the carbon nanoparticle-coated stirrer was an efficient stir bar for extraction analysis of some polycyclic aromatic hydrocarbons. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Thermal Stir Welding: A New Solid State Welding Process

    Science.gov (United States)

    Ding, R. Jeffrey

    2003-01-01

    Thermal stir welding is a new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating, stirring and forging elements of the process are all independent of each other and are separately controlled. Furthermore, the heating element of the process can be either a solid-state process (such as a thermal blanket, induction type process, etc), or, a fusion process (YG laser, plasma torch, etc.) The separation of the heating, stirring, forging elements of the process allows more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

  7. Gadolinium contrast-enhanced MRI sequence does not have an incremental value in the assessment of sacroiliitis in patients with early inflammatory back pain by using MRI in combination with pelvic radiographs: a 2-year follow-up study

    NARCIS (Netherlands)

    van Onna, M.; van Tubergen, A.; van der Heijde, D.; Jurik, A. G.; Landewé, R.

    2014-01-01

    To evaluate the potential incremental value in detecting sacroiliitis of the T1 post-gadolinium diethylenetriaminepenta-acetic acid (Gd-DTPA) MRI sequence of the sacroiliac joints (SIJ) compared with the combination of short tau inversion recovery (STIR) MRI sequence and pelvic radiographs in

  8. High-speed imaging at 3 tesla. A technical and clinical review with an emphasis on whole-brain 3D imaging

    International Nuclear Information System (INIS)

    Naganawa, Shinji; Kawai, Hisashi; Fukatsu, Hiroshi; Ishigaki, Takeo; Komada, Tomomi

    2005-01-01

    Improvements to the inherently high specific-absorption rate (SAR) of high-speed imaging at 3T are necessary in order to render this method clinically feasible. Various efforts have been undertaken to improve the associated hardware and software. In this review, we focus on whole-brain isotropic 3D imaging with a turbo spin-echo sequence with variable flip-angle echo trains (3D-TSE-VFL) and present its technical and clinical features. This sequence can be used to acquire images of various contrasts including T 2 -weighted, fat-suppressed T 2 -weighted, fluid-attenuated inversion recovery (FLAIR), fat-suppressed FLAIR, and STIR (short tau inversion recovery). Various aspects of 3D-TSE-VFL are discussed, including CSF (cerebrospinal fluid) and metal artifacts, STIR contrast, small-part visualization other than brain, and the possibility of serial subtraction. Some images from clinical cases are presented. (author)

  9. Ivy Sign on Fluid-Attenuated Inversion Recovery Images in Moyamoya Disease: Correlation with Clinical Severity and Old Brain Lesions

    OpenAIRE

    Seo, Kwon-Duk; Suh, Sang Hyun; Kim, Yong Bae; Kim, Ji Hwa; Ahn, Sung Jun; Kim, Dong-Seok; Lee, Kyung-Yul

    2015-01-01

    Purpose Leptomeningeal collateral, in moyamoya disease (MMD), appears as an ivy sign on fluid-attenuated inversion-recovery (FLAIR) images. There has been little investigation into the relationship between presentation of ivy signs and old brain lesions. We aimed to evaluate clinical significance of ivy signs and whether they correlate with old brain lesions and the severity of clinical symptoms in patients with MMD. Materials and Methods FLAIR images of 83 patients were reviewed. Each cerebr...

  10. Deformation During Friction Stir Welding

    Science.gov (United States)

    White, Henry J.

    2002-01-01

    Friction Stir Welding (FSW) is a solid state welding process that exhibits characteristics similar to traditional metal cutting processes. The plastic deformation that occurs during friction stir welding is due to the superposition of three flow fields: a primary rotation of a radially symmetric solid plug of metal surrounding the pin tool, a secondary uniform translation, and a tertiary ring vortex flow (smoke rings) surrounding the tool. If the metal sticks to the tool, the plug surface extends down into the metal from the outer edge of the tool shoulder, decreases in diameter like a funnel, and closes up beneath the pin. Since its invention, ten years have gone by and still very little is known about the physics of the friction stir welding process. In this experiment, an H13 steel weld tool (shoulder diameter, 0.797 in; pin diameter, 0.312 in; and pin length, 0.2506 in) was used to weld three 0.255 in thick plates. The deformation behavior during friction stir welding was investigated by metallographically preparing a plan view sections of the weldment and taking Vickers hardness test in the key-hole region.

  11. Effects of tool speeds and corresponding torque/energy on stir zone formation during friction stir welding/processing

    International Nuclear Information System (INIS)

    Cui, S; Chen, Z W

    2009-01-01

    The way processing parameters and the measurable thermomechanical responses relate to the individual and combined flows forming the different processed zones during friction stir welding/processing has been studied. Experimentally, a cast Al-7Si-0.3Mg alloy was used to provide readily identifiable processed zones. A series of friction stir experiments covering a wide range of tool forward and rotation speeds were conducted followed by the measurement of individual and combined stir areas. It has been found that the basic modes of material flow did not change but the relative volume of each flow depended on both forward and rotation speeds. The trends observed in the present data explain how pin rotation relates to the material transportation mechanism and the associated torque required. This data also explains how forward speed, not rotation speed, relates to specific energy and the volume of the total stir zone.

  12. Gimballed Shoulders for Friction Stir Welding

    Science.gov (United States)

    Carter, Robert; Lawless, Kirby

    2008-01-01

    In a proposed improvement of tooling for friction stir welding, gimballed shoulders would supplant shoulders that, heretofore, have been fixedly aligned with pins. The proposal is especially relevant to self-reacting friction stir welding. Some definitions of terms, recapitulated from related prior NASA Tech Briefs articles, are prerequisite to a meaningful description of the proposed improvement. In friction stir welding, one uses a tool that includes (1) a rotating shoulder on top (or front) of the workpiece and (2) a pin that rotates with the shoulder and protrudes from the shoulder into the depth of the workpiece. In conventional friction stir welding, the main axial force exerted by the tool on the workpiece is reacted through a ridged backing anvil under (behind) the workpiece. When conventional friction stir welding is augmented with an auto-adjustable pin-tool (APT) capability, the depth of penetration of the pin into the workpiece is varied in real time by a position- or forcecontrol system that extends or retracts the pin as needed to obtain the desired effect. In self-reacting (also known as self-reacted) friction stir welding as practiced heretofore, there are two shoulders: one on top (or front) and one on the bottom (or back) of the workpiece. In this case, a threaded shaft protrudes from the tip of the pin to beyond the back surface of the workpiece. The back shoulder is held axially in place against tension by a nut on the threaded shaft. Both shoulders rotate with the pin and remain aligned coaxially with the pin. The main axial force exerted on the workpiece by the tool and front shoulder is reacted through the back shoulder and the threaded shaft into the friction-stir-welding machine head, so that a backing anvil is no longer needed. A key transmits torque between the bottom shoulder and the threaded shaft, so that the bottom shoulder rotates with the shaft. This concludes the prerequisite definitions of terms.

  13. Effect of inversion time on the precision of myocardial late gadolinium enhancement quantification evaluated with synthetic inversion recovery MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Varga-Szemes, Akos; Schoepf, U.J.; De Cecco, Carlo N.; Fuller, Stephen R.; Suranyi, Pal [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Geest, Rob J. van der [Leiden University Medical Center, Department of Radiology, Leiden (Netherlands); Spottiswoode, Bruce S. [Siemens Medical Solutions, Chicago, IL (United States); Muscogiuri, Giuseppe [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Bambino Gesu Children' s Hospital IRCCS, Department of Imaging, Rome (Italy); Wichmann, Julian L. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany); Mangold, Stefanie [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Maurovich-Horvat, Pal; Merkely, Bela [Semmelweis University, MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Budapest (Hungary); Litwin, Sheldon E. [Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Vliegenthart, Rozemarijn [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University of Groningen, University Medical Center Groningen, Center for Medical Imaging-North East Netherlands, Department of Radiology, Groningen (Netherlands)

    2017-08-15

    To evaluate the influence of inversion time (TI) on the precision of myocardial late gadolinium enhancement (LGE) quantification using synthetic inversion recovery (IR) imaging in patients with myocardial infarction (MI). Fifty-three patients with suspected prior MI underwent 1.5-T cardiac MRI with conventional magnitude (MagIR) and phase-sensitive IR (PSIR) LGE imaging and T1 mapping at 15 min post-contrast. T1-based synthetic MagIR and PSIR images were calculated with a TI ranging from -100 to +150 ms at 5-ms intervals relative to the optimal TI (TI{sub 0}). LGE was quantified using a five standard deviation (5SD) and full width at half-maximum (FWHM) thresholds. Measurements were compared using one-way analysis of variance. The MagIR{sub sy} technique provided precise assessment of LGE area at TIs ≥ TI{sub 0}, while precision was decreased below TI{sub 0}. The LGE area showed significant differences at ≤ -25 ms compared to TI{sub 0} using 5SD (P < 0.001) and at ≤ -65 ms using the FWHM approach (P < 0.001). LGE measurements did not show significant difference over the analysed TI range in the PSIR{sub sy} images using either of the quantification methods. T1 map-based PSIR{sub sy} images provide precise quantification of MI independent of TI at the investigated time point post-contrast. MagIR{sub sy}-based MI quantification is precise at TI{sub 0} and at longer TIs while showing decreased precision at TI values below TI{sub 0}. (orig.)

  14. Gimbaled-shoulder friction stir welding tool

    Science.gov (United States)

    Carter, Robert W. (Inventor); Lawless, Kirby G. (Inventor)

    2010-01-01

    A gimbaled-shoulder friction stir welding tool includes a pin and first and second annular shoulders coupled to the pin. At least one of the annular shoulders is coupled to the pin for gimbaled motion with respect thereto as the tool is rotated by a friction stir welding apparatus.

  15. Rapid T1 quantification based on 3D phase sensitive inversion recovery

    Directory of Open Access Journals (Sweden)

    Warntjes Marcel JB

    2010-08-01

    Full Text Available Abstract Background In Contrast Enhanced Magnetic Resonance Imaging fibrotic myocardium can be distinguished from healthy tissue using the difference in the longitudinal T1 relaxation after administration of Gadolinium, the so-called Late Gd Enhancement. The purpose of this work was to measure the myocardial absolute T1 post-Gd from a single breath-hold 3D Phase Sensitivity Inversion Recovery sequence (PSIR. Equations were derived to take the acquisition and saturation effects on the magnetization into account. Methods The accuracy of the method was investigated on phantoms and using simulations. The method was applied to a group of patients with suspected myocardial infarction where the absolute difference in relaxation of healthy and fibrotic myocardium was measured at about 15 minutes post-contrast. The evolution of the absolute R1 relaxation rate (1/T1 over time after contrast injection was followed for one patient and compared to T1 mapping using Look-Locker. Based on the T1 maps synthetic LGE images were reconstructed and compared to the conventional LGE images. Results The fitting algorithm is robust against variation in acquisition flip angle, the inversion delay time and cardiac arrhythmia. The observed relaxation rate of the myocardium is 1.2 s-1, increasing to 6 - 7 s-1 after contrast injection and decreasing to 2 - 2.5 s-1 for healthy myocardium and to 3.5 - 4 s-1 for fibrotic myocardium. Synthesized images based on the T1 maps correspond very well to actual LGE images. Conclusions The method provides a robust quantification of post-Gd T1 relaxation for a complete cardiac volume within a single breath-hold.

  16. The Effect of Premixed Al-Cu Powder on the Stir Zone in Friction Stir Welding of AA3003-H18

    Science.gov (United States)

    Abnar, B.; Kazeminezhad, M.; Kokabi, A. H.

    2015-02-01

    In this research, 3-mm-thick AA3003-H18 non-heat-treatable aluminum alloy plates were joined by friction stir welding (FSW). It was performed by adding pure Cu and premixed Cu-Al powders at various rotational speeds of 800, 1000, and 1200 rpm and constant traveling speeds of 100 mm/min. At first, the powder was filled into the gap (0.2 or 0.4 mm) between two aluminum alloy plates, and then the FSW process was performed in two passes. The microstructure, mechanical properties, and formation of intermetallic compounds were investigated in both cases of using pure Cu and premixed Al-Cu powders. The results of using pure Cu and premixed Al-Cu powders were compared in the stir zone at various rotational speeds. The copper particle distribution and formation of Al-Cu intermetallic compounds (Al2Cu and AlCu) in the stir zone were desirable using premixed Al-Cu powder into the gap. The hardness values were significantly increased by formation of Al-Cu intermetallic compounds in the stir zone and it was uniform throughout the stir zone when premixed Al-Cu powder was used. Also, longitudinal tensile strength from the stir zone was higher when premixed Al-Cu powder was used instead of pure Cu powder.

  17. Non-contrast MRA using an inflow-enhanced, inversion recovery SSFP technique in pediatric abdominal imaging

    International Nuclear Information System (INIS)

    Serai, Suraj; Towbin, Alexander J.; Podberesky, Daniel J.

    2012-01-01

    Abdominal contrast-enhanced MR angiography (CE-MRA) is routinely performed in children. CE-MRA is challenging in children because of patient motion, difficulty in obtaining intravenous access, and the inability of young patients to perform a breath-hold during imaging. The combination of pediatric-specific difficulties in imaging and the safety concerns regarding the risk of gadolinium-based contrast agents in patients with impaired renal function has renewed interest in the use of non-contrast (NC) MRA techniques. At our institution, we have optimized 3-D NC-MRA techniques for abdominal imaging. The purpose of this work is to demonstrate the utility of an inflow-enhanced, inversion recovery balanced steady-state free precession-based (b-SSFP) NC-MRA technique. (orig.)

  18. Reconstruction of Clear-PEM data with STIR

    CERN Document Server

    Martins, M V; Rodrigues, P; Trindade, A; Oliveira, N; Correia, M; Cordeiro, H; Ferreira, N C; Varela, J; Almeida, P

    2006-01-01

    The Clear-PEM scanner is a device based on planar detectors that is currently under development within the Crystal Clear Collaboration, at CERN. The basis for 3D image reconstruction in Clear-PEM is the software for tomographic image reconstruction (STIR). STIR is an open source object-oriented library that efficiently deals with the 3D positron emission tomography data sets. This library was originally designed for the traditional cylindrical scanners. In order to make its use compatible with planar scanner data, new functionalities were introduced into the library's framework. In this work, Monte Carlo simulations of the Clear-PEM scanner acquisitions were used as input for image reconstruction with the 3D OSEM algorithm available in STIR. The results presented indicate that dual plate PEM data can be accurately reconstructed using the enhanced STIR framework.

  19. Effect of silica nanoparticles on the phase inversion of liquid-liquid dispersions

    International Nuclear Information System (INIS)

    Asadabadi, Maliheh Raji; Abolghasemi, Hossein; Nasab, Payman Davoodi; Maragheh, Mohammad Ghannadi

    2013-01-01

    The effect of silica nanoparticles on phase inversion of liquid-liquid dispersions in a stirred vessel was investigated. The studied systems were toluene dispersed in water and vice versa. In the first set of experiments, phase inversion behavior of systems without Silica nanoparticles was evaluated and subsequent experiments were conducted in the presence of the nanoparticles. For this purpose, Silica nanoparticles of different concentrations (0.01, 0.03, 0.05, 0.07 wt%) were dispersed in water. The nanofluid stability was examined using an ultraviolet-visible (UV-vis) spectrophotometer. The results indicated that increase in silica nanoparticle concentrations up to 0.07 wt% led to increase in agitation speed of phase inversion 43-53.5% and 38.5-45% in the case of O/W and W/O dispersions, respectively. Consequently, the tendency of dispersions to inversion diminished as nanoparticle concentrations increased. Finally, 0.05 wt% of silica nanoparticle was selected as the optimum on the range studied

  20. The Effect of Specific Conditions on Cu, Ni, Zn and Al Recovery from PCBS Waste Using Acidophilic Bacterial Strains

    Directory of Open Access Journals (Sweden)

    Mrážiková A.

    2016-03-01

    Full Text Available The objective of this work was to evaluate the influence of static, stirring and shaking conditions on copper, zinc, nickel and aluminium dissolution from printed circuit boards (PCBs using the mixed acidophilic bacterial culture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The results revealed that static conditions were the most effective in zinc and aluminium dissolution. Zinc was removed almost completely under static conditions, whereas maximum of nickel dissolution was reached under the stirring conditions. The highest copper recovery (36% was reached under stirring conditions. The shaking conditions appeared to be the least suitable. The relative importance of these systems for the bioleaching of copper and nickel decreased in the order: stirring, static conditions, shaking.

  1. Efficacy of the fluid attenuated inversion recovery (FLAIR) sequence of MRI as a preoperative diagnosis of hippocampal sclerosis

    International Nuclear Information System (INIS)

    Morioka, Takato; Nishio, Shunji; Mihara, Futoshi; Muraishi, Mitsuteru; Hisada, Kei; Hasuo, Kanehiro; Fukui, Masashi

    1998-01-01

    A newly advanced MRI pulse sequence, the FLAIR (fluid attenuated inversion recovery) imaging, in which a long TE spin echo sequence is used with suppression of the CSF with an inversion pulse, displays the CSF space as a no-signal intensity area. There have been only a few reports on the FLAIR pulse sequence of temporal lobe epilepsy (TLE) as yet. We examined 9 cases of intractable TLE by FLAIR images and analyzed the advantages and disadvantages of the FLAIR pulse sequence for decision making on temporal lobectomy. All patients underwent anterior temporal lobectomy with hippocampectomy, and the diagnoses were confirmed histologically after surgery. Abnormally high T2 signals (HT2S) were more conspicuous with the FLAIR sequence than with any of the conventional sequences. Tilted axial plane, orientated along to the long axis of the hippocampal body, clearly demonstrated hippocampal atrophy (HA). Selection of a FLAIR sequence into the routine MR examination of patients with TLE is recommended. (author)

  2. Flexible Friction Stir Joining Technology

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lim, Yong Chae [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mahoney, Murray [MegaStir Technologies LLC, Orem, UT (United States); Sanderson, Samuel [MegaStir Technologies LLC, Orem, UT (United States); Larsen, Steve [MegaStir Technologies LLC, Orem, UT (United States); Steel, Russel [MegaStir Technologies LLC, Orem, UT (United States); Fleck, Dale [MegaStir Technologies LLC, Orem, UT (United States); Fairchild, Doug P [ExxonMobil, Upstream Research Company (URC), Houston, TX (United States); Wasson, Andrew J [ExxonMobil, Upstream Research Company (URC), Houston, TX (United States); Babb, Jon [MegaStir Technologies LLC, Orem, UT (United States); Higgins, Paul [MegaStir Technologies LLC, Orem, UT (United States)

    2015-07-23

    Reported herein is the final report on a U.S. Department of Energy (DOE) Advanced Manufacturing Office (AMO) project with industry cost-share that was jointly carried out by Oak Ridge National Laboratory (ORNL), ExxonMobil Upstream Research Company (ExxonMobil), and MegaStir Technologies (MegaStir). The project was aimed to advance the state of the art of friction stir welding (FSW) technology, a highly energy-efficient solid-state joining process, for field deployable, on-site fabrications of large, complex and thick-sectioned structures of high-performance and high-temperature materials. The technology innovations developed herein attempted to address two fundamental shortcomings of FSW: 1) the inability for on-site welding and 2) the inability to weld thick section steels, both of which have impeded widespread use of FSW in manufacturing. Through this work, major advance has been made toward transforming FSW technology from a “specialty” process to a mainstream materials joining technology to realize its pervasive energy, environmental, and economic benefits across industry.

  3. Development of a sensitive determination method for benzotriazole UV stabilizers in enviromental water samples with stir bar sorption extraction and liquid desorption prior to ultra-high performance liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Montesdeoca-Esponda, Sarah; del Toro-Moreno, Adrián; Sosa-Ferrera, Zoraida; Santana-Rodríguez, José Juan

    2013-07-01

    Benzotriazole UV stabilizers are emerging compounds used in personal care products and can enter surface water after passing through wastewater treatment plants without being removed. Because these analytes are strongly hydrophobic, there is an environmental risk of accumulation in solid matrices and magnification through the trophic chain. In this work, a method based on stir bar sorption extraction with liquid desorption is presented for the extraction of benzotriazole UV stabilizers from water samples. Stir bar sorptive extraction was combined with ultra-high performance LC with MS/MS detection. All important factors affecting the stir bar sorptive extraction procedure are discussed, and the optimized method was applied to seawater and wastewater samples from Gran Canaria Island, providing good selectivity and sensitivity with LODs and limits of quantification in the range of 18.4-55.1 and 61.5-184 ng/L, respectively. Recoveries between 68.4-92.2% were achieved for the more polar compounds, whereas the recoveries were lower for the two less polar compounds, most likely due to their strong absorption into the polydimethylsiloxane stir bar phase that does not allows the complete desorption. The repeatability studies gave RSDs of between 6.45 and 12.6% for all compounds in the real samples. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

  5. Electrodeposition of uranium in stirred liquid cadmium cathode

    International Nuclear Information System (INIS)

    Koyama, T.; Tanaka, H.

    1997-01-01

    The electrodeposition of U in a liquid Cd cathode was known to be hampered by the formation of dendritic U on the Cd surface. Electrotransports of uranium to the stirred liquid Cd cathode were carried out at 773 K for different cathode current densities and different Reynolds number of stirring. The maximum amount of U taken in the liquid Cd cathode without forming dendrites was found to increase with an increasing Reynolds number of stirring and decrease with increasing cathode current density. (orig.)

  6. Mercury speciation and analysis in drinking water by stir bar sorptive extraction with in situ propyl derivatization and thermal desorption-gas chromatography-mass spectrometry.

    Science.gov (United States)

    Ito, Rie; Kawaguchi, Migaku; Sakui, Norihiro; Honda, Hidehiro; Okanouchi, Noriya; Saito, Koichi; Nakazawa, Hiroyuki

    2008-10-31

    A method for mercury analysis and speciation in drinking water was developed, which involved stir bar sorptive extraction (SBSE) with in situ propyl derivatization and thermal desorption (TD)-GC-MS. Ten millilitre of tap water or bottled water was used. After a stir bar, pH adjustment agent and derivatization reagent were added, SBSE was performed. Then, the stir bar was subjected to TD-GC-MS. The detection limits were 0.01 ng mL(-1) (ethylmercury; EtHg), 0.02 ng mL(-1) (methylmercury; MeHg), and 0.2 ng mL(-1) (Hg(II) and diethylmercury (DiEtHg)). The method showed good linearity and correlation coefficients. The average recoveries of mercury species (n=5) in water samples spiked with 0.5, 2.0, and 6.0 ng mL(-1) mercury species were 93.1-131.1% (RSDmercury species in water samples.

  7. Diffusion-weighted whole-body MR imaging with background body signal suppression: a feasibility study at 3.0 Tesla

    International Nuclear Information System (INIS)

    Muertz, Petra; Krautmacher, Carsten; Traeber, Frank; Schild, Hans H.; Willinek, Winfried A.; Gieseke, Juergen

    2007-01-01

    The purpose was to provide a diffusion-weighted whole-body magnetic resonance (MR) imaging sequence with background body signal suppression (DWIBS) at 3.0 Tesla. A diffusion-weighted spin-echo echo-planar imaging sequence was combined with the following methods of fat suppression: short TI inversion recovery (STIR), spectral attenuated inversion recovery (SPAIR), and spectral presaturation by inversion recovery (SPIR). Optimized sequences were implemented on a 3.0- and a 1.5-Tesla system and evaluated in three healthy volunteers and six patients with various lesions in the neck, chest, and abdomen on the basis of reconstructed maximum intensity projection images. In one patient with metastases of malignant melanoma, DWIBS was compared with 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET). Good fat suppression for all regions and diagnostic image quality in all cases could be obtained at 3.0 Tesla with the STIR method. In comparison with 1.5 Tesla, DWIBS images at 3.0 Tesla were judged to provide a better lesion-to-bone tissue contrast. However, larger susceptibility-induced image distortions and signal intensity losses, stronger blurring artifacts, and more pronounced motion artifacts degraded the image quality at 3.0 Tesla. A good correlation was found between the metastases as depicted by DWIBS and those as visualized by FDG-PET. DWIBS is feasible at 3.0 Tesla with diagnostic image quality. (orig.)

  8. Damage Tolerance Behavior of Friction Stir Welds in Aluminum Alloys

    Science.gov (United States)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process used in the fabrication of various aerospace structures. Self-reacting and conventional friction stir welding are variations of the friction stir weld process employed in the fabrication of cryogenic propellant tanks which are classified as pressurized structure in many spaceflight vehicle architectures. In order to address damage tolerance behavior associated with friction stir welds in these safety critical structures, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data describing fracture behavior, residual strength capability, and cyclic mission life capability of friction stir welds at ambient and cryogenic temperatures have been generated and will be presented in this paper. Fracture behavior will include fracture toughness and tearing (R-curve) response of the friction stir welds. Residual strength behavior will include an evaluation of the effects of lack of penetration on conventional friction stir welds, the effects of internal defects (wormholes) on self-reacting friction stir welds, and an evaluation of the effects of fatigue cycled surface cracks on both conventional and selfreacting welds. Cyclic mission life capability will demonstrate the effects of surface crack defects on service load cycle capability. The fracture data will be used to evaluate nondestructive inspection and proof test requirements for the welds.

  9. Bio-processing of copper from combined smelter dust and flotation concentrate: a comparative study on the stirred tank and airlift reactors.

    Science.gov (United States)

    Vakylabad, Ali Behrad; Schaffie, Mahin; Ranjbar, Mohammad; Manafi, Zahra; Darezereshki, Esmaeel

    2012-11-30

    To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu(2)S, CuS, and Cu(5)FeS(4).Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Calculation of energy costs of composite biomass stirring at biogas stations

    Science.gov (United States)

    Suslov, D. Yu; Temnikov, D. O.

    2018-03-01

    The paper is devoted to the study of the equipment to produce biogas fuel from organic wastes. The bioreactor equipped with a combined stirring system ensuring mechanical and bubbling stirring is designed. The method of energy cost calculation of the combined stirring system with original design is suggested. The received expressions were used in the calculation of the stirring system installed in the 10 m3 bioreactor: power consumed by the mixer during the start-up period made Nz =9.03 kW, operating power of the mixer made NE =1.406 kW, compressor power for bubbling stirring made NC =18.5 kW. Taking into account the operating mode of single elements of the stirring system, the energy cost made 4.38% of the total energy received by the biogas station.

  11. Polydimethylsiloxane/MIL-100(Fe) coated stir bar sorptive extraction-high performance liquid chromatography for the determination of triazines in environmental water samples.

    Science.gov (United States)

    Lei, Yun; Chen, Beibei; You, Linna; He, Man; Hu, Bin

    2017-12-01

    Polydimethylsiloxane (PDMS)/MIL-100(Fe) coated stir bar was prepared by sol gel technique, and good preparation reproducibility was achieved with relative standard deviations (RSDs) ranging from 2.6% to 7.5% (n=7) and 3.6% to 10.8% (n=7) for bar-to-bar and batch-to-batch, respectively. Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/MIL-100(Fe) stir bar showed better extraction efficiency for target triazines compounds. It also exhibited relatively fast extraction/desorption kinetics and long lifespan. Based on it, a method of PDMS/MIL-100(Fe) coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for the determination of six triazines (simazine, atrazine, prometon, ametryn, prometryne and prebane) in environmental water samples. Several parameters affecting SBSE of six target triazines including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.021-0.079μgL -1 . The repeatability RSDs were in the range of 2.3-6.3% (n=7, c=0.5μgL -1 ) and the enrichment factors (EFs) ranged from 51.1 to 102-fold (theoretical EF was 200-fold). The proposed method was applied to the analysis of target triazines in environmental water samples, with recoveries of 98.0-118% and 94.0-107% for spiked East Lake water and local pond water samples, respectively. Copyright © 2017. Published by Elsevier B.V.

  12. Evaluation of myelination and myelination disorders with turbo inversion recovery magnetic resonance imaging

    International Nuclear Information System (INIS)

    Daldrup, H.E.; Schuierer, G.; Link, T.M.; Moeller, H.; Bick, U.; Peters, P.E.; Kurlemann, G.

    1997-01-01

    The aim of our work was to determine the efficacy of turbo inversion recovery spin echo (TIRSE) pulse sequences in differentiating patients with normal and abnormal myelination. Twenty neurological normal children (aged 5 months to 12 years) as well as 65 children presenting clinically with neurologic developmental deficits (aged 2 months to 10 years) were examined using TIRSE, T1-weighted SE, and T2-weighted turbo SE pulse sequences. Contrast-to-noise-ratio (CNR) between myelinated white and gray matter was compared for the different pulse sequences. In addition, two readers analyzed all images qualitatively by consensus. The CNR values were significantly higher on TIRSE images as compared with conventional images (p < 0.05). Forty-two neurologically abnormal patients displayed a normal myelination on all sequences, whereas 23 showed an abnormal myelination. The TIRSE sequence provided a sensitive and specific depiction of an abnormal myelination in all of these patients. The TIRSE sequence provided additional information to conventional pulse sequences in determining myelination disorders in children, especially in children older than 2 years. (orig.)

  13. Microstructural characterization in dissimilar friction stir welding between 304 stainless steel and st37 steel

    International Nuclear Information System (INIS)

    Jafarzadegan, M.; Feng, A.H.; Abdollah-zadeh, A.; Saeid, T.; Shen, J.; Assadi, H.

    2012-01-01

    In the present study, 3 mm-thick plates of 304 stainless steel and st37 steel were welded together by friction stir welding at a welding speed of 50 mm/min and tool rotational speed of 400 and 800 rpm. X-ray diffraction test was carried out to study the phases which might be formed in the welds. Metallographic examinations, and tensile and microhardness tests were used to analyze the microstructure and mechanical properties of the joint. Four different zones were found in the weld area except the base metals. In the stir zone of the 304 stainless steel, a refined grain structure with some features of dynamic recrystallization was evidenced. A thermomechanically-affected zone was characterized on the 304 steel side with features of dynamic recovery. In the other side of the stir zone, the hot deformation of the st37 steel in the austenite region produced small austenite grains and these grains transformed to fine ferrite and pearlite and some products of displacive transformations such as Widmanstatten ferrite and martensite by cooling the material after friction stir welding. The heat-affected zone in the st37 steel side showed partially and fully refined microstructures like fusion welding processes. The recrystallization in the 304 steel and the transformations in the st37 steel enhanced the hardness of the weld area and therefore, improved the tensile properties of the joint. - Highlights: ► FSW produced sound welds between st37 low carbon steel and 304 stainless steel. ► The SZ of the st37 steel contained some products of allotropic transformation. ► The material in the SZ of the 304 steel showed features of dynamic recrystallization. ► The finer microstructure in the SZ increased the hardness and tensile strength.

  14. Mechanical properties of friction stir welded 11Cr-ferritic/martensitic steel

    International Nuclear Information System (INIS)

    Yano, Y.; Sato, Y.S.; Sekio, Y.; Ohtsuka, S.; Kaito, T.; Ogawa, R.; Kokawa, H.

    2013-01-01

    Friction stir welding was applied to the wrapper tube materials, 11Cr-ferritic/martensitic steel, designed for fast reactors and defect-free welds were successfully produced. The mechanical and microstructural properties of the friction stir welded steel were subsequently investigated. The hardness values of the stir zone were approximately 550 Hv (5.4 GPa) with minimal dependence on the rotational speed, even though they were much higher than those of the base material. However, tensile strengths and elongations of the stir zones were high at 298 K, compared to those of the base material. The excellent tensile properties are attributable to the fine grain formation during friction stir welding

  15. A case of Marchiafava-Bignami disease: MRI findings on spin-echo and fluid attenuated inversion recovery (FLAIR) images

    International Nuclear Information System (INIS)

    Yamamoto, Takashi; Ashikaga, Ryuichiro; Araki, Yutaka; Nishimura, Yasumasa

    2000-01-01

    Marchiafava-Bignami disease (MBD) was diagnosed in a 56-year-old man. Spin-echo (SE) magnetic resonance imaging (MRI) at the acute phase showed normal signal areas in the central layer of the corpus callosum (CC), although the intensity of these areas revealed abnormal hyperintensity on fluid attenuated inversion recovery (FLAIR). On follow-up SE MRI at the late phase, the central layer of the CC showed fluid-like intensity. On FLAIR MRI, the lesions of the CC turned into hypointense cores surrounded by hyperintense rims indicating central necrosis and peripheral demyelination. Degenerative changes of the CC in MBD were clearly demonstrated by FLAIR MRI

  16. A sublimate sorbent for stir-bar sorptive extraction of aqueous endocrine disruptor pesticides for gas chromatography-electron capture detection.

    Science.gov (United States)

    Huang, Yu-Wen; Lee, Hua Kwang; Shih, Hou-Kuang; Jen, Jen-Fon

    2018-06-06

    A dumbbell-shaped magnetic stir-bar with sublimate sorbent was prepared for the stir bar sorptive extraction (SBSE) of pesticides in an aqueous sample prior to gas chromatography-micro-electron capture detection (GC-μECD). Cyclododecane (CDD) was coated onto a magnetic stir-bar surface as a sublimate sorbent, and steel balls were placed on both ends to form a dumbbell-shaped magnetic stir-bar for SBSE. Four EDC pesticides including chlorpyrifos, ethion, bromopropylate, and λ-cyhalothrin in aqueous samples were selected as model species to examine the proposed SBSE and the following desorption. The parameters studied were those affecting the extraction efficiencies including the coating (solvent for CDD and thickness), extraction (sample pH, stirring rate, time, and salting out effect), dissolution solvent volume, and the loss of CDD sublimated in air. The maximum extraction efficiency was obtained under the following conditions. The stir bar (with CDD thickness of 5.2 μm) was added into a 10 mL sample solution (at pH 7) for a 20-min extraction at 600 rpm. Then, the stir bar was gently removed from the sample solution, disassembled, and immersed into a 0.2 mL insert tube consisting of 3 μL hexane to dissolve; 1 μL was used for GC-ECD analysis. The linear ranges were 0.005-5 μg L -1 with coefficients of determination ranging from 0.9950 - 0.9994. Detection limits (based on S/N = 3) of the four EDCs were 0.4-4.5 ngL -1 with a relative standard deviation (RSD) of 2.4-6.3%, and quantitation limits (based on S/N = 5) were 1-15 ngL -1 . The relative recoveries of the spiked samples were in the range of 83.2-98.7% with RSDs of 2.1-8.4% in farm field waters. The proposed sublimation sorbent obtained excellent enrichment factors (101-834) and provided a simple, rapid, sensitive, and eco-friendly sample preparation method. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. [Optimization of stir-baking with vinegar technology for Curcumae Radix by orthogonal test].

    Science.gov (United States)

    Shi, Dianhua; Su, Benzheng; Sun, Lili; Zhang, Jun; Qu, Yongsheng

    2011-05-01

    To optimize the stir-baking with vinegar technology for Curcumae Radix. The intrinsic quality (the content of Curcumin) and traditional outward appearance were chosen as indexes. The best technology was determined by orthogonal test L9 (3(4)). The factors of the moistening time, stir-baking temperature and stir-baking time were investigated. The optimal technology was as follows: the quantity of vinegar was 10%, the moistening time was 10 min, the stir-baking temperature was 130 degrees C and the stir-baking time was 10 min. The optimal stir-baking with vinegar technology for Curcumae Radix is reasonable, which can be used to guide the standardized production of Curcumae Radix stir-baked with vinegar.

  18. Bio-processing of copper from combined smelter dust and flotation concentrate: A comparative study on the stirred tank and airlift reactors

    Energy Technology Data Exchange (ETDEWEB)

    Vakylabad, Ali Behrad, E-mail: alibehzad86@yahoo.co.uk [Department of Mining Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Engineers of Nano and Bio Advanced Sciences Company (ENBASCo.), ATIC, Mohaghegh University (Iran, Islamic Republic of); Schaffie, Mahin [Department of Chemical Engineering, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Ranjbar, Mohammad [Department of Mining Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Manafi, Zahra [Sarcheshmeh Copper Complex, National Iranian Copper Industry Company (Iran, Islamic Republic of); Darezereshki, Esmaeel [Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Energy and Environmental Engineering Research Center (EERC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Flotation concentrate and smelter dust were sampled and combined. Black-Right-Pointing-Pointer Copper bioleaching from the combined was investigated. Black-Right-Pointing-Pointer Two bio-reactors were investigated and optimized: stirred and airlift. Black-Right-Pointing-Pointer STRs had better technical conditions and situations for bacterial leaching. - Abstract: To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu{sub 2}S, CuS, and Cu{sub 5}FeS{sub 4}.Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results.

  19. Bio-processing of copper from combined smelter dust and flotation concentrate: A comparative study on the stirred tank and airlift reactors

    International Nuclear Information System (INIS)

    Vakylabad, Ali Behrad; Schaffie, Mahin; Ranjbar, Mohammad; Manafi, Zahra; Darezereshki, Esmaeel

    2012-01-01

    Highlights: ► Flotation concentrate and smelter dust were sampled and combined. ► Copper bioleaching from the combined was investigated. ► Two bio-reactors were investigated and optimized: stirred and airlift. ► STRs had better technical conditions and situations for bacterial leaching. - Abstract: To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu 2 S, CuS, and Cu 5 FeS 4 .Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results.

  20. Thermal Stir Welding Development at Marshall Space Flight Center

    Science.gov (United States)

    Ding, Robert J.

    2008-01-01

    Solid state welding processes have become the focus of welding process development at NASA's Marshall Space Flight Center. Unlike fusion weld processes such as tungsten inert gas (TIG), variable polarity plasma arc (VPPA), electron beam (EB), etc., solid state welding processes do not melt the material during welding. The resultant microstructure can be characterized as a dynamically recrystallized morphology much different than the casted, dentritic structure typical of fusion weld processes. The primary benefits of solid state processes over fusion weld processes include superior mechanic properties and the elimination of thermal distortion and residual stresses. These solid state processes attributes have profoundly influenced the direction of advanced welding research and development within the NASA agency. Thermal Stir Welding (TSW) is a new solid state welding process being developed at the Marshall Space Flight Center. Unlike friction stir welding, the heating, stirring and forging elements of the weld process can be decoupled for independent control. An induction coil induces energy into a workpiece to attain a desired plastic temperature. An independently controlled stir rod, captured within non-rotating containment plates, then stirs the plasticized material followed by forging plates/rollers that work the stirred weld joint. The independent control (decoupling) of heating, stirring and forging allows, theoretically, for the precision control of microstructure morphology. The TSW process is being used to evaluate the solid state joining of Haynes 230 for ARES J-2X applications. It is also being developed for 500-in (12.5 mm) thick commercially pure grade 2 titanium for navy applications. Other interests include Inconel 718 and stainless steel. This presentation will provide metallurgical and mechanical property data for these high melting temperature alloys.

  1. Friction stir method for forming structures and materials

    Science.gov (United States)

    Feng, Zhili; David, Stan A.; Frederick, David Alan

    2011-11-22

    Processes for forming an enhanced material or structure are disclosed. The structure typically includes a preform that has a first common surface and a recess below the first common surface. A filler is added to the recess and seams are friction stir welded, and materials may be stir mixed.

  2. Friction stir welding tool

    Science.gov (United States)

    Tolle,; Charles R. , Clark; Denis E. , Barnes; Timothy, A [Ammon, ID

    2008-04-15

    A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

  3. Low temperature friction stir welding of P91 steel

    Directory of Open Access Journals (Sweden)

    Prasad Rao Kalvala

    2016-08-01

    Full Text Available Bead-on-plate friction stir welds were made on P91 alloy with low and high rotational speeds (100 and 1000 RPM to study their effects on weld microstructural changes and impression creep behavior. Temperatures experienced by the stir zone were recorded at the weld tool tip. Different zones of welds were characterized for their microstructural changes, hardness and creep behavior (by impression creep tests. The results were compared with submerged arc fusion weld. Studies revealed that the stir zone temperature with 100 RPM was well below Ac1 temperature of P91 steel while it was above Ac3 with 1000 RPM. The results suggest that the microstructural degradation in P91 welds can be controlled by low temperature friction stir welding technique.

  4. Shear rate analysis of water dynamic in the continuous stirred tank

    Science.gov (United States)

    Tulus; Mardiningsih; Sawaluddin; Sitompul, O. S.; Ihsan, A. K. A. M.

    2018-02-01

    Analysis of mixture in a continuous stirred tank reactor (CSTR) is an important part in some process of biogas production. This paper is a preliminary study of fluid dynamic phenomenon in a continuous stirred tank numerically. The tank is designed in the form of cylindrical tank equipped with a stirrer. In this study, it is considered that the tank is filled with water. Stirring is done with a stirring speed of 10rpm, 15rpm, 20rpm, and 25rpm. Mathematical modeling of stirred tank is derived. The model is calculated by using the finite element method that are calculated using CFD software. The result shows that the shear rate is high on the front end portion of the stirrer. The maximum shear rate tend to a stable behaviour after the stirring time of 2 second. The relation between the speed and the maximum shear rate is in the form of linear equation.

  5. Stir bar sorptive extraction and liquid chromatography-tandem mass spectrometry determination of polar and non-polar emerging and priority pollutants in environmental waters.

    Science.gov (United States)

    Aparicio, Irene; Martín, Julia; Santos, Juan Luis; Malvar, José Luis; Alonso, Esteban

    2017-06-02

    An analytical method based on stir bar sorptive extraction (SBSE) was developed and validated for the determination of environmental concern pollutants in environmental waters by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Target compounds include six water and oil repellents (perfluorinated compounds), four preservatives (butylated hydroxytoluene and three parabens), two plasticizers (bisphenol A and di(2-ethylhexyl)phthalate), seven surfactants (four linear alkylbenzene sulfonates, nonylphenol and two nonylphenol ethoxylates), a flame retardant (hexabromocyclododecane), four hormones, fourteen pharmaceutical compounds, an UV-filter (2-ethylhexyl 4-methoxycinnamate) and nine pesticides. To achieve the simultaneous extraction of polar and non-polar pollutants two stir bar coatings were tested, the classic polydimethylsiloxane (PDMS) coating and the novel ethylene glycol modified silicone (EG-silicone). The best extraction recoveries were obtained using EG-silicone coating. The effects of sample pH, volume and ionic strength and extraction time on extraction recoveries were evaluated. The analytical method was validated for surface water and tap water samples. The method quantification limits ranged from 7.0ngL -1 to 177ngL -1 . The inter-day precision, expressed as relative standard deviation, was lower than 20%. Accuracy, expressed as relative recovery values, was in the range from 61 to 130%. The method was applied for the determination of the 48 target compounds in surface and tap water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Etched poly(ether ether ketone) jacket stir bar with detachable dumbbell-shaped structure for stir bar sorptive extraction.

    Science.gov (United States)

    Zhou, Wei; Wang, Chenlu; Wang, Xuemei; Chen, Zilin

    2018-06-08

    Development of stir bar sorptive extraction (SBSE) device with high stability and extraction efficiency is critical and challenging by date. In this work, etched poly(ether ether ketone) (PEEK) tube with high mechanical strength and large specific surface area was used as jacket for SBSE device. By etching with concentrated sulfuric acid, the smooth outer surface of PEEK become porous with plenty of micro holes, which was beneficial for coating of sorbents and significantly improved the extraction performance. After functionalized by bio-polydopamine method, strong hydrophobic p-naphtholbenzein molecular was immobilized onto the chemical resistant PEEK surface (PNB@E-PEEK) as stationary phase. We also firstly developed a simple detachable dumbbell-shaped structure for improving the workability of PEEK jacket stir bar. The dumbbell-shaped construction can eliminate the friction between stir bar and container, and the design of detachable structure make elution can be accomplished easier with small amount of organic solvent. It was interesting that the developed detachable dumbbell-shaped PNB@E-PEEK stir bar showed exceptional stability and extraction efficiency for SBSE enrichment of multiple analytes including several Sudan dyes, triazines, polycyclic aromatic hydrocarbons (PAHs), alkaloids and flavonoid. By coupling with high performance liquid chromatography-ultraviolet detection (HPLC-UV), PNB@E-PEEK stir bar based SBSE-HPLC-UV method was applied for the analysis of common Sudan dye pollutants. The method showed low limits of detection (0.02-0.03 ng/mL), good linearity (R 2  ≥ 0.9979) and good reproducibility (relative standard deviation ≤ 7.96%). It has been successfully applied to determine three dye pollutants in tap and lake water. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Recovery of resources for advanced life support space applications: effect of retention time on biodegradation of two crop residues in a fed-batch, continuous stirred tank reactor

    Science.gov (United States)

    Strayer, R. F.; Finger, B. W.; Alazraki, M. P.; Cook, K.; Garland, J. L.

    2002-01-01

    Bioreactor retention time is a key process variable that will influence costs that are relevant to long distance space travel or long duration space habitation. However. little is known about the effects of this parameter on the microbiological treatment options that are being proposed for Advanced Life Support (ALS) systems. Two bioreactor studies were designed to examine this variable. In the first one, six retention times ranging from 1.3 to 21.3 days--were run in duplicate, 81 working-volume continuous stirred tank reactors (CSTR) that were fed ALS wheat residues. Ash-free dry weight loss, carbon mineralization, soluble TOC reduction, changes in fiber content (cellulose, hemicellulose, and lignin), bacterial numbers, and mineral recoveries were monitored. At short retention times--1.33 days--biodegradation was poor (total: 16-20%, cellulose - 12%, hemicellulose - 28%) but soluble TOC was decreased by 75-80% and recovery of major crop inorganic nutrients was adequate, except for phosphorus. A high proportion of the total bacteria (ca. 83%) was actively respiring. At the longest retention time tested, 21.3 days, biodegradation was good (total: 55-60%, cellulose ca. 70%, hemicellulose - ca. 55%) and soluble TOC was decreased by 80%. Recovery of major nutrients, except phosphorus, remained adequate. A very low proportion of total bacteria was actively respiring (ca. 16%). The second bioreactor study used potato residue to determine if even shorter retention times could be used (range 0.25-2.0 days). Although overall biodegradation deteriorated, the degradation of soluble TOC continued to be ca. 75%. We conclude that if the goal of ALS bioprocessing is maximal degradation of crop residues, including cellulose, then retention times of 10 days or longer will be needed. If the goal is to provide inorganic nutrients with the smallest volume/weight bioreactor possible, then a retention time of 1 day (or less) is sufficient.

  8. Weld Nugget Temperature Control in Thermal Stir Welding

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2014-01-01

    A control system for a thermal stir welding system is provided. The control system includes a sensor and a controller. The sensor is coupled to the welding system's containment plate assembly and generates signals indicative of temperature of a region adjacent and parallel to the welding system's stir rod. The controller is coupled to the sensor and generates at least one control signal using the sensor signals indicative of temperature. The controller is also coupled to the welding system such that at least one of rotational speed of the stir rod, heat supplied by the welding system's induction heater, and feed speed of the welding system's weld material feeder are controlled based on the control signal(s).

  9. Friction stir welding of F82H steel for fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Sanghoon, E-mail: shnoh@kaeri.re.kr [Fusion Structural Materials Division, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Nuclear Materials Division, Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon (Korea, Republic of); Ando, Masami; Tanigawa, Hiroyasu [Fusion Structural Materials Division, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka (Japan); Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto (Japan)

    2016-09-15

    In the present study, friction stir welding was employed to join F82H steels and develop a potential joining technique for a reduced activation ferritic/martensitic steel. The microstructures and mechanical properties on the joint region were investigated to evaluate the applicability of friction stir welding. F82H steel sheets were successfully butt-joined with various welding parameters. In welding conditions, 100 rpm and 100 mm/min, the stirred zone represented a comparable hardness distribution with a base metal. Stirred zone induced by 100 rpm reserved uniformly distributed precipitates and very fine ferritic grains, whereas the base metal showed a typical tempered martensite with precipitates on the prior austenite grain boundary and lath boundary. Although the tensile strength was decreased at 550 °C, the stirred zone treated at 100 rpm showed comparable tensile behavior with base metal up to 500 °C. Therefore, friction stir welding is considered a potential welding method to preserve the precipitates of F82H steel.

  10. Friction stir welding of F82H steel for fusion applications

    International Nuclear Information System (INIS)

    Noh, Sanghoon; Ando, Masami; Tanigawa, Hiroyasu; Fujii, Hidetoshi; Kimura, Akihiko

    2016-01-01

    In the present study, friction stir welding was employed to join F82H steels and develop a potential joining technique for a reduced activation ferritic/martensitic steel. The microstructures and mechanical properties on the joint region were investigated to evaluate the applicability of friction stir welding. F82H steel sheets were successfully butt-joined with various welding parameters. In welding conditions, 100 rpm and 100 mm/min, the stirred zone represented a comparable hardness distribution with a base metal. Stirred zone induced by 100 rpm reserved uniformly distributed precipitates and very fine ferritic grains, whereas the base metal showed a typical tempered martensite with precipitates on the prior austenite grain boundary and lath boundary. Although the tensile strength was decreased at 550 °C, the stirred zone treated at 100 rpm showed comparable tensile behavior with base metal up to 500 °C. Therefore, friction stir welding is considered a potential welding method to preserve the precipitates of F82H steel.

  11. One-pot synthesis of zeolitic imidazolate framework-8/poly (methyl methacrylate-ethyleneglycol dimethacrylate) monolith coating for stir bar sorptive extraction of phytohormones from fruit samples followed by high performance liquid chromatography-ultraviolet detection.

    Science.gov (United States)

    You, Linna; He, Man; Chen, Beibei; Hu, Bin

    2017-11-17

    In this work, zeolitic imidazolate framework-8 (ZIF-8)/poly (methyl methacrylate-ethyleneglycol dimethacrylate) (MMA-EGDMA) composite monolith was in situ synthesized on stir bar by one-pot polymerization. Compared with the neat monolith, ZIF-8/poly(MMA-EGDMA) composite monolith has larger surface area and pore volume. It also exhibits higher extraction efficiency for target phytohormones than poly(MMA-EGDMA) monolith and commercial polyethylene glycol (PEG) coated stir bar. Based on it, a method of ZIF-8/poly(MMA-EGDMA) monolith coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detection (HPLC-UV) was established for the analysis of five phytohormones in apple and pear samples. The developed method exhibited low limits of detection (0.11-0.51μg/L), wide linear range (0.5-500μg/L) and good recoveries (82.7-111%), which demonstrated good application potential of the ZIF-8/monolith coated stir bar in trace analysis of organic compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Fast fluid-attenuated inversion-recovery imaging: first experience with a 3D version in epilepsy

    International Nuclear Information System (INIS)

    Wieshmann, U.C.; Symms, M.R.; Bartlett, P.A.; Shorvon, S.D.; Barker, G.J.; Stevens, J.M.

    1998-01-01

    We developed a 3D version of fast fluid-attenuated inversion-recovery imaging (FLAIR) which provides images with a slice thickness of 1.5 mm. We present our initial experience with 3D fast FLAIR in patients with epilepsy. We compared 3D fast FLAIR (slice thickness 1.5 mm), 2D fast FLAIR (slice thickness 5 mm) and a 3D spoiled GRASS (IRSPGR) sequence (slice thickness 1.5 mm) in 10 patients with lesional epilepsy (head injury 1, hippocampal sclerosis 2, low-grade glioma 2, dysembryoplastic neuroepithelial tumour 2, polymicrogyria 1, perinatal infarct 1 and presumed thrombosed aneurysm 1). Both 2D and 3D fast FLAIR sequences yielded higher conspicuity for lesions than the T1-weighted IRSPGR sequence, except in the patient with polymicrogyria. The extent of the lesion, in particular that of low-grade tumours, was best assessed on 3D fast FLAIR images. 3D fast FLAIR may be a useful additional tool especially for imaging low-grade tumours. (orig.)

  13. Steady shear viscosity of stirred yoghurts with varying ropiness

    NARCIS (Netherlands)

    van Marle, M.E.; van Marle, M.E.; van den Ende, Henricus T.M.; de Kruif, C.G.; de Kruif, C.G.; Mellema, J.

    1999-01-01

    Stirred yogurt was viewed as a concentrated dispersion of aggregates consisting of protein particles. The steady-shear behavior of three types of stirred yogurt with varying ropiness was investigated experimentally. To describe the shear-dependent viscosity, a microrheological model was used which

  14. Friction stir processing on high carbon steel U12

    Energy Technology Data Exchange (ETDEWEB)

    Tarasov, S. Yu., E-mail: tsy@ispms.ru; Rubtsov, V. E., E-mail: rvy@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Melnikov, A. G., E-mail: melnikov-ag@tpu.ru [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    Friction stir processing (FSP) of high carbon steel (U12) samples has been carried out using a milling machine and tools made of cemented tungsten carbide. The FSP tool has been made in the shape of 5×5×1.5 mm. The microstructural characterization of obtained stir zone and heat affected zone has been carried out. Microhardness at the level of 700 MPa has been obtained in the stir zone with microstructure consisting of large grains and cementitte network. This high-level of microhardness is explained by bainitic reaction developing from decarburization of austenitic grains during cementite network formation.

  15. Friction Stir Welding Process: A Green Technology

    OpenAIRE

    Esther T. Akinlabi; Stephen A. Akinlabi

    2012-01-01

    Friction Stir Welding (FSW) is a solid state welding process invented and patented by The Welding Institute (TWI) in the United Kingdom in 1991 for butt and lap welding of metals and plastics. This paper highlights the benefits of friction stir welding process as an energy efficient and a green technology process in the field of welding. Compared to the other conventional welding processes, its benefits, typical applications and its use in joining similar and dissimilar materia...

  16. Microstructure Evolution during Friction Stir Spot Welding of TRIP Steel

    DEFF Research Database (Denmark)

    Lomholt, Trine Colding; Pantleon, Karen; Somers, Marcel A. J.

    2010-01-01

    In this study, the feasibility of friction stir spot welding of TRIP steel is investigated. In addition to manufacturing successful welds, the present study aims at a fundamental understanding of the mechanisms occurring at the (sub)micron scale during friction stir spot welding. As one of the ma...... electron microscopy, and electron backscatter diffraction. Microhardness measurements and lap-shear tensile tests completed the investigations of the welded samples and allow evaluation of the quality of the welds.......In this study, the feasibility of friction stir spot welding of TRIP steel is investigated. In addition to manufacturing successful welds, the present study aims at a fundamental understanding of the mechanisms occurring at the (sub)micron scale during friction stir spot welding. As one of the main...... parameters to control friction stir welding, the influence of the rotational speed of the tool was investigated. Three different rotational speeds (500 rpm, 1000 rpm and 1500 rpm, respectively) were applied. The microstructure of the welded samples was investigated with reflected light microscopy, scanning...

  17. Predictors of short-term outcome in patients with acute middle cerebral artery occlusion: unsuitability of fluid-attenuated inversion recovery vascular hyperintensity scores

    Directory of Open Access Journals (Sweden)

    Chan-chan Li

    2018-01-01

    Full Text Available Fluid-attenuated inversion recovery (FLAIR vascular hyperintensity (FVH is used to assess leptomeningeal collateral circulation, but clinical outcomes of patients with FVH can be very different. The aim of the present study was to assess a FVH score and explore its relationship with clinical outcomes. Patients with acute ischemic stroke due to middle cerebral artery M1 occlusion underwent magnetic resonance imaging and were followed up at 10 days (National Institutes of Health Stroke Scale and 90 days (modified Rankin Scale to determine short-term clinical outcomes. Effective collateral circulation indirectly improved recovery of neurological function and short-term clinical outcome by extending the size of the pial penumbra and reducing infarct lesions. FVH score showed no correlation with 90-day functional clinical outcome and was not sufficient as an independent predictor of short-term clinical outcome.

  18. Lateral position detection and control for friction stir systems

    Science.gov (United States)

    Fleming, Paul; Lammlein, David; Cook, George E.; Wilkes, Don Mitchell; Strauss, Alvin M.; Delapp, David; Hartman, Daniel A.

    2010-12-14

    A friction stir system for processing at least a first workpiece includes a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing the first workpiece. A detection system is provided for obtaining information related to a lateral alignment of the rotating member. The detection system comprises at least one sensor for measuring a force experienced by the rotary tool or a parameter related to the force experienced by the rotary tool during processing, wherein the sensor provides sensor signals. A signal processing system is coupled to receive and analyze the sensor signals and determine a lateral alignment of the rotating member relative to a selected lateral position, a selected path, or a direction to decrease a lateral distance relative to the selected lateral position or selected path. In one embodiment, the friction stir system can be embodied as a closed loop tracking system, such as a robot-based tracked friction stir welding (FSW) or friction stir processing (FSP) system.

  19. Hybrid friction stir welding for dissimilar materials through electro-plastic effect

    Science.gov (United States)

    Liu, Xun; Lan, Shuhuai; Ni, Jun

    2018-05-29

    A hybrid Friction Stir Welding approach and device for dissimilar materials joining employing Electro-Plastic Effect. The approach and device include an introduction of high density, short period current pulses into traditional friction stir welding process, which therefore can generate a localized softened zone in the workpiece during plastic stirring without significant additional temperature increase. This material softened zone is created by high density current pulses based on Electro-Plastic Effect and will move along with the friction stir welding tool. Smaller downward force, larger processing window and better joint quality for dissimilar materials are expected to be achieved through this hybrid welding technique.

  20. Program plan: DWPF/HLWDP stirred Melter Program Plan

    International Nuclear Information System (INIS)

    Smith, M.E.

    1994-01-01

    Slurry Fed Melters (SFM) have been developed in the United States, Europe, and Japan for the conversion of high-level radioactive waste (HLW) to borosilicate glass for permanent disposal. The newest design, the stirred melter, combines the high production rates and high glass quality features of the Joule-heated melters with the low-cost, compact, simple maintenance features of the pot melters. However, further engineering design and demonstrations are needed to operate the stirred melter on a large scale. This document outlines the program which develops a full scale stirred melter for the DWPF (240 pph), and provides a basis which will allow further scale-up of the technology for use in the Hanford High Level Waste Disposal Program (HLWDP) for up to four times the reference capacity

  1. Superplastic forming of 7475 Al sheet after friction stir processing (FSP)

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, M.; Bingel, W.H.; Fuller, C. [Rockwell Scientific Co., Thousand Oaks, CA (United States); Barnes, A.J. [Superform USA, Riverside, CA (United States)

    2004-07-01

    Since the invention of friction stir welding (FSW) in 1991, an increasing number of successful applications have been found for this unique solid-state welding technique. More recently, attention has been given to utilizing the mechanics of friction stirring to thermo-mechanically modify the microstructure of aluminum alloys to create or enhance superplasticity. Until now, superplasticity induced by friction stir processing (FSP) has only been demonstrated in small samples and evaluated by hot tensile elongation testing. The present work describes what we believe to be the first biaxial testing and full size component superplastic forming of friction stir processed aluminum sheet. The remarkable formability demonstrated in these 'first time' trials is described in detail. (orig.)

  2. Stirring turbulence with turbulence

    NARCIS (Netherlands)

    Cekli, H.E.; Joosten, R.; van de Water, W.

    2015-01-01

    We stir wind-tunnel turbulence with an active grid that consists of rods with attached vanes. The time-varying angle of these rods is controlled by random numbers. We study the response of turbulence on the statistical properties of these random numbers. The random numbers are generated by the

  3. Diagnostic performance of dark-blood T2-weighted CMR for evaluation of acute myocardial injury.

    Science.gov (United States)

    Srichai, Monvadi B; Lim, Ruth P; Lath, Narayan; Babb, James; Axel, Leon; Kim, Daniel

    2013-01-01

    We compared the image quality and diagnostic performance of 2 fat-suppression methods for black-blood T2-weighted fast spin-echo (FSE), which are as follows: (a) short T1 inversion recovery (STIR; FSE-STIR) and (b) spectral adiabatic inversion recovery (SPAIR; FSE-SPAIR), for detection of acute myocardial injury. Edema-sensitive T2-weighted FSE cardiac magnetic resonance (CMR) imaging is useful in detecting acute myocardial injury but may experience reduced myocardial signal and signal dropout. The SPAIR pulse aims to eliminate artifacts associated with the STIR pulse. A total of 65 consecutive patients referred for CMR evaluation of myocardial structure and function underwent FSE-STIR and FSE-SPAIR, in addition to cine and late gadolinium enhancement (LGE) CMR. T2-weighted FSE images were independently evaluated by 2 readers for image quality and artifacts (Likert scale of 1-5; best-worst) and presence of increased myocardial signal suggestive of edema. In addition, clinical CMR interpretation, incorporating all CMR sequences available, was recorded for comparison. Diagnostic performance of each T2-weighted sequence was measured using recent (T2, and wall motion. There was a statistically significant difference in sensitivity between the clinical interpretation and each of the T2-weighted sequences but not between each T2-weighted sequence. Although FSE-SPAIR demonstrated significantly improved image quality and decreased artifacts, isolated interpretations of each T2-weighted technique demonstrated high specificity but overall low sensitivity for the detection of myocardial injury, with no difference in accuracy between the techniques. However, real-world interpretation in combination with cine and LGE CMR methods significantly improves the overall sensitivity and diagnostic performance.

  4. Heat Control via Torque Control in Friction Stir Welding

    Science.gov (United States)

    Venable, Richard; Colligan, Kevin; Knapp, Alan

    2004-01-01

    In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

  5. Recent developments in Micro Friction Stir Welding: A review

    International Nuclear Information System (INIS)

    Sithole, Keydon; Rao, Veeredhi Vasudeva

    2016-01-01

    The advent of friction stir welding (FSW) in 1991 has been evolutionary in the joining of metals and related materials. Friction stir welding has enabled the joining of metals that could not be joined by other welding processes. Research has shown that dissimilar materials with very different properties, plastics, composites and even wood can be joined by FSW. Recent activities in the application of FSW has seen the development of micro friction stir welding (μFSW), which is the FSW of very thin sections of thickness 1000 μm (1 mm) or less. Micro friction stir welding further extends the applications of FSW to areas such as copper electrical contacts, tailor-welded blanks, wood. Though μFSW is relatively new development significant work has been done to date with interesting research findings being reported. This paper aims to review developments in μFSW to date. The focus of the paper will be on problems peculiar to μFSW due to downscaling to the micro scale and other practical considerations. (paper)

  6. Calibration and performance of a stirred benthic chamber

    Science.gov (United States)

    Buchholtz-ten Brink, M. R.; Gust, G.; Chavis, D.

    1989-07-01

    The physical and chemical boundary layer parameters characteristic for a benthic chamber were cross-calibrated by the use of two methods in the laboratory: (1) flush-mounted hot-film sensors, which measure the friction velocity u ∗, and (2) the alabaster dissolution technique, which measures the equivalent film thickness z. Tests of five stirring devices were made, using both techniques, to improve the stirring mechanism in the MANOP Lander flux chambers. The stirring device that was finally implemented consisted of four rods and produced spatially averaged friction velocities u ∗ ranging from 0.1 to 0.5 cm s -1 (i.e. mean film thickness z from 500 to 180 μm) when running at speeds from 3 to 9 rpm. The friction velocity field at the sediment surface is related to the rpm of the stirring device and the penetration depth of the chamber into the sediments; combinations of both can create z and u ∗ inside the chamber that duplicate those of many natural environments. The log-log calibration relationship found between u ∗ and transfer coefficients K' also provides a means to predict the mass-transfer resistance of solutes at the sediment-water interface from measurements of mean bottom stress.

  7. Weld defect identification in friction stir welding using power spectral density

    Science.gov (United States)

    Das, Bipul; Pal, Sukhomay; Bag, Swarup

    2018-04-01

    Power spectral density estimates are powerful in extraction of useful information retained in signal. In the current research work classical periodogram and Welch periodogram algorithms are used for the estimation of power spectral density for vertical force signal and transverse force signal acquired during friction stir welding process. The estimated spectral densities reveal notable insight in identification of defects in friction stir welded samples. It was observed that higher spectral density against each process signals is a key indication in identifying the presence of possible internal defects in the welded samples. The developed methodology can offer preliminary information regarding presence of internal defects in friction stir welded samples can be best accepted as first level of safeguard in monitoring the friction stir welding process.

  8. Recovery and treatment of uranium from uranium-containing solution by liquid membrane emulsion technology

    International Nuclear Information System (INIS)

    Xia Liangshu; Zhou Yantong; Xiao Yiqun; Peng Anguo; Xiao Jingshui; Chen Wei

    2014-01-01

    The recovery and treatment of uranium from uranium-containing solution using liquid membrane emulsion (LME) technology were studied in this paper, which contained the best volume ratio of membrane materials, stirring speed during emulsion process, the conditions of extracting, such as temperature, pH, initial concentration of uranium. Moreover, the mechanism for extracting uranium was also discussed. The best experimental conditions of emulsifying were acquired. The volume fractions of P 204 and liquid paraffin are 0.1 and 0.05, the volume ratios of Span80 and sulphonated kerosene to P 204 are 0.06 and 0.79 respectively, stirring speed is controlled in 2 000 r/min, and the concentration of inner phase is 4 mol/L. The recovery rate of uranium is up to 99% through the LME extracted uranium for 0.5 h at pH 2.5 and room temperature when the initial concentration is less than 400 mg/L and the volume ratio is 5 between the uranium-containing waste water and LME. The calculation results of Gibbs free energy show that the reaction process is spontaneous. (authors)

  9. Optimizing the stirring strategy for the vibrating intrinsic reverberation chamber

    NARCIS (Netherlands)

    Serra, Ramiro; Serra, Ramiro; Leferink, Frank Bernardus Johannes

    2010-01-01

    This work describes the definition, application and assessment of a factorial plan with the aim of gaining insight on what kind of stirring strategy could work the best in a vibrating intrinsic reverberation chamber. Three different stirring strategies were defined as factors of a factorial

  10. continuous stirred tank reactor (CSTR)

    African Journals Online (AJOL)

    AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search ... stirred tank reactor (CSTR) and the small and large intestines as plug flow reactor (PFR) ... from the two equations are used for the reactor sizing of the modeled reactors.

  11. Applications of Friction Stir Processing during Engraving of Soft Materials

    Directory of Open Access Journals (Sweden)

    V. Kočović

    2015-12-01

    Full Text Available Friction stir processing has extensive application in many technological operations. Application area of friction stir processing can be extended to the processing of non-metallic materials, such as wood. The paper examines the friction stir processing contact between a specially designed hard and temperature-resistant rotating tool and workpiece which is made of wood. Interval of speed slip and temperature level under which the combustion occurs and carbonization layer of soft material was determined. The results of the research can be applied in technological process of wood engraving operations which may have significant technological and aesthetic effects.

  12. Bioleaching of uranium in batch stirred tank reactor: Process optimization using Box–Behnken design

    International Nuclear Information System (INIS)

    Eisapour, M.; Keshtkar, A.; Moosavian, M.A.; Rashidi, A.

    2013-01-01

    Highlights: ► High amount of uranium recovery achieved using Acidithiobacillus ferrooxidans. ► ANOVA shows individual variables and their squares are statistically significant. ► The model can accurately predict the behavior of uranium recovery. ► The model shows that pulp density has the greatest effect on uranium recovery. - Abstract: To design industrial reactors, it is important to identify and optimize the effective parameters of the process. Therefore, in this study, a three-level Box–Behnken factorial design was employed combining with a response surface methodology to optimize pulp density, agitation speed and aeration rate in uranium bioleaching in a stirred tank reactor using a pure native culture of Acidithiobacillus ferrooxidans. A mathematical model was then developed by applying the least squares method using the software Minitab Version 16.1.0. The second order model represents the uranium recovery as a function of pulp density, agitation speed and aeration rate. An analysis of variance was carried out to investigate the effects of individual variables and their combined interactive effects on uranium recovery. The results showed that the linear and quadratic terms of variables were statistically significant whilst the interaction terms were statistically insignificant. The model estimated that a maximum uranium extraction (99.99%) could be obtained when the pulp density, agitation speed and aeration rate were set at optimized values of 5.8% w/v, 510 rpm and 250 l/h, respectively. A confirmatory test at the optimum conditions resulted in a uranium recovery of 95%, indicating a marginal error of 4.99%. Furthermore, control tests were performed to demonstrate the effect of A. ferrooxidans in uranium bioleaching process and showed that the addition of this microorganism greatly increases the uranium recovery

  13. Microstructure and properties of friction stir butt-welded AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Wang Xunhong; Wang Kuaishe

    2006-01-01

    Friction stir welding (FSW) is a relatively new joining technique particularly for magnesium and aluminum alloys that are difficult to fusion weld. In this paper, an excellent friction stir weld of AZ31 magnesium alloy was obtained at proper parameter. In the friction stir zone (FSZ), the microstructure of the base material (BM) is replaced by fine grains and small particles of intermetallic compounds. The average microhardness of the friction stir zone is higher than that of the base material. The maximum tensile strength of joint can reach 93% that of the base material. And the failure locations are almost at the heating affected zone

  14. Certification of a weld produced by friction stir welding

    Science.gov (United States)

    Obaditch, Chris; Grant, Glenn J

    2013-10-01

    Methods, devices, and systems for providing certification of friction stir welds are disclosed. A sensor is used to collect information related to a friction stir weld. Data from the sensor is compared to threshold values provided by an extrinsic standard setting organizations using a certification engine. The certification engine subsequently produces a report on the certification status of the weld.

  15. Effect of Fluidized Bed Stirring on Drying Process of Adhesive Particles

    Directory of Open Access Journals (Sweden)

    P. Hoffman

    2017-04-01

    Full Text Available This paper presents an attempt to optimize fluidized bed drying of wet and adhesive particles (with an initial diameter of about 580 mm with the use of stirring, and discusses the influence of stirring on the total drying time. The goal was to demonstrate the positive effect of stirring a fluidized bed to the drying time, to find the optimal parameters (stirrer design, speed, and size. Experiments were conducted on a drying chamber in batch operation. The objective was to evaluate the effect of stirring on the total drying time. The drying chambers were 85 mm, 100 mm, and 140 mm in diameter. An optimal stirrer shape and speed were specified. Our arrangement of the fluidized bed resulted in a decrease in drying time by up to 40 %.

  16. Polydimethylsiloxane/covalent triazine frameworks coated stir bar sorptive extraction coupled with high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental water samples.

    Science.gov (United States)

    Zhong, Cheng; He, Man; Liao, Huaping; Chen, Beibei; Wang, Cheng; Hu, Bin

    2016-04-08

    In this work, covalent triazine frameworks (CTFs) were introduced in stir bar sorptive extraction (SBSE) and a novel polydimethylsiloxane(PDMS)/CTFs stir bar coating was prepared by sol-gel technique for the sorptive extraction of eight phenols (including phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-chloro-m-cresol and 2,4-dichlorophenol, 2,4,6-trichlorophenol) from environmental water samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The prepared PDMS/CTFs coated stir bar showed good preparation reproducibility with the relative standard deviations (RSDs) ranging from 3.5 to 5.7% (n=7) in one batch, and from 3.7 to 9.3% (n=7) among different batches. Several parameters affecting SBSE of eight target phenols including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.08-0.30 μg/L. The linear range was 0.25-500 μg/L for 2-nitrophenol, 0.5-500 μg/L for phenol, 2-chlorophenol, 4-nitrophenol as well as 2,4-dimethylphenol, and 1-500 μg/L for p-chloro-m-cresol, 2,4-dichlorophenol as well as 2,4,6-trichlorophenol, respectively. The intra-day relative standard deviations (RSDs) were in the range of 4.3-9.4% (n=7, c=2 μg/L) and the enrichment factors ranged from 64.9 to 145.6 fold (theoretical enrichment factor was 200-fold). Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/CTFs stir bar showed better extraction efficiency for target phenol compounds. The proposed method was successfully applied to the analysis of phenols in environmental water samples and good relative recoveries were obtained with the spiking level at 2, 10, 50 μg/L, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Quantitative magnetization transfer imaging of rodent glioma using selective inversion recovery.

    Science.gov (United States)

    Xu, Junzhong; Li, Ke; Zu, Zhongliang; Li, Xia; Gochberg, Daniel F; Gore, John C

    2014-03-01

    Magnetization transfer (MT) provides an indirect means to detect noninvasively variations in macromolecular contents in biological tissues, but, so far, there have been only a few quantitative MT (qMT) studies reported in cancer, all of which used off-resonance pulsed saturation methods. This article describes the first implementation of a different qMT approach, selective inversion recovery (SIR), for the characterization of tumor in vivo using a rodent glioma model. The SIR method is an on-resonance method capable of fitting qMT parameters and T1 relaxation time simultaneously without mapping B0 and B1 , which is very suitable for high-field qMT measurements because of the lower saturation absorption rate. The results show that the average pool size ratio (PSR, the macromolecular pool versus the free water pool) in rat 9 L glioma (5.7%) is significantly lower than that in normal rat gray matter (9.2%) and white matter (17.4%), which suggests that PSR is potentially a sensitive imaging biomarker for the assessment of brain tumor. Despite being less robust, the estimated MT exchange rates also show clear differences from normal tissues (19.7 Hz for tumors versus 14.8 and 10.2 Hz for gray and white mater, respectively). In addition, the influence of confounding effects, e.g. B1 inhomogeneity, on qMT parameter estimates is investigated with numerical simulations. These findings not only help to better understand the changes in the macromolecular contents of tumors, but are also important for the interpretation of other imaging contrasts, such as chemical exchange saturation transfer of tumors. Copyright © 2013 John Wiley & Sons, Ltd.

  18. Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

    Science.gov (United States)

    2013-08-01

    Sterling, R.J. Steel, C.-O. Pettersson. “Microstructure and mechanical properties of friction stir welded SAF 2507 super duplex stainless steel.” Mater...MICROSTRUCTURAL CHARACTERIZATION OF FRICTION STIR WELDED ALUMINUM-STEEL JOINTS By ERIN ELIZABETH PATTERSON A thesis submitted in...for his work producing the dissimilar weld samples used in this study. Without his work, this project would not have been possible. I would also

  19. Creep and inverse stress relaxation behaviors of carbon nanotube yarns.

    Science.gov (United States)

    Misak, H E; Sabelkin, V; Miller, L; Asmatulu, R; Mall, S

    2013-12-01

    Creep, creep recovery and inverse stress relaxation behaviors of carbon nanotube yarns that consisted of 1-, 30-, and 100-yarn(s) were characterized. Primary and secondary creep stages were observed over the duration of 336 h. The primary creep stage lasted for about 4 h at an applied load equal to 75% of the ultimate tensile strength. The total strain in the primary stage was significantly larger in the carbon nanotube multi-yarn than in the carbon nanotube 1-yarn. In the secondary stage, 1-yarn also had a smaller steady state strain rate than the multi-yarn, and it was independent of number of yarns in multi-yarn. Strain response under cyclic creep loading condition was comparable to its counterpart in non-cyclic (i.e., standard) creep test except that strain response during the first cycle was slightly different from the subsequent cycles. Inverse creep (i.e., strain recovery) was observed in the 100-yarn during the cyclic creep tests after the first unloading cycle. Furthermore, inverse stress relaxation of the multi-yarns was characterized. Inverse stress relaxation was larger and for longer duration with the larger number of yarns.

  20. C18-coated stir bar sorptive extraction combined with high performance liquid chromatography-electrospray tandem mass spectrometry for the analysis of sulfonamides in milk and milk powder.

    Science.gov (United States)

    Yu, Chunhe; Hu, Bin

    2012-02-15

    A simple, rapid, sensitive, inexpensive and less sample consuming method of C(18)-stir bar sorptive extraction (SBSE)-high performance liquid chromatography (HPLC)-tandem mass spectrometry (MS/MS) was proposed for the determination of six sulfonamides in milk and milk powder samples. C(18) silica particles coated stir bar was prepared by adhesion method, and two kinds of adhesive glue, polydimethylsiloxane (PDMS) sol and epoxy glue were tried. It was found that the C(18)-coated stir bar prepared by PDMS sol as adhesive glue is more robust than that prepared by epoxy glue when liquid desorption was employed, in terms of both lifetime and organic solvent tolerance. The preparation of C(18) stir bar was simple with good mechanic strength and the stir bar could be reused for more than 20 times. Granular coating has relatively high specific surface area and is propitious to sorptive extraction based process. Compared to conventional PDMS SBSE coating, C(18) coating shows good affinity to the target polar/weak polar sulfonamides. To achieve optimum SBSE extraction performance, several parameters including extraction and desorption time, ionic strength, sample pH and stirring speed were investigated. The detection limits of the proposed method for six sulfonamides were in the range of 0.9-10.5 μg/L for milk and 2.7-31.5 μg/kg for milk powder. Good linearities were obtained for sulfonamides with the correlation coefficients (R) above 0.9922. Finally, the proposed method was successfully applied to the determination of sulfonamides in milk and milk powder samples and satisfied recoveries of spiked target compounds in real samples were obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. The Inverse Response Law: Theory and Relevance to the Aftermath of Disasters

    Directory of Open Access Journals (Sweden)

    Suzanne Phibbs

    2018-05-01

    Full Text Available The Inverse Care Law is principally concerned with the effect of market forces on health care which create inequities in access to health services through privileging individuals who possess the forms of social capital that are valued within health care settings. The fields of disaster risk reduction need to consider the ways in which inequities, driven by economic and social policy as well as institutional decision-making, create vulnerabilities prior to a disaster, which are then magnified post disaster through entrenched structural differences in access to resources. Drawing on key principles within the Inverse Care Law, the Inverse Response Law refers to the idea that people in lower socio-economic groups are more likely to be impacted and to experience disparities in service provision during the disaster response and recovery phase. In a market model of recovery, vulnerable groups struggle to compete for necessary services creating inequities in adaptive capacity as well as in social and wellbeing outcomes over time. Both the Inverse Care Law and the Inverse Response Law focus on the structural organisation of services at a macro level. In this article, the Inverse Care Law is outlined, its application to medical treatment following disasters considered and an explanation of the Inverse Response Law provided. Case studies from recent disasters, in London, New Zealand, Puerto Rico and Mexico City are examined in order to illustrate themes at work relating to the Inverse Response Law.

  2. In-syringe magnetic-stirring-assisted liquid-liquid microextraction for the spectrophotometric determination of Cr(VI) in waters.

    Science.gov (United States)

    Henríquez, Camelia; Horstkotte, Burkhard; Solich, Petr; Cerdà, Víctor

    2013-08-01

    A fully automated method for the determination of chromate is described. It is based on the selective reaction of Cr(VI) with diphenylcarbazide in acidic media to form a colored complex of Cr(III) with the oxidation product diphenylcarbazone. The reaction was performed within the syringe of an automatic burette containing a magnetic stirrer for homogenization of the sample and the required reagents. In-syringe stirring was made possible using a specially designed driving device placed around the syringe barrel to achieve a rotating magnetic field in the syringe, forcing the stirrer to spin. In a second step, the reaction mixture in the syringe was neutralized to allow in-syringe magnetic-stirring-assisted dispersive liquid-liquid microextraction of the complex into 125 μL of n-hexanol. After phase separation by droplet flotation over 30 s, the organic phase was propelled into a coupled spectrophotometric detection cell. The entire multistep procedure including in-system standard preparation was done within 270 s. The method was used for the analysis of natural waters, achieving average analyte recovery of 103%, a limit of detection of 0.26 μg L(-1), and a repeatability of less than 4% relative standard deviation.

  3. Unraveling the Processing Parameters in Friction Stir Welding

    Science.gov (United States)

    Schneider, Judy; Nunes, Arthur C., Jr.

    2005-01-01

    In friction stir welding (FSW), a rotating threaded pin tool is translated along a weld seam, literally stirring the edges of the seam together. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path or paths is required. In this study, various markers are used to trace the flow paths of the metal. X-ray radiographs record the segmentation and position of the wire. Several variations in the trajectories can be differentiated within the weld zone.

  4. Effect of Stirring and Seeding on Whey Protein Fibril Formation

    NARCIS (Netherlands)

    Bolder, S.G.; Sagis, L.M.C.; Venema, P.; Linden, van der E.

    2007-01-01

    The effect of stirring and seeding on the formation of fibrils in whey protein isolate (WPI) solutions was studied. More fibrils of a similar length are formed when WPI is stirred during heating at pH 2 and 80 C compared to samples that were heated at rest. Addition of seeds did not show an

  5. A Rotating Plug Model of Friction Stir Welding Heat Transfer

    Science.gov (United States)

    Raghulapadu J. K.; Peddieson, J.; Buchanan, G. R.; Nunes, A. C.

    2006-01-01

    A simplified rotating plug model is employed to study the heat transfer phenomena associated with the fiction stir welding process. An approximate analytical solution is obtained based on this idealized model and used both to demonstrate the qualitative influence of process parameters on predictions and to estimate temperatures produced in typical fiction stir welding situations.

  6. Lesion discrimination in optic neuritis using high-resolution fat-suppressed fast spin-echo MRI

    International Nuclear Information System (INIS)

    Gass, A.; Moseley, I.F.; Barker, G.J.; Jones, S.; MacManus, D.; McDonald, W.I.; Miller, D.H.

    1996-01-01

    Fast spin-echo (FSE) is a new sequence with acquisition times currently down to one-sixteenth of those obtained with conventional spin-echo sequences, which allows high-resolution (512 x 512 matrix) images to be acquired in an acceptable time. We compared the higher resolution of FSE with the medium resolution of a short inversion-time inversion-recovery (STIR) sequence in depicting the optic nerves of healthy controls and patients with optic neuritis. Optic nerve MRI examinations were performed in 18 patients with optic neuritis and 10 normal controls. Two sequences were obtained coronally: fat-suppressed FSE (FSE TR 3250 ms/TEef 68 ms, echo-train length 16, 4 excitations, 24 cm rectangular field of view, 3 mm interleaved contiguous slices, in-plane resolution 0.5 x 0.5 mm) and STIR (TR 2000 ms/TE 50 ms/TI 175 ms, in-plane resolution 0.8 x 0.8 mm, slice thickness 5 mm). FSE demonstrated much more anatomical detail than STIR, e. g. distinction of optic nerve and sheath. Lesions were seen in 20 of 21 symptomatic nerves using FSE and in 18 of 21 using STIR. Nerve swelling or partial cross-sectional lesions of the optic nerve were each seen only on FSE in 3 cases. Fat-suppressed FSE imaging of the optic nerve improves anatomical definition and increases lesion detection in optic neuritis. (orig.). With 5 figs

  7. Improvement of lipase production at different stirring speeds and oxygen levels

    Directory of Open Access Journals (Sweden)

    F.O.M. Alonso

    2005-03-01

    Full Text Available Lipase production by a Brazilian wild strain of Yarrowia lipolytica at different stirring speeds and air flow rates was studied. The relationship among lipid consumption, cell growth and lipase production by this microorganism is presented. The most pronounced effect of oxygen on lipase production was determined by stirring speed. Maximum lipase activity was detected in the late stationary phase at 200 rpm and an air flow rate of 1-2 dm³/min (0.8-1.7 vvm when the lipid source had been fully consumed. Higher stirring speeds resulted in mechanical and/or oxidative stress, while lower stirring speeds seemed to limit oxygen levels. An increase in the availability of oxygen at higher air flow rates led to faster lipid uptake and anticipation of enzyme release into the culture medium. The highest lipase production was obtained at 200 rpm and 1 dm³/min (0.8 vvm.

  8. ECMOR 4. 4th European conference on the mathematics of oil recovery. Topic E: History match and recovery optimization. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1994-01-01

    The report with collected proceedings from a conference, deals with mathematics of oil recovery with the focus on history match and recovery optimization. Topics of proceedings are as follow: Calculating optimal parameters for history matching; new technique to improve the efficiency of history matching of full-field models; flow constrained reservoir characterization using Bayesian inversion; analysis of multi-well pressure transient data; new approach combining neural networks and simulated annealing for solving petroleum inverse problems; automatic history matching by use of response surfaces and experimental design; determining the optimum location of a production well in oil reservoirs. Seven papers are prepared. 108 refs., 45 figs., 12 tabs.

  9. MR imaging in shoulder trauma. Value of STIR images

    International Nuclear Information System (INIS)

    Rand, T.; Trattnig, S.; Haller, J.; Imhof, H.; Nguyen, N.K.

    1998-01-01

    Purpose: To determine the adequacy of MR standard protocols by analyzing conventional T1- and T2-weighted SE sequences, and to evaluate the usefulness of additional fat-suppressed (STIR) images in shoulder trauma. Material and Methods: Paracoronal T1-weighted, T2-weighted SE, and STIR images were obtained on a 0.5 T superconductive system in 25 patients with shoulder trauma. In a separate evaluation of T1/T2 images and a combined evaluation of T1/T2 SE- and STIR images, we compared the number of patients with evidence of Hill-Sachs lesions, bone bruises, and/or rotator-cuff lesions. Results: Compared to the combined evaluation of T1/T2 and STIR images, the separate evaluation of T1/T2 SE images revealed identical results for rotator-cuff lesions and Hill-Sachs lesions, but different results for the bone bruises in the area of the major tubercle. Conclusion: Occult fractures of the major tubercle, indicated by areas of bone bruising, might be missed with MR using conventional SE images. We recommend the use of additional paracoronal fat-suppressed sequences in patients with clinically suspected lesions and equivocal findings on plain radiographs and on standard SE sequences. (orig.)

  10. The effect of feed rate and recycle rate variable on leaching process of Na2Zro3 with HCl in continuous stirred tank reactor (CSTR) series

    Science.gov (United States)

    Palupi, Bekti; Supranto, Sediawan, Wahyudi Budi; Setyadji, Moch.

    2017-05-01

    This time, the natural resources of zircon sand is processed into several zirconium products which is utilized for various industries, such as ceramics, glass industry, metal industry and nuclear industry. The process of zircon sand into zirconium products through several stages, one of them is leaching process of Na2ZrO3 with HCl. In this research, several variations of recycle-rate/feed-rate had been done to determine the effect on leaching process. The leaching was processed at temperature of 90°C, ratio of Na2ZrO3:HCl = 1g:30mL, and 142 rotary per minute of stirring speed for 30 minutes with variation of recycle-rate/feed-rate such as 0.478, 0.299, 0.218, 0.171 and 0.141. The diameter size of Na2ZrO3 powder that used are 0.088 to 0.149 mm. This process was carried out in Continuous Stirred Tank Reactor (CSTR) series with recycle. Based on this research, the greater of the recycle-rate/feed-rate variable, the obtained Zr recovery decreased. The correlation between recycle-rate/feed-rate and Zr recovery is shown by the equation y = -146.91x + 103.51, where y is the Zr recovery and x is the recycle-rate/feed-rate. The highest Zr recovery was 90.52% obtained at recycle-rate/feed-rate 0.141. The mathematical modeling involving the probability model P(r) = 2β2r2 exp(-βr2) can be applied to this leaching process with Sum of Squared Errors (SSE) values in the range of 6×10-7 - 7×10-6.

  11. The Effect of Rotation Stirring on Macrosegregation in Bi-Sn Alloy

    Directory of Open Access Journals (Sweden)

    Zulaida Yeni Muriani

    2017-01-01

    Full Text Available Macrosegregation is a defect that difficult to avoid in a metal alloy made by casting method. Macrosegregation can cause decreasing in mechanical properties of casting products. It will reduce their performance in industrial application. Macrosegregation is convinced occur during solidification time in liquid alloy. In the early solidified, The solids move upward/downward in liquid alloy during solidification are considered to contribute on macrosegregation formation. This movement occur due to the density differences between the solid and the surrounding liquid. This research want to observe the effect of stirring on macrosegregation formation for interfering on the movement of initial solidified solid. Stiring with rotation method is applied in this experiment at certain temperature. The temperature and the rotation speed of stirring are varied to observe the effect of rotation stirring on macrosegregation formation. The mold is covered by insulation jacket and kept the bottom part opened in order to obtain the directionally solidification. The result shows that the rotation stirring can change the macrostructure of casting but in case of composition distribution, the macrosegregation still appear. Increasing the rotation stirring will rise solid crystals up and the macrosegregation become more uniform and the treatment is better if conducting at lower temperature.

  12. Recovery of gold and uranium from calcines

    Energy Technology Data Exchange (ETDEWEB)

    Livesey-Goldblatt, E.

    1981-10-06

    The invention concerns the recovery of non-ferrous metals, such as gold, uranium or the like from iron oxide containing calcines which have the non-ferrous metal present in solid solution and/or encapsulated within the iron oxide. The calcine is reacted, while stirring vigorously, with sulphuric acid or another strong inorganic acid to cause the iron to form the ferric salt. The material obtained is mixed with water and the liquid and solid phases are separated from each other. The non-ferrous metal is then obtained from at least one of these phases by leaching, or the like.

  13. Recent Developments and Research Progress on Friction Stir Welding of Titanium Alloys: An Overview

    Science.gov (United States)

    Karna, Sivaji; Cheepu, Muralimohan; Venkateswarulu, D.; Srikanth, V.

    2018-03-01

    Titanium and its alloys are joined by various welding processes. However, Fusion welding of titanium alloys resulted solidification problems like porosity, segregation and columnar grains. The problems occurred in conventional welding processes can be resolved using a solid state welding i.e. friction stir welding. Aluminium and Magnesium alloys were welded by friction stir welding. However alloys used for high temperature applications such as titanium alloys and steels are arduous to weld using friction stir welding process because of tool limitations. Present paper summarises the studies on joining of Titanium alloys using friction stir welding with different tool materials. Selection of tool material and effect of welding conditions on mechanical and microstructure properties of weldments were also reported. Major advantage with friction stir welding is, we can control the welding temperature above or below β-transus temperature by optimizing the process parameters. Stir zone in below beta transus condition consists of bi-modal microstructure and microstructure in above β-transus condition has large prior β- grains and α/β laths present in the grain. Welding experiments conducted below β- transus condition has better mechanical properties than welding at above β-transus condition. Hardness and tensile properties of weldments are correlated with the stir zone microstructure.

  14. Inverse osmotic process for radioactive laundry waste

    Energy Technology Data Exchange (ETDEWEB)

    Ebara, K; Takahashi, S; Sugimoto, Y; Yusa, H; Hyakutake, H

    1977-01-07

    Purpose: To effectively recover the processing amount reduced in a continuous treatment. Method: Laundry waste containing radioactive substances discharged from a nuclear power plant is processed in an inverse osmotic process while adding starch digesting enzymes such as amylase and takadiastase, as well as soft spherical bodies such as sponge balls of a particle diameter capable of flowing in the flow of the liquid wastes along the inverse osmotic membrane pipe and having such a softness and roundness as not to damage the inverse osmotic membrane. This process can remove the floating materials such as thread dusts or hairs deposited on the membrane surface by the action of the soft elastic balls and remove paste or the like through decomposition by the digesting enzymes. Consequently, effective recovery can be attained for the reduced processing amount.

  15. Neuroblastoma

    International Nuclear Information System (INIS)

    Hall-Craggs, M.A.; Finn, J.P.; Dicks-Mireaux, C.; Kiely, E.M.; Pritchard, J.

    1989-01-01

    Twenty-one children with neuroblastoma (mean age, 36.7 months) were examined with high-field strength (1.5 T) MR imaging to define how accurately disease could be documented and to establish optimum sequences. Twenty-eight studies were obtained with T1- and T2-weighted spin-echo and short inversion-recovery (STIR) sequences. Thirteen children underwent surgery, 16 CT. MR imaging exactly predicted tumor extent and involvement of adjacent organs, vessels, and the spine in all patients undergoing surgery. STIR images defined tumor margins and node involvement most clearly. Following chemotherapy, MR imaging could not differentiate active tumor from maturing ganglioneuroma or residual hyperplasia. MR imaging was superior to CT in assessing intraabdominal, marrow, and spinal disease

  16. Friction stir spot welding of dissimilar aluminium alloys

    International Nuclear Information System (INIS)

    Bozkurt, Yahya

    2016-01-01

    Friction stir spot welding (FSSW) has been proposed as an effective technology to spot weld the so-called “difficult to be welded” metal alloys such as thin sheets aluminum alloys and dissimilar materials. FSSW is derived from friction stir welding technology, its principle benefit being low cost joining, lower welding temperature and shorter welding time than conventional welding methods. In this study, dissimilar AlMg 3 and AlCu 4 Mg 1 aluminium alloy plates were FSSWed by offsetting the low strength sheet on upper side of the weld. The effects of tool rotation speed on the microstructure, lap shear fracture load (LSFL), microhardness and fracture features of the weld are investigated by constant welding parameters. The maximum LSFL was obtained by increasing the tool rotational speed. However, the joints exhibited pull-out nugget fracture mode under lap shear tensile testing conditions. The largest completely bonded zone was observed as 5.86 mm which was narrower at the opposite position of the joint. Key words: friction stir spot welding, aluminium alloys, mechanical properties, dissimilar joint, welding parameters

  17. New Materials Design Through Friction Stir Processing Techniques

    International Nuclear Information System (INIS)

    Buffa, G.; Fratini, L.; Shivpuri, R.

    2007-01-01

    Friction Stir Welding (FSW) has reached a large interest in the scientific community and in the last years also in the industrial environment, due to the advantages of such solid state welding process with respect to the classic ones. The complex material flow occurring during the process plays a fundamental role in such solid state welding process, since it determines dramatic changes in the material microstructure of the so called weld nugget, which affects the effectiveness of the joints. What is more, Friction Stir Processing (FSP) is mainly being considered for producing high-strain-rate-superplastic (HSRS) microstructure in commercial aluminum alloys. The aim of the present research is the development of a locally composite material through the Friction Stir Processing (FSP) of two AA7075-T6 blanks and a different material insert. The results of a preliminary experimental campaign, carried out at the varying of the additional material placed at the sheets interface under different conditions, are presented. Micro and macro observation of the such obtained joints permitted to investigate the effects of such process on the overall joint performance

  18. Stir bar sorptive extraction with EG-Silicone coating for bisphenols determination in personal care products by GC-MS.

    Science.gov (United States)

    Cacho, Juan Ignacio; Campillo, Natalia; Viñas, Pilar; Hernández-Córdoba, Manuel

    2013-05-05

    An easy to perform analytical method for the determination of three bisphenol compounds (BPs) in commonly used personal care products (PCPs) is presented. Ethylene glycol-silicone (EG-Silicone) coated stir bars, which have recently become commercially available, are evaluated in this study for the simultaneous determination of bisphenol A (BPA), bisphenol F (BPF) and bisphenol Z (BPZ) by stir bar sorptive extraction (SBSE) in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). This new sorptive extraction phase allows the analysis of these compounds without any previous derivatization procedure. Different parameters affecting both SBSE extraction and thermal desorption were carefully optimized, using experimental designs based on the Taguchi orthogonal arrays. The procedure was applied to analyzing easily bought PCPs, providing detection limits of about 8 ng g(-1), with precisions lower than 11% in terms of relative standard deviation. Recovery studies performed at two different concentration levels provided satisfactory values for all the compounds. The analyzed personal care samples contained BPA at concentration levels ranging from 30.9 to 88.3 ng g(-1). Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Study of Low Flow Rate Ladle Bottom Gas Stirring Using Triaxial Vibration Signals

    Science.gov (United States)

    Yenus, Jaefer; Brooks, Geoffrey; Dunn, Michelle; Li, Zushu; Goodwin, Tim

    2018-02-01

    Secondary steelmaking plays a great role in enhancing the quality of the final steel product. The metal quality is a function of metal bath stirring in ladles. The metal bath is often stirred by an inert gas to achieve maximum compositional and thermal uniformity throughout the melt. Ladle operators often observe the top surface phenomena, such as level of meniscus disturbance, to evaluate the status of stirring. However, this type of monitoring has significant limitations in assessing the process accurately especially at low gas flow rate bubbling. The present study investigates stirring phenomena using ladle wall triaxial vibration at a low flow rate on a steel-made laboratory model and plant scale for the case of the vacuum tank degasser. Cold model and plant data were successfully modeled by partial least-squares regression to predict the amount of stirring. In the cold model, it was found that the combined vibration signal could predict the stirring power and recirculation speed effectively in specific frequency ranges. Plant trials also revealed that there is a high structure in each data set and in the same frequency ranges at the water model. In the case of industrial data, the degree of linear relationship was strong for data taken from a single heat.

  20. Time-Lapse Joint Inversion of Cross-Well DC Resistivity and Seismic Data: A Numerical Investigation

    Science.gov (United States)

    Time-lapse joint inversion of geophysical data is required to image the evolution of oil reservoirs during production and enhanced oil recovery, CO2 sequestration, geothermal fields during production, and to monitor the evolution of contaminant plumes. Joint inversion schemes red...

  1. Effects of Fusion Tack Welds on Self-Reacting Friction Stir Welds

    Science.gov (United States)

    Nunes, A. C., Jr.; Pendleton, M. L.; Brooke, S. A.; Russell, C. K.

    2012-01-01

    In order to know whether fusion tack welds would affect the strength of self-reacting friction stir seam welds in 2195-T87 aluminum alloy, the fracture stresses of 144 tensile test coupons cut from 24 welded panels containing segments of friction stir welds were measured. Each of the panels was welded under unique processing conditions. A measure of the effect of the tack welds for each panel was devised. An analysis of the measures of the tack weld effect supported the hypothesis that fusion tack welds do not affect the strength of self-reacting friction stir welds to a 5% level of confidence.

  2. Simultaneous inversion of seismic velocity and moment tensor using elastic-waveform inversion of microseismic data: Application to the Aneth CO2-EOR field

    Science.gov (United States)

    Chen, Y.; Huang, L.

    2017-12-01

    Moment tensors are key parameters for characterizing CO2-injection-induced microseismic events. Elastic-waveform inversion has the potential to providing accurate results of moment tensors. Microseismic waveforms contains information of source moment tensors and the wave propagation velocity along the wavepaths. We develop an elastic-waveform inversion method to jointly invert the seismic velocity model and moment tensor. We first use our adaptive moment-tensor joint inversion method to estimate moment tensors of microseismic events. Our adaptive moment-tensor inversion method jointly inverts multiple microseismic events with similar waveforms within a cluster to reduce inversion uncertainty for microseismic data recorded using a single borehole geophone array. We use this inversion result as the initial model for our elastic-waveform inversion to minimize the cross-correlated-based data misfit between observed data and synthetic data. We verify our method using synthetic microseismic data and obtain improved results of both moment tensors and seismic velocity model. We apply our new inversion method to microseismic data acquired at a CO2-enhanced oil recovery field in Aneth, Utah, using a single borehole geophone array. The results demonstrate that our new inversion method significantly reduces the data misfit compared to the conventional ray-theory-based moment-tensor inversion.

  3. Effects of Laser Peening, and Shot Peening, on Friction Stir Welding

    Science.gov (United States)

    Hatamleh, Omar; Hackel, Lloyd; Rankin, Jon; Truong, Chanh; Walter, Matt

    2006-01-01

    A viewgraph presentation describing the effects of laser peening and shot peening on friction stir welding is shown. The topics include: 1) Background; 2) Friction Stir Welding (FSW); 3) Microstructure; 4) Laser & Shot Peening; 5) Residual Stresses; 6) Tensile Behavior; 7) Fatigue Life & Surface Roughness; 8) Crack Growth; and 9) Benefits.

  4. Innovative bioelectrochemical-anaerobic-digestion integrated system for ammonia recovery and bioenergy production from ammonia-rich residues

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2015-01-01

    (SMRC) and a continuous stirred tank reactor (CSTR), to prevent ammonia toxicity during anaerobic digestion by in-situ ammonia recovery and electricity production (Figure 1). In batch experiment, the ammonia concentration in the CSTR decreased from 6 to 0.7 g-N/L with an average recovery rate of 0.18 g-N/L(CSTR...... performance was enhanced. In addition, the coexistence of other cations in CSTR or cathode had no negative effect on the ammonia transportation. In continuous reactor operation, 112% extra biogas production was achieved due to ammonia recovery. High-throughput molecular sequencing analysis showed an impact...... of ammonia recovery on the microbial community composition in the integrated system. Results clearly indicate the great potential of the SMRC-CSTR-coupled system for efficient and cost-effective ammonia recovery, energy production and treatment of ammonia-rich residues....

  5. Graphene oxide-coated stir bar sorptive extraction of trace aflatoxins from soy milk followed by high performance liquid chromatography-laser-induced fluorescence detection.

    Science.gov (United States)

    Ma, Haiyan; Ran, Congcong; Li, Mengjiao; Gao, Jinglin; Wang, Xinyu; Zhang, Lina; Bian, Jing; Li, Junmei; Jiang, Ye

    2018-04-01

    Mycotoxins are potential food pollutants produced by fungi. Among them, aflatoxins (AFs) are the most toxic. Therefore, AFs were selected as models, and a sensitive, simple and green graphene oxide (GO)-based stir bar sorptive extraction (SBSE) method was developed for extraction and determination of AFs with high performance liquid chromatography-laser-induced fluorescence detector (HPLC-LIF). This method improved the sensitivity of AFs detection and solved the deposition difficulty of the direct use of GO as adsorbent. Several parameters including a spiked amount of NaCl, stirring rate, extraction time and desorption time were investigated. Under optimal conditions, the quantitative method had low limits of detection of 2.4-8.0 pg/mL, which were better than some reported AFs analytical methods. The developed method has been applied to soy milk samples with good recoveries ranging from 80.5 to 102.3%. The prepared GO-based SBSE can be used as a sensitive screening technique for detecting AFs in soy milk.

  6. Microstructure and mechanical properties of friction stir welded SAF 2507 super duplex stainless steel

    International Nuclear Information System (INIS)

    Sato, Y.S.; Nelson, T.W.; Sterling, C.J.; Steel, R.J.; Pettersson, C.-O.

    2005-01-01

    The microstructure and mechanical properties of friction stir (FS) welded SAF 2507 super duplex stainless steel were examined. High-quality, full-penetration welds were successfully produced in the super duplex stainless steel by friction stir welding (FSW) using polycrystalline cubic boron nitride (PCBN) tool. The base material had a microstructure consisting of the ferrite matrix with austenite islands, but FSW refined grains of the ferrite and austenite phases in the stir zone through dynamic recrystallisation. Ferrite content was held between 50 and 60% throughout the weld. The smaller grain sizes of the ferrite and austenite phases caused increase in hardness and strength within the stir zone. Welded transverse tensile specimen failed near the border between the stir zone and TMAZ at the retreating side as the weld had roughly the same strengths as the base material

  7. Counteracting ammonia inhibition during anaerobic digestion by recovery using submersible microbial desalination cell

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2015-01-01

    Ammonia inhibition is one of the most frequent and serious problems in biogas plants. In this study, a novel hybrid system consisting of a submersible microbial desalination cell (SMDC) and a continuous stirred tank reactor (CSTR) was developed for counteracting ammonia inhibition during anaerobic...... digestion (AD) with simultaneous in situ ammonia recovery and electricity production. The SMDC was powered by acetate in a buffer solution, while synthetic ammonia-rich wastewater was used as the feeding of the CSTR. Under continuous operation, ammonia recovery rate of 86 g-N/m2 /day and current density...... of 4.33 A/m2 were achieved at steady-state condition. As a result, 112% extra biogas was produced due to ammonia recovery by the SMDC. High-throughput sequencing showed that ammonia recovery had an impact on the microbial community structures in the SMDC and CSTR. Considering the additional economic...

  8. Influence of fluid-attenuated inversion-recovery on stroke apparent diffusion coefficient measurements and its clinical application

    Energy Technology Data Exchange (ETDEWEB)

    Ni Jianming [Medical Imaging Department, Wuxi Second Hospital Affiliated Nanjing Medical University, 68 Zhong Shan Road, Wuxi, Jiangsu Province 214002 (China); Radiology Department, Huashan Hospital, Shanghai Medical College, Fudan University, 12 Urumqi Middle Road, Shanghai 200040 (China); Nuclear Medicine Department, Renji Hospital, Medical School of Jiaotong University, Dongfang Road 1630, Shanghai 200127 (China); Mogensen, Monique A. [Department of Radiology, Division of Neuroradiology, University of Southern California, Los Angeles, CA (United States); Chen Zengai [Radiology Department, Huashan Hospital, Shanghai Medical College, Fudan University, 12 Urumqi Middle Road, Shanghai 200040 (China); Nuclear Medicine Department, Renji Hospital, Medical School of Jiaotong University, Dongfang Road 1630, Shanghai 200127 (China); Shuang Chen; Shen Tianzhen [Radiology Department, Huashan Hospital, Shanghai Medical College, Fudan University, 12 Urumqi Middle Road, Shanghai 200040 (China); Huang Gang, E-mail: huang2802@163.co [Nuclear Medicine Department, Renji Hospital, Medical School of Jiaotong University, Dongfang Road 1630, Shanghai 200127 (China)

    2010-08-15

    Background and purpose: The application of a fluid-attenuated inversion-recovery pulse with a conventional diffusion-weighted MRI sequence (FLAIR DWI) decreases the partial volume effects from cerebrospinal fluid on apparent diffusion coefficient (ADC) measurements. For this reason, FLAIR DWI may be more useful in the evaluation of ischemic stroke, but few studies have looked at the effect of FLAIR on ADC measurements in this setting. This study quantitatively compares FLAIR DWI and conventional DWI in ischemic stroke of varying ages to assess the potential advantages of this technique. Methods: We respectively analyzed 139 DWI studies in patients with ischemic stroke with and without FLAIR at varying time points ranging from hyperacute to chronic. ADC values were measured in each lesion, as well as in the contralateral normal side. Comparisons were made between the ADC values obtained from the DWI sequences with and without FLAIR for both the lesion and the normal contralateral side. Results: The ADC measurements within the ischemic lesion were very similar on FLAIR DWI and conventional DWI for lesions less than 14 days old (p > 0.05), but were significantly decreased on FLAIR DWI for lesions between 15 and 30 days old and in lesions >31 days old (chronic stage) (p < 0.01). The contralateral ADC values were all significantly decreased on the FLAIR DWI sequence compared with conventional DWI (p < 0.01). Conclusions: The application of an inversion pulse does not significantly affect the ADC values for early stage ischemic stroke (less than 14 days from symptom onset), but results in a more accurate relative ADC measurement by reducing the cerebrospinal fluid partial volume effects of the normal contralateral side. In addition, combined with the conventional DWI, FLAIR DWI may be helpful in determining the age of ischemic lesions.

  9. Validated determination of losartan and valsartan in human plasma by stir bar sorptive extraction based on acrylate monolithic polymer, liquid chromatographic analysis and experimental design methodology.

    Science.gov (United States)

    Babarahimi, Vida; Talebpour, Zahra; Haghighi, Farideh; Adib, Nuoshin; Vahidi, Hamed

    2018-05-10

    In our previous work, a new monolithic coating based on vinylpyrrolidone-ethylene glycol dimethacrylate polymer was introduced for stir bar sorptive extraction. The formulation of the prepared vinylpyrrolidone-ethylene glycol dimethacrylate monolithic polymer was optimized and the satisfactory quality of prepared coated stir bar was demonstrated. In this work, the prepared stir bar was utilized in combination with ultrasound-assisted liquid desorption, followed by high-performance liquid chromatography with ultraviolet detection for the simultaneous determination of losartan (LOS) and valsartan (VAS) in human plasma samples. In a comparison study, the extraction efficiency of the prepared stir bar was accompanied much higher extraction efficiency than the two commercial stir bars (polydimethylsiloxand and polyacrylate) for both target compounds. In order to improve the desorption efficiency of LOS and VAS, the best values for effective parameters on desorption step were selected systematically. Also, the effective parameters on extraction step were optimized using a Box-Behnken design. Under the optimum conditions, the analytical performance of the proposed method displayed excellent linear dynamic ranges for LOS (24-1000 ng mL -1 ) and VAS (91-1000 ng mL -1 ), with correlation coefficients of 0.9998 and 0.9971 and detection limits of 7 and 27 ng mL -1 , respectively. The intra- and inter-day recovery ranged from 98 to 117%, and the relative standard deviations were less than 8%. Finally, the proposed technique was successfully applied to the analysis of LOS and VAS at their therapeutic levels in volunteer patient plasma sample. The obtained results were confirmed using liquid chromatography-mass spectrometry. The proposed technique was more rapid than previously reported stir bar sorptive extraction techniques based on monolithic coatings, and exhibited lower detection limits in comparison with similar methods for the determination of LOS and VLS in

  10. Stir-Frying of Chinese Cabbage and Pakchoi Retains Health-Promoting Glucosinolates

    NARCIS (Netherlands)

    Nugrahedi, Probo Y.; Oliviero, Teresa; Heising, Jenneke K.; Dekker, Matthijs; Verkerk, Ruud

    2017-01-01

    Stir-frying is a cooking method, originating from Asia, in which food is fried in small amount of very hot oil. Nowadays in many other parts of the world stir-frying is a very popular method to prepare vegetables, because it is fast and fried vegetables are tasty. However, the retention of

  11. Inverse osmotic process for radioactive laundry waste

    International Nuclear Information System (INIS)

    Ebara, Katsuya; Takahashi, Sankichi; Sugimoto, Yoshikazu; Yusa, Hideo; Hyakutake, Hiroshi.

    1977-01-01

    Purpose: To effectively recover the processing amount reduced in a continuous treatment. Method: Laundry waste containing radioactive substances discharged from a nuclear power plant is processed in an inverse osmotic process while adding starch digesting enzymes such as amylase and takadiastase, as well as soft spherical bodies such as sponge balls of a particle diameter capable of flowing in the flow of the liquid wastes along the inverse osmotic membrane pipe and having such a softness and roundness as not to damage the inverse osmotic membrane. This process can remove the floating materials such as thread dusts or hairs deposited on the membrane surface by the action of the soft elastic balls and remove paste or the like through decomposition by the digesting enzymes. Consequently, effective recovery can be attained for the reduced processing amount. (Furukawa, Y.)

  12. Spinal cord microstructure integrating phase-sensitive inversion recovery and diffusional kurtosis imaging

    Energy Technology Data Exchange (ETDEWEB)

    Panara, V.; Navarra, R; Caulo, M. [University ' ' G. d' Annunzio' ' , Department of Neuroscience, Imaging and Clinical Sciences, Chieti (Italy); University ' ' G. d' Annunzio' ' , ITAB Institute of Advanced Biomedical Technologies, Chieti (Italy); Mattei, P.A. [University ' ' G. d' Annunzio' ' , ITAB Institute of Advanced Biomedical Technologies, Chieti (Italy); University ' ' G. d' Annunzio' ' , Department of Medicine and Science of Aging, Ophthalmology Clinic, Chieti (Italy); Piccirilli, E. [University ' ' G. d' Annunzio' ' , ITAB Institute of Advanced Biomedical Technologies, Chieti (Italy); Cotroneo, A.R.; Uncini, A. [University ' ' G. d' Annunzio' ' , Department of Neuroscience, Imaging and Clinical Sciences, Chieti (Italy); Papinutto, N.; Henry, R.G. [University of California, San Francisco, Department of Neurology, San Francisco, CA (United States)

    2017-08-15

    The aim of this prospective study was to determine the feasibility in terms of repeatability and reproducibility of diffusional kurtosis imaging (DKI) for microstructural assessment of the normal cervical spinal cord (cSC) using a phase-sensitive inversion recovery (PSIR) sequence as the anatomical reference for accurately defining white-matter (WM) and gray-matter (GM) regions of interests (ROIs). Thirteen young healthy subjects were enrolled to undergo DKI and PSIR sequences in the cSC. The repeatability and reproducibility of kurtosis metrics and fractional anisotropy (FA) were calculated in GM, WM, and cerebral-spinal-fluid (CSF) ROIs drawn by two independent readers on PSIR images of three different levels (C1-C4). The presence of statistically significant differences in DKI metrics for levels, ROIs (GM, WM, and CSF) repeatability, reproducibility, and inter-reader agreement was evaluated. Intra-class correlation coefficients between the two readers ranged from good to excellent (0.75 to 0.90). The inferior level consistently had the highest concordance. The lower values of scan-rescan variability for all DKI parameters were found for the inferior level. Statistically significant differences in kurtosis values were not found in the lateral white-matter bundles of the spinal cord. The integration of DKI and PSIR sequences in a clinical MR acquisition to explore the regional microstructure of the cSC in healthy subjects is feasible, and the results obtainable are reproducible. Further investigation will be required to verify the possibility to translate this method to a clinical setting to study patients with SC involvement especially in the absence of MRI abnormalities on standard sequences. (orig.)

  13. The effect of time and stirring on product white colorant from titanium dioxide

    International Nuclear Information System (INIS)

    Ratnawati; Linda A; Yoshi; Zaenal K; Andri Y

    2018-01-01

    White Colorant is the main raw material in the paint making process in the depots. It made from TiO 2 pigment. The process of making white colorant requires a great stirring time and energy to mix the materials such as binders, pigments, solvents, and additives. The aim of this study is to get the optimum stirring time and speed from mixing the materials needed to obtain white colorant from TiO 2 pigment that meet the specification desired by paint Factory in Tangerang that is particle size of TiO 2 (10 μm to 30 μm), viscosity 1000 cps to 6000 cps, total solids 79 % to 83 %, DE color is 0.5, and CR is 80 % to 100 %. Variations made were stirring speed (1000, 1100 and 1200) rpm and stirring time(10, 15, 20, 25 and 30) minutes. The optimum results obtained are particle size of 15 μm, viscosity 1900 cps, total solids 81.81 %, color DE 0.49 and color CR 98.12 % at stirring condition 1200 rp min 15 minutes. (author)

  14. Immersed friction stir welding of ultrafine grained accumulative roll-bonded Al alloy

    International Nuclear Information System (INIS)

    Hosseini, M.; Danesh Manesh, H.

    2010-01-01

    In this research, ultrafine grained strips of commercial pure strain hardenable aluminum (AA1050) were produced by accumulative roll-bonding (ARB) technique. These strips were joined by friction stir welding (FSW) in immersed (underwater) and conventional (in-air) conditions to investigate the effect of the immersion method on the microstructure and mechanical properties of the joint, aiming to reduce the deterioration of the mechanical properties of the joint. Transmission electron microscopy and X-ray diffraction analyses were used to evaluate the microstructure, showing smaller grains and subgrains in the stir zone of the immersed FSW condition with respect to the conventional FSW method. The hardness and tensile properties of the immersed friction stir welded sample and ARBed base metal show more similarity compared to the conventional friction stir welded sample. Moreover, the aforementioned method can result in the enhancement of the superplasticity tendency of the material.

  15. Modelling of peak temperature during friction stir processing of magnesium alloy AZ91

    Science.gov (United States)

    Vaira Vignesh, R.; Padmanaban, R.

    2018-02-01

    Friction stir processing (FSP) is a solid state processing technique with potential to modify the properties of the material through microstructural modification. The study of heat transfer in FSP aids in the identification of defects like flash, inadequate heat input, poor material flow and mixing etc. In this paper, transient temperature distribution during FSP of magnesium alloy AZ91 was simulated using finite element modelling. The numerical model results were validated using the experimental results from the published literature. The model was used to predict the peak temperature obtained during FSP for various process parameter combinations. The simulated peak temperature results were used to develop a statistical model. The effect of process parameters namely tool rotation speed, tool traverse speed and shoulder diameter of the tool on the peak temperature was investigated using the developed statistical model. It was found that peak temperature was directly proportional to tool rotation speed and shoulder diameter and inversely proportional to tool traverse speed.

  16. Influence of friction stir welding parameters on titanium-aluminum heterogeneous lap joining configuration

    Science.gov (United States)

    Picot, Florent; Gueydan, Antoine; Hug, Éric

    2017-10-01

    Lap joining configuration for Friction Stir Welding process is a methodology mostly dedicated to heterogeneous bonding. This welding technology was applied to join pure titanium with pure aluminum by varying the rotation speed and the movement speed of the tool. Regardless of the process parameters, it was found that the maximum strength of the junction remains almost constant. Microstructural observations by means of Scanning Electron Microscopy and Energy Dispersive Spectrometry analysis enable to describe the interfacial join and reveal asymmetric Cold Lap Defects on the sides of the junction. Chemical analysis shows the presence of one exclusive intermetallic compound through the interface identified as TiAl3. This compound is responsible of the crack spreading of the junction during the mechanical loading. The original version of this article supplied to AIP Publishing contained an accidental inversion of the authors, names. An updated version of this article, with the authors names formatted correctly was published on 20 October 2017.

  17. Biodegradation of phenolic waste liquors in stirred-tank, packed-bed, and fluidized-bed bioreactors

    Energy Technology Data Exchange (ETDEWEB)

    Holladay, D W; Hancher, G W; Chilcote, D D; Scott, C D

    1978-11-01

    The biological degradation of phenolic scrub liquors similar to those that arise in coal conversion processes was studied for symbiotic bacterial populations contained in a continuously stirred tank bioreactor, a three-phase packed-bed bioreactor, and a three-phase, fluidized-bed bioreactor. The conversions of phenol compounds were comparable in the three-phase, packed-bed bioreactor and the continuously stirred tank bioreactor; however, the packed-bed bioreactor degradation rates were as much as twice those in the continuously stirred tank bioreactor, and packed-bed bioreactor retention times were as low as one- tenth those of the continuously stirred tank bioreactors (minimum time was 12 hours).

  18. Preparation of a novel sorptive stir bar based on vinylpyrrolidone-ethylene glycol dimethacrylate monolithic polymer for the simultaneous extraction of diazepam and nordazepam from human plasma.

    Science.gov (United States)

    Torabizadeh, Mahsa; Talebpour, Zahra; Adib, Nuoshin; Aboul-Enein, Hassan Y

    2016-04-01

    A new monolithic coating based on vinylpyrrolidone-ethylene glycol dimethacrylate polymer was introduced for stir bar sorptive extraction. The polymerization step was performed using different contents of monomer, cross-linker and porogenic solvent, and the best formulation was selected. The quality of the prepared vinylpyrrolidone-ethylene glycol dimethacrylate stir bars was satisfactory, demonstrating good repeatability within batch (relative standard deviation < 3.5%) and acceptable reproducibility between batches (relative standard deviation < 6.0%). The prepared stir bar was utilized in combination with ultrasound-assisted liquid desorption, followed by high-performance liquid chromatography with ultraviolet detection for the simultaneous determination of diazepam and nordazepam in human plasma samples. To optimize the extraction step, a three-level, four-factor, three-block Box-Behnken design was applied. Under the optimum conditions, the analytical performance of the proposed method displayed excellent linear dynamic ranges for diazepam (36-1200 ng/mL) and nordazepam (25-1200 ng/mL), with correlation coefficients of 0.9986 and 0.9968 and detection limits of 12 and 10 ng/mL, respectively. The intra- and interday recovery ranged from 93 to 106%, and the relative standard deviations were less than 6%. Finally, the proposed method was successfully applied to the analysis of diazepam and nordazepam at their therapeutic levels in human plasma. The novelty of this study is the improved polarity of the stir bar coating and its application for the simultaneous extraction of diazepam and its active metabolite, nordazepam in human plasma sample. The method was more rapid than previously reported stir bar sorptive extraction techniques based on monolithic coatings, and exhibited lower detection limits in comparison with similar methods for the determination of diazepam and nordazepam in biological fluids. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. STIR: Microwave Response of Carbon Nanotubes in Polymer Nanocomposite Welds

    Science.gov (United States)

    2016-01-28

    STIR: RDRL-ROE-M: Microwave Response of Carbon Nanotubes in Polymer Nanocomposite Welds Thrust 1 of the STIR project examines the heat response of...polymer composites loaded with carbon nanotubes (CNTs) to microwave irradiation. This involves (1) a study of how CNT loading affects dielectric...properties of polymer composites and (2) a study of how CNT loading affects the heating response to microwave radiation. Our hypothesis is that the

  20. Personalized mapping of the deep brain with a white matter attenuated inversion recovery (WAIR) sequence at 1.5-tesla: Experience based on a series of 156 patients.

    Science.gov (United States)

    Zerroug, A; Gabrillargues, J; Coll, G; Vassal, F; Jean, B; Chabert, E; Claise, B; Khalil, T; Sakka, L; Feschet, F; Durif, F; Boyer, L; Coste, J; Lemaire, J-J

    2016-08-01

    Deep brain mapping has been proposed for direct targeting in stereotactic functional surgery, aiming to personalize electrode implantation according to individual MRI anatomy without atlas or statistical template. We report our clinical experience of direct targeting in a series of 156 patients operated on using a dedicated Inversion Recovery Turbo Spin Echo sequence at 1.5-tesla, called White Matter Attenuated Inversion Recovery (WAIR). After manual contouring of all pertinent structures and 3D planning of trajectories, 312 DBS electrodes were implanted. Detailed anatomy of close neighbouring structures, whether gray nuclei or white matter regions, was identified during each planning procedure. We gathered the experience of these 312 deep brain mappings and elaborated consistent procedures of anatomical MRI mapping for pallidal, subthalamic and ventral thalamic regions. We studied the number of times the central track anatomically optimized was selected for implantation of definitive electrodes. WAIR sequence provided high-quality images of most common functional targets, successfully used for pure direct stereotactic targeting: the central track corresponding to the optimized primary anatomical trajectory was chosen for implantation of definitive electrodes in 90.38%. WAIR sequence is anatomically reliable, enabling precise deep brain mapping and direct stereotactic targeting under routine clinical conditions. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  1. Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions

    Science.gov (United States)

    2013-01-01

    REPORT Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions 14. ABSTRACT 16. SECURITY...properties and of the attendant ballistic-impact failure mechanisms in prototypical friction stir welding (FSW) joints found in armor structures made of high...mechanisms, friction stir welding M. Grujicic, B. Pandurangan, A. Arakere, C-F. Yen, B. A. Cheeseman Clemson University Office of Sponsored Programs 300

  2. Stir Bar Sorptive Extraction (SBSE), a novel extraction technique for aqueous samples: theory and principles

    NARCIS (Netherlands)

    Baltussen, H.A.; Sandra, P.J.F.; David, F.; Cramers, C.A.M.G.

    1999-01-01

    The theory and practice of a novel approach for sample enrichment, namely the application of stir bars coated with the sorbent polydimethylsiloxane (PDMS) and referred to as stir bar sorptive extraction (SBSE) are presented. Stir bars with a length of 10 and 40 mm coated with 55 and 219 L of PDMS

  3. The effect of magnetisation transfer contrast on cerebrospinal fluid on motion artefacts on fluid-attenuated inversion-recovery images

    International Nuclear Information System (INIS)

    Aprile, I.; Principi, M.; Ottaviano, P.; Scapeccia, M.

    2003-01-01

    We assessed possible advantages of the use of fluid-attenuated inversion-recovery (FLAIR) sequences with magnetisation-transfer contrast (MTC) over conventional FLAIR images. We carried out cranial MRI at 1 tesla on 50 patients with both sequences. In nine patients with multiple sclerosis (MS) we performed a quantitative comparison of the two sequences, looking at the contrast-to-noise ratio between lesions and normal white matter and counting the number of lesions shown using each method. A qualitative comparison on all patients consisted of the analysis of the appearance of the normal parenchyma, of any lesions, and of artefacts, with particular reference to cerebrospinal fluid (CSF) motion artefacts. The quantitative analysis showed no meaningful difference between the two sequences. The cerebral parenchyma and lesions appeared substantially the same with both techniques. With FLAIR MTC there was a clear, and consistent reduction in CSF motion artefacts. FLAIR MTC sequences can usefully be used in place of the conventional sequence at 1 tesla. (orig.)

  4. Microstructural evolution in friction stir welding of nanostructured ODS alloys

    International Nuclear Information System (INIS)

    Chen, C.-L.; Tatlock, G.J.; Jones, A.R.

    2010-01-01

    Nanostructured oxide dispersion strengthened (ODS) Fe-based alloys manufactured by mechanical alloying (MA) are generally considered to be promising candidate materials for high-temperature applications up to at least 1100 o C because of their excellent creep strength and good oxidation resistance. However, a key issue with these alloys is the difficulty in using fusion welding techniques to join components due to oxide particle agglomeration and loss in the weld zone and the disruption and discontinuity in the grain structure introduced at the bond. In this study, the evolution of microstructure has been comprehensively studied in friction stir welds in a ferritic ODS alloy. Initially, electron backscattering diffraction (EBSD) was used to analyze the grain orientation, the grain boundary geometries and recrystallization behaviour. It suggested that deformation heterogeneities were introduced during the friction stirring process which facilitated the onset of recrystallization. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used to observe the effects of the friction stir welding (FSW) process on the grain structure and the distribution of Y 2 O 3 and other particles in the metal substrates in the FSW and adjacent regions, after the alloys had been recrystallized at temperatures up to 1380 o C for 1 h in air. The results show that fine-equiaxed grains and a uniform distribution of oxide particles were present in the friction stirred region but that the grain boundaries in the parent metal were pinned by particles. Friction stirring appeared to release these boundaries and allowed secondary recrystallization to occur after further heat treatment. The FSW process appears to be a promising technique for joining ferritic ODS alloys in the form of sheet and tube.

  5. Investigation of the L-Glutamic acid polymorphism: Comparison between stirred and stagnant conditions

    Science.gov (United States)

    Tahri, Yousra; Gagnière, Emilie; Chabanon, Elodie; Bounahmidi, Tijani; Mangin, Denis

    2016-02-01

    This work highlights the effect of the stirring, the temperature and the supersaturation on the cooling crystallization of L-Glutamic acid (LGlu) polymorphs. First, solubility measurements of the metastable polymorph α and the stable polymorph β were performed. Then, crystallization experiments were carried out in stirred vessel and in stagnant cell. All these experiments were monitored by in situ devices. The effect of the temperature on the LGlu polymorphs was found to be more relevant than the supersaturation in the stirred crystallizer. In the stagnant cell, only the stable form β crystallized regardless of the operating conditions. Moreover, an unexpected and new habit of the β form was discovered and confirmed. These results suggest that the temperature and the stirring can strongly affect the nucleation and the growth kinetics of polymorphic forms.

  6. A posteriori error estimates in voice source recovery

    Science.gov (United States)

    Leonov, A. S.; Sorokin, V. N.

    2017-12-01

    The inverse problem of voice source pulse recovery from a segment of a speech signal is under consideration. A special mathematical model is used for the solution that relates these quantities. A variational method of solving inverse problem of voice source recovery for a new parametric class of sources, that is for piecewise-linear sources (PWL-sources), is proposed. Also, a technique for a posteriori numerical error estimation for obtained solutions is presented. A computer study of the adequacy of adopted speech production model with PWL-sources is performed in solving the inverse problems for various types of voice signals, as well as corresponding study of a posteriori error estimates. Numerical experiments for speech signals show satisfactory properties of proposed a posteriori error estimates, which represent the upper bounds of possible errors in solving the inverse problem. The estimate of the most probable error in determining the source-pulse shapes is about 7-8% for the investigated speech material. It is noted that a posteriori error estimates can be used as a criterion of the quality for obtained voice source pulses in application to speaker recognition.

  7. A novel miniaturized zinc oxide/hydroxylated multiwalled carbon nanotubes as a stir-brush microextractor device for carbamate pesticides analysis

    International Nuclear Information System (INIS)

    Makkliang, Fonthip; Kanatharana, Proespichaya; Thavarungkul, Panote; Thammakhet, Chongdee

    2016-01-01

    A novel miniaturized “stir-brush microextractor” was prepared using a zinc oxide/hydroxylated multiwalled carbon nanotubes (ZnO/MWCNTs–OH) coated stainless steel brush connected to a small dc motor. The synthesized zinc oxide on each strand of stainless steel had a flower-like nanostructure when observed by a scanning electron microscope (SEM). This structure produced a large surface area before it was coated with the hydroxylated multiwalled carbon nanotubes sorbent. Under optimal conditions, the developed device provided a good linearity for the extraction of carbofuran and carbaryl, in the range of 25–500 ng mL"−"1 and 50–500 ng mL"−"1, respectively, with low limits of detection of 17.5 ± 2.0 ng mL"−"1 and 13.0 ± 1.8 ng mL"−"1. It also provided a good stir-brush-to-stir-brush reproducibility (% relative standard deviation < 5.6%, n = 6). The device was applied for the extraction and preconcentration of carbamate pesticides in fruit and vegetable samples prior to analysis with a gas chromatograph coupled with a flame ionization detector (GC–FID). Carbofuran was found at 9.24 ± 0.93 ng g"−"1 and carbaryl was detected at 7.05 ± 0.61 ng g"−"1 with good recoveries in the range of 73.7 ± 10.0% to 108.4 ± 2.6% for carbofuran and 75.7 ± 10.0% to 111.7 ± 5.7% for carbaryl. - Highlights: • A brush as the sampling tool was first introduced. • A novel miniaturized and portable stir brush microextractor was developed for carbamate pesticides extraction. • Large surface area of ZnO flower-like nanostructure coated with MWCNTs–OH on each brush fiber was observed.

  8. A novel miniaturized zinc oxide/hydroxylated multiwalled carbon nanotubes as a stir-brush microextractor device for carbamate pesticides analysis

    Energy Technology Data Exchange (ETDEWEB)

    Makkliang, Fonthip; Kanatharana, Proespichaya [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Thavarungkul, Panote [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Physics, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Thammakhet, Chongdee, E-mail: chongdee.t@psu.ac.th [Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand)

    2016-04-21

    A novel miniaturized “stir-brush microextractor” was prepared using a zinc oxide/hydroxylated multiwalled carbon nanotubes (ZnO/MWCNTs–OH) coated stainless steel brush connected to a small dc motor. The synthesized zinc oxide on each strand of stainless steel had a flower-like nanostructure when observed by a scanning electron microscope (SEM). This structure produced a large surface area before it was coated with the hydroxylated multiwalled carbon nanotubes sorbent. Under optimal conditions, the developed device provided a good linearity for the extraction of carbofuran and carbaryl, in the range of 25–500 ng mL{sup −1} and 50–500 ng mL{sup −1}, respectively, with low limits of detection of 17.5 ± 2.0 ng mL{sup −1} and 13.0 ± 1.8 ng mL{sup −1}. It also provided a good stir-brush-to-stir-brush reproducibility (% relative standard deviation < 5.6%, n = 6). The device was applied for the extraction and preconcentration of carbamate pesticides in fruit and vegetable samples prior to analysis with a gas chromatograph coupled with a flame ionization detector (GC–FID). Carbofuran was found at 9.24 ± 0.93 ng g{sup −1} and carbaryl was detected at 7.05 ± 0.61 ng g{sup −1} with good recoveries in the range of 73.7 ± 10.0% to 108.4 ± 2.6% for carbofuran and 75.7 ± 10.0% to 111.7 ± 5.7% for carbaryl. - Highlights: • A brush as the sampling tool was first introduced. • A novel miniaturized and portable stir brush microextractor was developed for carbamate pesticides extraction. • Large surface area of ZnO flower-like nanostructure coated with MWCNTs–OH on each brush fiber was observed.

  9. The Effect of Stirring on the Morphology of Birnessite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Marcos A. Cheney

    2008-01-01

    Full Text Available The effect of mechanical stirring on the morphology of hexagonal layer-structure birnessite nanoparticles produced from decomposition of KMnO4 in dilute aqueous H2SO4 is investigated, with characterization by X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, high-resolution transmission electron microscopy (HRTEM, thermogravimetric analysis (TGA, and N2 adsorption (BET. Mechanical stirring during an initial stage of synthesis is shown to produce black birnessite containing nanofibers, whereas granular particulates of brown birnessite are produced without stirring. This is the first reduction synthesis of black birnessite nanoparticles with dendritic morphology without any use of organic reductant, and suggests that a particular morphology can arise from structural preferences of Mn in acidic conditions rather than particular organic reactants. These results enlighten the possibility of synthesizing nanoparticles with controlled size and morphology.

  10. A Brief Introduction to the Theory of Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and is already an important welding process for the aerospace industry, where welds of optimal quality are demanded. The structure of welds determines weld properties. The structure of friction stir welds is determined by the flow field in the weld metal in the vicinity of the weld tool. A simple kinematic model of the FSW flow field developed at Marshall Space Flight Center, which enables the basic features of FSW microstructure to be understood and related to weld process parameters and tool design, is explained.

  11. Reduction of CSF flow artifact in fast fluid attenuated inversion recovery MR imaging. Study of excitation width in 180deg inversion pulse

    International Nuclear Information System (INIS)

    Tsuchihashi, Toshio; Yoshizawa, Satoshi; Maki, Toshio; Kitagawa, Matsuo; Suzuki, Ken; Fujita, Isao

    1998-01-01

    A technique that increases slice thickness so that it becomes wider than the excitation width of the 180deg inversion pulse and in which TR is partitioned twice has been investigated with regard to fast FLAIR. This is a technique that reduces the flow artifact of CSF. It is thought that, with this technique, the flow artifact is reduced because the CSF that flows onto the slice reaches the null point. The cross talk effect of the 180deg inversion pulse appears as a high CSF signal. As a result, the number of slices needs to be partitioned two or three times before imaging. Thus the imaging time is doubled or tripled. Considering the cross talk effect of the 180deg inversion pulse and the imaging time needed for this technique, the optimal imaging technique would be one that uses an inversion pulse that is four times slice thickness plus slice space and for which the number of slices is partitioned twice. Furthermore, the null point of CSF was dependent on dividing TR in half. (author)

  12. Friction stir weld tools having fine grain structure

    Science.gov (United States)

    Grant, Glenn J.; Frye, John G.; Kim, Jin Yong; Lavender, Curt A.; Weil, Kenneth Scott

    2016-03-15

    Tools for friction stir welding can be made with fewer process steps, lower cost techniques, and/or lower cost ingredients than other state-of-the-art processes by utilizing improved compositions and processes of fabrication. Furthermore, the tools resulting from the improved compositions and processes of fabrication can exhibit better distribution and homogeneity of chemical constituents, greater strength, and/or increased durability. In one example, a friction stir weld tool includes tungsten and rhenium and is characterized by carbide and oxide dispersoids, by carbide particulates, and by grains that comprise a solid solution of the tungsten and rhenium. The grains do not exceed 10 micrometers in diameter.

  13. Fatigue and Damage Tolerance of Friction Stir Welded Joints for Aerospace Applications

    NARCIS (Netherlands)

    Lemmen, H.J.K.

    2010-01-01

    Friction stir welding is a young welding process with high potential to replace riveted joints in aerospace structures like the fuselage. Friction stir welding is a robust process and capable of welding high strength aluminum alloys. Therefore it can lead to both costs and weight savings. To

  14. Corrosion Performance of Friction Stir Linear Lap Welded AM60B Joints

    Science.gov (United States)

    Kish, J. R.; Birbilis, N.; McNally, E. M.; Glover, C. F.; Zhang, X.; McDermid, J. R.; Williams, G.

    2017-11-01

    A corrosion investigation of friction stir linear lap welded AM60B joints used to fabricate an Mg alloy-intensive automotive front end sub-assembly was performed. The stir zone exhibited a slightly refined grain size and significant break-up and re-distribution of the divorced Mg17Al12 (β-phase) relative to the base material. Exposures in NaCl (aq) environments revealed that the stir zone was more susceptible to localized corrosion than the base material. Scanning vibrating electrode technique measurements revealed differential galvanic activity across the joint. Anodic activity was confined to the stir zone surface and involved initiation and lateral propagation of localized filaments. Cathodic activity was initially confined to the base material surface, but was rapidly modified to include the cathodically-activated corrosion products in the filament wake. Site-specific surface analyses revealed that the corrosion observed across the welded joint was likely linked to variations in Al distribution across the surface film/metal interface.

  15. A passive inverse filter for Green's function retrieval.

    Science.gov (United States)

    Gallot, Thomas; Catheline, Stefan; Roux, Philippe; Campillo, Michel

    2012-01-01

    Passive methods for the recovery of Green's functions from ambient noise require strong hypotheses, including isotropic distribution of the noise sources. Very often, this distribution is nonisotropic, which introduces bias in the Green's function reconstruction. To minimize this bias, a spatiotemporal inverse filter is proposed. The method is tested on a directive noise field computed from an experimental active seismic data set. The results indicate that the passive inverse filter allows the manipulation of the spatiotemporal degrees of freedom of a complex wave field, and it can efficiently compensate for the noise wavefield directivity. © 2012 Acoustical Society of America.

  16. Recovery of Copper from Copper Slag by Hydrometallurgy Method, from Iraqi Factories Waste

    Directory of Open Access Journals (Sweden)

    Bahaa Sami Mahdi

    2018-05-01

    Full Text Available   In this research, the recovery of copper from copper slag is investigated using hydrometallurgy method. Slag samples were taken from Al-Shaheed State Company. The results of the chemical analysis showed that the slag contained 11.4% of copper. The recovery process included two stages; the first stage is leaching using diluted sulfuric acid. The most important variables that effect on the leaching process was studied, such as acid concentration, hydrogen peroxide adding, particle size, liquid to solid, stirring speed and leaching time by changing the condition and the stabilizing of other factors at room temperature.               The second stage is precipitation of copper from leaching solution by zinc powder with different weights and times, at room temperature and 1.5 PH value. The results of the first stage manifested that about 99.7% of the copper have been dissolved at the following operational conditions: 50% acid concentration, 5 ml hydrogen peroxide adding, particle size (-75+53 micron, 1:10 liquid to solid, 500 rpm stirring speed and 25 min of leaching time. The highest percentage of copper precipitation in the second stage was 99.8% when added 3gm zinc powder at 20 min. The XRD result revealed that the predominant phase was pure copper. The results of EDS exhibited that a few percentage of oxygen appeared with copper powder. The final of copper recovery ratio was 99.3% with 99.2% purity.

  17. The investigation of typical welding defects for 5456 aluminum alloy friction stir welds

    International Nuclear Information System (INIS)

    Chen Huabin; Yan Keng; Lin Tao; Chen Shanben; Jiang Chengyu; Zhao Yong

    2006-01-01

    The external factors on the friction stir welding defects are so abundant that the experiments of friction stir welding were conducted for 5456 aluminum alloy. With the changes of the tool tilt angle and material condition, defects can be generated. These defects can be conventional ones (lack of penetration or voids), or lazy S, which are unique to friction stir welding. However, the origin of the defects remains an area of uncertainty. In this study, an attempt has been made to investigate the formation of these defects. The typical welding defects of friction stir welding joint for 5456 aluminum alloy were analyzed and discussed, respectively, by using optical microscopy (OM), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscope (SEM). The microscopic examination of the nugget zone and fracture location of the weld confirms that the tilt angle can change the plastic material flow patterns in the stir zone and accordingly control the weld properties. In addition, the oxide layer from the initial butt surface during FSW is dispersed at the grain boundary. These A1 2 O 3 particles are actually the major cause of failure of the joint

  18. Polyaniline/cyclodextrin composite coated stir bar sorptive extraction combined with high performance liquid chromatography-ultraviolet detection for the analysis of trace polychlorinated biphenyls in environmental waters.

    Science.gov (United States)

    Lei, Yun; He, Man; Chen, Beibei; Hu, Bin

    2016-04-01

    A novel polyaniline/α-cyclodextrin (PANI/α-CD) composite coated stir bar was prepared by sol-gel process for the analysis of polychlorinated biphenyls (PCBs) in this work. The preparation reproducibility of the PANI/α-CD-coated stir bar was good, with relative standard deviations (RSDs) ranging from 2.3% to 3.7% (n=7) and 2.0% to 3.8% (n=7) for bar to bar and batch to batch, respectively. Based on it, a novel method of PANI/α-CD-coated stir bar sorptive extraction (SBSE) followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection was developed for the determination of trace PCBs in environmental waters. To obtain the best extraction performance for target PCBs, several parameters affecting SBSE, such as extraction time, stirring rate, and ionic strength were investigated. Under optimal experimental conditions, the limits of detection (LODs) of the proposed method for seven PCBs were in the range of 0.048-0.22 μg/L, and the RSDs were 5.3-9.8% (n=7, c=1 μg/L). Enrichment factors (EFs) ranging from 39.8 to 68.4-fold (theoretical EF, 83.3-fold) for target analytes were achieved. The proposed method was successfully applied for the determination of seven target PCBs in Yangtze River water and East Lake water, and the recoveries were in the range of 73.0-120% for the spiked East Lake water samples and 82.7-121% for the spiked Yangtze River water samples, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Modelling of baffled stirred tanks

    Energy Technology Data Exchange (ETDEWEB)

    Ahlstedt, H.; Lahtinen, M. [Tampere Univ. of Technology (Finland). Energy and Process Engineering

    1996-12-31

    The three-dimensional flow field of a baffled stirred tank has been calculated using four different turbulence models. The tank is driven by a Rushton-type impeller. The boundary condition for the impeller region has been given as a source term or by calculating the impeller using the sliding mesh technique. Calculated values have been compared with measured data. (author)

  20. Modelling of baffled stirred tanks

    Energy Technology Data Exchange (ETDEWEB)

    Ahlstedt, H; Lahtinen, M [Tampere Univ. of Technology (Finland). Energy and Process Engineering

    1997-12-31

    The three-dimensional flow field of a baffled stirred tank has been calculated using four different turbulence models. The tank is driven by a Rushton-type impeller. The boundary condition for the impeller region has been given as a source term or by calculating the impeller using the sliding mesh technique. Calculated values have been compared with measured data. (author)

  1. Counteracting ammonia inhibition during anaerobic digestion by recovery using submersible microbial desalination cell.

    Science.gov (United States)

    Zhang, Yifeng; Angelidaki, Irini

    2015-07-01

    Ammonia inhibition is one of the most frequent and serious problems in biogas plants. In this study, a novel hybrid system consisting of a submersible microbial desalination cell (SMDC) and a continuous stirred tank reactor (CSTR) was developed for counteracting ammonia inhibition during anaerobic digestion (AD) with simultaneous in situ ammonia recovery and electricity production. The SMDC was powered by acetate in a buffer solution, while synthetic ammonia-rich wastewater was used as the feeding of the CSTR. Under continuous operation, ammonia recovery rate of 86 g-N/m(2) /day and current density of 4.33 A/m(2) were achieved at steady-state condition. As a result, 112% extra biogas was produced due to ammonia recovery by the SMDC. High-throughput sequencing showed that ammonia recovery had an impact on the microbial community structures in the SMDC and CSTR. Considering the additional economic benefits of biogas enhancement and possible wastewater treatment, the SMDC may represent a cost-effective and environmentally friendly method for waste resources recovery and biomethanation of ammonia-rich residues. © 2015 Wiley Periodicals, Inc.

  2. Mechanical properties of friction stir welded aluminum alloys 5083 and 5383

    Directory of Open Access Journals (Sweden)

    Jeom Kee Paik

    2009-09-01

    Full Text Available The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships. While various welding methods are used today to fabricate aluminum ship structures, namely gas metallic arc welding (GMAW, laser welding and friction stir welding (FSW, FSW technology has been recognized to have many advantages for the construction of aluminum structures, as it is a low-cost welding process. In the present study, mechanical properties of friction stir welded aluminum alloys are examined experimentally. Tensile testing is undertaken on dog-bone type test specimen for aluminum alloys 5083 and 5383. The test specimen includes friction stir welded material between identical alloys and also dissimilar alloys, as well as unwelded (base alloys. Mechanical properties of fusion welded aluminum alloys are also tested and compared with those of friction stir welded alloys. The insights developed from the present study are documented together with details of the test database. Part of the present study was obtained from the Ship Structure Committee project SR-1454 (Paik, 2009, jointly funded by its member agencies.

  3. Performance Improvement of Friction Stir Welds by Better Surface Finish

    Science.gov (United States)

    Russell, Sam; Nettles, Mindy

    2015-01-01

    The as-welded friction stir weld has a cross section that may act as a stress concentrator. The geometry associated with the stress concentration may reduce the weld strength and it makes the weld challenging to inspect with ultrasound. In some cases, the geometry leads to false positive nondestructive evaluation (NDE) indications and, in many cases, it requires manual blending to facilitate the inspection. This study will measure the stress concentration effect and develop an improved phased array ultrasound testing (PAUT) technique for friction stir welding. Post-welding, the friction stir weld (FSW) tool would be fitted with an end mill that would machine the weld smooth, trimmed shaved. This would eliminate the need for manual weld preparation for ultrasonic inspections. Manual surface preparation is a hand operation that varies widely depending on the person preparing the welds. Shaving is a process that can be automated and tightly controlled.

  4. Sustainability of Welding Process through Bobbin Friction Stir Welding

    Science.gov (United States)

    Sued, M. K.; Samsuri, S. S. M.; Kassim, M. K. A. M.; Nasir, S. N. N. M.

    2018-03-01

    Welding process is in high demand, which required a competitive technology to be adopted. This is important for sustaining the needs of the joining industries without ignoring the impact of the process to the environment. Friction stir welding (FSW) is stated to be benefitting the environment through low energy consumption, which cannot be achieved through traditional arc welding. However, this is not well documented, especially for bobbin friction stir welding (BFSW). Therefore, an investigation is conducted by measuring current consumption of the machine during the BFSW process. From the measurement, different phases of BFSW welding process and its electrical demand are presented. It is found that in general total energy in BFSW is about 130kW inclusive of all identified process phases. The phase that utilise for joint formation is in weld phase that used the highest total energy of 120kWs. The recorded total energy is still far below the traditional welding technology and the conventional friction stir welding (CFSW) energy demand. This indicates that BFSW technology with its vast benefit able to sustain the joining technology in near future.

  5. Impact of stirring speed, glycerin and sodium chloride concentrations on photoprotective nanoemulsions

    Directory of Open Access Journals (Sweden)

    Débora Granemann e Silva

    2014-09-01

    Full Text Available New technologies that improve the physical as the sensory properties of sunscreens can help to increase its continued use and impact on health. The use of nanoemulsions in the development of photoprotective vehicles is an advantage, since nanostructured components may have superior properties regarding their performance when compared to conventional products. The advantages of using nanobiotechnology in manufacture of cosmetic and dermatological formulations arise from the protection of compounds from chemical or enzymatic degradation, from the control of their release, and also to the prolonged retention time of cosmetic ingredients in the stratum corneum. Thus, this study aimed to evaluate the impact of stirring speed and of glycerin and sodium chloride concentrations in the development and effectiveness of a nanoemulsion containing ethylhexyl methoxycinnamate and benzophenone-3. The results of statistical analyses regarding the impact of the variables in the process of nanoemulsion development showed that these parameters affect the phase inversion temperature (PIT. However, this did not affect the particle size and the photoprotective efficacy in vitro.

  6. Determination of short chain chlorinated paraffins in water by stir bar sorptive extraction-thermal desorption-gas chromatography-triple quadrupole tandem mass spectrometry.

    Science.gov (United States)

    Tölgyessy, P; Nagyová, S; Sládkovičová, M

    2017-04-21

    A simple, robust, sensitive and environment friendly method for the determination of short chain chlorinated paraffins (SCCPs) in water using stir bar sorptive extraction (SBSE) coupled to thermal desorption-gas chromatography-triple quadrupole tandem mass spectrometry (TD-GC-QqQ-MS/MS) was developed. SBSE was performed using 100mL of water sample, 20mL of methanol as a modifier, and a commercial sorptive stir bar (with 10mm×0.5mm PDMS layer) during extraction period of 16h. After extraction, the sorptive stir bar was thermally desorbed and online analysed by GC-MS/MS. Method performance was evaluated for MilliQ and surface water spiked samples. For both types of matrices, a linear dynamic range of 0.5-3.0μgL -1 with correlation coefficients >0.999 and relative standard deviations (RSDs) of the relative response factors (RRFs) <12% was established. The limits of quantification (LOQs) of 0.06 and 0.08μgL -1 , and the precision (repeatability) of 6.4 and 7.7% (RSDs) were achieved for MilliQ and surface water, respectively. The method also showed good robustness, recovery and accuracy. The obtained performance characteristics indicate that the method is suitable for screening and monitoring and compliance checking with environmental quality standards (EQS, set by the EU) for SCCPs in surface waters. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Determination of synthetic phenolic antioxidants in soft drinks by stir-bar sorptive extraction coupled to gas chromatography-mass spectrometry.

    Science.gov (United States)

    Cacho, Juan Ignacio; Campillo, Natalia; Viñas, Pilar; Hernández-Córdoba, Manuel

    2015-01-01

    The synthetic phenolic antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ) were pre-concentrated by stir-bar sorptive extraction and thermally desorbed (SBSE-TD) before analysis by GC-MS. Several parameters affecting the derivatisation step and both SBSE extraction and thermal desorption were carefully optimised. When the analyses of BHA and TBHQ in their acetylated, silylated and underivatised forms were compared, the best results were obtained when the in-situ derivatisation procedure with acetic anhydride was employed. Quantification was carried out using carvacrol as the internal standard, providing quantification limits of between 0.11 and 0.15 ng ml(-1), depending on the compound. Recovery assays for samples spiked at two concentration levels, 1 and 5 ng ml(-1), provided recoveries in the 81-117% range. The proposed method was applied in the analysis canned soft drinks and the analytes were found in five of the 10 samples analysed.

  8. Stirring the Ashes of Public Discourse.

    Science.gov (United States)

    Marinara, Martha

    Sylvia Plath's confessional poem, "Lady Lazarus" can be used to illustrate a connection between autobiography and social critique. "You poke and stir" among the institutions that form social relations--the educational system, the court system, the economic system--to find individuals whose lives, whose joys and pains, and…

  9. Microstructure evolution and texture development in a friction stir-processed AISI D2 tool steel

    Science.gov (United States)

    Yasavol, N.; Abdollah-zadeh, A.; Vieira, M. T.; Jafarian, H. R.

    2014-02-01

    Crystallographic texture developments during friction stir processing (FSP) of AISI D2 tool were studied with respect to grain sizes in different tool rotation rates. Comparison of the grain sizes in various rotation rates confirmed that grain refinement occurred progressively in higher rotation rates by severe plastic deformation. It was found that the predominant mechanism during FSP should be dynamic recovery (DRV) happened concurrently with continuous dynamic recrystallization (CDRX) caused by particle-stimulated nucleation (PSN). The developed shear texture relates to the ideal shear textures of D1 and D2 in bcc metals. The prevalence of highly dense arrangement of close-packed planes of bcc and the lowest Taylor factor showed the lowest compressive residual stress which is responsible for better mechanical properties compared with the grain-precipitate refinement.

  10. Effect of welding speed on microstructural and mechanical properties of friction stir welded Inconel 600

    International Nuclear Information System (INIS)

    Song, K.H.; Fujii, H.; Nakata, K.

    2009-01-01

    In order to evaluate the properties of a friction stir welded Ni base alloy, Inconel 600 (single phase type) was selected. Sound friction stir welds without weld defect were obtained at 150 and 200 mm/min in welding speed, however, a groove like defect occurred at 250 mm/min. The electron back scattered diffraction (EBSD) method was used to analyze the grain boundary character distribution. As a result, dynamic recrystallization was observed at all conditions, and the grain refinement was achieved in the stir zone, and it was gradually accelerated from 19 μm in average grain size of the base material to 3.4 μm in the stir zone with increasing the welding speed. It also has an effect on the mechanical properties so that friction stir welded zone showed 20% higher microhardness and 10% higher tensile strength than those of base material.

  11. Optimization of friction stir welding process parameters to maximize tensile strength of stir cast AA6061-T6/AlNp composite

    International Nuclear Information System (INIS)

    Ashok Kumar, B.; Murugan, N.

    2014-01-01

    Highlights: • AA6061/AlN p cast composite was welded by FSW process. • Regression models were developed to predict UTS and elongation of the FS welded joint. • FS welded joint using the optimized parameters exhibited maximum UTS and joint efficiency. • Defect free weld joint was obtained with optimized parameters value. - Abstract: Aluminium Matrix Composites (AMCs) reinforced with particulate form of reinforcement has replaced monolithic alloys in many engineering industries due to its superior mechanical properties and tailorable thermal and electrical properties. As aluminium nitride (AlN) has high specific strength, high thermal conductivity, high electrical resistivity, low dielectric constant, low coefficient of thermal expansion and good compatibility with aluminium alloy, Al/AlN composite is extensively used in electronic packaging industries. Joining of AMCs is unavoidable in many engineering applications. Friction Stir Welding (FSW) is one of the most suitable welding process to weld the AMCs reinforced with particulate form of ceramics without deteriorating its superior mechanical properties. An attempt has been made to develop regression models to predict the Ultimate Tensile Strength (UTS) and Percent Elongation (PE) of the friction stir welded AA6061 matrix composite reinforced with aluminium nitride particles (AlN p ) by correlating the significant parameters such as tool rotational speed, welding speed, axial force and percentage of AlN p reinforcement in the AA6061 matrix. Statistical software SYSTAT 12 and statistical tools such as analysis of variance (ANOVA) and student’s t test, have been used to validate the developed models. It was observed from the investigation that these factors independently influenced the UTS and PE of the friction stir welded composite joints. The developed regression models were optimized to maximize UTS of friction stir welded AA6061/AlN p composite joints

  12. Gas-solid hydroxyethylation of potato starch in a stirred vibrating fluidized bed reactor

    NARCIS (Netherlands)

    Kuipers, N.J M; Stamhuis, Eize; Beenackers, A.A C M

    A novel reactor for modifying cohesive C-powders such as in the gas-solid hydroxyethylation of semidry potato starch is characterized, the so-called stirred vibrating fluidized bed reactor. Good fluidization characteristics are obtained in this reactor for certain combinations of stirring and

  13. Friction Stir Processing of Cast Superalloys, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR effort examines the feasibility of an innovative fabrication technology incorporating sand casting and friction stir processing (FSP) for producing...

  14. Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy.

    Science.gov (United States)

    Campanelli, Sabina Luisa; Casalino, Giuseppe; Casavola, Caterina; Moramarco, Vincenzo

    2013-12-18

    Friction Stir Welding (FSW) is a solid-state joining process; i.e. , no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.

  15. Chiral imprinted polymers as enantiospecific coatings of stir bar sorptive extraction devices.

    Science.gov (United States)

    Gomez-Caballero, Alberto; Guerreiro, Antonio; Karim, Kal; Piletsky, Sergey; Goicolea, M Aranzazu; Barrio, Ramon J

    2011-10-15

    This paper reports the design of Molecularly Imprinted Polymers (MIP) with affinity towards (S)-citalopram using computational modeling for the selection of functional monomers and monomer:template ratio. Acrylamide was selected as functional monomer and the final complex functional monomer/template resulted in a 3:1 ratio. The polymer was synthesized by radical polymerization initiated by UV onto magnetic stir-bars in order to obtain a stir bar sorptive extraction (SBSE) device capable of selective enantiomeric recognition. After successful template removal, the parameters affecting the SBSE procedure (sample volume, ionic strength, extraction time and pH) were optimized for the effective rebinding of the target analyte. The resultant chirally imprinted polymer based stir-bar was able to selectively extract (S)-citalopram from a racemic mixture in an aqueous media with high specificity (specificity factor 4) between 25 and 500 μgL(-1). The MIP coated stir-bars can have significance for enantiospecific sample pre-concentration and subsequent analysis without the need for any chiral chromatographic separation. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Multiple pass and multiple layer friction stir welding and material enhancement processes

    Science.gov (United States)

    Feng, Zhili [Knoxville, TN; David, Stan A [Knoxville, TN; Frederick, David Alan [Harriman, TN

    2010-07-27

    Processes for friction stir welding, typically for comparatively thick plate materials using multiple passes and multiple layers of a friction stir welding tool. In some embodiments a first portion of a fabrication preform and a second portion of the fabrication preform are placed adjacent to each other to form a joint, and there may be a groove adjacent the joint. The joint is welded and then, where a groove exists, a filler may be disposed in the groove, and the seams between the filler and the first and second portions of the fabrication preform may be friction stir welded. In some embodiments two portions of a fabrication preform are abutted to form a joint, where the joint may, for example, be a lap joint, a bevel joint or a butt joint. In some embodiments a plurality of passes of a friction stir welding tool may be used, with some passes welding from one side of a fabrication preform and other passes welding from the other side of the fabrication preform.

  17. Pulsed ultrasonic stir welding system

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    An ultrasonic stir welding system includes a welding head assembly having a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. During a welding operation, ultrasonic pulses are applied to the rod as it rotates about its longitudinal axis. The ultrasonic pulses are applied in such a way that they propagate parallel to the longitudinal axis of the rod.

  18. In-Space Friction Stir Welding Machine, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Longhurst Engineering, PLC, and Vanderbilt University propose an in-space friction stir welding (FSW) machine for joining complex structural aluminum components. The...

  19. Effect of microstructure on properties of friction stir welded Inconel Alloy 600

    International Nuclear Information System (INIS)

    Sato, Y.S.; Arkom, P.; Kokawa, H.; Nelson, T.W.; Steel, R.J.

    2008-01-01

    Friction stir welding (FSW) has been widely used to metals with moderate melting temperatures, primarily Al alloys. Recently, tool materials that withstand high stresses and temperatures necessary for FSW of materials with high melting temperatures have been developed. In the present study, polycrystalline cubic boron nitride (PCBN) tool was used for partially penetrated FSW of Inconel Alloy 600, and a defect-free weld was successfully produced. Microstructural characteristics, mechanical and corrosion properties in the weld were examined. The weld had better mechanical properties than the base material due to formation of fine grain structure in the stir zone, but exhibited slightly the lower corrosion resistance in a part of the stir zone and heat-affected zone (HAZ)

  20. Friction stir welding process to repair voids in aluminum alloys

    Science.gov (United States)

    Rosen, Charles D. (Inventor); Litwinski, Edward (Inventor); Valdez, Juan M. (Inventor)

    1999-01-01

    The present invention provides an in-process method to repair voids in an aluminum alloy, particularly a friction stir weld in an aluminum alloy. For repairing a circular void or an in-process exit hole in a weld, the method includes the steps of fabricating filler material of the same composition or compatible with the parent material into a plug form to be fitted into the void, positioning the plug in the void, and friction stir welding over and through the plug. For repairing a longitudinal void (30), the method includes machining the void area to provide a trough (34) that subsumes the void, fabricating filler metal into a strip form (36) to be fitted into the trough, positioning the strip in the trough, and rewelding the void area by traversing a friction stir welding tool longitudinally through the strip. The method is also applicable for repairing welds made by a fusing welding process or voids in aluminum alloy workpieces themselves.

  1. Modelling of the temperature field that accompanies friction stir welding

    Directory of Open Access Journals (Sweden)

    Nosal Przemysław

    2017-01-01

    Full Text Available The thermal modelling of the Friction Stir Welding process allows for better recognition and understanding of phenomena occurring during the joining process of different materials. It is of particular importance considering the possibilities of process technology parameters, optimization and the mechanical properties of the joint. This work demonstrates the numerical modelling of temperature distribution accompanying the process of friction stir welding. The axisymmetric problem described by Fourier’s type equation with internal heat source is considered. In order to solve the diffusive initial value problem a fully implicit scheme of the finite difference method is applied. The example under consideration deals with the friction stir welding of a plate (0.7 cm thick made of Al 6082-T6 by use of a tool made of tungsten alloy, whereas the material subjected to welding was TiC powder. Obtained results confirm both quantitatively and qualitatively experimental observations that the superior temperature corresponds to the zone where the pin joints the shoulder.

  2. Reverberation chambers a la carte: an overview of the different mode-stirring techniques

    NARCIS (Netherlands)

    Serra, R.; Marvin, A.C.; Moglie, F.; Mariani Primiani, V.; Cozza, A.; Arnaut, L.R.; Huang, Y.; Hatfield, M.O.; Klingler, M.; Leferink, F.

    2017-01-01

    Reverberation chambers (RC), a name inspired in room acoustics, are also known in literature as reverberating, reverb, mode-stirred or mode-tuned chambers. In their basic form, they consist of a shielded metallic enclosure, forming a cavity resonator, together with some mode-stirring mechanism. The

  3. Reverberation Chambers à La Carte : An Overview of the Different Mode-Stirring Techniques

    NARCIS (Netherlands)

    Serra, Ramiro; Marvin, Andy C.; Moglie, Franco; Mariani Primiani, Valter; Cozza, Andrea; Arnaut, Luk R.; Huang, Yi; Hatfield, Michael O.; Klingler, Marco; Leferink, Frank

    2017-01-01

    Reverberation chambers (RC), a name inspired in room acoustics, are also known in literature as reverberating, reverb, mode-stirred or mode-tuned chambers. In their basic form, they consist of a shielded metallic enclosure, forming a cavity resonator, together with some mode-stirring mechanism. The

  4. Structural Phase Evolution in Ultrasonic-Assisted Friction Stir Welded 2195 Aluminum Alloy Joints

    Science.gov (United States)

    Eliseev, A. A.; Fortuna, S. V.; Kalashnikova, T. A.; Chumaevskii, A. V.; Kolubaev, E. A.

    2017-10-01

    The authors examined the structural and phase state of fixed joints produced by method of friction stir welding (FSW) and ultrasonic-assisted friction stir welding (UAFSW) from extruded profile of aluminum alloy AA2195. In order to identify the role of ultrasonic application in the course of welding, such characteristics, as volume fraction and average size of secondary particles are compared in the base material and stir zones of FSW and UAFSW joints. By applying the methods of SEM and TEM analysis, researchers established the complex character of phase transitions as a result of ultrasonic application.

  5. Experimental studies of parameters affecting the heat generation in friction stir welding process

    Directory of Open Access Journals (Sweden)

    Mijajlović Miroslav M.

    2012-01-01

    Full Text Available Heat generation is a complex process of transformation of a specific type of energy into heat. During friction stir welding, one part of mechanical energy delivered to the welding tool is consumed in the welding process, another is used for deformational processes etc., and the rest of the energy is transformed into heat. The analytical procedure for the estimation of heat generated during friction stir welding is very complex because it includes a significant number of variables and parameters, and many of them cannot be fully mathematically explained. Because of that, the analytical model for the estimation of heat generated during friction stir welding defines variables and parameters that dominantly affect heat generation. These parameters are numerous and some of them, e. g. loads, friction coefficient, torque, temperature, are estimated experimentally. Due to the complex geometry of the friction stir welding process and requirements of the measuring equipment, adequate measuring configurations and specific constructional solutions that provide adequate measuring positions are necessary. This paper gives an overview of the process of heat generation during friction stir welding, the most influencing parameters on heat generation, constructional solutions for the measuring equipment needed for these experimental researches and examples of measured values.

  6. Comparison of MRI sequences for evaluation of multiple sclerosis of the cervical spinal cord at 3 T

    International Nuclear Information System (INIS)

    Philpott, Cristina; Brotchie, Peter

    2011-01-01

    Purpose: Debate remains regarding the utility of the traditional STIR (short inversion time recovery) sequence in aiding MRI diagnosis of spinal cord lesions in patients with multiple sclerosis (MS) and this sequence is not included in the current imaging guidelines. A recent study proposed a T1 weighted STIR as a superior alternative to the traditional STIR and T2 fast spin echo (FSE). Thus, the aim of this study was to compare the sensitivity of T2, standard STIR and T1 weighted STIR sequences in the evaluation of MS plaques on our 3 T system. Methods and materials: A retrospective analysis of patients with multiple sclerosis who presented to our institution over a period of 5 months and who had cervical cord lesions was undertaken. Patients had been examined with our institutional protocol which included T2 FSE, STIR and the recommended T1 STIR. Quantitative analysis of the lesions versus background cord using sample T-tests was performed for each sequence, and comparative analysis of the lesion contrast:background cord ratios of the 3 sequences (using two-way ANOVA tests) was performed. Results: The T2 sequence was not as sensitive in detecting lesions versus the traditional STIR and T1 weighted STIR, with 10% of lesions not detected using statistical analysis (p < 0.05). The traditional STIR also demonstrated greater contrast ratios than the T2 sequence (p < 0.05) suggesting increased sensitivity. However, the T1 STIR demonstrated even greater contrast ratios than both the traditional STIR and T2 sequences (p < 0.05). Conclusion: This study confirms earlier findings of the traditional STIRs increased sensitivity versus the T2 sequence. However, the new “T1 weighted STIR” appears to be even more sensitive than both these sequences showing potential promise as an alternative method to monitor demyelinating plaques of MS.

  7. Effect of electromagnetic stirring on solidification structure of austenitic stainless steel in horizontal continuous casting

    Directory of Open Access Journals (Sweden)

    ZHOU Shu-cai

    2007-08-01

    Full Text Available An investigation on the influence of low frequency rotary electromagnetic stirring on solidification structure of austenitic stainless steel in horizontal continuous casting was experimentally conducted and carried out on an industrial trial basis. The results show that application of appropriate electromagnetic stirring parameters can obviously improve the macrostructure of austenitic stainless steel, in which both columnar and equiaxed grains can be greatly refined and shrinkage porosity or cavity zone along centerline can be remarkably decreased due to eliminating intracrystalline and enlarging equiaxed grains zone. The industrial trials verify that the electromagnetic stirring intensity of austenitic stainless steel should be higher than that of plain carbon steel. Electromagnetic stirring has somewhat affected the macrostructure of austenitic stainless steel even if the magnetic flux density of the electromagnetic stirring reaches 90 mT (amplitude reaches 141 mT in average at frequency f=3-4Hz, which provides a reference for the optimization of design and process parameters when applying the rotary electromagnetic stirrer.

  8. Friction Stir Processing of Cast Superalloys, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I effort examines the feasibility of an innovative fabrication technology incorporating sand casting and friction stir processing (FSP) for producing...

  9. Applying a nonlinear, pitch-catch, ultrasonic technique for the detection of kissing bonds in friction stir welds.

    Science.gov (United States)

    Delrue, Steven; Tabatabaeipour, Morteza; Hettler, Jan; Van Den Abeele, Koen

    2016-05-01

    Friction stir welding (FSW) is a promising technology for the joining of aluminum alloys and other metallic admixtures that are hard to weld by conventional fusion welding. Although FSW generally provides better fatigue properties than traditional fusion welding methods, fatigue properties are still significantly lower than for the base material. Apart from voids, kissing bonds for instance, in the form of closed cracks propagating along the interface of the stirred and heat affected zone, are inherent features of the weld and can be considered as one of the main causes of a reduced fatigue life of FSW in comparison to the base material. The main problem with kissing bond defects in FSW, is that they currently are very difficult to detect using existing NDT methods. Besides, in most cases, the defects are not directly accessible from the exposed surface. Therefore, new techniques capable of detecting small kissing bond flaws need to be introduced. In the present paper, a novel and practical approach is introduced based on a nonlinear, single-sided, ultrasonic technique. The proposed inspection technique uses two single element transducers, with the first transducer transmitting an ultrasonic signal that focuses the ultrasonic waves at the bottom side of the sample where cracks are most likely to occur. The large amount of energy at the focus activates the kissing bond, resulting in the generation of nonlinear features in the wave propagation. These nonlinear features are then captured by the second transducer operating in pitch-catch mode, and are analyzed, using pulse inversion, to reveal the presence of a defect. The performance of the proposed nonlinear, pitch-catch technique, is first illustrated using a numerical study of an aluminum sample containing simple, vertically oriented, incipient cracks. Later, the proposed technique is also applied experimentally on a real-life friction stir welded butt joint containing a kissing bond flaw. Copyright © 2016

  10. Gauge fixing, BRS invariance and Ward identities for randomly stirred flows

    International Nuclear Information System (INIS)

    Berera, Arjun; Hochberg, David

    2009-01-01

    The Galilean invariance of the Navier-Stokes equation is shown to be akin to a global gauge symmetry familiar from quantum field theory. This symmetry leads to a multiple counting of infinitely many inertial reference frames in the path integral approach to randomly stirred fluids. This problem is solved by fixing the gauge, i.e., singling out one reference frame. The gauge fixed theory has an underlying Becchi-Rouet-Stora (BRS) symmetry which leads to the Ward identity relating the exact inverse response and vertex functions. This identification of Galilean invariance as a gauge symmetry is explored in detail, for different gauge choices and by performing a rigorous examination of a discretized version of the theory. The Navier-Stokes equation is also invariant under arbitrary rectilinear frame accelerations, known as extended Galilean invariance (EGI). We gauge fix this extended symmetry and derive the generalized Ward identity that follows from the BRS invariance of the gauge-fixed theory. This new Ward identity reduces to the standard one in the limit of zero acceleration. This gauge-fixing approach unambiguously shows that Galilean invariance and EGI constrain only the zero mode of the vertex but none of the higher wavenumber modes.

  11. Gauge fixing, BRS invariance and Ward identities for randomly stirred flows

    Energy Technology Data Exchange (ETDEWEB)

    Berera, Arjun [School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3JZ (United Kingdom)], E-mail: ab@ph.ed.ac.uk; Hochberg, David [Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir Km. 4, 28850 Torrejon de Ardoz, Madrid (Spain)], E-mail: hochbergd@inta.es

    2009-06-21

    The Galilean invariance of the Navier-Stokes equation is shown to be akin to a global gauge symmetry familiar from quantum field theory. This symmetry leads to a multiple counting of infinitely many inertial reference frames in the path integral approach to randomly stirred fluids. This problem is solved by fixing the gauge, i.e., singling out one reference frame. The gauge fixed theory has an underlying Becchi-Rouet-Stora (BRS) symmetry which leads to the Ward identity relating the exact inverse response and vertex functions. This identification of Galilean invariance as a gauge symmetry is explored in detail, for different gauge choices and by performing a rigorous examination of a discretized version of the theory. The Navier-Stokes equation is also invariant under arbitrary rectilinear frame accelerations, known as extended Galilean invariance (EGI). We gauge fix this extended symmetry and derive the generalized Ward identity that follows from the BRS invariance of the gauge-fixed theory. This new Ward identity reduces to the standard one in the limit of zero acceleration. This gauge-fixing approach unambiguously shows that Galilean invariance and EGI constrain only the zero mode of the vertex but none of the higher wavenumber modes.

  12. A membrane stirrer for product recovery and substrate feeding.

    Science.gov (United States)

    Femmer, T; Carstensen, F; Wessling, M

    2015-02-01

    During fermentation processes, in situ product recovery (ISPR) using submerged membranes allows a continuous operation mode with effective product removal. Continuous recovery reduces product inhibition and organisms in the reactor are not exposed to changing reaction conditions. For an effective in situ product removal, submerged membrane systems should have a sufficient large membrane area and an anti-fouling concept integrated in a compact device for the limited space in a lab-scale bioreactor. We present a new membrane stirrer with integrated filtration membranes on the impeller blades as well as an integrated gassing concept in an all-in-one device. The stirrer is fabricated by rapid prototyping and is equipped with a commercial micromesh membrane. Filtration performance is tested using a yeast cell suspension with different stirring speeds and aeration fluxes. We reduce membrane fouling by backflushing through the membrane with the product stream. © 2014 Wiley Periodicals, Inc.

  13. Achievement report on developing inverse manufacturing system in fiscal 1998; 1998 nendo inverse manufacturing system no kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Research and development has been performed on a circulating type production system, or an inverse manufacturing system, to minimize the environmental load in the entire life cycle of industrial products from design to manufacturing, maintenance, recovery, and re-utilization. In developing the recycling information system, discussion and extraction were executed on the data to be exchanged between manufacturers and users in the inverse society. A new individual parts history control system was developed. In developing the recycling processing system, a prototype system was evaluated by using hypothetical data, wherein the possibility of improving the recycling processing efficiency and reducing the cost was verified. In addition, trial design was made on a recycling processing plant in consideration of the cost effect to get the future plant image. In fabricating the inverse manufacturing products, a prototype concept model was made for information terminal devices. Development was performed on such elementary technologies as the easy-to-disintegrate structure technology, self-integration connecting structure and environmental hysteresis detection system. (NEDO)

  14. Torque Control of Friction Stir Welding, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Longhurst Engineering, PLC and Vanderbilt University propose the innovation of torque control of friction stir welding (FSW) as a replacement to force control of...

  15. The Role of Friction Stir Welding in Nuclear Fuel Plate Fabrication

    International Nuclear Information System (INIS)

    Burkes, D.; Medvedev, P.; Chapple, M.; Amritkar, A.; Wells, P.; Charit, I

    2009-01-01

    The friction bonding process combines desirable attributes of both friction stir welding and friction stir processing. The development of the process is spurred on by the need to fabricate thin, high density, reduced enrichment fuel plates for nuclear research reactors. The work seeks to convert research and test reactors currently operating on highly enriched uranium fuel to operate on low enriched uranium fuel without significant loss in reactor performance, safety characteristics, or significant increase in cost. In doing so, the threat of global nuclear material proliferation will be reduced. Feasibility studies performed on the process show that this is a viable option for mass production of plate-type nuclear fuel. Adapting the friction stir weld process for nuclear fuel fabrication has resulted in the development of several unique ideas and observations. Preliminary results of this adaptation and process model development are discussed

  16. The effect of postprocessing on tensile property and microstructure evolution of friction stir welding aluminum alloy joint

    International Nuclear Information System (INIS)

    Hu, Z.L.; Wang, X.S.; Pang, Q.; Huang, F.; Qin, X.P.; Hua, L.

    2015-01-01

    Friction stir welding is an efficient manufacturing method for joining aluminum alloy and can dramatically reduce grain size conferring excellent plastic deformation properties. Consequently, friction stir welding is used to manufacture tailor welded blanks to optimize weight or performance in the final component. In the study, the microstructural evolution and mechanical properties of friction stir welding joint during plastic forming and subsequent heat treatment were investigated. The microstructural characteristics of the friction stir welding joints were studied by Electron Backscattered Diffraction and Transmission Electron Microscopy. The mechanical properties were evaluated by tensile and microhardness tests. It is found that the tensile and yield strengths of friction stir welding joints are significantly improved after severe plastic deformation due to the grain refinement. Following heat treatment, the strength of the friction stir welding joints significantly decrease due to the obvious abnormal grain growth. Careful attention must be given to the processing route of any friction stir welding joint intended for plastic forming, especially the annealing between forming passes. Severe plastic deforming of the friction stir welding joint leads to a high level of stored energy/dislocation density, which causes the abnormal grain growth during subsequent heat treatment, and consequently reduce the mechanical properties of the friction stir welding joint. - Highlights: • Great changes are observed in the microstructure of FSW joint after postprocessing. • Postprocessing shows great effect on the microstructure stability of FSW joint. • The weld shows more significant decrease in strength than the BM due to the AGG. • Attention must be given to the processing route of FSW joint for plastic forming

  17. Lung MRI of invasive fungal infection at 3 Tesla: evaluation of five different pulse sequences and comparison with multidetector computed tomography (MDCT)

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Chenggong; Tan, Xiangliang; Li, Caixia; Wu, Yuankui; Hao, Peng; Xiong, Wei; Xu, Yikai [Southern Medical University, Department of Medical Imaging Center, Nanfang Hospital, Guangzhou, Guangdong (China); Wei, Qi; Feng, Ru; Xu, Jun [Southern Medical University, Department of Hematology, Nanfang Hospital, Guangzhou (China); Chan, Queenie [Philips Healthcare, New Territories (China)

    2014-09-18

    To evaluate the diagnostic performance of five MR sequences to detect pulmonary infectious lesions in patients with invasive fungal infection (IFI), using multidetector computed tomography (MDCT) as the reference standard. Thirty-four immunocompromised patients with suspected IFI underwent MDCT and MRI. The MR studies were performed using five pulse sequences at 3.0 T: T2-weighted turbo spin echo (TSE), short-tau inversion recovery (STIR), spectrally selective attenuated inversion recovery (SPAIR), T1-weighted high resolution isotropic volume excitation (e-THRIVE) and T1-weighted fast field echo (T1-FFE). The size, lesion-to-lung contrast ratio and the detectability of pulmonary lesions on MR images were assessed. Image quality and artefacts on different sequences were also rated. A total of 84 lesions including nodules (n = 44) and consolidation (n = 40) were present in 75 lobes. SPAIR and e-THRIVE images achieved high overall lesion-related sensitivities for the detection of pulmonary abnormalities (90.5 % and 86.9 %, respectively). STIR showed the highest lesion-to-lung contrast ratio for nodules (21.8) and consolidation (17.0), whereas TSE had the fewest physiological artefacts. MRI at 3.0 T can depict clinically significant pulmonary IFI abnormalities with high accuracy compared to MDCT. SPAIR and e-THRIVE are preferred sequences for the detection of infectious lesions of 5 mm and larger. (orig.)

  18. Effect of tool geometry on friction stir spot welding of polypropylene sheets

    Directory of Open Access Journals (Sweden)

    M. K. Bilici

    2012-10-01

    Full Text Available The effects of tool geometry and properties on friction stir spot welding properties of polypropylene sheets were studied. Four different tool pin geometries, with varying pin angles, pin lengths, shoulder diameters and shoulder angles were used for friction stir spot welding. All the welding operations were done at the room temperature. Lap-shear tensile tests were carried out to find the weld static strength. Weld cross section appearance observations were also done. From the experiments the effect of tool geometry on friction stir spot weld formation and weld strength were determined. The optimum tool geometry for 4 mm thick polypropylene sheets were determined. The tapered cylindrical pin gave the biggest and the straight cylindrical pin gave the lowest lap-shear fracture load.

  19. Stirred cell ultrafiltration of lignin from black liquor generated from South African kraft mills

    CSIR Research Space (South Africa)

    Kekana, Paul

    2016-12-01

    Full Text Available Ultrafiltration of lignin from black liquor was carried out in a stirred batch cell using polyethersulfone membranes. Parameters such as operating pressure, feed concentration, stirring rate and membrane cut-off size were varied and their effects...

  20. Numerical optimisation of friction stir welding: review of future challenges

    DEFF Research Database (Denmark)

    Tutum, Cem Celal; Hattel, Jesper Henri

    2011-01-01

    During the last decade, the combination of increasingly more advanced numerical simulation software with high computational power has resulted in models for friction stir welding (FSW), which have improved the understanding of the determining physical phenomena behind the process substantially....... This has made optimisation of certain process parameters possible and has in turn led to better performing friction stir welded products, thus contributing to a general increase in the popularity of the process and its applications. However, most of these optimisation studies do not go well beyond manual...

  1. Fast fluid-attenuated inversion-recovery MR image in the intracranial tumors: comparison with fast spin-echo image

    International Nuclear Information System (INIS)

    Choi, Hye Young; Kwang, Hyoen Joo; Baek, Seoung Yeon; Lee, Sun Wha

    1997-01-01

    To evaluate the significance of fluid-attenuated inversion recovery(FLAIR) magnetic resonance(MR) images for the diagnosis of intracranial tumors. MR imaging was used to study 15 patients with various intracranial tumors and were compared the findings according to fast spin echo and fast FLAIR images. In 12 of 15 patients, tumor signal intensities on FLAIR images were consistent with those shown on T2-weighted(T2W) images. In seven of eight patients who had cystic or necrotic components within the mass, FLAIR images showed isosignal intensity and in the other patient, high signal intensity was seen. There was variation in the signal intensity from cerebrospinal fluid(CSF). In 12 of 13 patients in whom edema was associated with tumor, FLAIR images were clearer than T2W images as their signal intensity was brighter. In eight patients, however, FLAIR and T2W images provided a similar definition of the margin between edema and tumor. In six patients with intratumoral hemorrhage except the chronic cystic stage. We concluded that in the diagnosis of intracranial tumors, FLAIR images can supplement conventional spin-echo images

  2. A fundamental study on the structural integrity of magnesium alloys joined by friction stir welding

    Science.gov (United States)

    Rao, Harish Mangebettu

    The goal of this research is to study the factors that influence the physical and mechanical properties of lap-shear joints produced using friction stir welding. This study focuses on understanding the effect of tool geometry and weld process parameters including the tool rotation rate, tool plunge depth and dwell time on the mechanical performance of similar magnesium alloy and dissimilar magnesium to aluminum alloy weld joints. A variety of experimental activities were conducted including tensile and fatigue testing, fracture surface and failure analysis, microstructure characterization, hardness measurements and chemical composition analysis. An investigation on the effect of weld process conditions in friction stir spot welding of magnesium to magnesium produced in a manner that had a large effective sheet thickness and smaller interfacial hook height exhibited superior weld strength. Furthermore, in fatigue testing of friction stir spot welded of magnesium to magnesium alloy, lap-shear welds produced using a triangular tool pin profile exhibited better fatigue life properties compared to lap-shear welds produced using a cylindrical tool pin profile. In friction stir spot welding of dissimilar magnesium to aluminum, formation of intermetallic compounds in the stir zone of the weld had a dominant effect on the weld strength. Lap-shear dissimilar welds with good material mixture and discontinues intermetallic compounds in the stir zone exhibited superior weld strength compared to lap-shear dissimilar welds with continuous formation of intermetallic compounds in the stir zone. The weld structural geometry like the interfacial hook, hook orientation and bond width also played a major role in influencing the weld strength of the dissimilar lap-shear friction stir spot welds. A wide scatter in fatigue test results was observed in friction stir linear welds of aluminum to magnesium alloys. Different modes of failure were observed under fatigue loading including crack

  3. An innovative bioelectrochemical-anaerobic digestion-coupled system for in-situ ammonia recovery and biogas enhancement: process performance and microbial ecology

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    (SMRC) and a continuous stirred tank reactor (CSTR), to prevent ammonia toxicity during anaerobic digestion by in-situ ammonia recovery and electricity production. In batch experiment, the ammonia concentration in the CSTR decreased from 6 to 0.7 g-N/L with an average recovery rate of 0.18 g-N/L(CSTR...... performance was enhanced. In addition, the coexistence of other cations in CSTR or cathode had no negative effect on the ammonia transportation. In continuous reactor operation, 112% extra biogas production was achieved due to ammonia recovery. High-throughput molecular sequencing analysis showed an impact...... of ammonia recovery on the microbial community composition in the integrated system. Results clearly indicate the great potential of the SMRC-CSTR-coupled system for efficient and cost-effective ammonia recovery, energy production and treatment of ammonia-rich residues....

  4. Effect of shoulder to pin ratio on magnesium alloy Friction Stir Welding

    Science.gov (United States)

    Othman, N. H.; Ishak, M.; Shah, L. H.

    2017-09-01

    This study focuses on the effect of shoulder to pin diameter ratio on friction stir welding of magnesium alloy AZ31. Two pieces of AZ31 alloy with thickness of 2 mm were friction stir welded by using conventional milling machine. The shoulder to pin diameter ratio used in this experiment are 2.25, 2.5, 2.75, 3, 3.33, 3.66, 4.5, 5 and 5.5. The rotational speed and welding speed used in this study are 1000 rpm and 100 mm/min, respectively. Microstructure observation of welded area was studied by using optical microscope. Equiaxed grains were observed at the TMAZ and stir zone indicating fully plastic deformation. The grain size of stir zone increased with decreasing shoulder to pin ratio from ratio 3.33 to 5.5 due to higher heat input. It is observed that, surface galling and faying surface defect is produced when excessive heat input is applied. To evaluate the mechanical properties of this specimen, tensile test was used in this study. Shoulder to pin ratio 5.5 shows lowest tensile strength while shoulder to pin diameter ratio 3.33 shows highest tensile strength with weld efficiency 91 % from based metal.

  5. Understanding Friction Stir Welding

    Science.gov (United States)

    Nunes, A. C., Jr.

    2018-01-01

    This Technical Memorandum explains the friction stir welding process in terms of two basic concepts: the concentration of deformation in a shear surface enveloping the tool and the composition of the overall plastic flow field around the tool from simple flow field components. It is demonstrated how weld structure may be understood and torque, drag, and lateral tool forces may be estimated using these concepts. Some discrepancies between computations and accompanying empirical data are discussed in the text. This work is intended to be helpful to engineers in diagnosing problems and advancing technology.

  6. Natural aging behaviour of friction stir welded 6005A-T6 aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Peng; Sun, Daqian; Li, Hongmei, E-mail: lihongmei@jlu.edu.cn

    2013-08-01

    By local thermal cycles and hardness measurements, supported by transmission electron microscopy, the post-weld natural aging behaviour of friction stir welded 6005A-T6 aluminium alloy was investigated. The results show that the softening in the nugget zone and thermo-mechanically affected zone immediately after welding is mainly caused by the high peak temperatures and rapid cooling rates, resulting in the original β″ precipitates dissolving and restraining re-precipitation. On the one hand, the hardness recovery in both microstructural zones during post-weld natural aging is attributed to the formation of clusters or GP zones depending on the natural aging time. On the other hand, the softening in the heat-affected zone after welding is due to the transformation of the β′′ to β′ precipitates and the precipitation of Q′. Natural aging has little effect on the microstructure and hardness of the heat-affected zone. The mechanism of natural aging behaviour was discussed.

  7. Efficient full waveform inversion using the excitation representation of the source wavefield

    KAUST Repository

    Kalita, Mahesh; Alkhalifah, Tariq Ali

    2017-01-01

    Full waveform inversion (FWI) is an iterative method of data-fitting, aiming at high-resolution recovery of the unknown model parameters. However, its conventional implementation is a cumbersome process, requiring a long computational time and large

  8. Mechanical properties and microstructural evaluation of AA1100 to AZ31 dissimilar friction stir welds

    Energy Technology Data Exchange (ETDEWEB)

    Azizieh, M., E-mail: azizieh@gmail.com [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Sadeghi Alavijeh, A. [School of Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Avenue, Surrey, BC V3T 0A3 (Canada); Abbasi, M. [High Temperature Energy Materials, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Balak, Z. [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Kim, H.S. [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2016-02-15

    In this paper, microstructure and mechanical properties of dissimilar friction stir welds of AA1100 and AZ31 were investigated to understand the effects of rotational and travel speed as well as pin position. The tensile results of welded samples revealed that the sound welds were formed when the stirring pin deviated from the centreline to the AZ31 side. The X-ray diffraction shows that Al{sub 3}Mg{sub 2} and Al{sub 12}Mg{sub 17} intermetallics formation occurs in the stir zone during the welding process. High hardness of these intermetallic phases increased the hardness of the stir zone to 110 Hv. The best tensile results were obtained in the sample processed in the range of 28–32 (rev/mm) rotational to travel speed ratio. - Highlights: • For Al to Mg friction stir welding, tool offset must be to Mg side. • There is an optimum rotational speed for obtain the highest strength. • Intermetallics form in any welding condition. • The volume fraction of intermetallic is directly related to FSW peak temperature.

  9. The erosion performance of cold spray deposited metal matrix composite coatings with subsequent friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Peat, Tom, E-mail: tompeat12@gmail.com [Department of Mechanical & Aerospace Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ (United Kingdom); Galloway, Alexander; Toumpis, Athanasios [Department of Mechanical & Aerospace Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ (United Kingdom); McNutt, Philip [TWI Ltd., Granta Park, Cambridge CB21 6AL (United Kingdom); Iqbal, Naveed [TWI Technology Centre, Wallis Way, Catcliff, Rotherham, S60 5TZ (United Kingdom)

    2017-02-28

    Highlights: • WC-CoCr, Cr{sub 3}C{sub 2}-NiCr and Al{sub 2}O{sub 3} coatings were cold spray deposited on AA5083 and friction stir processed. • The SprayStirred WC-CoCr demonstrated a hardness increase of 100% over the cold sprayed coating. • As-deposited and SprayStirred coatings were examined under slurry erosion test conditions. • Mass and volume loss was measured following 20-min exposure to the slurry. • The WC-CoCr and Al2O3 demonstrated a reduction in volume loss of approx. 40% over the cold sprayed coating. - Abstract: This study forms an initial investigation into the development of SprayStir, an innovative processing technique for generating erosion resistant surface layers on a chosen substrate material. Tungsten carbide – cobalt chromium, chromium carbide – nickel chromium and aluminium oxide coatings were successfully cold spray deposited on AA5083 grade aluminium. In order to improve the deposition efficiency of the cold spray process, coatings were co-deposited with powdered AA5083 using a twin powder feed system that resulted in thick (>300 μm) composite coatings. The deposited coatings were subsequently friction stir processed to embed the particles in the substrate in order to generate a metal matrix composite (MMC) surface layer. The primary aim of this investigation was to examine the erosion performance of the SprayStirred surfaces and demonstrate the benefits of this novel process as a surface engineering technique. Volumetric analysis of the SprayStirred surfaces highlighted a drop of approx. 40% in the level of material loss when compared with the cold spray deposited coating prior to friction stir processing. Micro-hardness testing revealed that in the case of WC-CoCr reinforced coating, the hardness of the SprayStirred material exhibits an increase of approx. 540% over the unaltered substrate and 120% over the as-deposited composite coating. Microstructural examination demonstrated that the increase in the hardness of the

  10. Analysing the strength of friction stir welded dissimilar aluminium alloys using Sugeno Fuzzy model

    Science.gov (United States)

    Barath, V. R.; Vaira Vignesh, R.; Padmanaban, R.

    2018-02-01

    Friction stir welding (FSW) is a promising solid state joining technique for aluminium alloys. In this study, FSW trials were conducted on two dissimilar plates of aluminium alloy AA2024 and AA7075 by varying the tool rotation speed (TRS) and welding speed (WS). Tensile strength (TS) of the joints were measured and a Sugeno - Fuzzy model was developed to interconnect the FSW process parameters with the tensile strength. From the developed model, it was observed that the optimum heat generation at WS of 15 mm.min-1 and TRS of 1050 rpm resulted in dynamic recovery and dynamic recrystallization of the material. This refined the grains in the FSW zone and resulted in peak tensile strength among the tested specimens. Crest parabolic trend was observed in tensile strength with variation of TRS from 900 rpm to 1200 rpm and TTS from 10 mm.min-1 to 20 mm.min-1.

  11. Acoustic 2D full waveform inversion to solve gas cloud challenges

    Directory of Open Access Journals (Sweden)

    Srichand Prajapati

    2015-09-01

    Full Text Available The existing conventional inversion algorithm does not provide satisfactory results due to the complexity of propagated wavefield though the gas cloud. Acoustic full waveform inversion has been developed and applied to a realistic synthetic offshore shallow gas cloud feature with Student-t approach, with and without simultaneous sources encoding. As a modeling operator, we implemented the grid based finite-difference method in frequency domain using second order elastic wave equation. Jacobin operator and its adjoint provide a necessary platform for solving full waveform inversion problem in a reduced Hessian matrix. We invert gas cloud model in 5 frequency band selected from 1 to 12 Hz, each band contains 3 frequencies. The inversion results are highly sensitive to the misfit. The model allows better convergence and recovery of amplitude losses. This approach gives better resolution then the existing least-squares approach. In this paper, we implement the full waveform inversion for low frequency model with minimum number of iteration providing a better resolution of inversion results.

  12. Anodising and corrosion resistance of AA 7050 friction stir welds

    International Nuclear Information System (INIS)

    Atz Dick, Pedro; Knörnschild, Gerhard H.; Dick, Luís F.P.

    2017-01-01

    Highlights: • Sulphuric Anodizing films of AA7050 friction stir welds are 25% thinner on the nugget zone. • Semicoherent MgZn_2 precipitates locally pin the formation of anodic oxide film. • Coarse Al_7Cu_2Fe precipitates anodize irregularly and produces locally thicker films. • Localized corrosion occurs preferentially on the nugget zone and is related to the thinner oxide film and irregular anodizing on stirring voids. - Abstract: The influence of friction stir welding on the sulphuric anodising and corrosion of AA7050 was studied in 0.1 M NaCl by the scanning vibrating electrode technique under simultaneous polarization. The oxide films obtained were characterized by scanning electron microscopy. The porous oxide films are up to 25% thicker on the thermomechanically and heat affected zones and 25% thinner on the nugget. This thinner defective oxide film explains the lower pitting resistance of the nugget zone. Individual pit current transients were indirectly determined from current maps. However, the calculated values are lower than expected, due to underestimation of electrolyte conductivity near pits.

  13. Evaluation of chondromalacia of the patella with axial inversion recovery-fast spin-echo imaging.

    Science.gov (United States)

    Lee, S H; Suh, J S; Cho, J; Kim, S J; Kim, S J

    2001-03-01

    The purpose of our study was to assess the accuracy of inversion recovery-fast spin-echo (IR-FSE) imaging for the evaluation of chondromalacia of the patella. Eighty-six patients were included, they underwent magnetic resonance (MR) examination and subsequent knee arthroscopy. Medial and lateral facets of the patella were evaluated separately. Axial images were obtained by using IR-FSE (TR/TE/TI = 3000/25/150 msec; echo train length, 8; 4-mm thickness; 12-cm field of view; 512 x 256 matrix; two, number of excitations) with a 1.5-T MR machine. MR interpretation of chondromalacia was made on the basis of the arthroscopic grading system. Of a total of 172 facets graded, arthroscopy revealed chondromalacia in 14 facets with various grades (G0, 158; G1, 1; G2, 3; G3, 6; G4, 4). Sensitivity, specificity, and accuracy in the chondromalacia grades were 57.1%, 93.0%, and 90.1%, respectively. There was one false-negative case (G4) and 11 false-positive cases (G1, eight; G2, two; G3, one). Sensitivity and specificity corrected by one grade difference were improved to 85.7% and 98.1%, respectively. When cartilage changes were grouped into early (corresponding to grade 1 and 2) and advanced (grade 3 and 4) diseases, sensitivity and specificity of the early and advanced diseases were 75% and 94% and 80% and 99%, respectively. IR-FSE imaging of the knee revealed high specificity but low sensitivity for the evaluation of chondromalacia of the patella.

  14. Effect of process parameters on mechanical properties of friction stir spot welded magnesium to aluminum alloys

    International Nuclear Information System (INIS)

    Rao, H.M.; Yuan, W.; Badarinarayan, H.

    2015-01-01

    Highlights: • Lap-shear failure load of ∼2.5 kN was achieved in dissimilar Mg to Al spot welds. • Failure load depends on both welding geometrical features and IMCs formation. • Thin and discontinuous IMCs formed in stir zone are beneficial for weld strength. • Low heat input and good material mixing/interlocking is essential for high strength. - Abstract: Friction stir spot welding was applied to dissimilar cast magnesium (Mg) alloy AM60B and wrought aluminum (Al) alloy 6022-T4 under various welding conditions. The influence of tool rotation rate and shoulder plunge depth on lap-shear failure load was examined. Welds were made at four different tool rotation rates of 1000, 1500, 2000 and 2500 revolution per minute (rpm) and various tool shoulder plunge depths from 0 mm to 0.9 mm. The cross section of each weld exhibited the formation of intermetallic compounds (IMCs) in the stir zone. An increase in tool rotation rate decreased the width of the stir zone and resulted in lower lap-shear failure loads. The stir zone width increased and interlocking of IMCs was observed with an increase in tool shoulder plunge depth at 1000 rpm. High lap-shear failure loads were achieved in welds having a large stir zone width with formation of discontinuous IMCs at the tip of the interfacial hook. An average lap-shear failure load of 2.5 kN was achieved for welds made at 1000 rpm and 0.9 mm shoulder plunge. The present study suggests that the mechanical properties of friction stir spot welded dissimilar alloys are greatly influenced by the stir zone width, interfacial hooks and IMCs which are all weld process dependent

  15. Effect of weld morphology on mechanical response and failure of friction stir welds in a naturally aged aluminium alloy

    International Nuclear Information System (INIS)

    Imam, Murshid; Biswas, Kajal; Racherla, Vikranth

    2013-01-01

    Highlights: ► Friction stir welds of AA 6063-T4 are obtained using three tool pin profiles. ► Signature of weld defects in mechanical response of welds is investigated. ► Correlation between peak temperatures in HAZs and their hardness is studied. ► Reasons for strengthening of WNZ and softening of HAZs are found using TEM and XRD. ► A FEM model for the weld zone is developed and validated. -- Abstract: Friction stir butt welds in 6063-T4 aluminium alloy were obtained using square and two tapered tool pin profiles. Tensile tests at 0°, 45°, and 90° to the weld line, hardness contours in the weld cross-section, temperatures in the heat affected zones, cross-sectional macrographs, transmission electron micrographs, and X-ray diffraction studies were used to characterize the welds. In transverse weld specimen, tunnel defects appearing at higher weld speeds for tapered pin profiles, were found to result in mechanical instabilities, i.e. sharp drops in load–displacement curves, much before macroscopic necking occured. Further, in comparison to the base metal, a marked reduction in ductility was observed even in transverse specimen with defect free welds. Hardness contours in the weld cross-section suggest that loss in ductility is due to significant softening in heat affected zone on the retreating side. Transmission electron microscopy images demonstrate that while recovery and overaging are responsible for softening in the heat affected zone, grain size refinement from dynamic recrystallization is responsible for strengthening of the weld nugget zone. X-ray diffraction studies in the three weld zones: weld nugget zone, heat affected zone, and the base metal corroborate these findings. A weld zone model, for use in forming simulations on friction stir welded plates of naturally aged aluminium alloys, was proposed based on mechanical characterization tests. The model was validated using finite element analysis.

  16. Some microstructural characterisations in a friction stir welded oxide dispersion strengthened ferritic steel alloy

    International Nuclear Information System (INIS)

    Legendre, F.; Poissonnet, S.; Bonnaillie, P.; Boulanger, L.; Forest, L.

    2009-01-01

    The goal of this study is to characterize microstructure of a friction stir welded oxide dispersion strengthened alloy. The welded material is constituted by two sheets of an yttria-dispersion-strengthened PM 2000 ferritic steel. Different areas of the friction stir welded product were analyzed using field emission gun secondary electron microscopy (FEG-SEM) and electron microprobe whereas nanoindentation was used to evaluate mechanical properties. The observed microstructural evolution, including distribution of the yttria dispersoids, after friction stir welding process is discussed and a correlation between the microstructure and the results of nanoindentation tests is established.

  17. Optimization of MR imaging for extracranial head and neck lesions

    International Nuclear Information System (INIS)

    Dalley, R.W.; Maravilla, K.R.; Cohen, W.

    1989-01-01

    The authors have used a 1.5T MR imager to study 28 pathologically proven extracranial head and neck lesions. Multiple pulse sequences were performed pre-and/or post-gadolinium, including T1-weighted, short TI inversion-recovery (STIR), spin-density, and T2-weighted sequences. T1-weighted images provided excellent anatomic detail but relatively poor muscle/lesion contrast. Gadolinium often improved lesion visibility; however, discrimination from surrounding fat was impaired. Postcontrast T2-weighted images seemed to provide better lesion conspicuity than did pre-gadolinium images. STIR imaging provided the highest lesion conspicuity in fatty areas. No single sequence was optimal for all head and neck imaging. The authors analyze the advantages and limitations of each sequence and formulate rational imaging protocols based on the primary region of interest

  18. Near Net Manufacturing Using Thin Gage Friction Stir Welding

    Science.gov (United States)

    Takeshita, Jennifer; Potter, David; Holquin, Michael

    2006-01-01

    Friction Stir Welding (FSW) and near net spin forming of FSW aluminumn blanks were investigated for large-scale pressure vessel applications. With a specific focus on very thin gage 2xxx and 7xxx aluminum alloys, the program concentrated on the following: the criteria used for material selection, a potential manufacturing flow, and the effectiveness and associated risks of near net spin forming. Discussion will include the mechanical properties of the friction stir welds and the parent material from before and after the spin forming process. This effort was performed under a NASA Space Exploration initiative focused on increasing the affordability, reliability and performance of pressure vessels larger than 10 ft. diameter.

  19. Safe Control for Spiral Recovery of Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Chang-Jian Ru

    2014-01-01

    Full Text Available With unmanned aerial vehicles (UAVs widely used in both military and civilian fields, many events affecting their safe flying have emerged. That UAV’s entering into the spiral is such a typical safety issue. To solve this safety problem, a novel recovery control approach is proposed. First, the factors of spiral are analyzed. Then, based on control scheduling of state variables and nonlinear dynamic inversion control laws, the spiral recovery controller is designed to accomplish guidance and control of spiral recovery. Finally, the simulation results have illustrated that the proposed control method can ensure the UAV autonomous recovery from spiral effectively.

  20. Overview of Computational Fluid Dynamics (CFD) simulation of stirred vessel

    International Nuclear Information System (INIS)

    Mohd Rizal Mamat; Azraf Azman; Anwar Abdul Rahman; Noraishah Othman

    2010-01-01

    Stirred vessel is one of many widely used equipment in industrial process and chemical industry. The design of stirred vessel typically follows a certain standard chemical engineering practice that may also involve empirical data acquired from experiments. However the design may still take a different route which is computational engineering simulation and analysis. CFD has been identified as one of the possible tools for such purposes. CFD enables the flow fields variables such as velocity, temperature and pressure in the whole computational domain to be obtained and as such it presents an advantage over the experimental setup. (author)

  1. A Survey on Friction Stir Welding Of Dissimilar Magnesium Alloys

    Science.gov (United States)

    Unnikrishnan, M. A.; Raja, Dhas. J. Edwin

    2017-10-01

    There is a consistent demand for superior materials in every industry. The areas on demand are automobile and aerospace sectors in major.. The most commonly used material in these fields is Aluminium.Though it possess all the properties up to some extent constant demand is pushing for alternate materials. Dissimilar alloys have been a relatively new approach towards these fields.. Friction stir welding dissimilar alloys is a big leap in Automobile sector. In this paper a detailed review of Friction stir welding of Dissimilar Magnesium alloys has been done. This work will serve as a reference to subsequent researchers.

  2. Temporal pole signal abnormality on MR imaging in temporal lobe epilepsy with hippocampal sclerosis: a fluid-attenuated inversion-recovery study.

    Science.gov (United States)

    Carrete, Henrique; Abdala, Nitamar; Lin, Kátia; Caboclo, Luís Otávio; Centeno, Ricardo Silva; Sakamoto, Américo Ceiki; Szjenfeld, Jacob; Nogueira, Roberto Gomes; Yacubian, Elza Márcia Targas

    2007-09-01

    To determine the frequency and regional involvement of temporal pole signal abnormality (TPA) in patients with hippocampal sclerosis (HS) using fluid-attenuated inversion-recovery (FLAIR) MR imaging, and to correlate this feature with history. Coronal FLAIR images of the temporal pole were assessed in 120 patients with HS and in 30 normal subjects, to evaluate gray-white matter demarcation. Ninety (75%) of 120 patients had associated TPA. The HS side made difference regarding the presence of TPA, with a left side prevalence (p=0.04, chi2 test). The anteromedial zone of temporal pole was affected in 27 (30%) out of 90 patients. In 63 (70%) patients the lateral zone were also affected. Patients with TPA were younger at seizure onset (p=0.018), but without association with duration of epilepsy. Our FLAIR study show temporal pole signal abnormality in 3/4 of patients with HS, mainly seen on the anteromedial region, with a larger prevalence when the left hippocampus was involved.

  3. Temporal pole signal abnormality on MR imaging in temporal lobe epilepsy with hippocampal sclerosis: a fluid-attenuated inversion-recovery study

    International Nuclear Information System (INIS)

    Carrete Junior, Henrique; Abdala, Nitamar; Szjenfeld, Jacob; Nogueira, Roberto Gomes; Lin, Katia; Caboclo, Luis Otavio; Centeno, Ricardo Silva; Sakamoto, Americo Ceiki; Yacubian, Elza Marcia Targas

    2007-01-01

    Objective: To determine the frequency and regional involvement of temporal pole signal abnormality (TPA) in patients with hippocampal sclerosis (HS) using fluid-attenuated inversion-recovery (FLAIR) MR imaging, and to correlate this feature with history. Method: Coronal FLAIR images of the temporal pole were assessed in 120 patients with HS and in 30 normal subjects, to evaluate gray-white matter demarcation. Results: Ninety (75%) of 120 patients had associated TPA. The HS side made difference regarding the presence of TPA, with a left side prevalence (p=0.04, χ 2 test). The anteromedial zone of temporal pole was affected in 27 (30%) out of 90 patients. In 63 (70%) patients the lateral zone were also affected. Patients with TPA were younger at seizure onset (p=0.018), but without association with duration of epilepsy. Conclusion: Our FLAIR study show temporal pole signal abnormality in 3/4 of patients with HS, mainly seen on the anteromedial region, with a larger prevalence when the left hippocampus was involved. (author)

  4. A Review of Permanent Magnet Stirring During Metal Solidification

    Science.gov (United States)

    Zeng, Jie; Chen, Weiqing; Yang, Yindong; Mclean, Alexander

    2017-12-01

    Rather than using conventional electromagnetic stirring (EMS) with three-phase alternating current, permanent magnet stirring (PMS), based on the use of sintered NdFeB material which has excellent magnetic characteristics, can be employed to generate a magnetic field for the stirring of liquid metal during solidification. Recent experience with steel casting indicates that PMS requires less than 20 pct of the total energy compared with EMS. Despite the excellent magnetic density properties and low power consumption, this relatively new technology has received comparatively little attention by the metal casting community. This paper reviews simulation modeling, experimental studies, and industrial trials of PMS conducted during recent years. With the development of magnetic simulation software, the magnetic field and associated flow patterns generated by PMS have been evaluated. Based on the results obtained from laboratory experiments, the effects of PMS on metal solidification structures and typical defects such as surface pinholes and center cavities are summarized. The significance of findings obtained from trials of PMS within the metals processing sector, including the continuous casting of steel, are discussed with the aim of providing an overview of the relevant parameters that are of importance for further development and industrial application of this innovative technology.

  5. The improvement of ultrasonic characteristics in weld metal of austenitic stainless steel using magnetic stirring method

    International Nuclear Information System (INIS)

    Arakawa, T.; Tomisawa, Y.

    1988-01-01

    The magnetic stirring welding process was tested to save the difficulty of ultrasonic testing of austenitic stainless steel overlayed welds, due to grain refinement of weld solidification structure. The testing involved stirring the molten pool with Lorenz force induced by the interaction of welding current and alternative magnetic field applied from the outside magnetic coil. This report summarizes improvement of ultrasonic characteristic in austenitic stainless steel overlayed welds caused by magnetic stirring welding process

  6. Towards adjoint-based inversion of time-dependent mantle convection with nonlinear viscosity

    Science.gov (United States)

    Li, Dunzhu; Gurnis, Michael; Stadler, Georg

    2017-04-01

    We develop and study an adjoint-based inversion method for the simultaneous recovery of initial temperature conditions and viscosity parameters in time-dependent mantle convection from the current mantle temperature and historic plate motion. Based on a realistic rheological model with temperature-dependent and strain-rate-dependent viscosity, we formulate the inversion as a PDE-constrained optimization problem. The objective functional includes the misfit of surface velocity (plate motion) history, the misfit of the current mantle temperature, and a regularization for the uncertain initial condition. The gradient of this functional with respect to the initial temperature and the uncertain viscosity parameters is computed by solving the adjoint of the mantle convection equations. This gradient is used in a pre-conditioned quasi-Newton minimization algorithm. We study the prospects and limitations of the inversion, as well as the computational performance of the method using two synthetic problems, a sinking cylinder and a realistic subduction model. The subduction model is characterized by the migration of a ridge toward a trench whereby both plate motions and subduction evolve. The results demonstrate: (1) for known viscosity parameters, the initial temperature can be well recovered, as in previous initial condition-only inversions where the effective viscosity was given; (2) for known initial temperature, viscosity parameters can be recovered accurately, despite the existence of trade-offs due to ill-conditioning; (3) for the joint inversion of initial condition and viscosity parameters, initial condition and effective viscosity can be reasonably recovered, but the high dimension of the parameter space and the resulting ill-posedness may limit recovery of viscosity parameters.

  7. High strain rate superplasticity in a friction stir processed 7075 Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, R.S.; Mahoney, M.W.; McFaden, S.X.; Mara, N.A.; Mukherjee, A.K.

    1999-12-31

    In this paper, the authors report the first results using friction stir processing (FSP). In the last ten years, a new technique of Friction Stir Welding (FSW) has emerged as an exciting solid state joining technique for aluminum alloys. This technique, developed by The Welding Institute (TWI), involves traversing a rotating tool that produces intense plastic deformation through a stirring action. The localized heating is produced by friction between the tool shoulder and the sheet top surface, as well as plastic deformation of the material in contact with the tool. This results in a stirred zone with a very fine grain size in a single pass. Mahoney et al. observed a grain size of 3 {micro}m in a 7075 Al alloy. This process can be easily adopted as a processing technique to obtain fine grain size. FSP of a commercial 7075 Al alloy resulted in significant enhancement of superplastic properties. The optimum superplastic strain rate was 10{sup {minus}2}s{sup {minus}1} at 490 C in the FSP 7075 Al alloy, an improvement of more than an order of magnitude in strain rate. The present results suggest an exciting possibility to use a simple FSP technique to enhance grain size dependent properties.

  8. Microstructure-based modeling of tensile deformation of a friction stir welded AZ31 Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    He, Weijun, E-mail: weijun.he@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Zheng, Li [College of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870 (China); Xin, Renlong, E-mail: rlxin@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Liu, Qing [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China)

    2017-02-27

    The deformation and fracture behaviors of friction stir welded (FSWed) Mg alloys are topics under investigation. The microstructure and texture of a FSWed Mg alloy were characterized by electron back scattered diffraction. Four characteristic sub-zones with different orientations in the FSWed Mg alloy joint were identified. The texture distribution across the stir zones and transition zone were obviously inhomogeneous. For comparison, four sub-regions in the base material were also characterized. Based on the experimental microstructure and texture, a crystal plasticity finite element model was developed to represent the friction stir welded Mg alloy. Simulations were carried out to study the effect of texture variation on the deformation behaviors during transverse tension. Compared with the base material case, strong macroscopic strain localization was observed for the FSWed joint case after transverse tension. Strain localization may have contributed to the decayed elongation of the FSWed joint in the transverse tension. Texture variation in the thermal-mechanical affected zone did not change the deformation mechanism in the stir zones, while it did decrease the strain localization, thus assuming to improve the elongation of the friction stir welded Mg alloy.

  9. Microstructure-based modeling of tensile deformation of a friction stir welded AZ31 Mg alloy

    International Nuclear Information System (INIS)

    He, Weijun; Zheng, Li; Xin, Renlong; Liu, Qing

    2017-01-01

    The deformation and fracture behaviors of friction stir welded (FSWed) Mg alloys are topics under investigation. The microstructure and texture of a FSWed Mg alloy were characterized by electron back scattered diffraction. Four characteristic sub-zones with different orientations in the FSWed Mg alloy joint were identified. The texture distribution across the stir zones and transition zone were obviously inhomogeneous. For comparison, four sub-regions in the base material were also characterized. Based on the experimental microstructure and texture, a crystal plasticity finite element model was developed to represent the friction stir welded Mg alloy. Simulations were carried out to study the effect of texture variation on the deformation behaviors during transverse tension. Compared with the base material case, strong macroscopic strain localization was observed for the FSWed joint case after transverse tension. Strain localization may have contributed to the decayed elongation of the FSWed joint in the transverse tension. Texture variation in the thermal-mechanical affected zone did not change the deformation mechanism in the stir zones, while it did decrease the strain localization, thus assuming to improve the elongation of the friction stir welded Mg alloy.

  10. Probing weld quality monitoring in friction stir welding through characterization of signals by fractal theory

    Energy Technology Data Exchange (ETDEWEB)

    Das, Bipul; Bag, Swarup; Pal, Sukhomay [Indian Institute of Technology Guwahati, Assam (India)

    2017-05-15

    Providing solutions towards the improvisation of welding technologies is the recent trend in the Friction stir welding (FSW) process. We present a monitoring approach for ultimate tensile strength of the friction stir welded joints based on information extracted from process signals through implementing fractal theory. Higuchi and Katz algorithms were executed on current and tool rotational speed signals acquired during friction stir welding to estimate fractal dimensions. Estimated fractal dimensions when correlated with the ultimate tensile strength of the joints deliver an increasing trend with the increase in joint strength. It is observed that dynamicity of the system strengthens the weld joint, i.e., the greater the fractal dimension, the better will be the quality of the weld. Characterization of signals by fractal theory indicates that the single-valued indicator can be an alternative for effective monitoring of the friction stir welding process.

  11. Probing weld quality monitoring in friction stir welding through characterization of signals by fractal theory

    International Nuclear Information System (INIS)

    Das, Bipul; Bag, Swarup; Pal, Sukhomay

    2017-01-01

    Providing solutions towards the improvisation of welding technologies is the recent trend in the Friction stir welding (FSW) process. We present a monitoring approach for ultimate tensile strength of the friction stir welded joints based on information extracted from process signals through implementing fractal theory. Higuchi and Katz algorithms were executed on current and tool rotational speed signals acquired during friction stir welding to estimate fractal dimensions. Estimated fractal dimensions when correlated with the ultimate tensile strength of the joints deliver an increasing trend with the increase in joint strength. It is observed that dynamicity of the system strengthens the weld joint, i.e., the greater the fractal dimension, the better will be the quality of the weld. Characterization of signals by fractal theory indicates that the single-valued indicator can be an alternative for effective monitoring of the friction stir welding process.

  12. Evaluation of Microstructure, Mechanical Properties and Corrosion Resistance of Friction Stir-Welded Aluminum and Magnesium Dissimilar Alloys

    Science.gov (United States)

    Verma, Jagesvar; Taiwade, Ravindra V.; Sapate, Sanjay G.; Patil, Awanikumar P.; Dhoble, Ashwinkumar S.

    2017-10-01

    Microstructure, mechanical properties and corrosion resistance of dissimilar friction stir-welded aluminum and magnesium alloys were investigated by applying three different rotational speeds at two different travel speeds. Sound joints were obtained in all the conditions. The microstructure was examined by an optical and scanning electron microscope, whereas localized chemical information was studied by energy-dispersive spectroscopy. Stir zone microstructure showed mixed bands of Al and Mg with coarse and fine equiaxed grains. Grain size of stir zone reduced compared to base metals, indicated by dynamic recrystallization. More Al patches were observed in the stir zone as rotational speed increased. X-ray diffraction showed the presence of intermetallics in the stir zone. Higher tensile strength and hardness were obtained at a high rotational speed corresponding to low travel speed. Tensile fractured surface indicated brittle nature of joints. Dissimilar friction stir weld joints showed different behaviors in different corrosive environments, and better corrosion resistance was observed at a high rotational speed corresponding to low travel speed (FW3) in a sulfuric and chloride environments. Increasing travel speed did not significantly affect on microstructure, mechanical properties and corrosion resistance as much as the rotational speed.

  13. The inhomogeneous microstructure and deformation of similar and dissimilar Al-Zn containing Mg friction stir welds

    Science.gov (United States)

    Hiscocks, Jessica

    The magnesium-based aluminum-zinc alloys have excellent stiffness to weight ratios, and may be combined by friction stir welding to expand the possible applications. The high aluminum alloy AZ80 in particular has the advantage of being relatively stiff but still extrudable. However limited friction stir welding research is available for this alloy and extrapolation from the extensive work in aluminum alloys is impractical due differences in precipitation behaviour, and magnesium's high plastic anisotropy and tendency to form strong textures during friction stir welding. This work investigates the correlations between local friction stir welded microstructures, textures, residual strains, and the local deformation behaviour based on strain mapping during tensile tests. Covering bead-on-plate and butt configurations, joining of similar and dissimilar materials, and a range of processing conditions, many findings of interest for deformation modelling and industrial applications are presented. Synchrotron x-ray diffraction study of an entire friction stir weld was used to determine texture, residual strain and dislocation density data from a single experiment. A number of unique findings were made, mainly related to the asymmetric distribution of properties both between sides of the weld and through the depth. Particularly in the case of strain measurements, features not detectable at coarser measurement spacing or by line scan are presented and compared for multiple processing conditions. Investigation of the longitudinal material flow during welding showed that even when periodicity in grain size, precipitate distribution, or texture was not observed, periodic changes in texture intensity resulting from compaction of material behind the tool were present, providing evidence that movement of nugget material remained periodic. Strain localisation and fracture behaviour were found to be completely different between good quality similar and dissimilar friction stir welds

  14. Structure and Mechanical Properties of Friction Stir Weld Joints of Magnesium Alloy AZ31

    Science.gov (United States)

    Nagasawa, T.; Otsuka, M.; Yokota, T.; Ueki, T.

    The applicability of friction stir welding to hot rolled sheet of commercial magnesium alloy AZ31 plates has been investigated. Friction stir weld joint showed mechanical strength comparable to that of base material, though the ductility remained at one half of that of the latter. The results are consistent with the microstructure which is characterized by a fine grained bond layer bounded by-intermediate grained base metals. It is found that both anodizing treatment and insertion of aluminum foil between batting faces do not degrade the joint properties at all. The results suggest that friction stir welding can be potentially applied to magnesium alloy.

  15. Turbulence modeling of the Von Karman flow: Viscous and inertial stirrings

    International Nuclear Information System (INIS)

    Poncet, Sebastien; Schiestel, Roland; Monchaux, Romain

    2008-01-01

    The present work considers the turbulent Von Karman flow generated by two counter-rotating smooth flat (viscous stirring) or bladed (inertial stirring) disks. Numerical predictions based on one-point statistical modeling using a low-Reynolds number second-order full stress transport closure (RSM model) are compared to velocity measurements performed at CEA (Commissariat a l'Energie Atomique, France). The main and significant novelty of this paper is the use of a drag force in the momentum equations to reproduce the effects of inertial stirring instead of modeling the blades themselves. The influences of the rotational Reynolds number, the aspect ratio of the cavity, the rotating disk speed ratio and of the presence or not of impellers are investigated to get a precise knowledge of both the dynamics and the turbulence properties in the Von Karman configuration. In particular, we highlighted the transition between the merged and separated boundary layer regimes and the one between the Batchelor [Batchelor, G.K., 1951. Note on a class of solutions of the Navier-Stokes equations representing steady rotationally-symmetric flow. Quat. J. Mech. Appl. Math. 4 (1), 29-41] and the Stewartson [Stewartson, K., 1953. On the flow between two rotating coaxial disks. Proc. Camb. Philos. Soc. 49, 333-341] flow structures in the smooth disk case. We determined also the transition between the one cell and the two cell regimes for both viscous and inertial stirrings

  16. MR diagnosis of bone metastases at 1.5 T and 3 T. Can STIR imaging be omitted?

    Energy Technology Data Exchange (ETDEWEB)

    Ohlmann-Knafo, S.; Tarnoki, A.D.; Tarnoki, D.L.; Pickuth, D. [Caritasklinikum Saarbruecken St. Theresia (Germany). Dept. of Diagnostic and Interventional Radiology

    2015-10-15

    To date, no prospective comparative study of the diagnostic value of STIR versus T1-weighted (T1w) sequences at both 1.5 T and 3 T has been performed with special focus on the detectability of bone metastases. 212 oncological patients had a whole-body MRI at 1.5 T and/or at 3 T. The standard protocol comprised STIR and T1w sequences. All patients who showed typical signs of bone metastases were included in the study. Evaluation of the images was performed by the calculation of the number of metastases by three independent readers and by visual assessment on a 4-point scale. 86 patients fulfilled the inclusion criteria. The total number of metastases was significantly higher on T1w than on STIR images at both field strengths (p < 0.05). T1w revealed a sensitivity of 99.72 % (3 T) and 100.00 % (1.5 T) versus STIR with 70.99 % (3 T) and 79.34 % (1.5 T). In 53 % (38/72) of all patients, STIR detected fewer bone metastases in comparison with T1w at 3 T. At 1.5 T, STIR showed inferior results in 37.5 % (18/48) of all patients. Qualitative analysis indicated a significantly better lesion conspicuity, lesion delineation and an improved image quality on T1w compared to STIR imaging at both field strengths (p < 0.05) with similar results for T1w at 1.5 T and 3 T, but inferior results for STIR especially at 3 T. The whole-body MRI protocol for the detection of bone metastases could safely be limited to the T1w sequence in adults, especially at 3 T. There is no need for an additional STIR sequence. These initial results will have a major impact on the department's workflow if confirmed by larger studies as they will help reduce examination time and therefore save financial resources.

  17. Microstructure and mechanical properties of friction stir welded Al/Mg2Si metal matrix cast composite

    International Nuclear Information System (INIS)

    Nami, H.; Adgi, H.; Sharifitabar, M.; Shamabadi, H.

    2011-01-01

    In this research, friction stir weldability of 15 wt.% Mg 2 Si particulate aluminum matrix cast composite and effects of tool rotation speed and number of welding passes on microstructure and mechanical properties of the joints were investigated. Microstructural observations were carried out by employing optical and scanning electron microscopy of the cross sections perpendicular to the tool traverse direction. Mechanical properties including microhardness and tensile strength were evaluated in detail. The results showed fragmentation of Mg 2 Si particles and Mg 2 Si needles existing in eutectic structure in stir zone. Also, homogeneous distribution of Mg 2 Si particles was observed in the stir zone as a result of stirring with high plastic strains. Tension test results indicated that tensile strength of the joint had an optimum at 1120 rpm tool rotation speed and decreased with increasing of the number of welding passes. Hardness of the joint increased due to modification of solidification microstructure of the base composite. This research indicates that friction stir welding is a good candidate for joining of 15 wt.% Mg 2 Si aluminum matrix composite castings.

  18. Thermal modelling of friction stir welding

    DEFF Research Database (Denmark)

    Schmidt, Henrik Nikolaj Blicher; Hattel, Jesper Henri

    2008-01-01

    The objective of the present work is to present the basic elements of the thermal modelling of friction stir welding as well as to clarify some of the uncertainties in the literature regarding the different contributions to the heat generation. Some results from a new thermal pseudomechanical model...... in which the temperature-dependent yield stress of the weld material controls the heat generation are also presented....

  19. Comparison of increased venous contrast in ischemic stroke using phase-sensitive MR imaging with perfusion changes on flow-sensitive alternating inversion recovery at 3 Tesla

    International Nuclear Information System (INIS)

    Yamashita, Eijiro; Kanasaki, Yoshiko; Fujii, Shinya; Ogawa, Toshihide; Tanaka, Takuro; Hirata, Yoshiharu

    2011-01-01

    Background Increased venous contrast in ischemic stroke using susceptibility-weighted imaging has been widely reported, although few reports have compared increased venous contrast areas with perfusion change areas. Purpose To compare venous contrast on phase-sensitive MR images (PSI) with perfusion change on flow-sensitive alternating inversion recovery (FAIR) images, and to discuss the clinical use of PSI in ischemic stroke. Material and Methods Thirty patients with clinically suspected acute infarction of the middle cerebral artery (MCA) territory within 7 days of onset were evaluated. Phase-sensitive imaging (PSI), flow-sensitive alternating inversion recovery (FAIR), diffusion-weighted imaging (DWI) and magnetic resonance angiography (MRA) were obtained using 3 Tesla scanner. Two neuroradiologists independently reviewed the MR images, as well as the PSI, DWI, and FAIR images. They were blinded to the clinical data and to each other's findings. The abnormal area of each image was ultimately identified after both neuroradiologists reached consensus. We analyzed areas of increased venous contrast on PSI, perfusion changes on FAIR images and signal changes on DWI for each case. Results Venous contrast increased on PSI and hypoperfusion was evident on FAIR images from 22 of the 30 patients (73%). The distribution of the increased venous contrast was the same as that of the hypoperfused areas on FAIR images in 16 of these 22. The extent of these lesions was larger than that of lesions visualized by on DWI in 18 of the 22 patients. Hypointense signals reflecting hemorrhage and no increased venous contrast on PSI and hyperperfusion on FAIR images were found in six of the remaining eight patients (20%). Findings on PSI were normal and hypoperfusion areas were absent on FAIR images of two patients (7%). Conclusion Increased venous contrast on PSI might serve as an index of misery perfusion and provide useful information

  20. Bobbin-Tool Friction-Stir Welding of Thick-Walled Aluminum Alloy Pressure Vessels

    Energy Technology Data Exchange (ETDEWEB)

    Dalder, E C; Pastrnak, J W; Engel, J; Forrest, R S; Kokko, E; Ternan, K M; Waldron, D

    2007-06-06

    It was desired to assemble thick-walled Al alloy 2219 pressure vessels by bobbin-tool friction-stir welding. To develop the welding-process, mechanical-property, and fitness-for-service information to support this effort, extensive friction-stir welding-parameter studies were conducted on 2.5 cm. and 3.8 cm. thick 2219 Al alloy plate. Starting conditions of the plate were the fully-heat-treated (-T62) and in the annealed (-O) conditions. The former condition was chosen with the intent of using the welds in either the 'as welded' condition or after a simple low-temperature aging treatment. Since preliminary stress-analyses showed that stresses in and near the welds would probably exceed the yield-strength of both 'as welded' and welded and aged weld-joints, a post-weld solution-treatment, quenching, and aging treatment was also examined. Once a suitable set of welding and post-weld heat-treatment parameters was established, the project divided into two parts. The first part concentrated on developing the necessary process information to be able to make defect-free friction-stir welds in 3.8 cm. thick Al alloy 2219 in the form of circumferential welds that would join two hemispherical forgings with a 102 cm. inside diameter. This necessitated going to a bobbin-tool welding-technique to simplify the tooling needed to react the large forces generated in friction-stir welding. The bobbin-tool technique was demonstrated on both flat-plates and plates that were bent to the curvature of the actual vessel. An additional issue was termination of the weld, i.e. closing out the hole left at the end of the weld by withdrawal of the friction-stir welding tool. This was accomplished by friction-plug welding a slightly-oversized Al alloy 2219 plug into the termination-hole, followed by machining the plug flush with both the inside and outside surfaces of the vessel. The second part of the project involved demonstrating that the welds were fit for the intended

  1. Microstructural characterizations and mechanical properties in underwater friction stir welding of aluminum and magnesium dissimilar alloys

    International Nuclear Information System (INIS)

    Zhao, Yong; Lu, Zhengping; Yan, Keng; Huang, Linzhao

    2015-01-01

    Highlights: • Aluminum and magnesium alloys were joined by underwater friction stir welding. • Underwater FSW was conducted to improve properties of joint with lower heat input. • Microstructures and mechanical properties of dissimilar joint were investigated. • Intermetallic compounds developed in the fracture interface were analyzed. • Fracture features of the tensile samples were analyzed. - Abstract: Formation of intermetallic compounds in the stir zone of dissimilar welds affects the mechanical properties of the joints significantly. In order to reduce heat input and control the amount and morphological characteristics of brittle intermetallic compounds underwater friction stir welding of 6013 Al alloy and AZ31 Mg alloy was carried out. Microstructures, mechanical properties, elements distribution, and the fracture surface of the joints were analyzed by optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, etc. The result shows that sound dissimilar joint with good mechanical properties can be obtained by underwater friction stir welding. Al and Mg alloys were stirred together and undergone the process of recrystallization, forming complex intercalated flow patterns in the stir zone. Tensile strength of the dissimilar joint was up to 152.3 MPa. Maximum hardness (142HV) appeared in the middle of the centerline of the specimen. Intermetallic compounds layer consisting of Al 3 Mg 2 and Mg 17 Al 12 formed in the Al/Mg interface and resulted in the fracture of the joint

  2. Bilateral mesial temporal sclerosis: MRI with high-resolution fast spin-echo and fluid-attenuated inversion-recovery sequences

    Energy Technology Data Exchange (ETDEWEB)

    Oppenheim, C.; Dormont, D.; Lehericy, S.; Marsault, C. [Dept. of Neuroradiology, Groupe Hospitalier Pite-Salpetriere, Paris (France); Hasboun, D. [Dept. of Neuroradiology, Groupe Hospitalier Pite-Salpetriere, Paris (France)]|[Dept. of Neurology, Paris VI Univ. (France); Bazin, B.; Samson, S.; Baulac, M. [Dept. of Neurology, Paris VI Univ. (France)

    1999-07-01

    We report a retrospective analysis of MRI in 206 patients with intractable seizures and describe the findings in bilateral mesial temporal sclerosis (MTS) on fast spin-echo (FSE) and fast fluid-attenuated inversion-recovery (fFLAIR) sequences. Criteria for MTS were atrophy, signal change and loss of the digitations of the head of the hippocampus. In patients with bilateral MRI signs of MTS, correlation with clinical electro, volumetric MRI data and neuropsychological tests, when available, was performed. Bilateral MTS was observed in seven patients. Bilateral loss of the digitations and signal change of fFLAIR was seen in all seven. In three, bilateral atrophy was obvious. In two patients, mild bilateral atrophy was observed and in two others, the hippocampi were: asymmetrical, with obvious atrophy on only one side. Volumetric data confirmed bilateral symmetrical atrophy in five patients, and volumes were at the lowest of the normal range in other two. The EEG showed temporal abnormalities in all patients, unilateral in five and bilateral in two. All patients had memory impairment and neuropsychological data confirmed visual and verbal memory deficits; two patients failed the Wada test on both sides. High-resolution T2-weighted FSE and fFLAIR sequences allow diagnosis of bilateral MTS, which has important therapeutic and prognostic implications. (orig.)

  3. Bilateral mesial temporal sclerosis: MRI with high-resolution fast spin-echo and fluid-attenuated inversion-recovery sequences

    International Nuclear Information System (INIS)

    Oppenheim, C.; Dormont, D.; Lehericy, S.; Marsault, C.; Hasboun, D.; Bazin, B.; Samson, S.; Baulac, M.

    1999-01-01

    We report a retrospective analysis of MRI in 206 patients with intractable seizures and describe the findings in bilateral mesial temporal sclerosis (MTS) on fast spin-echo (FSE) and fast fluid-attenuated inversion-recovery (fFLAIR) sequences. Criteria for MTS were atrophy, signal change and loss of the digitations of the head of the hippocampus. In patients with bilateral MRI signs of MTS, correlation with clinical electro, volumetric MRI data and neuropsychological tests, when available, was performed. Bilateral MTS was observed in seven patients. Bilateral loss of the digitations and signal change of fFLAIR was seen in all seven. In three, bilateral atrophy was obvious. In two patients, mild bilateral atrophy was observed and in two others, the hippocampi were: asymmetrical, with obvious atrophy on only one side. Volumetric data confirmed bilateral symmetrical atrophy in five patients, and volumes were at the lowest of the normal range in other two. The EEG showed temporal abnormalities in all patients, unilateral in five and bilateral in two. All patients had memory impairment and neuropsychological data confirmed visual and verbal memory deficits; two patients failed the Wada test on both sides. High-resolution T2-weighted FSE and fFLAIR sequences allow diagnosis of bilateral MTS, which has important therapeutic and prognostic implications. (orig.)

  4. Physics-based process model approach for detecting discontinuity during friction stir welding

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Amber; Pfefferkorn, Frank E.; Duffie, Neil A.; Ferrier, Nicola J.; Smith, Christopher B.; Malukhin, Kostya; Zinn, Michael

    2015-02-12

    The goal of this work is to develop a method for detecting the creation of discontinuities during friction stir welding. This in situ weld monitoring method could significantly reduce the need for post-process inspection. A process force model and a discontinuity force model were created based on the state-of-the-art understanding of flow around an friction stir welding (FSW) tool. These models are used to predict the FSW forces and size of discontinuities formed in the weld. Friction stir welds with discontinuities and welds without discontinuities were created, and the differences in force dynamics were observed. In this paper, discontinuities were generated by reducing the tool rotation frequency and increasing the tool traverse speed in order to create "cold" welds. Experimental force data for welds with discontinuities and welds without discontinuities compared favorably with the predicted forces. The model currently overpredicts the discontinuity size.

  5. Effects of mechanical force on grain structures of friction stir welded oxide dispersion strengthened ferritic steel

    International Nuclear Information System (INIS)

    Han, Wentuo; Kimura, Akihiko; Tsuda, Naoto; Serizawa, Hisashi; Chen, Dongsheng; Je, Hwanil; Fujii, Hidetoshi; Ha, Yoosung; Morisada, Yoshiaki; Noto, Hiroyuki

    2014-01-01

    The weldability of oxide dispersion strengthened (ODS) ferritic steels is a critical obstructive in the development and use of these steels. Friction stir welding has been considered to be a promising way to solve this problem. The main purpose of this work was to reveal the effects of mechanical force on grain structures of friction stir welded ODS ferritic steel. The grain appearances and the misorientation angles of grain boundaries in different welded zones were investigated by the electron backscatter diffraction (EBSD). Results showed that the mechanical force imposed by the stir tool can activate and promote the recrystallization characterized by the transformation of boundaries from LABs to HABs, and contribute to the grain refinement. The type of recrystallization in the stir zone can be classified as the continuous dynamic recrystallization (CDRX)

  6. Effects of mechanical force on grain structures of friction stir welded oxide dispersion strengthened ferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Han, Wentuo, E-mail: hanwentuo@hotmail.com [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Tsuda, Naoto [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Serizawa, Hisashi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Chen, Dongsheng [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Je, Hwanil [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Ha, Yoosung [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Morisada, Yoshiaki [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Noto, Hiroyuki [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2014-12-15

    The weldability of oxide dispersion strengthened (ODS) ferritic steels is a critical obstructive in the development and use of these steels. Friction stir welding has been considered to be a promising way to solve this problem. The main purpose of this work was to reveal the effects of mechanical force on grain structures of friction stir welded ODS ferritic steel. The grain appearances and the misorientation angles of grain boundaries in different welded zones were investigated by the electron backscatter diffraction (EBSD). Results showed that the mechanical force imposed by the stir tool can activate and promote the recrystallization characterized by the transformation of boundaries from LABs to HABs, and contribute to the grain refinement. The type of recrystallization in the stir zone can be classified as the continuous dynamic recrystallization (CDRX)

  7. Friction Stir Processing of ODS and FM Steels

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Suk Hoon; Chun, Young Bum; Noh, Sang Hoon; Jang, Jin Sung; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    In ODS steels, it is well known that uniform nano-oxide dispersoids act as pinning points to obstruct dislocation and grain boundary motion, however, those advantages will be disappeared while the material is subjected to the high temperature of conventional fusion welding. Rotary friction welding, also referred to as friction stir welding (FSW), has shown great promise as a method for welding traditionally difficult to weld materials such as aluminum alloys. This relatively new technology has more recently been applied to higher melting temperature alloys such as steels, nickel-based and titanium alloys. Friction stir processing (FSP) is a method of changing the properties of a metal through intense, localized plastic deformation. FSW is the precursor of the FSP technique. When ideally implemented, this process mixes the material without changing the phase and creates a microstructure with fine, equiaxed grains. This homogeneous grain structure, separated by high-angle boundaries, allows some alloys to take on superplastic properties. In this study, FSW is used as a substitutive welding process between FMS tube and ODS parts. The dimension of tube is 7.0 OD, 0.5 T. During the FSW, dynamic-recrystallized grains are developed; the uniform oxides dispersion is preserved in the metal matrix. The microstructure and microtexture of the material near the stir zone is found to be influenced by the rotational behavior of the tool. The additive effect from FSP on sample surface is considered. Since the mechanical alloying (MA) and FSP commonly apply extreme shear deformation on materials, the dispersion of oxide particle in ODS steels is very active during both processes. Friction stir welding appears to be a very promising technique for the welding of FMS and ODS steels in the form of sheet and tube. FSW could successfully produce defect-free welds on FMS tubes and ODS ring assembly. FSW produces a fine grain structure consisting of ferrite and martensite, and the oxide

  8. Friction Stir Processing of ODS and FM Steels

    International Nuclear Information System (INIS)

    Kang, Suk Hoon; Chun, Young Bum; Noh, Sang Hoon; Jang, Jin Sung; Kim, Tae Kyu

    2013-01-01

    In ODS steels, it is well known that uniform nano-oxide dispersoids act as pinning points to obstruct dislocation and grain boundary motion, however, those advantages will be disappeared while the material is subjected to the high temperature of conventional fusion welding. Rotary friction welding, also referred to as friction stir welding (FSW), has shown great promise as a method for welding traditionally difficult to weld materials such as aluminum alloys. This relatively new technology has more recently been applied to higher melting temperature alloys such as steels, nickel-based and titanium alloys. Friction stir processing (FSP) is a method of changing the properties of a metal through intense, localized plastic deformation. FSW is the precursor of the FSP technique. When ideally implemented, this process mixes the material without changing the phase and creates a microstructure with fine, equiaxed grains. This homogeneous grain structure, separated by high-angle boundaries, allows some alloys to take on superplastic properties. In this study, FSW is used as a substitutive welding process between FMS tube and ODS parts. The dimension of tube is 7.0 OD, 0.5 T. During the FSW, dynamic-recrystallized grains are developed; the uniform oxides dispersion is preserved in the metal matrix. The microstructure and microtexture of the material near the stir zone is found to be influenced by the rotational behavior of the tool. The additive effect from FSP on sample surface is considered. Since the mechanical alloying (MA) and FSP commonly apply extreme shear deformation on materials, the dispersion of oxide particle in ODS steels is very active during both processes. Friction stir welding appears to be a very promising technique for the welding of FMS and ODS steels in the form of sheet and tube. FSW could successfully produce defect-free welds on FMS tubes and ODS ring assembly. FSW produces a fine grain structure consisting of ferrite and martensite, and the oxide

  9. Barbell-shaped stir bar sorptive extraction using dummy template molecularly imprinted polymer coatings for analysis of bisphenol A in water.

    Science.gov (United States)

    Liu, Ruimei; Feng, Feng; Chen, Guolin; Liu, Zhimin; Xu, Zhigang

    2016-07-01

    This study reports the development of a novel dummy template molecularly imprinted polymer (MIP)-coated barbell-shaped stir bar. The MIP stir bar coatings were prepared by using 2,2-bis(4-hydroxyphenyl)butane (BPB), 4,4'-dihydroxydiphenylmethane (BPF), 4-tert-butylphenol (PTBP), and tetrabromobisphenol A (TBBA) as dummy templates using a capillary in situ polymerization method. Uniform coatings can be prepared controllably. The method is simple, easy, and reproducible. The barbell-shaped stir bar was developed by using medical silicone tubes as wheels. The wheels could be removed and reinstalled when necessary; therefore, the barbell-shaped stir bar was easy to disassemble and reassemble. The novel MIP-coated stir bar showed good selectivity for the target analyte, bisphenol A (BPA). The established method is selective and sensitive with a lower detection limit for BPA of 0.003 μg/L. The dummy template MIP-coated stir bar is suitable for trace BPA analysis in real environmental water samples without template leakage. The novel stir bar can be used at least 100 times.

  10. Microstructural transformations and mechanical properties of cast NiAl bronze: Effects of fusion welding and friction stir processing

    International Nuclear Information System (INIS)

    Fuller, M.D.; Swaminathan, S.; Zhilyaev, A.P.; McNelley, T.R.

    2007-01-01

    A plate of as-cast NiAl bronze (NAB) material was sectioned from a large casting. A six-pass fusion weld overlay was placed in a machined groove; a portion of the weld reinforcement was removed by milling and a single friction stir processing (FSP) pass was conducted in a direction transverse to the axis of and over the weld overlay. A procedure was developed for machining of miniature tensile samples and the distributions of strength and ductility were evaluated for the fusion weld metal; for the stir zone (SZ) produced by the friction stir processing; and for a region wherein friction stir processing had taken place over the fusion weld. A region of low ductility in the heat affected zone (HAZ) of the fusion weld and in the thermomechanically affected zone (TMAZ) of friction stir processed material was attributed to partial reversion of an equilibrium lamellar eutectoid constituent upon local heating above ∼800 deg. C and formation of non-equilibrium transformation products upon subsequent cooling. The adverse effect on ductility is worse in the heat affected zone of the fusion weld than in the thermomechanically affected zone of friction stir processing due to the lower heat input of the latter process. The implications of this work to engineering applications of friction stir processing are discussed

  11. Phosphorus recovery from sewage sludge ash through an electrodialytic process

    DEFF Research Database (Denmark)

    Guedes, Paula; Couto, Nazare; Ottosen, Lisbeth M.

    2014-01-01

    The electrodialytic separation process (ED) was applied to sewage sludge ash (SSA) aiming at phosphorus (P) recovery. As the SSA may have high heavy metals contents, their removal was also assessed. Two SSA were sampled, one immediately after incineration (SA) and the other from an open deposit (SB......). Both samples were ED treated as stirred suspensions in sulphuric acid for 3,7 and 14 days. After 14 days, phosphorus was mainly mobilized towards the anode end (approx. 60% in the SA and 70% in the SB), whereas heavy metals mainly electromigrated towards the cathode end. The anolyte presented...... a composition of 98% of P, mainly as orthophosphate, and 2% of heavy metals. The highest heavy metal removal was achieved for Cu (ca. 80%) and the lowest for Pb and Fe (between 4% and 6%). The ED showed to be a viable method for phosphorus recovery from SSA, as it promotes the separation of P from the heavy...

  12. Characterization and Strain-Hardening Behavior of Friction Stir-Welded Ferritic Stainless Steel

    Science.gov (United States)

    Sharma, Gaurav; Dwivedi, Dheerendra Kumar; Jain, Pramod Kumar

    2017-12-01

    In this study, friction stir-welded joint of 3-mm-thick plates of 409 ferritic stainless steel (FSS) was characterized in light of microstructure, x-ray diffraction analysis, hardness, tensile strength, ductility, corrosion and work hardening properties. The FSW joint made of ferritic stainless steel comprises of three distinct regions including the base metal. In stir zone highly refined ferrite grains with martensite and some carbide precipitates at the grain boundaries were observed. X-ray diffraction analysis also revealed precipitation of Cr23C6 and martensite formation in heat-affected zone and stir zone. In tensile testing of the transverse weld samples, the failure eventuated within the gauge length of the specimen from the base metal region having tensile properties overmatched to the as-received base metal. The tensile strength and elongation of the longitudinal (all weld) sample were found to be 1014 MPa and 9.47%, respectively. However, in potentiodynamic polarization test, the corrosion current density of the stir zone was highest among all the three zones. The strain-hardening exponent for base metal, transverse and longitudinal (all weld) weld samples was calculated using various equations. Both the transverse and longitudinal weld samples exhibited higher strain-hardening exponents as compared to the as-received base metal. In Kocks-Mecking plots for the base metal and weld samples at least two stages of strain hardening were observed.

  13. A dense cell retention culture system using stirred ceramic membrane reactor.

    Science.gov (United States)

    Suzuki, T; Sato, T; Kominami, M

    1994-11-20

    A novel reactor design incorporating porous ceramic tubes into a stirred jar fermentor was developed. The stirred ceramic membrane reactor has two ceramic tubular membrane units inside the vessel and maintains high filtration flux by alternating use for filtering and recovering from clogging. Each filter unit was linked for both extraction of culture broth and gas sparging. High permeability was maintained for long periods by applying the periodical control between filtering and air sparging during the stirred retention culture of Saccharomyces cerevisiae. The ceramic filter aeration system increased the k(L)a to about five times that of ordinary gas sparing. Using the automatic feeding and filtering system, cell mass concentration reached 207 g/L in a short time, while it was 64 g/L in a fed-batch culture. More than 99% of the growing cells were retained in the fermentor by the filtering culture. Both yield and productivity of cells were also increased by controlling the feeding of fresh medium and filtering the supernatant of the dense cells culture. (c) 1994 John Wiley & Sons, Inc.

  14. Automatic Gap Detection in Friction Stir Welding Processes (Preprint)

    National Research Council Canada - National Science Library

    Yang, Yu; Kalya, Prabhanjana; Landers, Robert G; Krishnamurthy, K

    2006-01-01

    .... This paper develops a monitoring algorithm to detect gaps in Friction Stir Welding (FSW) processes. Experimental studies are conducted to determine how the process parameters and the gap width affect the welding process...

  15. Anterior temporal lobe white matter abnormal signal (ATLAS) as an indicator of seizure focus laterality in temporal lobe epilepsy: comparison of double inversion recovery, FLAIR and T2W MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Morimoto, Emiko; Kanagaki, Mitsunori; Okada, Tomohisa; Yamamoto, Akira; Togashi, Kaori [Kyoto University Graduate School of Medicine, Department of Diagnostic Imaging and Nuclear Medicine, Kyoto (Japan); Mori, Nobuyuki [Tenri Hospital, Department of Radiology, Tenri, Nara (Japan); Matsumoto, Riki; Ikeda, Akio; Takahashi, Ryosuke [Kyoto University Graduate School of Medicine, Department of Neurology, Kyoto (Japan); Mikuni, Nobuhiro [Sapporo Medical University, Department of Neurosurgery, Sapporo, Hokkaido (Japan); Kunieda, Takeharu; Miyamoto, Susumu [Kyoto University Graduate School of Medicine, Department of Neurosurgery, Kyoto (Japan); Paul, Dominik [Siemens AG Healthcare Sector, Erlangen (Germany)

    2013-01-15

    To investigate the diagnostic capability of anterior temporal lobe white matter abnormal signal (ATLAS) for determining seizure focus laterality in temporal lobe epilepsy (TLE) by comparing different MR sequences. This prospective study was approved by the institutional review board and written informed consent was obtained. Three 3D sequences (double inversion recovery (DIR), fluid-attenuated inversion recovery (FLAIR) and T2-weighted imaging (T2WI)) and two 2D sequences (FLAIR and T2WI) were acquired at 3 T. Signal changes in the anterior temporal white matter of 21 normal volunteers were evaluated. ATLAS laterality was evaluated in 21 TLE patients. Agreement of independent evaluations by two neuroradiologists was assessed using {kappa} statistics. Differences in concordance between ATLAS laterality and clinically defined seizure focus laterality were analysed using McNemar's test with multiple comparisons. Pre-amygdala high signals (PAHS) were detected in all volunteers only on 3D-DIR. Inter-evaluator agreement was moderate to almost perfect for each sequence. Correct diagnosis of seizure laterality was significantly more frequent on 3D-DIR than on any other sequences (P {<=} 0.031 for each evaluator). The most sensitive sequence for detecting ATLAS laterality was 3D-DIR. ATLAS laterality on 3D-DIR can be a good indicator for determining seizure focus localization in TLE. (orig.)

  16. Anterior temporal lobe white matter abnormal signal (ATLAS) as an indicator of seizure focus laterality in temporal lobe epilepsy: comparison of double inversion recovery, FLAIR and T2W MR imaging

    International Nuclear Information System (INIS)

    Morimoto, Emiko; Kanagaki, Mitsunori; Okada, Tomohisa; Yamamoto, Akira; Togashi, Kaori; Mori, Nobuyuki; Matsumoto, Riki; Ikeda, Akio; Takahashi, Ryosuke; Mikuni, Nobuhiro; Kunieda, Takeharu; Miyamoto, Susumu; Paul, Dominik

    2013-01-01

    To investigate the diagnostic capability of anterior temporal lobe white matter abnormal signal (ATLAS) for determining seizure focus laterality in temporal lobe epilepsy (TLE) by comparing different MR sequences. This prospective study was approved by the institutional review board and written informed consent was obtained. Three 3D sequences (double inversion recovery (DIR), fluid-attenuated inversion recovery (FLAIR) and T2-weighted imaging (T2WI)) and two 2D sequences (FLAIR and T2WI) were acquired at 3 T. Signal changes in the anterior temporal white matter of 21 normal volunteers were evaluated. ATLAS laterality was evaluated in 21 TLE patients. Agreement of independent evaluations by two neuroradiologists was assessed using κ statistics. Differences in concordance between ATLAS laterality and clinically defined seizure focus laterality were analysed using McNemar's test with multiple comparisons. Pre-amygdala high signals (PAHS) were detected in all volunteers only on 3D-DIR. Inter-evaluator agreement was moderate to almost perfect for each sequence. Correct diagnosis of seizure laterality was significantly more frequent on 3D-DIR than on any other sequences (P ≤ 0.031 for each evaluator). The most sensitive sequence for detecting ATLAS laterality was 3D-DIR. ATLAS laterality on 3D-DIR can be a good indicator for determining seizure focus localization in TLE. (orig.)

  17. Pulsed ultrasonic stir welding method

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.

  18. Microstructural characteristics and effects of TC4 titanium alloy processed by using friction stir welding

    Directory of Open Access Journals (Sweden)

    Bo LI

    2016-02-01

    Full Text Available Friction stir welding technique is used for the processing of TC4 titanium alloy under protective atmosphere, and it results with good formability. The research focues on the evolution mechanisms of α+β dual phase microstructure in stirred zone and the effects of processing parameters on structures hardness. The results show that with optimized technological parameters, stir zone structure experiences the α/β transformation, and finally changes to the α+β duplex structure which is based on the β phase. After mixing head leaves and the structure cools, the precipitated lamellar α phase is among and/or within-regions. Grain refining of α+β dual phase is obvious. The shortened α/β lamellar spacing distance may improve the strengthening effect of the α+β duplex phase and enhance the hardness of the stir zone. The increasing of the tool rotation speed could coarsen β-regions, while the increasing of the travel speed could help reduce the α phase ratio and generate needle-type Martensites.

  19. Colosed-Loop Control of the Thermal Stir Welding Process to Enable Rapid Process/Ppart Qualification, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermal Stir Welding (TSW) provides advancement over the more conventional Friction Stir Welding (C-FSW) process because it separates the primary processes variables...

  20. Closed-Loop Control of the Thermal Stir Welding Process to Enable Rapid Process/Part Qualification, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermal Stir Welding (TSW) provides advancement over the more conventional Friction Stir Welding (C-FSW) process because it separates the primary processes variables...

  1. Analysis of lime-slurry stirred tank carbonation reactor

    International Nuclear Information System (INIS)

    McAleese, J.P.; Belt, B.A.; Datesh, J.R.; Shaeffer, M.C.

    1977-01-01

    Gas residence time distributions were determined for a stirred tank carbonation reactor. Empirical correlations for the first and second moments of the residence time distribution (RTD) curves as functions of flow rates and impeller speeds were obtained. Decontamination factors for 85 Kr were measured

  2. Fungi solubilisation of low rank coal: performances of stirred tank, fluidised bed and packed bed reactors

    CSIR Research Space (South Africa)

    Oboirien, BO

    2013-02-01

    Full Text Available Coal biosolubilisation was investigated in stirred tank reactor, fluidised bed and fixed bed bioreactors with a view to highlight the advantages and shortcomings of each of these reactor configurations. The stirred aerated bioreactor and fluidised...

  3. The Effect of Vibration during Friction Stir Welding on Corrosion Behavior, Mechanical Properties, and Machining Characteristics of Stir Zone

    Directory of Open Access Journals (Sweden)

    Sajad Fouladi

    2017-10-01

    Full Text Available Different methods have been applied to refine various characteristics of the zone (or nugget obtained by friction stir welding (FSW. In the current research, joining components are vibrated normal to the weld line during FSW to refine the zone microstructure. This process is described as friction stir vibration welding (FSVW. The effect of FSVW on mechanical properties, corrosion behavior, and machining characteristics of the zone are investigated. Al5052 alloy specimens are welded using FSW and FSVW processes and their different characteristics are compared and discussed. The results show that the strength and ductility of the welded parts increase when the vibration is applied. The outcomes also show that corrosion resistance of the nugget for FSV-welded specimens is lower than FS welded samples, and machining force of the former specimens is higher than the latter ones. These are related to smaller grain size in the zone of FSV-welded specimens compared to FS welded parts. Smaller grain size leads to a greater volume fraction of grain boundaries and, correspondingly, higher strength and hardness, as well as lower corrosion resistance.

  4. Diffusion-weighted echo planar imaging in patients with recent myocardial infarction

    International Nuclear Information System (INIS)

    Deux, Jean-Francois; Maatouk, Mezri; Luciani, Alain; Lenczner, Gregory; Mayer, Julie; Kobeiter, Hicham; Rahmouni, Alain; Vignaud, Alexandre; Lim, Pascal; Dubois-Rande, Jean-Luc

    2011-01-01

    To evaluate a diffusion-weighted (DW) black blood MR sequence for the detection of myocardium signal abnormalities in patients with recent myocardial infarction (MI). A DW black blood EPI sequence was acquired at 1.5 T in 12 patients with recent MI. One slice per patient was acquired with b = 0 and b = 50 s/mm 2 . A standard short tau inversion recovery (STIR) T2-weighted sequence was acquired at the same level. Viability was assessed with delayed-enhancement sequences. Images were analyzed qualitatively and quantitatively. A non parametric Wilcoxon test was used for statistical analysis, with a significance level of P <.05. The mean quality of blood suppression was higher on DW EPI images than on STIR T2-weighted images (3.9 ± 0.3 and 3.0 ± 0.7, respectively; P = 0.01). Myocardial high signal areas were detected in respectively 100% (12/12) and 67% (8/12) of the patients on DW EPI and STIR T2-weighted images. The four patients (33%) with false-negative STIR T2 findings all had high signal areas on DW EPI images corresponding to the location of the MI on the delayed-enhanced images. DW EPI sequences are a feasible alternative to standard STIR T2-weighted sequences for detecting myocardium high signal areas in patients with recent MI. (orig.)

  5. Biotransformation of ferulic acid to vanillin in the packed bed-stirred fermentors.

    Science.gov (United States)

    Yan, Lei; Chen, Peng; Zhang, Shuang; Li, Suyue; Yan, Xiaojuan; Wang, Ningbo; Liang, Ning; Li, Hongyu

    2016-10-06

    We performed the biotransformation of ferulic acid to vanillin using Bacillus subtilis (B. subtilis) in the stirring packed-bed reactors filled with carbon fiber textiles (CFT). Scanning electron microscope (SEM), HPLC, qRT-PCR and ATP assay indicated that vanillin biotransformation is tightly related to cell growth, cellar activity and the extent of biofilm formation. The biotransformation was affected by hydraulic retention time (HRT), temperature, initial pH, stirring speed and ferulic acid concentration, and the maximum vanillin production was obtained at 20 h, 35 °C, 9.0, 200 rpm, 1.5 g/L, respectively. Repeated batch biotransformation performed under this optimized condition showed that the maximum productivity (0.047 g/L/h) and molar yield (60.43%) achieved in immobilized cell system were 1.84 and 3.61 folds higher than those achieved in free cell system. Therefore, the stirring reactor packed with CFT carrier biofilm formed by B. subtilis represented a valid biocatalytic system for the production of vanillin.

  6. Spondylodiscitis; Spondylodiszitis

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, U. [Universitaetsklinikum des Saarlandes, Klinik fuer Diagnostische und Interventionelle Neuroradiologie, Homburg/Saar (Germany)

    2011-09-15

    Despite highly sensitive imaging techniques, the diagnosis and treatment of spondylodiscitis are often delayed due to a lack of specific symptoms with back pain as the presenting complaint. Late diagnosis and neurological involvement at the time of diagnosis are risk factors for long-term neurological deficits. Unremitting back pain with signs of inflammation should give reason to suspect spondylodiscitis and to rule it out by imaging, especially if risk factors such as diabetes mellitus, malignant neoplasms or immunosuppression are present. Magnetic resonance imaging (MRI) is the imaging procedure of choice with high sensitivity and specificity and typically shows hypointense adjacent vertebrae on T1-weighted images with hyperintense signal on short tau inversion recovery (STIR) sequences and hyperintense disc spaces on T2-weighted images. (orig.) [German] Aufgrund unspezifischer Beschwerden mit Rueckenschmerzen als Leitsymptom wird die Spondylodiszitis trotz hochsensitiver Bildgebung oft erst spaet diagnostiziert und behandelt. Die spaete Diagnose und das Vorliegen neurologischer Symptomatik bei Diagnosestellung stellen Risikofaktoren fuer bleibende neurologische Schaeden dar. Anhaltende Rueckenschmerzen mit allgemeinen Entzuendungszeichen sollten - insbesondere bei Risikofaktoren wie Diabetes mellitus, Tumorerkrankungen oder Immunsuppression - Anlass geben, eine Spondylodiszitis radiologisch auszuschliessen. Die Bildgebung der Wahl ist die Magnetresonanztomographie, die die Diagnose einer Spondylodiszitis mit hoher Sensitivitaet und Spezifitaet erlaubt. Typischerweise zeigen sich in der T1-Wichtung hypointense benachbarte Wirbelkoerper mit hyperintensem Signal in der Short-tau-inversion-recovery(STIR)-Sequenz und hyperintensem Bandscheibenfach in der T2-Wichtung. (orig.)

  7. The Concept of Electrically Assisted Friction Stir Welding (EAFSW) and Application to the Processing of Various Metals

    National Research Council Canada - National Science Library

    Ferrando, William A

    2008-01-01

    This report introduces a novel variant of conventional friction stir welding (FSW). Since 1991, friction stir welding provides an alternative to arc welding as a metal joining method in numerous applications...

  8. Assessment of myocardial infarction in mice by Late Gadolinium Enhancement MR imaging using an inversion recovery pulse sequence at 9.4T

    Directory of Open Access Journals (Sweden)

    Herlihy Amy H

    2008-01-01

    Full Text Available Abstract Purpose To demonstrate the feasibility of using an inversion recovery pulse sequence and to define the optimal inversion time (TI to assess myocardial infarction in mice by late gadolinium enhancement (LGE MRI at 9.4T, and to obtain the maximal contrast between the infarcted and the viable myocardium. Methods MRI was performed at 9.4T in mice, two days after induction of myocardial infarction (n = 4. For cardiovascular MR imaging, a segmented magnetization-prepared fast low angle shot (MP-FLASH sequence was used with varied TIs ranging from 40 to 420 ms following administration of gadolinium-DTPA at 0.6 mmol/kg. Contrast-to-noise (CNR and signal-to-noise ratio (SNR were measured and compared for each myocardial region of interest (ROI. Results The optimal TI, which corresponded to a minimum SNR in the normal myocardium, was 268 ms ± 27.3. The SNR in the viable myocardium was significantly different from that found in the infarcted myocardium (17.2 ± 2.4 vs 82.1 ± 10.8; p = 0.006 leading to a maximal relative SI (Signal Intensity between those two areas (344.9 ± 60.4. Conclusion Despite the rapid heart rate in mice, our study demonstrates that LGE MRI can be performed at 9.4T using a protocol similar to the one used for clinical MR diagnosis of myocardial infarction.

  9. Differential diagnosis of benign and malignant vertebral compression fractures with MR imaging

    International Nuclear Information System (INIS)

    Staebler, A.; Krimmel, K.; Seiderer, M.; Gaertner, C.; Fritsch, S.; Raum, W.

    1992-01-01

    42 patients with known malignancy and vertebral compressions underwent MRI. Sagittal T 1 -weighted spin-echo images pre and post Gd-DTPA, out of phase long TR gradient-echo images (GE) and short T 1 inversion recovery images (STIR) were obtained at 1.0 T. In 39 of 42 cases a correct differentiation between osteoporotic and tumorous vertebral compression fractures was possible by quantification and correlation of SE and GE signal intensities. Gd-DTPA did not improve differential diagnosis, since both tumour infiltration and bone marrow oedema in acute compression fracture showed comparable enhancement. STIR-sequences were most sensitive for pathology but unspecific due to a comparable amount of water in tumour tissue and bone marrow oedema. Susceptibility-induced signal reduction in GE images and morphologic criteria proved to be most reliable for differentiation of benign and tumour-related fractures. (orig./GDG) [de

  10. MR imaging of scaphoid fractures

    DEFF Research Database (Denmark)

    Meincke, Louise; Radev, Dimitar; Eriksen, Rie Østbjerg

    2017-01-01

    the importance of early MRI and hereby predict bone bruise with the help of fat suppression sequence; however, only a limited selection articles compares various fat suppression techniques. The purpose of this prospective study was to compare the short tau inversion recovery (STIR) and T2 fat saturation (FAT SAT......) sequences, sectional directed along the scaphoid bone axis. In relation to background fat intensity suppression, this study sought the sequence that best evaluated posttraumatic bone marrow edema (bone bruise) on scaphoid injury musculoskeletal magnetic resonance imaging (MRI, 1.5 T extremity scanner......). Materials and methods: Two hundred and fifty-one patients with relevant trauma and positive clinical test for scaphoid bone fractures, exceeding no more than 14 days, underwent MRI examinations. A fast STIR and T2 FAT SAT fast spin echo sequence (FSE) were obtained using a comparable parameter setting (scan...

  11. Tensile behavior of friction stir welded AA 6061-T4 aluminum alloy joints

    International Nuclear Information System (INIS)

    Heidarzadeh, A.; Khodaverdizadeh, H.; Mahmoudi, A.; Nazari, E.

    2012-01-01

    Highlights: ► Range of parameters for defect-free friction stir welded AA 6061-T4 was reached. ► A model was developed for predicting UTS and EL of friction stir welded AA 6061-T4. ► The maximum values of UTS and EL of joints were estimated by developed model. ► The optimum values of FSW process parameters were determined. -- Abstract: In this investigation response surface methodology based on a central composite rotatable design with three parameters, five levels and 20 runs, was used to develop a mathematical model predicting the tensile properties of friction stir welded AA 6061-T4 aluminum alloy joints at 95% confidence level. The three welding parameters considered were tool rotational speed, welding speed and axial force. Analysis of variance was applied to validate the predicted model. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters on tensile properties of friction stir welded joints were analyzed in detail. The results showed that the optimum parameters to get a maximum of tensile strength were 920 rev/min, 78 mm/min and 7.2 kN, where the maximum of tensile elongation was obtained at 1300 rev/min, 60 mm/min and 8 kN.

  12. Friction stir welding of 6061 aluminium alloy

    International Nuclear Information System (INIS)

    Abdel Rahman, M.A.M.S.

    2009-01-01

    6061 AA (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio and good corrosion resistance such as marine frames, pipelines, storage tanks, and aircraft components [1]. It is also used for the manufacturing of fuel elements in the nuclear research reactors. Compared to many of the fusion welding processes that are routinely used for joining structural alloys, friction stir welding (FSW) is a solid state joining process in which the material that is being welded is not melted and recast [2]. The welding parameters such as tool rotational speed, welding traverse speed, and tool profile play a major role in deciding the weld quality. Several FSW tools (differ from each other in pin angle, shoulder diameter, and shoulder concavity) have been used to fabricate a number of joints in order to obtain a tool with which a sound weld can be produced. It was found that the FSW tool with tapered cone pin, concave shoulder, and shoulder diameter equal to four times the welded plate thickness is suitable to produce a sound weld. The effect of the traverse speed on the global and local tensile properties of friction stir welded joints has been investigated in the 6061-T6 AA. The global tensile properties of the FSW joints were improved with increasing the traverse speed at constant rotation rate. It is found that the global tensile strength of the FSW joint is limited by the local tensile strength of the nearest region to the weld center at which the cross section is composed mainly of the HAZ. The effect of the initial butt surface on the formation of the zigzag line on the tensile properties of the welds was examined by using three types of welding samples differ in the preparation of the initial butt surface. The first type of samples welded without removing the oxide layer from the initial butt surface (uncleaned butt surfaces joint). In the second type of samples the oxide layer was removed from

  13. Defect Detectability Improvement for Conventional Friction Stir Welds

    Science.gov (United States)

    Hill, Chris

    2013-01-01

    This research was conducted to evaluate the effects of defect detectability via phased array ultrasound technology in conventional friction stir welds by comparing conventionally prepped post weld surfaces to a machined surface finish. A machined surface is hypothesized to improve defect detectability and increase material strength.

  14. Engineered Alloy Structures by Friction Stir Reaction Processing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I effort examines the feasibility of an innovative surface modification technology incorporating friction stir reaction processing for producing...

  15. Friction Stir Welding of Dissimilar Al/Al and Al/Non-Al Alloys: A Review

    Science.gov (United States)

    Wang, Xiangbin; Pan, Yi; Lados, Diana A.

    2018-05-01

    Friction stir welding is a solid-state welding technique that has many advantages over traditional fusion welding, and has been widely adopted in the aerospace and automotive industries. This article reviews research developments in friction stir welding of dissimilar alloys systems, including combinations of aluminum alloys with Mg alloys, Cu, and steel. Microstructural evolution, hardness, tensile and fatigue properties, residual stresses, and corrosion behavior of dissimilar welds will be reported. The effects of processing parameters such as tool rotation and traverse speeds, tool position, material position, and tool geometry on the weld quality are also presented. Discussions on future research directions in friction stir welding will also be provided in the context of existing literature and future high-integrity applications.

  16. Tensile Properties of Friction Stir Welded Joints of AA 2024-T6 Alloy at Different Welding Speeds

    Science.gov (United States)

    Avula, Dhananjayulu; Devuri, Venkateswarlu; Cheepu, Muralimohan; Dwivedi, Dheerendra Kumar

    2018-03-01

    The influence of welding speed on the friction stir welded joint properties of hardness, tensile properties, defects and microstructure characterization are studied in the present study. The friction stir welding was conducted on AA2014-T6 heat treated alloy with 5 mm thickness plate in butt joint configuration. The welding speed was varied from 8 mm/min to 120 mm/min at the fixed travel speed and load conditions. It is observed that the welding speeds at higher rate with wide range can be possible to weld this alloy at higher rates of tool revolution suggesting that the inherent capability of friction stir welding technique for aluminum 2014 alloys. The strength of the joints gradually increases with enhancing of welding speed. The micro structural observations exhibited the formation of equiaxed grains in the stir zone and slightly in the thermo-mechanically affected zone. In addition, the size of the grains decreases with increase in welding speed owing to the presence of low heat input. Hence the hardness of the joints slightly increased in the stir zones over the other zones of the weld nugget. The joint strength initially increases with the welding speed and starts to decreases after reaching to the maximum value. The relationship between the welding conditions and friction stir welded joint properties has been discussed.

  17. An investigation into the mechanism for enhanced mechanical properties in friction stir welded AA2024-T3 joints coated with cold spraying

    Science.gov (United States)

    Li, N.; Li, W. Y.; Yang, X. W.; Feng, Y.; Vairis, A.

    2018-05-01

    Using cold spraying (CS), a surface layer with a modified microstructure and enhanced mechanical properties was formed on a 3.2 mm thick friction stir welded (FSWed) AA2024-T3 joint. The combined effect of "shot peening effect (SPE)" and "heat flow effect (HFE)" during CS were used to enhance joint mechanical properties. The microstructure evolution of the FSWed AA2024-T3 joints in the surface layer following CS coatings and their effect on mechanical properties were systematically characterized with electron back-scattered diffraction, transmission electron microscopy, differential scanning calorimetry and mechanical tests. Based on these experiments, a grain refinement, finer and more S phases, and improved amount of Guinier-Preston-Bagaryatsky (GPB) zones produced by CS treatments are proposed. The deposition of aluminum coating on the joint, lead to hardness recovery in the stir zone and the development of two low hardness zones as the density of GPB increased. The tensile properties of FSWed AA2024-T3 joints improved with the application of the aluminum coatings. Experiments and analysis of the enhanced mechanical properties mechanism indicate that SPE with a high plastic deformation and HFE with an intensive heat flow are necessary for the production of refined grains and increased numbers of GPB zones.

  18. The Effect of Friction Stir Welding on Corrosion Behavior of Ti-6Al-4V

    Science.gov (United States)

    Nasresfahani, Ali Reza; Soltanipur, Abdol Reza; Farmanesh, Khosro; Ghasemi, Ali

    2017-09-01

    Fusion welding can deteriorate corrosion behavior of Ti-6Al-4V alloy. However, the use of friction stir welding leads to a more appropriate corrosion resistance. In this study, the corrosion resistance of welded zones of Ti-6Al-4V alloy using friction stir welding technique is evaluated. For these purposes, the study of structural characteristics using SEM and FESEM equipped with EDS micro-analyses was conducted. Micro-hardness test was also employed to estimate the hardness of welded zones. Corrosion behavior was investigated by a potentiostat instrument. SEM micrographs, EDS and XRD analyses confirmed non-uniformity of chemical composition within the welded zones. The results reveal that the stir zone contains typical alpha and prior beta phases. Nevertheless, thermomechanical zone included equiaxed and bimodal lamellae structure. Furthermore, the presence of different types of phases and microstructure in the thermomechanical zone led to reduced corrosion resistance. The corresponding values of corrosion current density in the stir zone, thermomechanical zone and base metal were 0.048, 0.55 and 0.032 µA, respectively. Corresponding corrosion potential for these zones was estimated as -207, -110 and -157 mV. Evidently, the results show that corrosion resistance of thermomechanical zone is less than that of the stir zone and both zones have lower value than the base metal.

  19. Recovery of material parameters of soft hyperelastic tissue by an inverse spectral technique

    KAUST Repository

    Gou, Kun; Joshi, Sunnie; Walton, Jay R.

    2012-01-01

    An inverse spectral method is developed for recovering a spatially inhomogeneous shear modulus for soft tissue. The study is motivated by a novel use of the intravascular ultrasound technique to image arteries. The arterial wall is idealized as a

  20. Cascade degradation of organic matters in brewery wastewater using a continuous stirred microbial electrochemical reactor and analysis of microbial communities

    Science.gov (United States)

    Wang, Haiman; Qu, Youpeng; Li, Da; Ambuchi, John J.; He, Weihua; Zhou, Xiangtong; Liu, Jia; Feng, Yujie

    2016-01-01

    A continuous stirred microbial electrochemical reactor (CSMER), comprising of a complete mixing zone (CMZ) and microbial electrochemical zone (MEZ), was used for brewery wastewater treatment. The system realized 75.4 ± 5.7% of TCOD and 64.9 ± 4.9% of TSS when fed with brewery wastewater concomitantly achieving an average maximum power density of 304 ± 31 m W m−2. Cascade utilization of organic matters made the CSMER remove a wider range of substrates compared with a continuous stirred tank reactor (CSTR), in which process 79.1 ± 5.6% of soluble protein and 86.6 ± 2.2% of soluble carbohydrates were degraded by anaerobic digestion in the CMZ and short-chain volatile fatty acids were further decomposed and generated current in the MEZ. Co-existence of fermentative bacteria (Clostridium and Bacteroides, 19.7% and 5.0%), acetogenic bacteria (Syntrophobacter, 20.8%), methanogenic archaea (Methanosaeta and Methanobacterium, 40.3% and 38.4%) and exoelectrogens (Geobacter, 12.4%) as well as a clear spatial distribution and syntrophic interaction among them contributed to the cascade degradation process in CSMER. The CSMER shows great promise for practical wastewater treatment application due to high pre-hydrolysis and acidification rate, high energy recovery and low capital cost. PMID:27270788

  1. Physical Simulation of a Duplex Stainless Steel Friction Stir Welding by the Numerical and Experimental Analysis of Hot Torsion Tests

    Science.gov (United States)

    da Fonseca, Eduardo Bertoni; Santos, Tiago Felipe Abreu; Button, Sergio Tonini; Ramirez, Antonio Jose

    2016-09-01

    Physical simulation of friction stir welding (FSW) by means of hot torsion tests was performed on UNS S32205 duplex stainless steel. A thermomechanical simulator Gleeble 3800® with a custom-built liquid nitrogen cooling system was employed to reproduce the thermal cycle measured during FSW and carry out the torsion tests. Microstructures were compared by means of light optical microscopy and electron backscatter diffraction. True strain and strain rate were calculated by numerical simulation of the torsion tests. Thermomechanically affected zone (TMAZ) was reproduced at peak temperature of 1303 K (1030 °C), rotational speeds of 52.4 rad s-1 (500 rpm) and 74.5 rad s-1 (750 rpm), and 0.5 to 0.75 revolutions, which represent strain rate between 10 and 16 s-1 and true strain between 0.5 and 0.8. Strong grain refinement, similar to the one observed in the stir zone (SZ), was attained at peak temperature of 1403 K (1130 °C), rotational speed of 74.5 rad s-1 (750 rpm), and 1.2 revolution, which represent strain rate of 19 s-1 and true strain of 1.3. Continuous dynamic recrystallization in ferrite and dynamic recrystallization in austenite were observed in the TMAZ simulation. At higher temperature, dynamic recovery of austenite was also observed.

  2. Effect of stirring on striae in glass melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Yue, Yuanzheng

    2012-01-01

    Chemical striae have often negative effect on the glass properties, and hence, elimination of striae has been a key issue in glass science and technology. To produce highly homogeneous glasses, it is necessary to stir melts during the melting process. To explore the physical origin of the stria...

  3. A novel anisotropic inversion approach for magnetotelluric data from subsurfaces with orthogonal geoelectric strike directions

    Science.gov (United States)

    Schmoldt, Jan-Philipp; Jones, Alan G.

    2013-12-01

    The key result of this study is the development of a novel inversion approach for cases of orthogonal, or close to orthogonal, geoelectric strike directions at different depth ranges, for example, crustal and mantle depths. Oblique geoelectric strike directions are a well-known issue in commonly employed isotropic 2-D inversion of MT data. Whereas recovery of upper (crustal) structures can, in most cases, be achieved in a straightforward manner, deriving lower (mantle) structures is more challenging with isotropic 2-D inversion in the case of an overlying region (crust) with different geoelectric strike direction. Thus, investigators may resort to computationally expensive and more limited 3-D inversion in order to derive the electric resistivity distribution at mantle depths. In the novel approaches presented in this paper, electric anisotropy is used to image 2-D structures in one depth range, whereas the other region is modelled with an isotropic 1-D or 2-D approach, as a result significantly reducing computational costs of the inversion in comparison with 3-D inversion. The 1- and 2-D versions of the novel approach were tested using a synthetic 3-D subsurface model with orthogonal strike directions at crust and mantle depths and their performance was compared to results of isotropic 2-D inversion. Structures at crustal depths were reasonably well recovered by all inversion approaches, whereas recovery of mantle structures varied significantly between the different approaches. Isotropic 2-D inversion models, despite decomposition of the electric impedance tensor and using a wide range of inversion parameters, exhibited severe artefacts thereby confirming the requirement of either an enhanced or a higher dimensionality inversion approach. With the anisotropic 1-D inversion approach, mantle structures of the synthetic model were recovered reasonably well with anisotropy values parallel to the mantle strike direction (in this study anisotropy was assigned to the

  4. Simulation of MILD combustion using Perfectly Stirred Reactor model

    KAUST Repository

    Chen, Z.; Vanteru, Mahendra Reddy; Ruan, S.; Doan, N. A K; Roberts, William L.; Swaminathan, N.

    2016-01-01

    A simple model based on a Perfectly Stirred Reactor (PSR) is proposed for moderate or intense low-oxygen dilution (MILD) combustion. The PSR calculation is performed covering the entire flammability range and the tabulated chemistry approach is used

  5. Contrast-enhanced fast fluid-attenuated inversion recovery MR imaging in patients with brain tumors

    International Nuclear Information System (INIS)

    Kim, Chan Kyo; Na, Dong Gyu; Ryoo, Wook Jae; Byun Hong Sik; Yoon, Hye Kyung; Kim, Jong hyun

    2000-01-01

    To assess the feasibility of contrast-enhanced fast fluid-attenuated inversion recovery (fast FLAIR) MR imaging in patients with brain tumors. This study involved 31 patients with pathologically proven brain tumors and nine with clinically diagnosed metastases. In all patients, T2-weighted, fast FLAIR, images were visual contrast-enhanced T1-weighted MR images were obtained. Contrast-enhanced fast FLAIR images were visually compared with other MR sequences in terms of tumor conspicuity. In order to distinguish tumor and surrounding edema, contrast-enhanced fast FLAIR images were compared with fast FLAIR and T2-weighted images. The tumor-to- white matter contrast-to-noise ratios (CNRs), as demonstrated by T2-weighted, fast FLAIR, contrast-enhanced fast FLAIR and contrast-enhanced T1-weighted imaging, were quantitatively assessed and compared. For the visual assessment of tumor conspicuity, contrast-enhanced fast FLAIR image imaging superior to fast FLAIR in 60% of cases (24/40), and superior to T2-weighted in 70% (28/40). Contrast-enhanced fast FLAIR imaging was inferior to contrast-enhanced T1-weighted in 58% of cases (23/40). For distinguishing between tumor and surrounding edema, contrast-enhanced fast FLAIR imaging was superior to fast FLAIR or T2-weighted in 22 of 27 tumors with peritumoral edema (81%). Quantitatively, CNR was the highest on contrast-enhanced fast FLAIR image and the lowest on fast FLAIR. For the detection of leptomeningeal metastases, contrast-enhanced fast FLAIR was partially superior to contrast-enhanced T1-weighted imaging in two of three high-grade gliomas. Although contrast-enhanced fast FLAIR imaging should not be seen as a replacement for conventional modalities, it provides additional informaton for assessment of the extent of glial cell tumors and leptomeningeal metastases in patients with brain tumors. (author)

  6. Enabling Dissimilar Material Joining Using Friction Stir Scribe Technology

    Energy Technology Data Exchange (ETDEWEB)

    Hovanski, Yuri; Upadyay, Piyush; Kleinbaum, Sarah; Carlson, Blair; Boettcher, Eric; Ruokolainen, Robert

    2017-04-05

    One challenge in adapting welding processes to dissimilar material joining is the diversity of melting temperatures of the different materials. Although the use of mechanical fasteners and adhesives have mostly paved the way for near-term implementation of dissimilar material systems, these processes only accentuate the need for low-cost welding processes capable of joining dissimilar material components regardless of alloy, properties, or melting temperature. Friction stir scribe technology was developed to overcome the challenges of joining dissimilar material components where melting temperatures vary greatly, and properties and/or chemistry are not compatible with more traditional welding processes. Although the friction stir scribe process is capable of joining dissimilar metals and metal/polymer systems, a more detailed evaluation of several aluminum/steel joints is presented herein to demonstrate the ability to both chemically and mechanically join dissimilar materials.

  7. Mitigating Abnormal Grain Growth for Friction Stir Welded Al-Li 2195 Spun Formed Domes

    Science.gov (United States)

    Chen, Po-Shou; Russell, Carolyn

    2012-01-01

    Formability and abnormal grain growth (AGG) are the two major issues that have been encountered for Al alloy spun formed dome development using friction stir welded blanks. Material properties that have significant influence on the formability include forming range and strain hardening exponent. In this study, tensile tests were performed for two 2195 friction stir weld parameter sets at 400 F to study the effects of post weld anneal on the forming range and strain hardening exponent. It was found that the formability can be enhanced by applying a newly developed post weld anneal to heat treat the friction stir welded panels. This new post weld anneal leads to a higher forming range and much improved strain hardening exponent. AGG in the weld nugget is known to cause a significant reduction of ductility and fracture toughness. This study also investigated how AGG may be influenced by the heating rate to the solution heat treatment temperature. After post-weld annealing, friction stir welds were strained to 15% and 39% by compression at 400 F before they were subjected to SHT at 950 F for 1 hour. Salt bath SHT is very effective in reducing the grain size as it helps arrest the onset of AGG and promote normal recrystallization and grain growth. However, heat treating a 18 ft dome using a salt bath is not practical. Efforts are continuing at Marshall Space Flight Center to identify the welding parameters and heat treating parameters that can help mitigate the AGG in the friction stir welds.

  8. STIR-Physics: Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials

    Science.gov (United States)

    2016-11-02

    STIR- Physics : Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials We worked on a tapered fiber in cold atomic cloud...reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: STIR- Physics : Cold Atoms and Nanocrystals in Tapered Nanofiber...other than abstracts): Number of Peer-Reviewed Conference Proceeding publications (other than abstracts): Books Number of Manuscripts: 0.00Number of

  9. Tensile behavior of dissimilar friction stir welded joints of aluminium alloys

    International Nuclear Information System (INIS)

    Shanmuga Sundaram, N.; Murugan, N.

    2010-01-01

    The heat treatable aluminium alloy AA2024 is used extensively in the aircraft industry because of its high strength to weight ratio and good ductility. The non-heat treatable aluminium alloy AA5083 possesses medium strength and high ductility and used typically in structural applications, marine, and automotive industries. When compared to fusion welding processes, friction stir welding (FSW) process is an emerging solid state joining process which is best suitable for joining these alloys. The friction stir welding parameters such as tool pin profile, tool rotational speed, welding speed, and tool axial force influence the mechanical properties of the FS welded joints significantly. Dissimilar FS welded joints are fabricated using five different tool pin profiles. Central composite design with four parameters, five levels, and 31 runs is used to conduct the experiments and response surface method (RSM) is employed to develop the model. Mathematical regression models are developed to predict the ultimate tensile strength (UTS) and tensile elongation (TE) of the dissimilar friction stir welded joints of aluminium alloys 2024-T6 and 5083-H321, and they are validated. The effects of the above process parameters and tool pin profile on tensile strength and tensile elongation of dissimilar friction stir welded joints are analysed in detail. Joints fabricated using Tapered Hexagon tool pin profile have the highest tensile strength and tensile elongation, whereas the Straight Cylinder tool pin profile have the lowest tensile strength and tensile elongation. The results are useful to have a better understanding of the effects of process parameters, to fabricate the joints with desired tensile properties, and to automate the FS welding process.

  10. Apparent Diffusion Coefficient Maps of Pediatric Mass Lesions with Free-Breathing Diffusion-Weighted Magnetic Resonance: Feasibility Study

    International Nuclear Information System (INIS)

    Olsen, Oe.E.; Sebire, N.J.

    2006-01-01

    Purpose: To assess the technical feasibility of apparent diffusion coefficient (ADC) mapping based on free-breathing diffusion-weighted magnetic resonance (DW-MR) outside the CNS in children. Material and Methods: Twelve children with mass lesions of varied histopathology were scanned with short-tau inversion recovery (STIR), contrast-enhanced T1-weighted (CE-T1W), and diffusion-weighted (b = 0, 500 and 1,000 s/mm 2 ) sequences. ADC maps were calculated. Lesion-to-background signal intensity ratios were measured and compared between STIR/CE-T1W/ADC overall (Friedman test) and between viable embryonal tumors and other lesions (Kruskal-Wallis test). Results: ADC maps clearly depicted all lesions. Lesion-to-background signal intensity ratios of STIR (median 3.7), CE-T1W (median 1.4), and ADC (median 1.6) showed no overall difference (chi-square = 3.846; P = 0.146), and there was no difference between viable embryonal tumors and other lesions within STIR/CE-T1W/ADC (chi-square 1.118/0.669/<0.001; P = 0.290/0.414/1.000, respectively). Conclusion: ADC mapping is feasible in free-breathing imaging of pediatric mass lesions outside the CNS using standard clinical equipment. Keywords: Diffusion-weighted magnetic resonance imaging; infants and children; neoplasms

  11. Friction stir scribe welding technique for dissimilar joining of aluminium and galvanised steel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tianhao [Center for Friction Stir Processing, Department of Materials Science and Engineering, University of North Texas, Denton, TX, USA; Sidhar, Harpreet [Center for Friction Stir Processing, Department of Materials Science and Engineering, University of North Texas, Denton, TX, USA; Mishra, Rajiv S. [Center for Friction Stir Processing, Department of Materials Science and Engineering, University of North Texas, Denton, TX, USA; Hovanski, Yuri [Pacific Northwest National Laboratory, Energy Materials and Manufacturing, Richland, WA, USA; Upadhyay, Piyush [Pacific Northwest National Laboratory, Energy Materials and Manufacturing, Richland, WA, USA; Carlson, Blair [General Motors Technical Center, Warren, MI, USA

    2017-10-04

    Friction stir scribe technology, a derivative of friction stir welding, was applied for the dissimilar lap welding of an aluminum alloy and galvanized mild steel sheets. During the process, the rotating tool with a cobalt steel scribe first penetrated the top material — aluminum — and then the scribe cut the bottom material — steel. The steel was displaced into the upper material to produce a characteristic hook feature. Lap welds were shear tested, and their fracture paths were studied. Welding parameters affected the welding features including hook height, which turned out to be highly related to fracture position. Therefore, in this paper, the relationships among welding parameters, hook height, joint strength and fracture position are presented. In addition, influence of zinc coating on joint strength was also studied. Keywords: friction stir scribe technology; dissimilar material welding; zinc coating; hook height; joint strength; fracture position

  12. Recovery of material parameters of soft hyperelastic tissue by an inverse spectral technique

    KAUST Repository

    Gou, Kun

    2012-07-01

    An inverse spectral method is developed for recovering a spatially inhomogeneous shear modulus for soft tissue. The study is motivated by a novel use of the intravascular ultrasound technique to image arteries. The arterial wall is idealized as a nonlinear isotropic cylindrical hyperelastic body. A boundary value problem is formulated for the response of the arterial wall within a specific class of quasistatic deformations reflective of the response due to imposed blood pressure. Subsequently, a boundary value problem is developed via an asymptotic construction modeling intravascular ultrasound interrogation which generates small amplitude, high frequency time harmonic vibrations superimposed on the static finite deformation. This leads to a system of second order ordinary Sturm-Liouville boundary value problems that are then employed to reconstruct the shear modulus through a nonlinear inverse spectral technique. Numerical examples are demonstrated to show the viability of the method. © 2012 Elsevier Ltd. All rights reserved.

  13. The investigation of abnormal particle-coarsening phenomena in friction stir repair weld of 2219-T6 aluminum alloy

    International Nuclear Information System (INIS)

    Li, Bo; Shen, Yifu

    2011-01-01

    Highlights: → Defective friction stir welds were repaired by overlapping FSW technique. → Abnormal Al 2 Cu-coarsening phenomena were found in 2219-T6 friction stir repair weld. → Three formation mechanisms were proposed for reasonable explanations. -- Abstract: The single-pass friction stir weld of aluminum 2219-T6 with weld-defects was repaired by overlapping friction stir welding technique. However, without any post weld heat treatment process, it was found that the phenomena of abnormal particle-coarsening of Al 2 Cu had occurred in the overlapping friction stir repair welds. The detecting results of non-destructive X-ray inspection proved that not only one group of repair FSW process parameters could lead to occurrence of the abnormal phenomena. And the abnormally coarsened particles always appeared on the advancing side of repair welds rather than the retreating side where the fracture behaviors occurred after mechanical tensile testing. The size of the biggest particle lying in the dark bands of 'Onion-rings' was more than 150 μm. After the related investigation by scanning electron microscope and X-ray energy spectrometer, three types of formation mechanisms were proposed for reasonably explaining the abnormal phenomenon: Aggregation Mechanism, Diffusion Mechanisms I and II. Aggregation Mechanism was according to the motion-laws of stir-pin. Diffusion Mechanisms were based on the classical theories of precipitate growth in metallic systems. The combined action of the three detailed mechanisms contributed to the abnormal coarsening behavior of Al 2 Cu particles in the friction stir repair weld.

  14. TiB2 reinforced aluminum based in situ composites fabricated by stir casting

    International Nuclear Information System (INIS)

    Chen, Fei; Chen, Zongning; Mao, Feng; Wang, Tongmin; Cao, Zhiqiang

    2015-01-01

    In this study, a new technique involving mechanical stirring at the salts/aluminum interface was developed to fabricate TiB 2 particulate reinforced aluminum based in situ composites with improved particle distribution. Processing parameters in terms of stirring intensity, stirring duration and stirring start time were optimized according to the microstructure and mechanical properties evaluation. The results show that, the first and last 15 min of the entire 60 min holding are of prime importance to the particle distribution of the final composites. When applying 180 rpm (revolutions per minute) stirring at the salts/aluminum interface in these two intervals, a more uniform microstructure can be achieved and the Al-4 wt% TiB 2 composite thus produced exhibits superior mechanical performance. Synchrotron radiation X-ray computed tomography (SR-CT) was used to give a full-scale imaging of the particle distribution. From the SR-CT results, the in situ Al–xTiB 2 composites (x=1, 4 and 7, all in wt%) fabricated by the present technique are characterized by fine and clean TiB 2 particles distributed uniformly throughout the Al matrix. These composites not only have higher yield strength (σ 0.2 ) and ultimate tensile strength (UTS), but also exhibit superior ductility, with respect to the Al–TiB 2 composites fabricated by the conventional process. The σ 0.2 and UTS of the Al–7TiB 2 composite in the present work, are 260% and 180% higher than those of the matrix. A combined mechanism was also presented to interpret the improvements in yield strength of the composites as influenced by their microstructures and processing history. The predicted values are in good agreement with the experimental results, strongly supporting the strengthening mechanism we proposed. Fractography reveals that the composites thus fabricated, follow ductile fracture mechanism in spite of the presence of stiff reinforcements

  15. Characterization of Friction Stir Welded Tubes by Means of Tube Bulge Test

    International Nuclear Information System (INIS)

    D'Urso, G.; Longo, M.; Giardini, C.

    2011-01-01

    Mechanical properties of friction stir welded joints are generally evaluated by means of conventional tensile test. This testing method might provide insufficient information because maximum strain obtained in tensile test before necking is small; moreover, the application of tensile test is limited when the joint path is not linear or even when the welds are executed on curved surfaces. Therefore, in some cases, it would be preferable to obtain the joints properties from other testing methods. Tube bulge test can be a valid solution for testing circumferential or longitudinal welds executed on tubular workpieces. The present work investigates the mechanical properties and the formability of friction stir welded tubes by means of tube bulge tests. The experimental campaign was performed on tubular specimens having a thickness of 3 mm and an external diameter of 40 mm, obtained starting from two semi-tubes longitudinally friction stir welded. The first step, regarding the fabrication of tubes, was performed combining a conventional forming process and friction stir welding. Sheets in Al-Mg-Si-Cu alloy AA6060 T6 were adopted for this purpose. Plates having a dimension of 225x60 mm were bent (with a bending axis parallel to the main dimension) in order to obtain semi-tubes. A particular care was devoted to the fabrication of forming devices (punch and die) in order to minimize the springback effects. Semi-tubes were then friction stir welded by means of a CNC machine tool. Some preliminary tests were carried out by varying the welding parameters, namely feed rate and rotational speed. A very simple tool having flat shoulder and cylindrical pin was used. The second step of the research was based on testing the welded tubes by means of tube bulge test. A specific equipment having axial actuators with a conical shape was adopted for this study. Some analyses were carried out on the tubes bulged up to a certain pressure level. In particular, the burst pressure and the

  16. Microstructure and microtexture studies of a friction stir welded Al 6061 alloy

    International Nuclear Information System (INIS)

    Kumbhar, N.T.; Tewari, R.; Dey, G.K.; Bhanumurthy, K.; Sahoo, S.K.; Samajdar, I.

    2009-01-01

    Friction stir welding is a solid state joining technique used extensively for the joining of various metals and alloys and also has been applied to the joining of steels. The friction stir welding of Al and its alloys has been extensively delt with over a period exceeding the last decade and a half due to its numerous advantages over other conventional fusion welding techniques in terms of weld quality, efficiency, cost effectiveness etc. to name a few. This technique is being increasingly seeked by industries in mass production/engineering such as the railways, marine and aerospace industries. The friction stir welding of a precipitation hardened Al 6061 alloy plates of 6 mm. thickness was performed at various tool rotation speeds and tool traverse speeds with a constant tilt of 3 deg using a high strength steel (HSS) tool of appropriate dimensions. The cross section of the weld perpendicular to the welding direction was analyzed for a detailed microstructural investigation using electron probe microanalysis, orientation imaging microscopy and transmission electron microscopy. Various microstructural changes are observed in the various regions of the friction stir welded AA 6061. The nugget region which is highly deformed is characterized by the dissolution and reprecipitation of the coarse precipitates, grain size refinement and recrystallization. The adjoining regions near the nugget viz the thermomechanically affected zone (TMAZ) and the heat affected zone (HAZ) also show heterogeneous microstructure in terms of grain size and precipitation which is mainly attributed to the heating cycle experienced during welding. This heterogeneity is also evident from the plot of microhardness distribution across the cross section of the weld region. However, the electron probe microanalysis studies do not show any significant pickup of oxygen in the weld interior as compared to a little oxygen pickup upto 30 μm from the top surface. Further, using orientation imaging

  17. Noninvasive investigation of exocrine pancreatic function: Feasibility of cine dynamic MRCP with a spatially selective inversion-recovery pulse.

    Science.gov (United States)

    Yasokawa, Kazuya; Ito, Katsuyoshi; Tamada, Tsutomu; Yamamoto, Akira; Hayashida, Minoru; Tanimoto, Daigo; Higaki, Atsushi; Noda, Yasufumi; Kido, Ayumu

    2015-11-01

    To investigate the feasibility of noncontrast-enhanced cine dynamic magnetic resonance cholangiopancreatography (MRCP) with a spatially selective inversion-recovery (IR) pulse for evaluating exocrine pancreatic function in comparison with the N-benzoyl-L-tyrosyl-p-aminobenzoic acid (BT-PABA) test as a pancreatic exocrine function test. Twenty subjects with or without chronic pancreatitis were included. MRCP with a spatially selective IR pulse was repeated every 15 seconds for 5 minutes to acquire a total of 20 images (cine-dynamic MRCP). The median and mean frequency of the observation (the number of times) and the moving distance (mean secretion grading scores) of pancreatic juice inflow on cine-dynamic MRCP were compared with a BT-PABA test. The urinary PABA excretion rate (%) had significant positive correlations with both the mean secretion grade (r = 0.66, P = 0.002) and frequency of secretory inflow (r = 0.62, P = 0.004) in cine dynamic MRCP. Both the mean frequency of observations of pancreatic secretory inflow (1.4 ± 1.6 times vs. 14.3 ± 4.2 times, P Cine dynamic MRCP with a spatially selective IR pulse may have potential for estimating the pancreatic exocrine function noninvasively as a substitute for the BT-PABA test. © 2015 Wiley Periodicals, Inc.

  18. Arterial hyperintensity on BLADE fluid-attenuated inversion recovery images (FLAIR) in hyperacute territorial infarction: comparison with conventional FLAIR

    Energy Technology Data Exchange (ETDEWEB)

    Kwag, Eujean; Lim, Soo Mee; Park, Ji Eun; Chae, In Hye [Ewha Womans University School of Medicine, Department of Radiology, Mokdong Hospital, Seoul (Korea, Republic of)

    2014-09-15

    To evaluate the utility of BLADE fluid-attenuated inversion recovery images (FLAIR) magnetic resonance (MR) imaging compared to conventional FLAIR for the detection of arterial hyperintensity (AH) in hyperacute territorial infarction. We retrospectively analysed MR images of patients with hyperacute (<6 h) territorial infarction over a 9-month study period. Special attention was paid to the presence or absence of AH in the frontal, parietal and temporal lobes and the number of AHs in the sylvian fissure. We also evaluated the presence of three kinds of artefacts on BLADE FLAIR and conventional FLAIR images. AH was seen in 41 (91 %) patients with conventional FLAIR and 45 (100 %) patients with BLADE FLAIR images. More instances of AH were detected in the frontal, parietal and temporal lobes and within the sylvian fissure using BLADE FLAIR. Motion artefacts, pulsation artefacts from the sigmoid sinus and incomplete cerebrospinal fluid (CSF) nulling that reduced image quality were observed more frequently on conventional FLAIR images than on BLADE FLAIR images. BLADE FLAIR sequences are more sensitive than conventional FLAIR for the detection of AH in hyperacute territorial infarctions and provide better image quality by reducing artefacts. They may be used in place of conventional FLAIR for patients with hyperacute stroke. (orig.)

  19. An inverse problem approach to pattern recognition in industry

    Directory of Open Access Journals (Sweden)

    Ali Sever

    2015-01-01

    Full Text Available Many works have shown strong connections between learning and regularization techniques for ill-posed inverse problems. A careful analysis shows that a rigorous connection between learning and regularization for inverse problem is not straightforward. In this study, pattern recognition will be viewed as an ill-posed inverse problem and applications of methods from the theory of inverse problems to pattern recognition are studied. A new learning algorithm derived from a well-known regularization model is generated and applied to the task of reconstruction of an inhomogeneous object as pattern recognition. Particularly, it is demonstrated that pattern recognition can be reformulated in terms of inverse problems defined by a Riesz-type kernel. This reformulation can be employed to design a learning algorithm based on a numerical solution of a system of linear equations. Finally, numerical experiments have been carried out with synthetic experimental data considering a reasonable level of noise. Good recoveries have been achieved with this methodology, and the results of these simulations are compatible with the existing methods. The comparison results show that the Regularization-based learning algorithm (RBA obtains a promising performance on the majority of the test problems. In prospects, this method can be used for the creation of automated systems for diagnostics, testing, and control in various fields of scientific and applied research, as well as in industry.

  20. Friction stir welding of Aluminium matrix composites – A Review

    Directory of Open Access Journals (Sweden)

    Subramanya Prabhu

    2018-01-01

    Full Text Available Friction stir welding (FSW is established as one of the prominent welding techniques to join aluminium matrix composites (AMCs. It is a solid state welding process, takes place well below the melting temperature of the material, eliminates the detrimental effects of conventional fusion welding process. Although the process is capable to join AMCs, challenges are still open that need to be fulfill to widen its applications. This paper gives the outline of the friction stir welding technique used to join AMCs. Effect of process variables on the microstructure and mechanical properties of the joints, behavior of reinforcing materials during welding, effect of tool profiles on the joint strength are discussed in detail. Few improvements and direction for future research are also proposed.

  1. Microstructure evolution in dissimilar AA6060/copper friction stir welded joints

    Science.gov (United States)

    Kalashnikova, T. A.; Shvedov, M. A.; Vasilyev, P. A.

    2017-12-01

    Friction stir welding process has been applied for making a dissimilar copper/aluminum alloy joint. The grain microstructure and mechanical properties of the obtained joint were studied. The structure of the cross-section of the FSW compound was analyzed. The microstructural evolution of the joint was examined using optical microscopy. The mechanical properties of the intermetallic particles were evaluated by measuring the microhardness according to the Vickers method. The microhardness of the intermetallic particles was by a factor of 4 lower than that of the particles obtained by fusion welding. The results of the investigations enable using friction stir welding for making dissimilar joints.

  2. Ultrasonic stir welding process and apparatus

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2009-01-01

    An ultrasonic stir welding device provides a method and apparatus for elevating the temperature of a work piece utilizing at least one ultrasonic heater. Instead of relying on a rotating shoulder to provide heat to a workpiece an ultrasonic heater is utilized to provide ultrasonic energy to the workpiece. A rotating pin driven by a motor assembly performs the weld on the workpiece. A handheld version can be constructed as well as a fixedly mounted embodiment.

  3. Research on Stochastic Resonance Signal’s Recovery

    Directory of Open Access Journals (Sweden)

    Hao Wang

    2013-01-01

    Full Text Available Using stochastic resonance to detect weak periodic signals has been widely used in various fields of science, which attracts much attention of researchers due to its advantages of revealing recessive periodic laws. This paper utilized this method to seek the underlying rule of setting weather index, so we can find that how to obtain the accurate expression of original periodic law by further investigation. This paper deals with the noise-contained signal restoring on the basis of the established system coupling the inversion system and bistable system. The simulation shows that this signal recovery method inversion effect is better and the application range is wider.

  4. New method for exopolysaccharide determination in culture broth using stirred ultrafiltration cells.

    Science.gov (United States)

    Bergmaier, D; Lacroix, C; Guadalupe Macedo, M; Champagne, C P

    2001-10-01

    A new method to remove simple carbohydrates from culture broth prior to the quantification of exopolysaccharides (EPS) was developed and validated for the EPS-producing strain, Lactobacillus rhamnosus RW-9595M. This method uses ultrafiltration (UF) in stirred cells followed by polysaccharide detection in the retentate by the phenol-sulfuric acid method. The UF method was compared with a conventional method based on ethanol extraction, dialysis, protein removal by trichloroacetic acid (TCA) and freeze-drying. EPS production during pH-controlled batch fermentations in basal minimum medium, whey permeate (WP). and whey permeate supplemented with yeast extract, minerals and Tween-80 (SWP) was determined by the new UF and conventional methods. EPS recovery by the new method ranged from 83% to 104% for EPS added in the concentration range 40-1,500 mg/l in 0.1 M NaCl solution or culture medium. The UF method was rapid (8 h), accurate and simple, and required only a small sample volume (1-5 ml). A very high maximum EPS production was measured in SWP by both the UF and conventional methods (1,718 and 1,755 mg/l).

  5. The value of qualitative and quantitative assessment of lesion to cerebral cortex signal ratio on double inversion recovery sequence in the differentiation of demyelinating plaques from non-specific T2 hyperintensities

    Energy Technology Data Exchange (ETDEWEB)

    Hamcan, Salih; Battal, Bilal; Akgun, Veysel; Sari, Sebahattin; Tasar, Mustafa [Gulhane Military Medical School, Department of Radiology, Etlik, Ankara (Turkey); Oz, Oguzhan; Tasdemir, Serdar [Gulhane Military Medical School, Department of Neurology, Ankara (Turkey); Bozkurt, Yalcin [Golcuk Military Hospital, Department of Radiology, Kocaeli (Turkey)

    2017-02-15

    To assess the usefulness of the visual assessment and to determine diagnostic value of the lesion-to-cerebral cortex signal ratio (LCSR) measurement in the differentiation of demyelinating plaques and non-specific T2 hyperintensities on double inversion recovery (DIR) sequence. DIR and fluid-attenuated inversion recovery (FLAIR) sequences of 25 clinically diagnosed multiple sclerosis (MS) patients and 25 non-MS patients with non-specific T2-hyperintense lesions were evaluated visually and LCSRs were measured by two observers independently. On DIR sequence, the calculated mean LCSR ± SD for demyelinating plaques and non-specific T2-hyperintense lesions were 1.60 ± 0.26 and 0.75 ± 0.19 for observer1, and 1.61 ± 0.27 and 0.74 ± 0.19 for observer2. LCSRs of demyelinating plaques were significantly higher than other non-specific T2-hyperintense lesions on DIR sequence. By using the visual assessment demyelinating plaques were differentiated from non-specific T2-hyperintensities with 92.8 % sensitivity, 97.5 % specificity and 95.1 % accuracy for observer1 and 92.8 % sensitivity, 95 % specificity and 93.9 % accuracy for observer2. Visual assessment and LCSR measurement on DIR sequence seems to be useful for differentiating demyelinating MS plaques from supratentorial non-specific T2 hyperintensities. This feature can be used for diagnosis of MS particularly in patients with only supratentorial T2-hyperintense lesions who are categorized as radiologically possible MS. (orig.)

  6. A compact active grid for stirring pipe flow

    NARCIS (Netherlands)

    Verbeek, A.A.; Pos, R.C.; Stoffels, G.G.M.; Geurts, B.J.; Meer, van der Th.

    2013-01-01

    A compact active grid is developed with which a pipe flow can be stirred in order to enhance the turbulence. The active grid is composed of a stationary and a rotating disk with characteristic hole patterns. This active grid is placed inside the pipe, allowing flow to pass through it. With only one

  7. A compact active grid for stirring pipe flow

    NARCIS (Netherlands)

    Verbeek, Antonie Alex; Pos, R.C.; Stoffels, Genie G.M.; Geurts, Bernardus J.; van der Meer, Theodorus H.

    A compact active grid is developed with which a pipe flow can be stirred in order to enhance the turbulence. The active grid is composed of a stationary and a rotating disk with characteristic hole patterns. This active grid is placed inside the pipe, allowing flow to pass through it. With only one

  8. synthesis and characterization of al/sic composite made by stir casting method

    International Nuclear Information System (INIS)

    Ghauri, K.M.; Ahmad, A.; Ahmad, R.; Din, K.M.; Chaudhry, J.A.

    2013-01-01

    Ceramics contain a distinctive property of completely absence of slip planes and have least probability of deforming by the application of force. Among these ceramics, the silicon carbide occupies a competent place to be used as a reinforcing agent for aluminum or its alloys. It has the density close to aluminum and is best for making composite having good strength and good heat conductivity. Stir casting has been used to synthesize Al/SiC MMCs by reinforcing silicon carbide particles into aluminum matrix. The reason for using stir casting is to develop technology for the development of MMCs at affordable cost. The selection of SiC as reinforcement and Al as matrix is because of their easy availability. The practical data acquired, analyzed and optimized will be interpreted in the light of information available in the literature and be shared with the relevant industries. The present work was mainly carried out to characterize the SiC/Al composite which was produced by reinforcing the various proportions of SiC (5, 10, 15, 25 and 30%) in aluminum matrix using stir casting technique. Mechanical properties of test specimens made from stir-casted Aluminum-Silicon Carbide composites have been studied using metallographic and mechanical testing techniques. It was observed that as the volume fraction of SiC in the composite is gradually increased, the hardness and toughness increase. However, beyond a level of 25-30 percent SiC, the results are not very consistent, and depend largely on the uniformity of distribution of SiC in the aluminum matrix. (author)

  9. Sensitive determination of estrogens in environmental waters treated with polymeric ionic liquid-based stir cake sorptive extraction and liquid chromatographic analysis.

    Science.gov (United States)

    Chen, Lei; Mei, Meng; Huang, Xiaojia; Yuan, Dongxing

    2016-05-15

    A simple, sensitive and environmentally friendly method using polymeric ionic liquid-based stir cake sorptive extraction followed by high performance liquid chromatography with diode array detection (HPLC/DAD) has been developed for efficient quantification of six selected estrogens in environmental waters. To extract trace estrogens effectively, a poly (1-ally-3-vinylimidazolium chloride-co-ethylene dimethacrylate) monolithic cake was prepared and used as the sorbent of stir cake sorptive extraction (SCSE). The effects of preparation conditions of sorbent and extraction parameters of SCSE for estrogens were investigated and optimized. Under optimal conditions, the developed method showed satisfactory analytical performance for targeted analytes. Low limits of detection (S/N=3) and quantification limits (S/N=10) were achieved within the range of 0.024-0.057 µg/L and 0.08-0.19 µg/L, respectively. Good linearity of method was obtained for analytes with the correlation coefficients (R(2)) above 0.99. At the same time, satisfactory method repeatability and reproducibility was achieved in terms of intra- and inter-day precisions, respectively. Finally, the established SCSE-HPLC/DAD method was successfully applied for the determination of estrogens in different environmental water samples. Recoveries obtained for the determination of estrogens in spiked samples ranged from 71.2% to 108%, with RSDs below 10% in all cases. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Effect of ultrasonic stirring on the microstructure and mechanical properties of in situ Mg{sub 2}Si/Al composite

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jixing, E-mail: linjixing@163.com [Department of Material Engineering, Zhejiang Industry & Trade Vocational College, Wenzhou 325003 (China); College of Materials Science and Engineering, Jilin University, Changchun 130000 (China); Bai, Guangzhu [Department of Material Engineering, Zhejiang Industry & Trade Vocational College, Wenzhou 325003 (China); School of Materials Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Liu, Zheng [School of Mechanical and Electrical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Niu, Liyuan [Department of Material Engineering, Zhejiang Industry & Trade Vocational College, Wenzhou 325003 (China); Li, Guangyu [College of Materials Science and Engineering, Jilin University, Changchun 130000 (China); Wen, Cuie [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Melbourne, Victoria 3001 (Australia)

    2016-08-01

    In situ Mg{sub 2}Si/Al composites are receiving increasing attention for industrial applications because of their inherently stable interfaces, light weight, excellent combination of mechanical properties and low processing costs. The composite is formed through in situ nucleation and growth of a reinforcing phase Mg{sub 2}Si from the parent matrix during solidification. In this study, we report the effect of ultrasonic stirring with different times on the solidification structure and mechanical properties of in situ Mg{sub 2}Si/Al composites. X-ray diffraction analysis, optical microscopy and scanning electron microscopy were used to analyze the microstructural evolution of the composites. The mechanical properties of the composites were tested by using hardness and tensile testers. Our results showed that 40 s ultrasonic stirring resulted in the optimal impact on the refining both the primary and eutectic Mg{sub 2}Si particles and improving the shapes of the primary Mg{sub 2}Si particles. The composites with 40 s ultrasonic stirring exhibited simultaneously enhanced tensile strength and elongation and the tensile fracture morphology was shown to be quasi-cleavage with a large number of dimples. This study proves that ultrasonic stirring is effective in degassing, removal of impurities, refining, and improving the shapes of the reinforcing phase, leading to significantly enhance the mechanical performance of the composites. - Highlights: • Ultrasonic technique shows excellent impact during Al composite processing. • Ultrasonic stirring improves the shapes of Mg{sub 2}Si particles with higher circularity. • Ultrasonic stirring results in an increase in the tensile strength of the composite. • Ultrasonic stirring leads to a significantly increased elongation of the composite. • Tensile fracture of composite with ultrasonic stirring shows more ductile features.

  11. Chemical characterization and antioxidant activities comparison in fresh, dried, stir-frying and carbonized ginger.

    Science.gov (United States)

    Li, Yuxin; Hong, Yan; Han, Yanquan; Wang, Yongzhong; Xia, Lunzhu

    2016-02-01

    Ginger (Zingiber officinale Rosc.) is a common dietary adjunct that contributes to the taste and flavor of foods, and is also an important Traditional Chinese medicine (TCM). Different processing methods can produce different processed gingers with dissimilar chemical constituents and pharmacological activities. In this study, an ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/QTOF-MS) was applied to identify the complicated components from fresh, dried, stir-frying and carbonized ginger extracts. All of the 27 compounds were identified from four kinds of ginger samples (fresh, dried, stir-frying and carbonized ginger). Five main constituents (zingerone, 6-gingerol, 8-gingerol, 6-shogaol and 10-gingerol) in these four kinds of ginger sample extracts were simultaneously determined by UPLC-PDA. Meanwhile, the antioxidant effect of fresh, dried, stir-frying and carbonized gingers were evaluated by three assays (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzthiazolinesulfonic acid) diammonium salt (ABTS), and ferric reducing antioxidant power (FRAP)). The results demonstrated that antioxidant activity of dried ginger was the highest, for its phenolic contents are 5.2-, 1.1- and 2.4-fold higher than that of fresh, stir-frying and carbonized ginger, respectively, the antioxidant activities' results indicated a similar tendency with phenolic contents: dried ginger>stir-frying ginger>fresh ginger>carbonized ginger. The processing contributed to the decreased concentration of gingerols and the increased levels of shogaols, which reducing the antioxidant effects in pace with processing. This study elucidated the relationship of the heating process with the constituents and antioxidant activity, and provided a guide for choosing different kinds of ginger samples on clinical application. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Effects of welding parameters on friction stir spot welding of high density polyethylene sheets

    International Nuclear Information System (INIS)

    Bilici, Mustafa Kemal; Yukler, Ahmet Irfan

    2012-01-01

    Graphical abstract: (a) Schematic illustration of the cross section of a friction stir spot weld and (b) Geometry of the weld bonded area, x: nugget thickness and y: the thickness of the upper sheet. Highlights: → Welding parameters affect the FSSW nugget formation and the strength of the joint. → Melting of polyethylene occurred in the vicinity of the tool pin. → The joint that fractures with a pull nugget failure mode has a higher strength. -- Abstract: Friction stir spot welding parameters affect the weld strength of thermoplastics, such as high density polyethylene (HDPE) sheets. The effects of the welding parameters on static strength of friction stir spot welds of high density polyethylene sheets were investigated. For maximizing the weld strength, the selection of welding parameters is very important. In lap-shear tests two fracture modes were observed; cross nugget failure and pull nugget failure. The tool rotational speed, tool plunge depth and dwell time were determined to be important in the joint formation and its strength. The joint which had a better strength fails with a pull nugget failure morphology. Weld cross section image analysis of the joints were done with a video spectral comparator. The plunge rate of the tool was determined to have a negligible effect on friction stir spot welding.

  13. Mass transfer and power characteristics of stirred tank with Rushton and curved blade impeller

    Directory of Open Access Journals (Sweden)

    Thiyam Tamphasana Devi

    2017-04-01

    Full Text Available Present work compares the mass transfer coefficient (kLa and power draw capability of stirred tank employed with Rushton and curved blade impeller using computational fluid dynamics (CFD techniques in single and double impeller cases. Comparative analysis for different boundary conditions and mass transfer model has been done to assess their suitability. The predicted local kLa has been found higher in curved blade impeller than the Rushton impeller, whereas stirred tank with double impeller does not show variation due to low superficial gas velocity. The global kLa predicted has been found higher in curved blade impeller than the Rushton impeller in double and single cases. Curved blade impeller also exhibits higher power draw capability than the Rushton impeller. Overall, stirred tank with curved blade impeller gives higher efficiency in both single and double cases than the Rushton turbine

  14. Domestic solid waste and sewage improvement by anaerobic digestion: A stirred digester

    Energy Technology Data Exchange (ETDEWEB)

    Lebrato, J.; Perez-Rodriguez, J.L. [CSIC-UNSE, Instituto de Ciencia de Materiales, Sevilla (Spain); Maqueda, C. [CSIC Instituto de Recursos Naturales y Agrobiologia, Sevilla (Spain)

    1995-05-01

    The processing of the mixture of domestic solid waste and domestic sewage in an stirring digester was studied. The experimental set up consisted of six thermostatically controlled digesters of 1 l, each one in a bath at 35{+-}1oC and magnetically stirred. The best feeding for the culture was 1.7 g COD l{sup -1} day{sup -1}. The minimum hydraulic retention time was 6 days. The efficiency in COD removal of treatment varied between 90.1% and 72.4%. The biogas productivity was 0.19 l g{sup -1} COD day{sup -1}

  15. Recovery Process of Li, Al and Si from Lepidolite by Leaching with HF

    Directory of Open Access Journals (Sweden)

    Gustavo D. Rosales

    2017-03-01

    Full Text Available This work describes the development of a new process for the recovery of Li, Al and Si along with the proposal of a flow sheet for the precipitation of those metals. The developed process is comprised of lepidolite acid digestion with hydrofluoric acid, and the subsequent precipitation of the metals present in the leach liquor. The leaching operational parameters studied were: reaction time, temperature and HF concentration. The experimental results indicate that the optimal conditions to achieve a Li extraction higher than 90% were: solid-liquid ratio, 1.82% (w/v; temperature, 123 °C; HF concentration, 7% (v/v; stirring speed, 330 rpm; and reaction time, 120 min. Al and Si can be recovered as Na3AlF6 and K2SiF6. LiF was separated from the leach liquor during water evaporation, with recovery values of 92%.

  16. Process optimization of friction stir welding based on thermal models

    DEFF Research Database (Denmark)

    Larsen, Anders Astrup

    2010-01-01

    This thesis investigates how to apply optimization methods to numerical models of a friction stir welding process. The work is intended as a proof-of-concept using different methods that are applicable to models of high complexity, possibly with high computational cost, and without the possibility...... information of the high-fidelity model. The optimization schemes are applied to stationary thermal models of differing complexity of the friction stir welding process. The optimization problems considered are based on optimizing the temperature field in the workpiece by finding optimal translational speed....... Also an optimization problem based on a microstructure model is solved, allowing the hardness distribution in the plate to be optimized. The use of purely thermal models represents a simplification of the real process; nonetheless, it shows the applicability of the optimization methods considered...

  17. Hybrid multi-response optimization of friction stir spot welds: failure ...

    Indian Academy of Sciences (India)

    O O OJO

    2018-06-08

    Jun 8, 2018 ... Friction stir spot welding; effective bonded size; failure load; expelled flash volume; hybrid multi- response ... eliminated with the application of FSSW process. Conse- ... design of experiment is generally applied in either single.

  18. Stirring by swimming bodies

    International Nuclear Information System (INIS)

    Thiffeault, Jean-Luc; Childress, Stephen

    2010-01-01

    We consider the stirring of an inviscid fluid caused by the locomotion of bodies through it. The swimmers are approximated by non-interacting cylinders or spheres moving steadily along straight lines. We find the displacement of fluid particles caused by the nearby passage of a swimmer as a function of an impact parameter. We use this to compute the effective diffusion coefficient from the random walk of a fluid particle under the influence of a distribution of swimming bodies. We compare with the results of simulations. For typical sizes, densities and swimming velocities of schools of krill, the effective diffusivity in this model is five times the thermal diffusivity. However, we estimate that viscosity increases this value by two orders of magnitude.

  19. Limited role of gadolinium to detect active sacroiliitis on MRI in juvenile spondyloarthritis

    Energy Technology Data Exchange (ETDEWEB)

    Herregods, N.; Leus, A.; Verstraete, K.; Jans, L. [Ghent University Hospital, Department of Radiology and Medical Imaging, Ghent (Belgium); Jaremko, J.L. [University of Alberta Hospital, Department of Radiology and Diagnostic Imaging, Edmonton, AB (Canada); Baraliakos, X. [Ruhr-University Bochum, Rheumazentrum Ruhrgebiet, Herne (Germany); Dehoorne, J. [Ghent University Hospital, Department of Pediatric Rheumatology, Ghent (Belgium)

    2015-11-15

    The aim of this study is to determine the added diagnostic value of contrast-enhanced (CE) magnetic resonance imaging (MRI) compared to routine non contrast-enhanced MRI to detect active sacroiliitis in clinically juvenile spondyloarthritis (JSpA). A total of 80 children clinically suspected for sacroiliitis prospectively underwent MRI of the sacroiliac (SI) joints. Axial and coronal T1-weighted (T1), Short-tau inversion recovery (STIR) and fat-saturated T1-weighted gadolinium-DTPA (Gd) contrast-enhanced (T1/Gd) sequences were obtained. The presence of bone marrow edema (BME), capsulitis, enthesitis, high intra-articular STIR signal, synovial enhancement and a global diagnostic impression of the MRI for diagnosis of sacroiliitis was recorded. STIR and T1/Gd sequences had 100 % agreement for depiction of BME, capsulitis and enthesitis. High intra-articular STIR signal was seen in 18/80 (22.5 %) patients, 15 (83 %) of whom also showed synovial enhancement in the T1/Gd sequence. Sensitivity (SN) and specificity (SP) for a clinical diagnosis of JSpA were similar for high STIR signal (SN = 33 %, SP = 85 %) and T1/Gd synovial enhancement (SN = 36 %, SP = 92 %). Positive likelihood ratio (LR+) for JSpA was twice as high for synovial enhancement than high STIR signal (4.5 compared to 2.2). Global diagnostic impression was similar (STIR: SN = 55 %, SP = 87 %, LR + =4.2; T1/Gd: SN = 55 %, SP = 92 %, LR + = 6.9). MRI without contrast administration is sufficient to identify bone marrow edema, capsulitis and retroarticular enthesitis as features of active sacroiliitis in juvenile spondyloarthritis. In selected cases when high STIR signal in the joint is the only finding, gadolinium-enhanced images may help to confirm the presence of synovitis. (orig.)

  20. Abnormal hyperintensity within the subarachnoid space evaluated by fluid-attenuated inversion-recovery MR imaging: a spectrum of central nervous system diseases

    International Nuclear Information System (INIS)

    Maeda, M.; Sakuma, H.; Takeda, K.; Yagishita, A.; Yamamoto, T.

    2003-01-01

    A variety of central nervous system (CNS) diseases are associated with abnormal hyperintensity within the subarachnoid space (SAS) by fluid-attenuated inversion-recovery (FLAIR) MR imaging. Careful attention to the SAS can provide additional useful information that may not be available with conventional MR sequences. The purpose of this article is to provide a pictorial essay about CNS diseases and FLAIR images with abnormal hyperintensity within the SAS. We present several CNS diseases including subarachnoid hemorrhage, meningitis, leptomeningeal metastases, acute infarction, and severe arterial occlusive diseases such as moya-moya disease. We also review miscellaneous diseases or normal conditions that may exhibit cerebrospinal fluid hyperintensity on FLAIR images. Although the detection of abnormal hyperintensity suggests the underlying CNS diseases and narrows differential diagnoses, FLAIR imaging sometimes presents artifactual hyperintensity within the SAS that can cause the misinterpretation of normal SAS as pathologic conditions; therefore, radiologists should be familiar with such artifactual conditions as well as pathologic conditions shown as hyperintensity by FLAIR images. This knowledge is helpful in establishing the correct diagnosis. (orig.)

  1. MRI of meniscal bucket-handle tears

    Energy Technology Data Exchange (ETDEWEB)

    Magee, T.H.; Hinson, G.W. [Menorah Medical Center, Overland Park, KS (United States). Dept. of Radiology

    1998-09-01

    A meniscal bucket-handle tear is a tear with an attached fragment displaced from the meniscus of the knee joint. Low sensitivity of MRI for detection of bucket-handle tears (64% as compared with arthroscopy) has been reported previously. We report increased sensitivity for detecting bucket-handle tears with the use of coronal short tau inversion recovery (STIR) images. Results. By using four criteria for diagnosis of meniscal bucket-handle tears, our overall sensitivity compared with arthroscopy was 93% (28 of 30 meniscal bucket-handle tears seen at arthroscopy were detected by MRI). The meniscal fragment was well visualized in all 28 cases on coronal STIR images. The double posterior cruciate ligament sign was seen in 8 of 30 cases, the flipped meniscus was seen in 10 of 30 cases and a fragment in the intercondylar notch was seen in 18 of 30 cases. (orig.)

  2. Influence of Stored Strain on Fabricating of Al/SiC Nanocomposite by Friction Stir Processing

    Science.gov (United States)

    Khorrami, M. Sarkari; Kazeminezhad, M.; Kokabi, A. H.

    2015-05-01

    In this work, 1050 aluminum (Al) sheets were annealed and severely deformed by 1, 2, and 3 passes of constrained groove pressing process to obtain the various initial stored strain values of 0, 1.16, 2.32, and 3.48, respectively. Friction stir processing (FSP) was then applied using SiC nanoparticles to fabricate Al/SiC nanocomposite with approximately 1.5 vol pct reinforced particles. Microstructural examinations revealed that an increase in the initial stored strain of the base metal led to the formation of finer grain structure after 1 pass of FSP. The finer grain structure occurred in the stir zone where a sufficient amount of nanoparticles with a relatively proper distribution existed. However, the initial stored strain value had a contrary influence in the regions with low volume fraction of nanoparticles. In fact, more stored strain in the base metal provided more driving force for both nucleation and grain growth of newly recrystallized grains at the stir zone. Pinning effect of well-distributed nanoparticles could effectively retard grain growth leading to the formation of very fine grain structure. Also it was observed that the initial stored strain values did not have impressive rule in the microstructural evolutions at the stir zone during the second and third FSP passes signifying that all of the stored energy in the base metal would be released after 1 pass of FSP. The results obtained with microhardness measurement at the stir zone were fairly in agreement with those achieved by the microstructure assessments.

  3. Corrosion Behavior of Arc Weld and Friction Stir Weld in Al 6061-T6 Alloys

    International Nuclear Information System (INIS)

    Yoon, Byoung Hyun; Kim, Heung Ju; Chang, Woong Seong; Kweon, Young Gak

    2006-01-01

    For the evaluation of corrosion resistance of Al 6061-T6 Alloy, Tafel method and immersion test was performed with Friction Stir Weld(FSW) and Gas Metal Arc Weld(GMAW). The Tafel and immersion test results indicated that GMA weld was severely attacked compared with those of friction stir weld. It may be mainly due to the galvanic corrosion mechanism act on the GMA weld

  4. Microstructure characterization of Friction Stir Spot Welded TRIP steel

    DEFF Research Database (Denmark)

    Lomholt, Trine Colding; Adachi, Yoshitaka; Peterson, Jeremy

    2012-01-01

    Transformation Induced Plasticity (TRIP) steels have not yet been successfully joined by any welding technique. It is desirable to search for a suitable welding technique that opens up for full usability of TRIP steels. In this study, the potential of joining TRIP steel with Friction Stir Spot...

  5. Cladding of Advanced Al Alloys Employing Friction Stir Welding

    NARCIS (Netherlands)

    van der Stelt, A.A.; Bor, Teunis Cornelis; Geijselaers, Hubertus J.M.; Akkerman, Remko; van den Boogaard, Antonius H.

    2013-01-01

    In this paper an advanced solid state cladding process, based on Friction Stir Welding, is presented. The Friction Surface Cladding (FSC) technology enables the deposition of a solid-state coating using filler material on a substrate with good metallurgical bonding. A relatively soft AA1050 filler

  6. Mass conservative three-dimensional water tracer distribution from MCMC inversion of time-lapse GPR data

    NARCIS (Netherlands)

    Lalov, E.; Linde, N.; Vrugt, J.A.

    2012-01-01

    Time-lapse geophysical measurements are widely used to monitor the movement of water and solutes through the subsurface. Yet commonly used deterministic least squares inversions typically suffer from relatively poor mass recovery, spread overestimation, and limited ability to appropriately estimate

  7. Grain refinement of Aluminium alloys using friction stir processing

    International Nuclear Information System (INIS)

    Khraisheh, M.

    2004-01-01

    Full text.Friction Stir Processing (FSP) is a new advanced material processing technique used to refine and homogenize the microstructure of sheet metals. FSP is a solid state processing technique that uses a rapidly rotating non-consumable high strength tool steel pin that extends from a cylindrical shoulder. The rotating pin is forced with a predetermined load into the work piece and moved along with the work pieces, while the rotating pin deforms and stirs the locally heated material. It is a hot working process in which a large amount of deformation is imparted to the sheet. FS processed zone is characterized by dynamic recrystallization which results in grain refinement . this promising emerging process needs further investigations to develop optimum process parameters to produce the desired microstructure. In this work, we present preliminary results on the effects of rotational and translational speeds on grain refinement of AA5052. Under certain processing conditions, sub-micron grain structure was produced using this technique

  8. Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

    Science.gov (United States)

    2011-01-01

    structures in Finland; (b) manufacture of Al-Mg-Si-based alloy 181 FSW-joined bullet- train cabins in Japan; (c) fabrication of 182 Al-Cu-based alloy...Simonsen, Visualisation of Material 857Flow in an Autogenous Friction Stir Weld, Proc. 1st International 858Symp. FSW, Thousand Oaks, CA, 1999 85928...A.P. Reynolds, Visualization of Material Flow in an Autogenous 860Friction Stir Weld, Sci. Technol. Weld. Join., 2000, 5, p 120–124 86129. T.U. Seidel

  9. Numerical simulation on stir system of jet ballast in high level liquid waste storage tank

    International Nuclear Information System (INIS)

    Lu Yingchun

    2012-01-01

    The stir system of jet ballast in high level liquid waste storage tank was simulation object. Gas, liquid and solid were air, sodium nitrate liquor and titanium whitening, respectively. The mathematic model based on three-fluid model and the kinetic theory of particles was established for the stir system of jet ballast in high level liquid waste storage tank. The CFD commercial software was used for solving this model. The detail flow parameters as three phase velocity, pressure and phase loadings were gained. The calculated results agree with the experimental results, so they can well define the flow behavior in the tank. And this offers a basic method for the scale-up and optimization design of the stir system of jet ballast in high level liquid waste storage tank. (author)

  10. Novel use of non-echo-planar diffusion weighted MRI in monitoring disease activity and treatment response in active Grave's orbitopathy: An initial observational cohort study.

    Science.gov (United States)

    Lingam, Ravi Kumar; Mundada, Pravin; Lee, Vickie

    2018-01-10

    To examine the novel use of non-echo-planar diffusion weighted MRI (DWI) in depicting activity and treatment response in active Grave's orbitopathy (GO) by assessing, with inter-observer agreement, for a correlation between its apparent diffusion coefficients (ADCs) and conventional Short tau Inversion Recovery (STIR) MRI signal-intensity ratios (SIRs). A total of 23 actively inflamed muscles and 30 muscle response episodes were analysed in patients with active GO who underwent medical treatment. The MRI orbit scans included STIR sequences and non-echo-planar DWI were evaluated. Two observers independently assessed the images qualitatively for the presence of activity in the extraocular muscles (EOMs) and recorded the STIR signal-intensity (SI), SIR (SI ratio of EOM/temporalis muscle), and ADC values of any actively inflamed muscle on the pre-treatment scans and their corresponding values on the subsequent post-treatment scans. Inter-observer agreement was examined. There was a significant positive correlation (0.57, p < 0.001) between ADC and both SIR and STIR SI of the actively inflamed EOM. There was also a significant positive correlation (0.75, p < 0.001) between SIR and ADC values depicting change in muscle activity associated with treatment response. There was good inter-observer agreement. Our preliminary results indicate that quantitative evaluation with non-echo-planar DWI ADC values correlates well with conventional STIR SIR in detecting active GO and monitoring its treatment response, with good inter-observer agreement.

  11. Friction Stir Weld Restart+Reweld Repair Allowables

    Science.gov (United States)

    Clifton, Andrew

    2008-01-01

    A friction stir weld (FSW) repair method has been developed and successfully implemented on Al 2195 plate material for the Space Shuttle External Fuel Tank (ET). The method includes restarting the friction stir weld in the termination hole of the original weld followed by two reweld passes. Room temperature and cryogenic temperature mechanical properties exceeded minimum FSW design strength and compared well with the development data. Simulated service test results also compared closely to historical data for initial FSW, confirming no change to the critical flaw size or inspection requirements for the repaired weld. Testing of VPPA fusion/FSW intersection weld specimens exhibited acceptable strength and exceeded the minimum design value. Porosity, when present at the intersection was on the root side toe of the fusion weld, the "worst case" being 0.7 inch long. While such porosity may be removed by sanding, this "worst case" porosity condition was tested "as is" and demonstrated that porosity did not negatively affect the strength of the intersection weld. Large, 15-inch "wide panels" FSW repair welds were tested to demonstrate strength and evaluate residual stresses using photo stress analysis. All results exceeded design minimums, and photo stress analysis showed no significant stress gradients due to the presence of the restart and multi-pass FSW repair weld.

  12. Separate visualization of endolymphatic space, perilymphatic space and bone by a single pulse sequence; 3D-inversion recovery imaging utilizing real reconstruction after intratympanic Gd-DTPA administration at 3 tesla

    International Nuclear Information System (INIS)

    Naganawa, Shinji; Satake, Hiroko; Kawamura, Minako; Fukatsu, Hiroshi; Sone, Michihiko; Nakashima, Tsutomu

    2008-01-01

    Twenty-four hours after intratympanic administration of gadolinium contrast material (Gd), the Gd was distributed mainly in the perilymphatic space. Three-dimensional FLAIR can differentiate endolymphatic space from perilymphatic space, but not from surrounding bone. The purpose of this study was to evaluate whether 3D inversion-recovery turbo spin echo (3D-IR TSE) with real reconstruction could separate the signals of perilymphatic space (positive value), endolymphatic space (negative value) and bone (near zero) by setting the inversion time between the null point of Gd-containing perilymph fluid and that of the endolymph fluid without Gd. Thirteen patients with clinically suspected endolymphatic hydrops underwent intratympanic Gd injection and were scanned at 3 T. A 3D FLAIR and 3D-IR TSE with real reconstruction were obtained. In all patients, low signal of endolymphatic space in the labyrinth on 3D FLAIR was observed in the anatomically appropriate position, and it showed negative signal on 3D-IR TSE. The low signal area of surrounding bone on 3D FLAIR showed near zero signal on 3D-IR TSE. Gd-containing perilymphatic space showed high signal on 3D-IR TSE. In conclusion, by optimizing the inversion time, endolymphatic space, perilymphatic space and surrounding bone can be separately visualized on a single image using a 3D-IR TSE with real reconstruction. (orig.)

  13. Sampling of finite elements for sparse recovery in large scale 3D electrical impedance tomography

    International Nuclear Information System (INIS)

    Javaherian, Ashkan; Moeller, Knut; Soleimani, Manuchehr

    2015-01-01

    This study proposes a method to improve performance of sparse recovery inverse solvers in 3D electrical impedance tomography (3D EIT), especially when the volume under study contains small-sized inclusions, e.g. 3D imaging of breast tumours. Initially, a quadratic regularized inverse solver is applied in a fast manner with a stopping threshold much greater than the optimum. Based on assuming a fixed level of sparsity for the conductivity field, finite elements are then sampled via applying a compressive sensing (CS) algorithm to the rough blurred estimation previously made by the quadratic solver. Finally, a sparse inverse solver is applied solely to the sampled finite elements, with the solution to the CS as its initial guess. The results show the great potential of the proposed CS-based sparse recovery in improving accuracy of sparse solution to the large-size 3D EIT. (paper)

  14. Influence of the stirring time on the exfoliation of the Cloisite 30 B clay in PVC composite: structural characterization by XRD

    International Nuclear Information System (INIS)

    Cabral, Andreia M.V.; Rodrigues, Meiry G.F.

    2009-01-01

    This study aims to evaluate the influence of the stirring time on the exfoliation efficiency of the montmorillonite clay in PVC composites, prepared by the polymerization 'in situ' process. The work was performed in 2 steps. In first stage: tests of expansion with Cloisite 30B clay in MVC, which was used to assess the degree of expansion in MVC of each of them at different stirring times: 2, 4 and 6 h. After stirring, each system was kept in observation for 3 days to evaluate the changes in the decanted volume of the clay in the reactor. Second stage: the Influence of the stirring time for the clay exfoliation. Cloisite 30B clay was used to compare the influence of the stirring time for exfoliation and characterized by X-ray diffraction (XRD). (author)

  15. Phase behavior and phase inversion for dispersant systems

    International Nuclear Information System (INIS)

    Solheim, A.; Brandvik, P.J.

    1991-06-01

    This report describes some preliminary phase behavior studies and phase inversion temperature measurements in seawater, bunker oil and dispersant. The objectives have been to find new ways of characterizing dispersants for dispersing oil spill at sea and, perhaps, to throw new lights on the mechanism of dispersion formation (oil-in-water emulsification). The work has been focussed on the relation to phase behavior and the existence of microemulsion in equilibrium with excess oil and water phases. The dispersing process is also compared to the recommended conditions for emulsion formation. When forming an oil-in-water emulsion in an industrial process, it is recommended to choose an emulsifier which gives a phase inversion temperature (PIT) which is 20 - 60 o C higher than the actual temperature for use. The emulsification process must take place close to the PIT which is the temperature at which the emulsion change from oil-in-water emulsion to water-in-oil emulsion when the system is stirred. This condition corresponds to the temperature where the phase behavior change character. The purpose has been to find out if the composition of the dispersants corresponds to the recommendations for oil-in-water emulsification. The amount of experimental work has been limited. Two kinds of experiments have been carried out. Phase behavior studies have been done for seawater, bunker oil and four different dispersants where one had an optimal composition. The phase behavior was hard to interpret and is not recommended for standard dispersants test. The other experimental technique was PIT-measurements by conductivity measurements versus temperature. 4 figs., 1 tab., 4 refs

  16. Stirring by blinking rotlets in a bounded Stokes flow

    NARCIS (Netherlands)

    Woude, van der D.; Clercx, H.J.H.; Heijst, van G.J.F.; Meleshko, V.V.

    2004-01-01

    A blinking rotlet model is used for the analysis of stirring in a Stokes flow in a rectangular domain. After the two-dimensional biharmonic equation is solved analytically, the associated velocity field of a pair of blinking rotlets positioned symmetrically on the y -axis, is used studying the

  17. High-resolution STIR for 3-T MRI of the posterior fossa: visualization of the lower cranial nerves and arteriovenous structures related to neurovascular compression.

    Science.gov (United States)

    Hiwatashi, Akio; Yoshiura, Takashi; Yamashita, Koji; Kamano, Hironori; Honda, Hiroshi

    2012-09-01

    Preoperative evaluation of small vessels without contrast material is sometimes difficult in patients with neurovascular compression disease. The purpose of this retrospective study was to evaluate whether 3D STIR MRI could simultaneously depict the lower cranial nerves--fifth through twelfth--and the blood vessels in the posterior fossa. The posterior fossae of 47 adults (26 women, 21 men) without gross pathologic changes were imaged with 3D STIR and turbo spin-echo heavily T2-weighted MRI sequences and with contrast-enhanced turbo field-echo MR angiography (MRA). Visualization of the cranial nerves on STIR images was graded on a 4-point scale and compared with visualization on T2-weighted images. Visualization of the arteries on STIR images was evaluated according to the segments in each artery and compared with that on MRA images. Visualization of the veins on STIR images was also compared with that on MRA images. Statistical analysis was performed with the Mann-Whitney U test. There were no significant differences between STIR and T2-weighted images with respect to visualization of the cranial nerves (p > 0.05). Identified on STIR and MRA images were 94 superior cerebellar arteries, 81 anteroinferior cerebellar arteries, and 79 posteroinferior cerebellar arteries. All veins evaluated were seen on STIR and MRA images. There were no significant differences between STIR and MRA images with respect to visualization of arteries and veins (p > 0.05). High-resolution STIR is a feasible method for simultaneous evaluation of the lower cranial nerves and the vessels in the posterior fossa without the use of contrast material.

  18. Retractable Pin Tools for the Friction Stir Welding Process

    Science.gov (United States)

    1998-01-01

    Two companies have successfully commercialized a specialized welding tool developed at the Marshall Space Flight Center (MSFC). Friction stir welding uses the high rotational speed of a tool and the resulting frictional heat created from contact to crush, 'stir' together, and forge a bond between two metal alloys. It has had a major drawback, reliance on a single-piece pin tool. The pin is slowly plunged into the joint between two materials to be welded and rotated as high speed. At the end of the weld, the single-piece pin tool is retracted and leaves a 'keyhole,' something which is unacceptable when welding cylindrical objects such as drums, pipes and storage tanks. Another drawback is the requirement for different-length pin tools when welding materials of varying thickness. An engineer at the MSFC helped design an automatic retractable pin tool that uses a computer-controlled motor to automatically retract the pin into the shoulder of the tool at the end of the weld, preventing keyholes. This design allows the pin angle and length to be adjusted for changes in material thickness and results in a smooth hole closure at the end of the weld. Benefits of friction stir welding, using the MSFC retractable pin tool technology, include the following: The ability to weld a wide range of alloys, including previously unweldable and composite materials; provision of twice the fatigue resistance of fusion welds and no keyholes; minimization of material distortion; no creation of hazards such as welding fumes, radiation, high voltage, liquid metals, or arcing; automatic retraction of the pin at the end of the weld; and maintaining full penetration of the pin.

  19. Uso da sequência FLAIR-EPI na análise da esclerose mesial temporal EPI-FLAIR sequence in the evaluation of mesial temporal sclerosis

    Directory of Open Access Journals (Sweden)

    Marcos Alberto da Costa Machado Júnior

    2001-06-01

    Full Text Available O objetivo deste estudo é analisar as alterações morfológicas e de intensidade de sinal das regiões hipocampais em pacientes, com epilepsia temporal fármaco-resistente. Para tal, estudamos 8 pacientes com esclerose mesial temporal, utilizando aparelhagem de RM de 1,5T, com sequências Spin Eco - SE, Fast Spin Eco - FSE, Fluid Atenuation Inversion Recovery, com Eco Planar Imaging - FLAIR-EPI. Observamos a superioridade da sequência FLAIR na detecção do aumento da intensidade de sinal da região hipocampal, particularmente com cortes coronais, em relação às sequências SE e FSE, com a vantagem de ser uma técnica de rápida execução. A sequência STIR evidenciou adelgaçamento da cortical do hipocampo, na metade dos casos que apresentavam alteração de sinal.The purpose of this study is to evaluate morpholologycal and signal intensity changes in the hippocampus in patients with medically intractable temporal lobe epilepsy. We studied 8 patients with mesial temporal sclerosis using a 1.5 -T MR and the following sequences Spin Eco- SE, Fast Spin Echo- FSE, Fluid Atenuation Inversion Recovery Echo Planar Imaging - FLAIR-EPI. We noticed a sensitive increase signal intensity on FLAIR- EPI sequences, particularly, in coronal images, than on SE and FSE sequences. The STIR sequence showed a cortical hippocampus atrophy in half of the cases, in whom signal abnormalities were present.

  20. Combination of chemical suppression techniques for dual suppression of fat and silicone at diffusion-weighted MR imaging in women with breast implants

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Dow-Mu; Hughes, J. [Royal Marsden Hospital, Department of Radiology, Sutton (United Kingdom); Blackledge, M.; Leach, M.O.; Collins, D.J. [Institute of Cancer Research, CR UK-EPSRC Cancer Imaging Centre, Sutton (United Kingdom); Burns, S. [Nuada 3T MRI Centre, London (United Kingdom); Stemmer, A.; Kiefer, B. [Siemens Healthcare, Erlangen (Germany)

    2012-12-15

    Silicone breast prostheses prove technically challenging when performing diffusion-weighted MR imaging in the breasts. We describe a combined fat and chemical suppression scheme to achieve dual suppression of fat and silicone, thereby improving the quality of diffusion-weighted images in women with breast implants. MR imaging was performed at 3.0 and 1.5 T in women with silicone breast implants using short-tau inversion recovery (STIR) fat-suppressed echo-planar (EPI) diffusion-weighted MR imaging (DWI) on its own and combined with the slice-select gradient-reversal (SSGR) technique. Imaging was performed using dedicated breast imaging coils. Complete suppression of the fat and silicone signal was possible at 3.0 T using EPI DWI with STIR and SSGR, evaluated with dedicated breast coils. However, a residual silicone signal was still perceptible at 1.5 T using this combined approach. Nevertheless, a further reduction in silicone signal at 1.5 T could be achieved by employing thinner slice partitions and the addition of the chemical-selective fat-suppression (CHESS) technique. DWI using combined STIR and SSGR chemical suppression techniques is feasible to eliminate or reduce silicone signal from prosthetic breast implants. (orig.)

  1. Muscle MRI of classic infantile pompe patients: Fatty substitution and edema-like changes.

    Science.gov (United States)

    Pichiecchio, Anna; Rossi, Marta; Cinnante, Claudia; Colafati, Giovanna Stefania; De Icco, Roberto; Parini, Rossella; Menni, Francesca; Furlan, Francesca; Burlina, Alberto; Sacchini, Michele; Donati, Maria Alice; Fecarotta, Simona; Casa, Roberto Della; Deodato, Federica; Taurisano, Roberta; Di Rocco, Maja

    2017-06-01

    The aim of this study was to evaluate the muscle MRI pattern of 9 patients (median age: 6.5 ± 2.74 years) affected by classic infantile-onset Pompe disease who were treated with enzyme replacement therapy. We performed and qualitatively scored T1-weighted (T1-w) sequences of the facial, shoulder girdle, paravertebral, and lower limb muscles and short-tau inversion recovery (STIR) sequences of the lower limbs using the Mercuri and Morrow scales, respectively. On T1-w images, mild (grade 1) or moderate (grade 2) involvement was found in the tongue in 6 of 6 patients and in the adductor magnus muscle in 6 of 9. STIR hyperintensity was detected in all areas examined and was categorized as limited to mild in 5 of 8 patients. On T1-w sequences, mild/moderate adipose substitution in the adductor magnus and tongue muscles was documented. STIR edema-like alterations of thigh and calf muscles are novel findings. Correlations with biopsy findings and clinical parameters are needed to fully understand these findings. Muscle Nerve 55: 841-848, 2017. © 2016 Wiley Periodicals, Inc.

  2. Microstructure and mechanical properties of friction stir welded 18Cr–2Mo ferritic stainless steel thick plate

    International Nuclear Information System (INIS)

    Han, Jian; Li, Huijun; Zhu, Zhixiong; Barbaro, Frank; Jiang, Laizhu; Xu, Haigang; Ma, Li

    2014-01-01

    Highlights: • We focus on friction stir welding of 18Cr–2Mo ferritic stainless steel thick plate. • We produce high-quality joints with special tool and optimised welding parameters. • We compare microstructure and mechanical properties of steel and joint. • Friction stir welding is a method that can maintain the properties of joint. - Abstract: In this study, microstructure and mechanical properties of a friction stir welded 18Cr–2Mo ferritic stainless steel thick plate were investigated. The 5.4 mm thick plates with excellent properties were welded at a constant rotational speed and a changeable welding speed using a composite tool featuring a chosen volume fraction of cubic boron nitride (cBN) in a W–Re matrix. The high-quality welds were successfully produced with optimised welding parameters, and studied by means of optical microscopy (OM), scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) and standard hardness and impact toughness testing. The results show that microstructure and mechanical properties of the joints are affected greatly, which is mainly related to the remarkably fine-grained microstructure of equiaxed ferrite that is observed in the friction stir welded joint. Meanwhile, the ratios of low-angle grain boundary in the stir zone regions significantly increase, and the texture turns strong. Compared with the base material, mechanical properties of the joint are maintained in a comparatively high level

  3. Development of a process envelope for friction stir welding of DH36 steel – A step change

    International Nuclear Information System (INIS)

    Toumpis, Athanasios; Galloway, Alexander; Cater, Stephen; McPherson, Norman

    2014-01-01

    Highlights: • The friction stir welding speed on DH36 steel has been substantially increased. • Excellent quality welds offering potential economic advantages are obtained. • Friction stir welding of steel generates a very complex metallurgical system. • Slow and intermediate welding speed tensile samples fractured in the parent material. • Increasing traverse speed is seen to improve the impact toughness of the weld. - Abstract: Friction stir welding of steel presents an array of advantages across many industrial sectors compared to conventional fusion welding techniques. However, the fundamental knowledge of the friction stir welding process in relation to steel remains relatively limited. A microstructure and property evaluation of friction stir welded low alloy steel grade DH36 plate, commonly used in ship and marine applications has been undertaken. In this comprehensive study, plates of 2000 × 200 × 6 mm were butt welded together at varying rotational and traverse speeds. Samples were examined microscopically and by transverse tensile tests. In addition, the work was complemented by Charpy impact testing and micro-hardness testing in various regions of the weld. The study examined a wide range of process parameters; from this, a preliminary process parameter envelope has been developed and initial process parameter sets established that produce commercially attractive excellent quality welds through a substantial increase in the conventionally recognised weld traverse speed

  4. Nickel-base alloy overlay weld with improved ultrasonic flaw detection by magnetic stirring welding

    International Nuclear Information System (INIS)

    Takashi, Hirano; Kenji, Hirano; Masayuki, Watando; Takahiro, Arakawa; Minoru, Maeda

    2001-01-01

    Ultrasonic flaw detection is more difficult in Nickel-base alloy welds containing dendrites owing to the decrease ultrasonic transmissibility they cause. The present paper discusses application of magnetic stirring welding as a means for reducing dendrite growth with consequent improvement in ultrasonic transmissibility. Single pass and multi-pass welding tests were conducted to determine optimal welding conditions. By PT and macro observation subsequent to welding was carried out, optimal operation conditions were clarified. Overlay welding tests and UT clearly indicated ultrasonic beam transmissibility in overlay welds to be improved and detection capacity to be greater through application of magnetic stirring welding. Optimal operation conditions were determined based on examination of temper bead effects in the heat affected zone of low alloy steel by application of magnetic stirring welding to the butt welded joints between low alloy and stainless steel. Hardness in this zone of low alloy steel after the fourth layer was less than 350 HV. (author)

  5. Three-dimensional inversion recovery manganese-enhanced MRI of mouse brain using super-resolution reconstruction to visualize nuclei involved in higher brain function.

    Science.gov (United States)

    Poole, Dana S; Plenge, Esben; Poot, Dirk H J; Lakke, Egbert A J F; Niessen, Wiro J; Meijering, Erik; van der Weerd, Louise

    2014-07-01

    The visualization of activity in mouse brain using inversion recovery spin echo (IR-SE) manganese-enhanced MRI (MEMRI) provides unique contrast, but suffers from poor resolution in the slice-encoding direction. Super-resolution reconstruction (SRR) is a resolution-enhancing post-processing technique in which multiple low-resolution slice stacks are combined into a single volume of high isotropic resolution using computational methods. In this study, we investigated, first, whether SRR can improve the three-dimensional resolution of IR-SE MEMRI in the slice selection direction, whilst maintaining or improving the contrast-to-noise ratio of the two-dimensional slice stacks. Second, the contrast-to-noise ratio of SRR IR-SE MEMRI was compared with a conventional three-dimensional gradient echo (GE) acquisition. Quantitative experiments were performed on a phantom containing compartments of various manganese concentrations. The results showed that, with comparable scan times, the signal-to-noise ratio of three-dimensional GE acquisition is higher than that of SRR IR-SE MEMRI. However, the contrast-to-noise ratio between different compartments can be superior with SRR IR-SE MEMRI, depending on the chosen inversion time. In vivo experiments were performed in mice receiving manganese using an implanted osmotic pump. The results showed that SRR works well as a resolution-enhancing technique in IR-SE MEMRI experiments. In addition, the SRR image also shows a number of brain structures that are more clearly discernible from the surrounding tissues than in three-dimensional GE acquisition, including a number of nuclei with specific higher brain functions, such as memory, stress, anxiety and reward behavior. Copyright © 2014 John Wiley & Sons, Ltd.

  6. Inverse photoemission

    International Nuclear Information System (INIS)

    Namatame, Hirofumi; Taniguchi, Masaki

    1994-01-01

    Photoelectron spectroscopy is regarded as the most powerful means since it can measure almost perfectly the occupied electron state. On the other hand, inverse photoelectron spectroscopy is the technique for measuring unoccupied electron state by using the inverse process of photoelectron spectroscopy, and in principle, the similar experiment to photoelectron spectroscopy becomes feasible. The development of the experimental technology for inverse photoelectron spectroscopy has been carried out energetically by many research groups so far. At present, the heightening of resolution of inverse photoelectron spectroscopy, the development of inverse photoelectron spectroscope in which light energy is variable and so on are carried out. But the inverse photoelectron spectroscope for vacuum ultraviolet region is not on the market. In this report, the principle of inverse photoelectron spectroscopy and the present state of the spectroscope are described, and the direction of the development hereafter is groped. As the experimental equipment, electron guns, light detectors and so on are explained. As the examples of the experiment, the inverse photoelectron spectroscopy of semimagnetic semiconductors and resonance inverse photoelectron spectroscopy are reported. (K.I.)

  7. JOINING DISSIMILAR MATERIALS USING FRICTION STIR SCRIBE TECHNIQUE

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Piyush; Hovanski, Yuri; Jana, Saumyadeep; Fifield, Leonard S.

    2016-09-01

    Development of robust and cost effective method of joining dissimilar materials can provide a critical pathway to enable widespread use of multi-material design and components in mainstream industrial applications. The use of multi-material components such as Steel-Aluminum, Aluminum-Polymer allows design engineers to optimize material utilization based on service requirements and often lead weight and cost reductions. However producing an effective joint between materials with vastly different thermal, microstructural and deformation response is highly problematic using conventional joining and /or fastening methods. This is especially challenging in cost sensitive high volume markets that largely rely on low–cost joining solutions. Friction Stir Scribe technology was developed to meet the demands of joining materials with drastically different properties and melting regimes. The process enables joining of light metals like Magnesium and Aluminum to high temperature materials like Steels and Titanium. Additionally viable joints between polymer composites and metal can also be made using this method. This paper will present state of the art, progress made and challenges associated with this innovative derivative of Friction Stir welding in reference to joining dissimilar metals and polymer/metal combinations.

  8. Joining Dissimilar Materials Using Friction Stir Scribe Technique

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Piyush [Pacific Northwest National Laboratory, Richland 99352, WA e-mail: piyush.upadhyay@pnnl.gov; Hovanski, Yuri [Pacific Northwest National Laboratory, Richland 99352, WA; Jana, Saumyadeep [Pacific Northwest National Laboratory, Richland 99352, WA; Fifield, Leonard S. [Pacific Northwest National Laboratory, Richland 99352, WA

    2016-10-03

    Development of a robust and cost-effective method of joining dissimilar materials could provide a critical pathway to enable widespread use of multi-material designs and components in mainstream industrial applications. The use of multi-material components such as steel-aluminum and aluminum-polymer would allow design engineers to optimize material utilization based on service requirements and could often lead to weight and cost reductions. However, producing an effective joint between materials with vastly different thermal, microstructural, and deformation responses is highly problematic using conventional joining and/or fastening methods. This is especially challenging in cost sensitive, high volume markets that largely rely on low cost joining solutions. Friction stir scribe technology was developed to meet the demands of joining materials with drastically different properties and melting regimes. The process enables joining of light metals like magnesium and aluminum to high temperature materials like steel and titanium. Viable joints between polymer composites and metal can also be made using this method. This paper will present the state of the art, progress made, and challenges associated with this innovative derivative of friction stir welding in reference to joining dissimilar metals and polymer/metal combinations.

  9. Cryotherapy of skeletal neoplasms

    International Nuclear Information System (INIS)

    Richardson, M.L.; Lough, L.R.; Shuman, W.P.; Conrad, E.U.

    1989-01-01

    The authors reviewed MR examinations in six patients with giant cell tumor or chondrosarcoma who had undergone surgical curettage and subsequent cryotherapy. In five cases, the authors found a zone of varying thickness extending beyond the surgical margins consistent with cryotherapy injury to medullary bone. This zone appeared dark or intermediate in intensity on T1-weighted images and bright on T2-weighted and short inversion recovery (STIR) images, suggesting tissue edema. In one case, this marginal zone grew for 3 months as the cryotherapy injury evolved. These findings should be expected after cryotherapy and should not be confused with recurrent tumor

  10. Friction stir welding: multi-response optimisation using Taguchi-based GRA

    Directory of Open Access Journals (Sweden)

    Jitender Kundu

    2016-01-01

    Full Text Available In present experimental work, friction stir welding of aluminium alloy 5083- H321 is performed for optimisation of process parameters for maximum tensile strength. Taguchi’s L9 orthogonal array has been used for three parameters – tool rotational speed (TRS, traverse speed (TS, and tool tilt angle (TTA with three levels. Multi-response optimisation has been carried out through Taguchi-based grey relational analysis. The grey relational grade has been calculated for all three responses – ultimate tensile strength, percentage elongation, and micro-hardness. Analysis of variance is the tool used for obtaining grey relational grade to find out the significant process parameters. TRS and TS are the two most significant parameters which influence most of the quality characteristics of friction stir welded joint. Validation of predicted values done through confirmation experiments at optimum setting shows a good agreement with experimental values.

  11. Evaluation of Possible Prognostic Factors of Fulminant Acute Disseminated Encephalomyelitis (ADEM) on Magnetic Resonance Imaging with Fluid-Attenuated Inversion Recovery (FLAIR) and Diffusion-Weighted Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Donmez, F.Y.; Aslan, H.; Coskun, M. (Dept. of Radiology, Faculty of Medicine, Baskent Univ., Ankara (Turkey))

    2009-04-15

    Background: Acute disseminated encephalomyelitis (ADEM) may be a rapidly progressive disease with different clinical outcomes. Purpose: To investigate the radiological findings of fulminant ADEM on diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) images, and to correlate these findings with clinical outcome. Material and Methods: Initial and follow-up magnetic resonance imaging (MRI) scans in eight patients were retrospectively evaluated for distribution of lesions on FLAIR images and presence of hemorrhage or contrast enhancement. DWI of the patients was evaluated as to cytotoxic versus vasogenic edema. The clinical records were analyzed, and MRI results and clinical outcome were correlated. Results: Four of the eight patients died, three had full recovery, and one had residual cortical blindness. The distribution of the hyperintense lesions on FLAIR sequence was as follows: frontal (37.5%), parietal (50%), temporal (37.5%), occipital (62.5%), basal ganglia (50%), pons (37.5%), mesencephalon (37.5%), and cerebellum (50%). Three of the patients who died had brainstem involvement. Two patients had a cytotoxic edema, one of whom died, and the other developed cortical blindness. Six patients had vasogenic edema: three of these patients had a rapid progression to coma and died; three of them recovered. Conclusion: DWI is not always helpful for evaluating the evolution or predicting the outcome of ADEM. However, extension of the lesions, particularly brainstem involvement, may have an influence on the prognosis.

  12. Material Characterization of Dissimilar Friction Stir Spot Welded Aluminium and Copper Alloy

    Science.gov (United States)

    Sanusi, K. O.; Akinlabi, E. T.

    2017-08-01

    In this research study, material characterization of dissimilar friction stir spot welded Aluminium and Copper was evaluated. Rotational speeds of 800 rpm and transverse speeds of 50 mm/min, 150 mm/min and 250 mm/min were used. The total numbers of samples evaluated were nine altogether. The spot welds were characterised by microstructure characterization using optical microscope (OEM) and scanning electron microscopy technique (SEM) by observing the evolution of the microstructure across the weld’s cross-section. lap-shear test of the of the spot weld specimens were also done. From the results, it shows that welding of metals and alloys using Friction stir spot welding is appropriate and can be use in industrial applications.

  13. Friction stir welding of dissimilar AA2024 and AA7075 aluminum alloys

    International Nuclear Information System (INIS)

    Khodir, Saad Ahmed; Shibayanagi, Toshiya

    2008-01-01

    The present study focuses on the microstructure and mechanical properties of dissimilar joints of 2024-T3 Al alloy to 7075-T6 Al alloy produced by friction stir welding. Effects of welding speed and fixed location of base metals on microstructures, hardness distributions, and tensile properties of the welded joints were investigated. SEM-EDS analysis revealed that the stir zone contains a mixed structure and onion ring pattern with a periodic change of grain size as well as a heterogeneous distribution of alloying elements. The maximum tensile strength of 423.0 MPa was achieved for the joint produced at welding speed of 1.67 mm/s when 2024 Al alloy was located on the advancing side

  14. Controlling Force and Depth in Friction Stir Welding

    Science.gov (United States)

    Adams, Glynn; Loftus, Zachary; McCormac, Nathan; Venable, Richard

    2005-01-01

    Feedback control of the penetration force applied to a pin tool in friction stir welding has been found to be a robust and reliable means for controlling the depth of penetration of the tool. This discovery has made it possible to simplify depth control and to weld with greater repeatability, even on workpieces with long weld joints. Prior to this discovery, depths of penetration in friction stir welding were controlled by hard-tooled roller assemblies or by depth actuators controlled by feedback from such external sensors as linear variable-differential transformers or laser-based devices. These means of control are limited: A hard-tooled roller assembly confines a pin tool to a preset depth that cannot be changed easily during the welding process. A measurement by an external sensor is only an indirect indicative of the depth of penetration, and computations to correlate such a measurement with a depth of penetration are vulnerable to error. The present force-feedback approach exploits the proportionality between the depth and the force of penetration Unlike a depth measurement taken by an external sensor, a force measurement can be direct because it can be taken by a sensor coupled directly to the pin tool. The reading can be processed through a modern electronic servo control system to control an actuator to keep the applied penetration force at the desired level. In comparison with the older depth-control methods described above, this method offers greater sensitivity to plasticizing of the workpiece metal and is less sensitive to process noise, resulting in a more consistent process. In an experiment, a tapered panel was friction stir welded while controlling the force of penetration according to this method. The figure is a plot of measurements taken during the experiment, showing that force was controlled with a variation of 200 lb (890 N), resulting in control of the depth of penetration with a variation of 0.004 in. (0.1 mm).

  15. First experience of simultaneous PET/MRI for the early detection of cardiac involvement in patients with Anderson-Fabry disease

    Energy Technology Data Exchange (ETDEWEB)

    Nappi, Carmela; Altiero, Michele; Imbriaco, Massimo; Giudice, Caterina Anna; Spinelli, Letizia; Cuocolo, Alberto [University Federico II, Department of Advanced Biomedical Sciences, Naples (Italy); Nicolai, Emanuele; Aiello, Marco; Diomiaiuti, Claudio Tommaso [IRCCS SDN, Naples (Italy); Pisani, Antonio [University Federico II, Department of Public Health, Naples (Italy)

    2015-03-26

    Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder associated with severe multiorgan dysfunction and premature death. Early diagnosis and treatment strategies play a key role in patient outcome. We investigated the potential role of hybrid PET/MR imaging in the assessment of early cardiac involvement in AFD patients. Thirteen AFD patients without cardiac symptoms and with normal left ventricular function underwent simultaneous cardiac PET/MR imaging after administration of {sup 18}F-FDG. Cardiac FDG uptake was quantified by measuring the standardized uptake value in 17 myocardial segments in each subject. The coefficient of variation (COV, i.e. the standard deviation divided by the average) of the uptake of the 17 segments was calculated as an index of heterogeneity in the heart. Six patients exhibited focal late gadolinium enhancement (LGE) indicating intramyocardial fibrosis, and four of these also had positive short inversion time inversion recovery (STIR) sequences. All patients with LGE and positive STIR MR images showed focal FDG uptake in the corresponding myocardial segments indicating inflammation. Of the seven patients with negative LGE and STIR images, five showed homogeneous FDG cardiac uptake and two showed heterogeneous FDG uptake. The COV was significantly greater in patients with focal FDG uptake (0.25 ± 0.02) than in those without (0.14 ± 0.07, p < 0.01). PET/MR imaging is clinically feasible for the early detection of cardiac involvement in patients with AFD. Further studies evaluating the role of hybrid PET/MR imaging in management of the disease in larger patient populations are warranted. (orig.)

  16. First experience of simultaneous PET/MRI for the early detection of cardiac involvement in patients with Anderson-Fabry disease

    International Nuclear Information System (INIS)

    Nappi, Carmela; Altiero, Michele; Imbriaco, Massimo; Giudice, Caterina Anna; Spinelli, Letizia; Cuocolo, Alberto; Nicolai, Emanuele; Aiello, Marco; Diomiaiuti, Claudio Tommaso; Pisani, Antonio

    2015-01-01

    Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder associated with severe multiorgan dysfunction and premature death. Early diagnosis and treatment strategies play a key role in patient outcome. We investigated the potential role of hybrid PET/MR imaging in the assessment of early cardiac involvement in AFD patients. Thirteen AFD patients without cardiac symptoms and with normal left ventricular function underwent simultaneous cardiac PET/MR imaging after administration of 18 F-FDG. Cardiac FDG uptake was quantified by measuring the standardized uptake value in 17 myocardial segments in each subject. The coefficient of variation (COV, i.e. the standard deviation divided by the average) of the uptake of the 17 segments was calculated as an index of heterogeneity in the heart. Six patients exhibited focal late gadolinium enhancement (LGE) indicating intramyocardial fibrosis, and four of these also had positive short inversion time inversion recovery (STIR) sequences. All patients with LGE and positive STIR MR images showed focal FDG uptake in the corresponding myocardial segments indicating inflammation. Of the seven patients with negative LGE and STIR images, five showed homogeneous FDG cardiac uptake and two showed heterogeneous FDG uptake. The COV was significantly greater in patients with focal FDG uptake (0.25 ± 0.02) than in those without (0.14 ± 0.07, p < 0.01). PET/MR imaging is clinically feasible for the early detection of cardiac involvement in patients with AFD. Further studies evaluating the role of hybrid PET/MR imaging in management of the disease in larger patient populations are warranted. (orig.)

  17. Myocardial T1 mapping at 3.0 tesla using an inversion recovery spoiled gradient echo readout and bloch equation simulation with slice profile correction (BLESSPC) T1 estimation algorithm.

    Science.gov (United States)

    Shao, Jiaxin; Rapacchi, Stanislas; Nguyen, Kim-Lien; Hu, Peng

    2016-02-01

    To develop an accurate and precise myocardial T1 mapping technique using an inversion recovery spoiled gradient echo readout at 3.0 Tesla (T). The modified Look-Locker inversion-recovery (MOLLI) sequence was modified to use fast low angle shot (FLASH) readout, incorporating a BLESSPC (Bloch Equation Simulation with Slice Profile Correction) T1 estimation algorithm, for accurate myocardial T1 mapping. The FLASH-MOLLI with BLESSPC fitting was compared with different approaches and sequences with regards to T1 estimation accuracy, precision and image artifact based on simulation, phantom studies, and in vivo studies of 10 healthy volunteers and three patients at 3.0 Tesla. The FLASH-MOLLI with BLESSPC fitting yields accurate T1 estimation (average error = -5.4 ± 15.1 ms, percentage error = -0.5% ± 1.2%) for T1 from 236-1852 ms and heart rate from 40-100 bpm in phantom studies. The FLASH-MOLLI sequence prevented off-resonance artifacts in all 10 healthy volunteers at 3.0T. In vivo, there was no significant difference between FLASH-MOLLI-derived myocardial T1 values and "ShMOLLI+IE" derived values (1458.9 ± 20.9 ms versus 1464.1 ± 6.8 ms, P = 0.50); However, the average precision by FLASH-MOLLI was significantly better than that generated by "ShMOLLI+IE" (1.84 ± 0.36% variance versus 3.57 ± 0.94%, P < 0.001). The FLASH-MOLLI with BLESSPC fitting yields accurate and precise T1 estimation, and eliminates banding artifacts associated with bSSFP at 3.0T. © 2015 Wiley Periodicals, Inc.

  18. Friction Stir Weld Application and Tooling Design for the Multi-purpose Crew Vehicle Stage Adapter

    Science.gov (United States)

    Alcorn, John

    2013-01-01

    The Multi-Purpose Crew Vehicle (MPCV), commonly known as the Orion capsule, is planned to be the United States' next manned spacecraft for missions beyond low earth orbit. Following the cancellation of the Constellation program and creation of SLS (Space Launch System), the need arose for the MPCV to utilize the Delta IV Heavy rocket for a test launch scheduled for 2014 instead of the previously planned Ares I rocket. As a result, an adapter (MSA) must be used in conjunction with the MPCV to account for the variation in diameter of the launch vehicles; 5.5 meters down to 5.0 meters. Prior to ight article fabrication, a path nder (test article) will be fabricated to ne tune the associated manufacturing processes. The adapter will be comprised of an aluminum frustum (partial cone) that employs isogrid technology and circumferential rings on each end. The frustum will be fabricated by friction stir welding (FSW) three individual panels together on a Vertical Weld Tool (VWT) at NASA Marshall Space Flight Center. Subsequently, each circumferential ring will be friction stir welded to the frustum using a Robotic Weld Tool (RWT). The irregular geometry and large mass of the MSA require that extensive tooling preparation be put into support structures for the friction stir weld. The tooling on the VWT will be comprised of a set of conveyors mounted on pre-existing stanchions so that the MSA will have the ability to be rotated after each of the three friction stir welds. The tooling requirements to friction stir weld the rings with the RWT are somewhat more demanding. To support the mass of the MSA and resist the load of the weld tool, a system of mandrels will be mounted to stanchions and assembled in a circle. The goal of the paper will be to explain the design, fabrication, and assembly of the tooling, to explain the use of friction stir welding on the MSA path nder, and also to discuss the lessons learned and modi cations made in preparation for ight article fabrication

  19. Residual stresses analysis of friction stir welding using one-way FSI simulation

    International Nuclear Information System (INIS)

    Kang, Sung Wook; Jang, Beom Seon; Song, Ha Cheol

    2015-01-01

    When certain mechanisms, such as plastic deformations and temperature gradients, occur and are released in a structure, stresses remain because of the shape of the structure and external constraints. These stresses are referred to as residual stresses. The base material locally expands during heating in the welding process. When the welding is completed and cooled to room temperature, the residual stresses are left at nearly the yield strength level. In the case of friction stir welding, the maximum temperature is 80% to 90% of the melting point of the materials. Thus, the residual stresses in the welding process are smaller than those in other fusion welding processes; these stresses have not been considered previously. However, friction stir welding residual stresses are sometimes measured at approximately 70% or above. These residual stresses significantly affect fatigue behavior and lifetime. The present study investigates the residual stress distributions in various welding conditions and shapes of friction stir welding. In addition, the asymmetric feature is considered in temperature and residual stress distribution. Heat transfer analysis is conducted using the commercial computational fluid dynamics program Fluent, and results are used in the finite element structural analysis with the ANSYS Multiphysics software. The calculated residual stresses are compared with experimental values using the X-ray diffraction method.

  20. Estimating the workpiece-backingplate heat transfer coefficient in friction stirwelding

    DEFF Research Database (Denmark)

    Larsen, Anders; Stolpe, Mathias; Hattel, Jesper Henri

    2012-01-01

    Purpose - The purpose of this paper is to determine the magnitude and spatial distribution of the heat transfer coefficient between the workpiece and the backingplate in a friction stir welding process using inverse modelling. Design/methodology/approach - The magnitude and distribution of the heat...... in an inverse modeling approach to determine the heat transfer coefficient in friction stir welding. © Emerald Group Publishing Limited....

  1. Role of friction stir processing parameters on microstructure and ...

    Indian Academy of Sciences (India)

    The life of compo- nents depends on surface properties in many applications. ... The modified surface layer is called as surface composite (Attia. 2001). Friction stir .... The optical photomicrograph of as received copper plate is shown in figure 1a. ... It is essential to obtain a smooth crown appearance owing to the fact that ...

  2. Improving friction stir welding of blanks of different thicknesses

    Energy Technology Data Exchange (ETDEWEB)

    Fratini, L. [Dipartimento di Tecnologia Meccanica, Produzione e Ingegneria Gestionale, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy)], E-mail: abaqus@dtpm.unipa.it; Buffa, G. [Dipartimento di Tecnologia Meccanica, Produzione e Ingegneria Gestionale, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Shivpuri, R. [Ohio State University, Department of Industrial, Welding and Systems Engineering, 1971 Neil Avenue, 210 Baker Systems, Columbus, Ohio 43210 (United States)

    2007-06-25

    Friction stir welding (FSW) appears to be a promising process even in the welding of blanks of different thicknesses. Actually, such particular tailor welded blanks (TWBs) are usually characterized by a reduction in ductility due to the utilized fusion welding process. In this paper the authors, starting from a preliminary feasibility study, investigate the possibility to improve the mechanical performances of friction stir welded blanks of aluminum alloy with different thicknesses. Both experiments and a FE analyses are developed for a few case studies with different thickness ratios between the blanks. The numerical investigations are performed with the aim to highlight the material temperature distribution during the process in order to determine process conditions for which an almost symmetric thermal flow is obtained in the two blanks of the joint. In this way, a few simple process design rules are derived and verified through experiments. In particular a thickness ratio up to 2 was considered and a joint resistance of about the 80% of the parent material ultimate tensile strength was observed.

  3. Improving friction stir welding of blanks of different thicknesses

    International Nuclear Information System (INIS)

    Fratini, L.; Buffa, G.; Shivpuri, R.

    2007-01-01

    Friction stir welding (FSW) appears to be a promising process even in the welding of blanks of different thicknesses. Actually, such particular tailor welded blanks (TWBs) are usually characterized by a reduction in ductility due to the utilized fusion welding process. In this paper the authors, starting from a preliminary feasibility study, investigate the possibility to improve the mechanical performances of friction stir welded blanks of aluminum alloy with different thicknesses. Both experiments and a FE analyses are developed for a few case studies with different thickness ratios between the blanks. The numerical investigations are performed with the aim to highlight the material temperature distribution during the process in order to determine process conditions for which an almost symmetric thermal flow is obtained in the two blanks of the joint. In this way, a few simple process design rules are derived and verified through experiments. In particular a thickness ratio up to 2 was considered and a joint resistance of about the 80% of the parent material ultimate tensile strength was observed

  4. Effects of mixing and stirring on the critical behaviour

    International Nuclear Information System (INIS)

    Antonov, N V; Hnatich, Michal; Honkonen, Juha

    2006-01-01

    Stochastic dynamics of a nonconserved scalar order parameter near its critical point, subject to random stirring and mixing, is studied using the field-theoretic renormalization group. The stirring and mixing are modelled by a random external Gaussian noise with the correlation function ∼δ(t - t')k 4-d-y and the divergence-free (due to incompressibility) velocity field, governed by the stochastic Navier-Stokes equation with a random Gaussian force with the correlation function ∝ δ(t-t')k 4-d-y' . Depending on the relations between the exponents y and y' and the space dimensionality d, the model reveals several types of scaling regimes. Some of them are well known (model A of equilibrium critical dynamics and linear passive scalar field advected by a random turbulent flow), but there are three new non-equilibrium regimes (universality classes) associated with new nontrivial fixed points of the renormalization group equations. The corresponding critical dimensions are calculated in the two-loop approximation (second order of the triple expansion in y, y' and ε = 4 - d)

  5. Effect of impeller type and stirring frequency on the behavior of an AnSBBR in the treatment of low-strength wastewater.

    Science.gov (United States)

    Cubas, Selma A; Foresti, Eugenio; Rodrigues, José Alberto D; Ratusznei, Suzana M; Zaiat, Marcelo

    2011-01-01

    The influence of impeller type and stirring frequency on the performance of a mechanically stirred anaerobic sequencing batch reactor containing immobilized biomass on an inert support (AnSBBR--Anaerobic Sequencing Batch Biofilm Reactor) was evaluated. The biomass was immobilized on polyurethane foam cubes placed in a stainless-steel basket inside a glass cylinder. Each 8-h batch run consisted of three stages: feed (10 min), reaction (460 min) and discharge (10 min) at 30 °C. Experiments were performed with four impeller types, i.e., helical, flat-blade, inclined-blade and curved-blade turbines, at stirring frequencies ranging from 100 to 1100 rpm. Synthetic wastewater was used in all experiments with an organic-matter concentration of 530±37 mg/L measured as chemical oxygen demand (COD). The reactor achieved an organic-matter removal efficiency of around 87% under all investigated conditions. Analysis of the four impeller types and the investigated stirring frequencies showed that mass transfer in the liquid phase was affected not only by the applied stirring frequency but also by the agitation mode imposed by each impeller type. The best reactor performance at all stirring frequencies was obtained when agitation was provided by the flat-blade turbine impeller. Copyright © 2010 Elsevier Ltd. All rights reserved.

  6. Calculation of the inverse data space via sparse inversion

    KAUST Repository

    Saragiotis, Christos

    2011-01-01

    The inverse data space provides a natural separation of primaries and surface-related multiples, as the surface multiples map onto the area around the origin while the primaries map elsewhere. However, the calculation of the inverse data is far from trivial as theory requires infinite time and offset recording. Furthermore regularization issues arise during inversion. We perform the inversion by minimizing the least-squares norm of the misfit function by constraining the $ell_1$ norm of the solution, being the inverse data space. In this way a sparse inversion approach is obtained. We show results on field data with an application to surface multiple removal.

  7. Comparative evaluation of the porta hepatis/hepatoduodenal ligament with CT and MR imaging

    International Nuclear Information System (INIS)

    Silverman, P.M.; Feuerstein, I.M.; Zeman, R.K.; Jaffe, M.H.; Garra, B.S.

    1988-01-01

    CT and MR imaging were compared in a retrospective evaluation of 16 patients with abnormalities, predominantly neoplasms, of the porta hepatis/hepatoduodenal ligament. Masses on CT were of decreased density compared with that of liver and were seen in contrast to surrounding periportal fat. On MR images, T1-weighted images demonstrated findings similar to those of CT. T2-weighted images clearly depicted intrahepatic lesions but less distinctly depicted lesions surrounded by fat. Short inversion recovery (STIR) images better demonstrated tumor relative to fat. CT was better than all MR imaging sequences in one of 16 cases, whereas at least one MR imaging sequence was better than CT in six of 16. In nine cases, CT was equivalent to the best MR imaging sequence. In five of six cases where MR imaging was better than CT, STIR sequences were most favorable. In conclusion, MR imaging provided a valuable technique for assessing abnormalities of the porta hepatis/hepatoduodenal ligament

  8. The study on defects in aluminum 2219-T6 thick butt friction stir welds with the application of multiple non-destructive testing methods

    International Nuclear Information System (INIS)

    Li, Bo; Shen, Yifu; Hu, Weiye

    2011-01-01

    Research highlights: → Friction stir weld-defect forming mechanisms of thick butt-joints. → Relationship between weld-defects and friction stir welding process parameters. → Multiple non-destructive testing methods applied to friction stir welds. → Empirical criterion basing on mass-conservation for inner material-loss defects. → Nonlinear correlation between weld strengths and root-flaw lengths. -- Abstract: The present study focused on the relationship between primary friction stir welding process parameters and varied types of weld-defect discovered in aluminum 2219-T6 friction stir butt-welds of thick plates, meanwhile, the weld-defect forming mechanisms were investigated. Besides a series of optical metallographic examinations for friction stir butt welds, multiple non-destructive testing methods including X-ray detection, ultrasonic C-scan testing, ultrasonic phased array inspection and fluorescent penetrating fluid inspection were successfully used aiming to examine the shapes and existence locations of different weld-defects. In addition, precipitated Al 2 Cu phase coarsening particles were found around a 'kissing-bond' defect within the weld stirred nugget zone by means of scanning electron microscope and energy dispersive X-ray analysis. On the basis of volume conservation law in material plastic deformation, a simple empirical criterion for estimating the existence of inner material-loss defects was proposed. Defect-free butt joints were obtained after process optimization of friction stir welding for aluminum 2219-T6 plates in 17-20 mm thickness. Process experiments proved that besides of tool rotation speed and travel speed, more other appropriate process parameter variables played important roles at the formation of high-quality friction stir welds, such as tool-shoulder target depth, spindle tilt angle, and fixture clamping conditions on the work-pieces. Furthermore, the nonlinear correlation between weld tensile strengths and weld crack

  9. INVESTIGATION OF SINGLE-PASS/DOUBLE-PASS TECHNIQUES ON FRICTION STIR WELDING OF ALUMINIUM

    Directory of Open Access Journals (Sweden)

    N.A.A. Sathari

    2014-12-01

    Full Text Available The aim of this research is to study the effects of single-pass/ double-pass techniques on friction stir welding of aluminium. Two pieces of AA1100 with a thickness of 6.0 mm were friction stir welded using a CNC milling machine at rotational speeds of 1400 rpm, 1600 rpm and 1800 rpm respectively for single-pass and double-pass. Microstructure observations of the welded area were studied using an optical microscope. The specimens were tested by using a tensile test and Vickers hardness test to evaluate their mechanical properties. The results indicated that, at low rotational speed, defects such as ‘surface lack of fill’ and tunnels in the welded area contributed to a decrease in mechanical properties. Welded specimens using double-pass techniques show increasing values of tensile strength and hardness. From this investigation it is found that the best parameters of FSW welded aluminium AA1100 plate were those using double-pass techniques that produce mechanically sound joints with a hardness of 56.38 HV and 108 MPa strength at 1800 rpm compared to the single-pass technique. Friction stir welding, single-pass/ double-pass techniques, AA1100, microstructure, mechanical properties.

  10. Examination of the rheological properties of stirred joghurt during the long-term storage by using dynamic oscillation method

    Directory of Open Access Journals (Sweden)

    Milica Vilušić

    2003-07-01

    Full Text Available In this work the rheological properties of stirred yoghurt during the longterm storage at 4 and 8°C were investigated. The optimal quantity of additives, in order to increase dry matter content (whole milk powder and whey protein-lactalbumin, was preliminary determined and the fermentation was performed. During 42 days, i.e., 1st, 7th, 14th, 21st, 28th, 35th and 42nd day of storage of stirred yoghurt, in refrigerator at 4 and 8°C, the changes of pH value, acidity and rheological properties by using of dynamic oscillation method were observed. Results of this work indicated that an addition of whole milk powder and whey protein have an influence on rheological properties of stirred yoghurt. The long-term storage of stirred yoghurt and the results of dynamic oscilations showed permanently higher G’storage (elasticity modulus, where elastic properties of viscoelastic products dominate, in comparison with the G” loss (viscosity modulus. Increased moduls of elasticy and viscosity, as function of time, permanently occurs at pH value 4.00 and lower, as an indication of alteration of long casein chains in the coagulum structure. Different temperatures of storage had no influence on changes of rheological properties of examinated types of stirred yoghur. The relation of above mentioned moduls of elasticy and viscosity kept the same increasing tendency.

  11. Numerically Based Phase Transformation Maps for Dissimilar Aluminum Alloys Joined by Friction Stir-Welding

    Directory of Open Access Journals (Sweden)

    Carter Hamilton

    2018-05-01

    Full Text Available Sheets of aluminum 2017A-T451 and 7075-T651 were friction stir-welded in a butt-weld configuration. An existing computational model of the welding process for temperature distribution and material flow was adapted to estimate the phase transformations that occur across the weld zone. Near the weld center, process temperatures are sufficient to fully dissolve the equilibrium η phase in 7075 and partially dissolve the equilibrium S phase in 2017A. Upon cooling, Guinier–Preston (GP and Guinier–Preston–Bagaryatsky (GPB zones re-precipitate, and hardness recovers. Due to the more complete dissolution of the equilibrium phase in 7075, the hardness recovery skews toward whichever side of the weld, i.e., the advancing or retreating side, represents the 7075 workpiece. Phase transformation maps generated by the numerical simulation align not only with the hardness profiles taken across the weld zone, but also with positron lifetimes obtained through positron annihilation lifetime spectroscopy (PALS. Boundaries between the aluminum matrix and the secondary phases provide open volumes to trap positrons; therefore, positron lifetimes across the weld correspond with the phase transformations that occur in 7075 and 2017A during processing.

  12. Multiaxial fatigue of aluminium friction stir welded joints: preliminary results

    Directory of Open Access Journals (Sweden)

    D. G. Hattingh

    2015-07-01

    Full Text Available The aim of the present research is to check the accuracy of the Modified Wöhler Curve Method (MWCM in estimating the fatigue strength of friction stir (FS welded tubular joints of Al 6082-T6 subjected to in-phase and out-of-phase multiaxial fatigue loading. The welded samples being investigated were manufactured by equipping an MTS I-STIR process development system with a retracting tool that was specifically designed and optimised for this purpose. These specimens were tested under proportional and non-proportional tension and torsion, the effect of non-zero mean stresses being also investigated. The validation exercise carried out by using the generated experimental results allowed us to prove that the MWCM (applied in terms of nominal stresses is highly accurate in predicting the fatigue strength of the tested FS welded joints, its usage resulting in estimates falling with the uniaxial and torsional calibration scatter bands.

  13. The recovery of zinc from hot galvanizing slag in an anion-exchange membrane electrolysis reactor

    International Nuclear Information System (INIS)

    Ren Xiulian; Wei Qifeng; Hu Surong; Wei Sijie

    2010-01-01

    This paper reports the optimization of the process parameters for recovery of zinc from hot galvanizing slag in an anion-exchange membrane electrolysis reactor. The experiments were carried out in an ammoniacal ammonium chloride system. The influence of composition of electrolytes, pH, stirring rate, current density and temperature, on cathodic current efficiency, specific power consumption and anodic dissolution of Zn were investigated. The results indicate that the cathode current efficiency increases and the hydrogen evolution decreased with increasing the cathode current density. The partial current for electrodeposition of Zn has liner relationship with ω 1/2 (ω: rotation rate). The highest current efficiency for dissolving zinc was obtained when NH 4 Cl concentration was 53.46 g L -1 and the anodic dissolution of zinc was determined by mass transfer rate at stirring rate 0-300 r min -1 . Increase in temperature benefits to improve CE and dissolution of Zn, and reduce cell voltage. Initial pH of electrolytes plays an important role in the deposition and anodic dissolution of Zn. The results of single factor experiment show that about 50% energy consumption was saved for electrodeposition of Zn in the anion-exchange membrane electrolysis reactor.

  14. Investigation of the material flow and texture evolution in friction-stir welded aluminum alloy

    Science.gov (United States)

    Kang, Suk Hoon; Han, Heung Nam; Oh, Kyu Hwan; Cho, Jae-Hyung; Lee, Chang Gil; Kim, Sung-Joon

    2009-12-01

    The material flow and crystallographic orientation in aluminum alloy sheets joined by friction stir welding (FSW) were investigated by electron back scattered diffraction (EBSD). The microstructure and microtexture of the material near the stir zone was found to be influenced by the rotational behavior of the tool pin. It was found that, during FSW, the forward movement of the tool pin resulted in loose contact between the tool pin and the receding material at the advancing side. This material behavior inside the joined aluminum plates was also observed by an X-ray micrograph by inlaying a gold marker into the plates. As the advancing speed of the tool increases at a given rotation speed, the loose contact region widens. As the microtexture of the material near the stir zone is very close to the simple shear texture on the basis of the frame of the tool pin in the normal and tangent directions, the amount of incompletely rotated material due to the loose contact could be estimated from the tilt angle of the shear texture in the pole figure around the key hole.

  15. Improvement of Weldment Properties by Hot Forming Quenching of Friction Stir Welded TWB Sheet

    Directory of Open Access Journals (Sweden)

    Dae-Hoon Ko

    2014-04-01

    Full Text Available The purpose of this study is to improve the mechanical properties and formability of friction stir welded tailor-welded blanks (TWBs of Al6061 alloy with a new forming method called hot forming quenching (HFQ in which solid-solution heat-treated aluminum sheets are formed at elevated temperature. Forming and quenching during HFQ are simultaneously performed with the forming die for the solid-solution heat-treated sheet. In this study, specimens of aluminum TWBs were prepared by friction stir welding (FSW with a butt joint. The effectiveness of FSW joining was evaluated by observation of the macrostructure for different sheet thicknesses. In order to evaluate the formability of TWBs by HFQ, a hemisphere dome stretching test of the limit dome height achieved without specimen failure was performed with various tool temperatures. A Vickers test was also performed to measure weldment hardness as a function of position. The formability and mechanical properties of products formed by HFQ are compared with those formed by conventional forming methods, demonstrating the suitability of HFQ for sheet metal forming of friction stir welded TWBs.

  16. Characteristic evaluation of process parameters of friction stir welding of aluminium 2024 hybrid composites

    Science.gov (United States)

    Sadashiva, M.; Shivanand, H. K.; Vidyasagar, H. N.

    2018-04-01

    The Current work is aimed to investigate the effect of process parameters in friction stir welding of Aluminium 2024 base alloy and Aluminium 2024 matrix alloy reinforced with E Glass and Silicon Carbide reinforcements. The process involved a set of synthesis techniques incorporating stir casting methodology resulting in fabrication of the composite material. This composite material that is synthesized is then machined to obtain a plate of dimensions 100 mm * 50 mm * 6 mm. The plate is then friction stir welded at different set of parameters viz. the spindle speed of 600 rpm, 900 rpm and 1200 rpm and feed rate of 40 mm/min, 80 mm/min and 120 mm/min for analyzing the process capability. The study of the given set of parameters is predominantly important to understand the physics of the process that may lead to better properties of the joint, which is very much important in perspective to its use in advanced engineering applications, especially in aerospace domain that uses Aluminium 2024 alloy for wing and fuselage structures under tension.

  17. Regularized inversion of controlled source audio-frequency magnetotelluric data in horizontally layered transversely isotropic media

    International Nuclear Information System (INIS)

    Zhou, Jianmei; Shang, Qinglong; Wang, Hongnian; Wang, Jianxun; Yin, Changchun

    2014-01-01

    We present an algorithm for inverting controlled source audio-frequency magnetotelluric (CSAMT) data in horizontally layered transversely isotropic (TI) media. The popular inversion method parameterizes the media into a large number of layers which have fixed thickness and only reconstruct the conductivities (e.g. Occam's inversion), which does not enable the recovery of the sharp interfaces between layers. In this paper, we simultaneously reconstruct all the model parameters, including both the horizontal and vertical conductivities and layer depths. Applying the perturbation principle and the dyadic Green's function in TI media, we derive the analytic expression of Fréchet derivatives of CSAMT responses with respect to all the model parameters in the form of Sommerfeld integrals. A regularized iterative inversion method is established to simultaneously reconstruct all the model parameters. Numerical results show that the inverse algorithm, including the depths of the layer interfaces, can significantly improve the inverse results. It can not only reconstruct the sharp interfaces between layers, but also can obtain conductivities close to the true value. (paper)

  18. Application of variable threshold intensity to segmentation for white matter hyperintensities in fluid attenuated inversion recovery magnetic resonance images

    International Nuclear Information System (INIS)

    Yoo, Byung Il; Han, Ji Won; Oh, San Yeo Wool; Kim, Tae Hui; Lee, Jung Jae; Lee, Eun Young; MacFall, James R.; Payne, Martha E.; Kim, Jae Hyoung; Kim, Ki Woong

    2014-01-01

    White matter hyperintensities (WMHs) are regions of abnormally high intensity on T2-weighted or fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI). Accurate and reproducible automatic segmentation of WMHs is important since WMHs are often seen in the elderly and are associated with various geriatric and psychiatric disorders. We developed a fully automated monospectral segmentation method for WMHs using FLAIR MRIs. Through this method, we introduce an optimal threshold intensity (I O ) for segmenting WMHs, which varies with WMHs volume (V WMH ), and we establish the I O -V WMH relationship. Our method showed accurate validations in volumetric and spatial agreements of automatically segmented WMHs compared with manually segmented WMHs for 32 confirmatory images. Bland-Altman values of volumetric agreement were 0.96 ± 8.311 ml (bias and 95 % confidence interval), and the similarity index of spatial agreement was 0.762 ± 0.127 (mean ± standard deviation). Furthermore, similar validation accuracies were obtained in the images acquired from different scanners. The proposed segmentation method uses only FLAIR MRIs, has the potential to be accurate with images obtained from different scanners, and can be implemented with a fully automated procedure. In our study, validation results were obtained with FLAIR MRIs from only two scanner types. The design of the method may allow its use in large multicenter studies with correct efficiency. (orig.)

  19. Application of variable threshold intensity to segmentation for white matter hyperintensities in fluid attenuated inversion recovery magnetic resonance images

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Byung Il; Han, Ji Won; Oh, San Yeo Wool; Kim, Tae Hui [Seoul National University Bundang Hospital, Department of Neuropsychiatry, Seongnam, Gyeonggi-do (Korea, Republic of); Lee, Jung Jae; Lee, Eun Young [Kyungbook National University Chilgok Hospital, Department of Psychiatry, Buk-gu, Daegu (Korea, Republic of); MacFall, James R. [Duke University Medical Center, Neuropsychiatric Imaging Research Laboratory, Durham, NC (United States); Duke University Medical Center, Department of Radiology, Durham, NC (United States); Payne, Martha E. [Duke University Medical Center, Neuropsychiatric Imaging Research Laboratory, Durham, NC (United States); Duke University Medical Center, Department of Psychiatry and Behavioral Sciences, Durham, NC (United States); Kim, Jae Hyoung [Seoul National University Bundang Hospital, Department of Radiology, Seongnam, Gyeonggi-do (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Jongno-gu, Seoul (Korea, Republic of); Kim, Ki Woong [Seoul National University Bundang Hospital, Department of Neuropsychiatry, Seongnam, Gyeonggi-do (Korea, Republic of); Seoul National University College of Medicine, Department of Psychiatry, Jongno-gu, Seoul (Korea, Republic of); Seoul National University College of Natural Sciences, Department of Brain and Cognitive Science, Gwanak-gu, Seoul (Korea, Republic of)

    2014-04-15

    White matter hyperintensities (WMHs) are regions of abnormally high intensity on T2-weighted or fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI). Accurate and reproducible automatic segmentation of WMHs is important since WMHs are often seen in the elderly and are associated with various geriatric and psychiatric disorders. We developed a fully automated monospectral segmentation method for WMHs using FLAIR MRIs. Through this method, we introduce an optimal threshold intensity (I{sub O}) for segmenting WMHs, which varies with WMHs volume (V{sub WMH}), and we establish the I{sub O} -V{sub WMH} relationship. Our method showed accurate validations in volumetric and spatial agreements of automatically segmented WMHs compared with manually segmented WMHs for 32 confirmatory images. Bland-Altman values of volumetric agreement were 0.96 ± 8.311 ml (bias and 95 % confidence interval), and the similarity index of spatial agreement was 0.762 ± 0.127 (mean ± standard deviation). Furthermore, similar validation accuracies were obtained in the images acquired from different scanners. The proposed segmentation method uses only FLAIR MRIs, has the potential to be accurate with images obtained from different scanners, and can be implemented with a fully automated procedure. In our study, validation results were obtained with FLAIR MRIs from only two scanner types. The design of the method may allow its use in large multicenter studies with correct efficiency. (orig.)

  20. Microstructure of Semi-Solid Billets Produced by Electromagnetic Stirring and Behavior of Primary Particles during the Indirect Forming Process

    Directory of Open Access Journals (Sweden)

    Chul Kyu Jin

    2018-04-01

    Full Text Available An A356 alloy semi-solid billet was fabricated using electromagnetic stirring. After inserting the semi-solid billet into an indirect die, a thin plate of 1.2 mm thickness was fabricated by applying compression. The microstructure of the semi-solid billets fabricated in various stirring conditions (solid fraction and stirring force were analyzed. The deformation and behavior of the primary α-Al particles were analyzed for various parameters (solid fraction, die friction, compression rate, and compression pressure. In the stirred billets, a globular structure was dominant, while a dendrite structure was dominant in the unstirred billets. As the solid fraction decreased and the stirring current increased, the equivalent diameter and roundness of the primary α-Al particles decreased. The primary α-Al particle sizes were reduced as the compressing velocity increased, while a greater number of particles could move as the compressing pressure increased. As the path over which the motion occurred became smoother, the fluidity of the particles improved. Under compression, bonded primary α-Al particles became separated into individual particles again, as the bonds were broken. As wearing caused by friction and collisions between the particles during this motion occurred, the particle sizes were reduced, and the particle shapes become increasingly spheroid.

  1. The influence of stirring on the fading of the AlTi5B1 grain refiner in an Al–Fe alloy

    Directory of Open Access Journals (Sweden)

    I. Naglič

    2011-01-01

    Full Text Available An Al–Fe alloy, melted in an induction furnace with a graphite crucible, was grain refined with the AlTi5B1 grain refiner. The melt was stirred after the addition of the grain refiner. The first sample was cast two minutes after the addition of the grain refiner and the second sample fifteen minutes after the addition of the grain refiner. The melt was stirred again before the third sample was cast. The grain size was found to increase with the holding time. However, the grain size of the third sample, after stirring, decreased to a similar size to that of the first sample. The results indicate that the stirring of a grain-refined melt can restore the grain-refinement effect.

  2. Long T2 suppression in native lung 3-D imaging using k-space reordered inversion recovery dual-echo ultrashort echo time MRI.

    Science.gov (United States)

    Gai, Neville D; Malayeri, Ashkan A; Bluemke, David A

    2017-08-01

    Long T2 species can interfere with visualization of short T2 tissue imaging. For example, visualization of lung parenchyma can be hindered by breathing artifacts primarily from fat in the chest wall. The purpose of this work was to design and evaluate a scheme for long T2 species suppression in lung parenchyma imaging using 3-D inversion recovery double-echo ultrashort echo time imaging with a k-space reordering scheme for artifact suppression. A hyperbolic secant (HS) pulse was evaluated for different tissues (T1/T2). Bloch simulations were performed with the inversion pulse followed by segmented UTE acquisition. Point spread function (PSF) was simulated for a standard interleaved acquisition order and a modulo 2 forward-reverse acquisition order. Phantom and in vivo images (eight volunteers) were acquired with both acquisition orders. Contrast to noise ratio (CNR) was evaluated in in vivo images prior to and after introduction of the long T2 suppression scheme. The PSF as well as phantom and in vivo images demonstrated reduction in artifacts arising from k-space modulation after using the reordering scheme. CNR measured between lung and fat and lung and muscle increased from -114 and -148.5 to +12.5 and 2.8 after use of the IR-DUTE sequence. Paired t test between the CNRs obtained from UTE and IR-DUTE showed significant positive change (p lung-fat CNR and p = 0.03 for lung-muscle CNR). Full 3-D lung parenchyma imaging with improved positive contrast between lung and other long T2 tissue types can be achieved robustly in a clinically feasible time using IR-DUTE with image subtraction when segmented radial acquisition with k-space reordering is employed.

  3. Microstructure and wear behavior of friction stir processed cast hypereutectic aluminum silicon

    Directory of Open Access Journals (Sweden)

    Ahmad Rosli

    2017-01-01

    Full Text Available Hypereutectic as-cast Al-18Si-Cu-Ni alloy was subjected to friction stir processing (FSP. The resultant effect of FSP on the alloy was evaluated by microstructure analysis and wear tests (dry sliding. A significant microstructural modification and enhancement in wear behavior of Al-18Si-Cu-Ni alloy was recorded after friction stir processing. Wear resistance improvement was related to considerable modification in size, morphology and distribution of silicon particles, and hardness improvement. It was found that lower tool rotation speed was more effective to refine silicon particles and in turn increase wear resistance. Minimum Si particle mean area of about 47.8 µm2, and wear rate of 0.0155 mg/m was achieved.

  4. Microstructure of friction stir welded joints of 2017A aluminium alloy sheets.

    Science.gov (United States)

    Mroczka, K; Dutkiewicz, J; Pietras, A

    2010-03-01

    The present study examines a friction stir welded 2017A aluminium alloy. Transmission electron microscope investigations of the weld nugget revealed the average grain size of 5 microm, moderate density of dislocations as well as the presence of nanometric precipitates located mostly in grains interiors. Scanning electron microscope observations of fractures showed the presence of ductile fracture in the region of the weld nugget with brittle precipitates in the lower part. The microhardness analysis performed on the cross-section of the joints showed fairly small changes; however, after the artificial ageing process an increase in hardness was observed. The change of the joint hardness subject to the ageing process indicates partial supersaturation in the material during friction stir welding and higher precipitation hardening of the joint.

  5. Microstructures and electrochemical behaviors of the friction stir welding dissimilar weld.

    Science.gov (United States)

    Shen, Changbin; Zhang, Jiayan; Ge, Jiping

    2011-06-01

    By using optical microscope, the microstructures of 5083/6082 friction stir welding (FSW) weld and parent materials were analyzed. Meanwhile, at ambient temperature and in 0.2 mol/L NaHS03 and 0.6 mol/L NaCl solutionby gravimetric test, potentiodynamic polarization curve test, electrochemical impedance spectra (EIS) and scanning electron microscope (SEM) observation, the electrochemical behavior of 5083/6082 friction stir welding weld and parent materials were comparatively investigated by gravimetric test, potentiodynamic polarization curve test, electrochemical impedance spectra (EIS) and scanning electron microscope (SEM) observation. The results indicated that at given processing parameters, the anti-corrosion property of the dissimilar weld was superior to those of the 5083 and 6082 parent materials. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  6. Texture analysis of a friction stir processed 6061-T6 aluminum alloy using neutron diffraction

    International Nuclear Information System (INIS)

    Woo, W.; Choo, H.; Brown, D.W.; Vogel, S.C.; Liaw, P.K.; Feng, Z.

    2006-01-01

    Time-of-flight neutron diffraction was used to investigate the texture changes in friction stir-processed (FSP) 6061-T6 aluminum alloy plates. Two different specimens were prepared with the purpose of separating the effects of frictional heating and severe plastic deformation on the changes of the preferred orientation in the as-received rolled plates: a plate processed with both stirring pin and tool shoulder, i.e., a regular FSP plate subjected to both severe plastic deformation and frictional heating (Case 1); and a plate processed only with the tool shoulder, i.e., subjected mainly to frictional heating (Case 2). The diffraction peak intensities provide insights into the texture variations at various locations across the centerline and through the thickness of the FSP plates. Comparison of the texture variations between Cases 1 and 2 clearly shows that the severe plastic deformation from the stirring pin affects the preferred orientation during the FSP, while heating alone from the tool shoulder has little effect

  7. Development of liquid-nitrogen-cooling friction stir spot welding for AZ31 magnesium alloy joints

    Science.gov (United States)

    Wu, Dong; Shen, Jun; Zhou, Meng-bing; Cheng, Liang; Sang, Jia-xing

    2017-10-01

    A liquid-nitrogen-cooling friction stir spot welding (C-FSSW) technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone (SZ) and the heat-affected zone (HAZ) of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone (TMAZ) increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding (FSSW)-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time.

  8. [Study on detoxication of kansui radix on normal liver cells LO2 after stir-baking with vinegar].

    Science.gov (United States)

    Yan, Xiaojing; Zhang, Li; Li, Lin; Cao, Yudan; Li, Zhengjun; Tang, Yuping; Ding, Anwei

    2012-06-01

    To compare the toxicity on normal liver cells LO2 before and after Kansui Radix stir-baked with vinegar, and make a preliminary study on the mechanism of detoxication of Kansui Radix stir-baked with vinegar. The MTT method was adopted to detect the cell activity, with normal liver cells LO2 as the study object. The morphology of cells were observed, and the level or content of AST, ALT, LDH, SOD, Na+-K+-ATPase, Ca2+-Mg2+ -ATPase, GSH and MDA were determined in cell culture supernatant and splitting supernatant. Compared with the control group, Kansui can obviously inhibit the cell activity (P baked with vinegar can significantly decrease the cell proliferation inhibition and the trend of morphological variation, and obviously decrease the levels of ALT, AST, and LDH (P baking with rice vinegar can release the hepatotoxicity of Kansui Radix. Its possible mechanism was that Kansui Radix stir-baked with vinegar can decrease the influence of Kansui Radix on the permeability of liver cells LO2 membrane and oxidative damage, in order to provide basis for further exploration of the detoxication mechanism of Kansui Radix stir-baked with vinegar.

  9. Nonlinear Time Reversal Acoustic Method of Friction Stir Weld Assessment, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the project is demonstration of the feasibility of Friction Stir Weld (FSW) assessment by novel Nonlinear Time Reversal Acoustic (TRA) method. Time...

  10. Characterization of microstructure and mechanical properties of friction stir welded AlMg5- Al_2O_3 nanocomposites

    International Nuclear Information System (INIS)

    Babu, N. Kishore; Kallip, Kaspar; Leparoux, Marc; AlOgab, Khaled A.; Reddy, G.M.; Talari, M.K.

    2016-01-01

    In the present study, powder metallurgy processed unmilled AlMg5, milled AlMg5 and milled AlMg5-0.5 vol% Al_2O_3 nanocomposite have been successfully friction stir welded (FSW). The effect of friction stir welding on the evolution of weld microstructures; hardness and tensile properties were studied and discussed in detail. FSW of unmilled AlMg5 resulted in significant grain refinement and strain hardening in the nugget zone induced by the thermo-mechanical processing, thereby increasing the stir zone hardness and tensile strengths to 100 HV and 324 MPa when compared to 80 HV and 300 MPa of base metal, respectively. In contrast, the FSW of milled AlMg5 and milled AlMg5-0.5 vol% Al_2O_3 samples showed a reduction in UTS values to 375 MPa and 401 MPa in the stir zone compared to 401 MPa and 483 MPa of respective base metal values. Transmission electron microscopic (TEM) investigation of weld stir zones revealed the homogenous distribution of Al_4C_3 nanophases in milled AlMg5 and Al_2O_3 nanoparticles in milled AlMg5-0.5 vol% Al_2O_3 samples throughout the aluminium matrix. It was revealed that the pre-stored energy from the prior ball milling and hot pressing processes, higher deformation energy and grain boundary pinning effect due to the presence of reinforcement particles has resulted in a higher recrystallization tendency and retarded grain growth during FSW of milled samples. The welds prepared with milled AlMg5-0.5 vol% Al_2O_3 exhibited higher hardness and tensile strength in the stir zone when compared to all other conditions which was attributed to Hall Petch effect due to fine grain size and Orowan strengthening effect due to Al_2O_3 reinforcements.

  11. Friction stir welding of single crystal aluminium

    DEFF Research Database (Denmark)

    Fonda, Richard Warren; Wert, John A.; Reynolds, A.P.

    2007-01-01

    Friction stir welds were prepared in different orientations in an aluminium single crystal. The welds were quenched to preserve the microstructure surrounding the tool and then electron backscattered diffraction was used to reveal the generation of grain boundaries and the evolution...... of crystallographic texture around the tool in each weld. The extent of both dynamic recrystallisation and conventional recrystallisation varied considerably as a function of weld orientation. As the base plate begins to interact with the deformation field surrounding the tool, regions of the single crystal rotate...

  12. Systematic investigation of the fatigue performance of a friction stir welded low alloy steel

    International Nuclear Information System (INIS)

    Toumpis, Athanasios; Galloway, Alexander; Molter, Lars; Polezhayeva, Helena

    2015-01-01

    Highlights: • The fatigue behaviour of a friction stir welded low alloy steel has been assessed. • The welds’ fatigue lives outperform the International Institute of Welding’s recommendations for fusion welds. • The slow weld exhibits the best fatigue performance of the investigated welds. • Fracture surface analysis shows that minor embedded flaws do not offer crack initiation sites. • Process-related surface breaking flaws have a significant effect on the fatigue life. - Abstract: A comprehensive fatigue performance assessment of friction stir welded DH36 steel has been undertaken to address the relevant knowledge gap for this process on low alloy steel. A detailed set of experimental procedures specific to friction stir welding has been put forward, and the consequent study extensively examined the weld microstructure and hardness in support of the tensile and fatigue testing. The effect of varying welding parameters was also investigated. Microstructural observations have been correlated to the weldments’ fatigue behaviour. The typical fatigue performance of friction stir welded steel plates has been established, exhibiting fatigue lives well above the weld detail class of the International Institute of Welding even for tests at 90% of yield strength, irrespective of minor instances of surface breaking flaws which have been identified. An understanding of the manner in which these flaws impact on the fatigue performance has been established, concluding that surface breaking irregularities such as these produced by the tool shoulder’s features on the weld top surface can be the dominant factor for crack initiation under fatigue loading

  13. Noise-sustained and controlled synchronization of stirred excitable media by external forcing

    International Nuclear Information System (INIS)

    Zhou Changsong; Kurths, Juergen

    2005-01-01

    Most of the previous studies on constructive effects of noise in spatially extended systems have focused on static media, e.g., of the reaction-diffusion type. Because many active chemical or biological processes occur in a fluid environment with mixing, we investigate here the interplay among noise, excitability, mixing and external forcing in excitable media advected by a chaotic flow, in a two-dimensional FitzHugh-Nagumo model described by a set of reaction-advection-diffusion equations. In the absence of external forcing, noise may generate sustained coherent oscillations of the media in a range of noise intensities and stirring rates. We find that these noise-sustained oscillations can be synchronized by external periodic signals much smaller than the threshold. Analysis of the locking regions in the parameter space of the signal period, stirring rate and noise intensity reveals that the mechanism underlying the synchronization behaviour is a matching between the time scales of the forcing signal and the noise-sustained oscillations. The results demonstrate that, in the presence of a suitable level of noise, the stirred excitable media act as self-sustained oscillatory systems and become much easier to be entrained by weak external forcing. Our results may be verified in experiments and are useful to understand the synchronization of population dynamics of oceanic ecological systems by annual cycles

  14. Noise-sustained and controlled synchronization of stirred excitable media by external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Changsong; Kurths, Juergen [Institute of Physics, University of Potsdam, PF 601553, 14415 Potsdam (Germany)

    2005-01-01

    Most of the previous studies on constructive effects of noise in spatially extended systems have focused on static media, e.g., of the reaction-diffusion type. Because many active chemical or biological processes occur in a fluid environment with mixing, we investigate here the interplay among noise, excitability, mixing and external forcing in excitable media advected by a chaotic flow, in a two-dimensional FitzHugh-Nagumo model described by a set of reaction-advection-diffusion equations. In the absence of external forcing, noise may generate sustained coherent oscillations of the media in a range of noise intensities and stirring rates. We find that these noise-sustained oscillations can be synchronized by external periodic signals much smaller than the threshold. Analysis of the locking regions in the parameter space of the signal period, stirring rate and noise intensity reveals that the mechanism underlying the synchronization behaviour is a matching between the time scales of the forcing signal and the noise-sustained oscillations. The results demonstrate that, in the presence of a suitable level of noise, the stirred excitable media act as self-sustained oscillatory systems and become much easier to be entrained by weak external forcing. Our results may be verified in experiments and are useful to understand the synchronization of population dynamics of oceanic ecological systems by annual cycles.

  15. Friction stir processing: a new grain refinement technique to achieve high strain rate superplasticity in commercial alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, R.S. [Missouri Univ., Rolla, MO (United States). Dept. of Metallurgical Engineering; Mahoney, M.W. [Rockwell International Corp., Thousand Oaks, CA (United States). Science Center

    2001-07-01

    Friction stir processing is a new thermo-mechanical processing technique that leads to a microstructure amenable for high strain rate superplasticity in commercial aluminum alloys. Friction stirring produces a combination of very fine grain size and high grain boundary misorientation angles. Preliminary results on a 7075 Al demonstrate high strain rate superplasticity in the temperature range of 430-510 C. For example, an elongation of >1000% was observed at 490 C and 1 x 10{sup -2} s{sup -1}. This demonstrates a new possibility to economically obtain a superplastic microstructure in commercial aluminum alloys. Based on these results, a three-step manufacturing process to fabricate complex shaped components can be envisaged: cast sheet or hot-pressed powder metallurgy sheet + friction stir processing + superplastic forging or forming. (orig.)

  16. The Simulation of Precipitation Evolutions and Mechanical Properties in Friction Stir Welding with Post-Weld Heat Treatments

    Science.gov (United States)

    Zhang, Z.; Wan, Z. Y.; Lindgren, L.-E.; Tan, Z. J.; Zhou, X.

    2017-12-01

    A finite element model of friction stir welding capable of re-meshing is used to simulate the temperature variations. Re-meshing of the finite element model is used to maintain a fine mesh resolving the gradients of the solution. The Kampmann-Wagner numerical model for precipitation is then used to study the relation between friction stir welds with post-weld heat treatment (PWHT) and the changes in mechanical properties. Results indicate that the PWHT holding time and PWHT holding temperature need to be optimally designed to obtain FSW with better mechanical properties. Higher precipitate number with lower precipitate sizes gives higher strength in the stirring zone after PWHT. The coarsening of precipitates in HAZ are the main reason to hinder the improvement of mechanical property when PWHT is used.

  17. Reinforcement with alumina particles at the interface region of AA6101-T6 and AA1350 alloys during friction stir welding

    Science.gov (United States)

    Ashok Kumar, R.; Thansekhar, M. R.

    2018-04-01

    This paper deals the combinational effect of friction stir welding and friction stir processing on dissimilar AA6101-T6 and AA1350 aluminium alloys. For that, alumina particles are reinforced at interface region of AA6101-T6 and AA1350 aluminium alloys. Friction Stir Welding and Friction Stir Processing are done simultaneously for various sizes of groove. To analyze the welding quality and surface modifications, mechanical, wear and microstructural tests are carried out. Among these, smallest groove of 0.5 mm width and 1 mm depth reveals highest tensile and bending strengths and largest groove of 2 mm width and 3 mm depth gives maximum hardness and wear resistance. Taguchi technique shows that groove width is most influencing parameter. Developed second order models with interaction predict the responses with minimum error.

  18. Ductile damage development in friction stir welded aluminum (AA2024) joints

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau

    2008-01-01

    Ductile damage development in a friction stir welded aluminum joint subjected to tension is analyzed numerically by FE-analysis, based on a total Lagrangian formulation. An elastic-viscoplastic constitutive relation that accounts for nucleation and growth of microvoids is applied. Main focus...

  19. Triple-layer appearance of Brodmann area 4 at thin-section double inversion-recovery MR imaging.

    Science.gov (United States)

    Kim, Eung Yeop; Kim, Dong-Hyun; Chang, Jong-Hee; Yoo, Eunhye; Lee, Jae-Wook; Park, Hae-Jeong

    2009-02-01

    To investigate whether thin-section axial double inversion-recovery (DIR) brain magnetic resonance (MR) imaging at 3.0 T can help distinguish the primary motor cortex (PMC), or Brodmann area 4, from other selected cortical regions, including the primary sensory cortex (PSC), or Brodmann areas 1-3, on the basis of the presence of a "triple-layer" appearance. This prospective study was approved by the institutional review board; informed consent was obtained from patients. This study included 191 patients (94 female, age range, 5-80 years; 97 male, age range, 5-76 years) with normal findings at 3.0-T MR imaging. The presence or absence of a triple-layer appearance within selected cortical regions on DIR images was graded independently by two neuroradiologists as definitely present (grade 2), probably present (grade 1), or definitely absent (grade 0). Ten additional patients with tumors underwent DIR imaging and intraoperative cortical mapping for further validation of the PMC. A myelin-stained brain specimen image in a patient not imaged with DIR was correlated with a representative set of DIR images. A triple-layer appearance was found in the PMC bilaterally in 184 of 191 patients; grade 0 was assigned in only seven patients, who were all younger than 10 years. Grades were significantly lower in patients younger than 10 years than in others (P .0018). Interobserver agreement was excellent (weighted kappa = 0.843). The PMC determined on DIR images was confirmed with cortical mapping in all 10 patients with tumors. Triple-layer appearance was not present in the other cortical regions examined, including the PSC (P < .01). The triple-layer appearance on DIR images corresponded to the myelin band within the PMC present on the myelin-stained specimen image. A triple-layer appearance was found in the PMC at thin-section 3.0-T DIR imaging but not in other examined brain regions and therefore might be useful as an adjunct sign for identification of motor regions.

  20. On an inverse source problem for enhanced oil recovery by wave motion maximization in reservoirs

    KAUST Repository

    Karve, Pranav M.; Kucukcoban, Sezgin; Kallivokas, Loukas F.

    2014-01-01

    to increase the mobility of otherwise entrapped oil. The goal is to arrive at the spatial and temporal description of surface sources that are capable of maximizing mobility in the target reservoir. The focusing problem is posed as an inverse source problem

  1. Thermal Management in Friction-Stir Welding of Precipitation-Hardening Aluminum Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Piyush; Reynolds, Anthony

    2015-05-25

    Process design and implementation in FSW is mostly dependent on empirical information gathered through experience. Basic science of friction stir welding and processing can only be complete when fundamental interrelationships between process control parameters and response variables and resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters like tool rotation and translation rate and forge axis force have complicated and interactive relationships to the process response variables such as peak temperature, time at temperature etc. Of primary influence to the other process response parameters are temperature and its gradient at the deformation and heat affected zones. Through review of pertinent works in the literature and some experimental results from boundary condition work performed in precipitation hardening aluminum alloys this paper will partially elucidate the nature and effects of temperature transients caused by variation of thermal boundaries in Friction Stir Welding.

  2. Spatially resolved positron annihilation spectroscopy on friction stir weld induced defects.

    Science.gov (United States)

    Hain, Karin; Hugenschmidt, Christoph; Pikart, Philip; Böni, Peter

    2010-04-01

    A friction stir welded (FSW) Al alloy sample was investigated by Doppler broadening spectroscopy (DBS) of the positron annihilation line. The spatially resolved defect distribution showed that the material in the joint zone becomes completely annealed during the welding process at the shoulder of the FSW tool, whereas at the tip, annealing is prevailed by the deterioration of the material due to the tool movement. This might be responsible for the increased probability of cracking in the heat affected zone of friction stir welds. Examination of a material pairing of steel S235 and the Al alloy Silafont36 by coincident Doppler broadening spectroscopy (CDBS) indicates the formation of annealed steel clusters in the Al alloy component of the sample. The clear visibility of Fe in the CDB spectra is explained by the very efficient trapping at the interface between steel cluster and bulk.

  3. Origin of unusual fracture in stirred zone for friction stir welded 2198-T8 Al-Li alloy joints

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Y. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Ni, D.R., E-mail: drni@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Xiao, B.L.; Ma, Z.Y. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wu, W.; Zhang, R.X. [AVIC Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024 (China); Zeng, Y.S., E-mail: yszeng@hotmail.com [AVIC Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024 (China)

    2017-05-02

    Friction stir welded (FSW) joints of conventional precipitation-hardened aluminum alloys usually fracture in the lowest hardness zone (LHZ) during tension testing. However, all of the FSW joints of a 2198-T8 Al-Li alloy fractured in the stirred zone (SZ) instead of the LHZ with the welding parameters of 800 rpm-200 mm/min and 1600 rpm-200 mm/min under the condition that no welding defects existed in the SZ. The experiment results revealed that lazy S was not the dominant factor resulting in the unusual fracture. The SZ consisted of three subzones, i.e., the shoulder-affected zone, the pin-affected zone, and the transition zone between them. While the former two zones were characterized by fine and equiaxed recrystallized grains, incompletely dynamically recrystallized microstructure containing coarse elongated non-recrystallized grains was observed in the transition zone. The transition zone exhibited the lowest average Taylor factor in the SZ, resulting in a region that was crystallographically weak. Furthermore, obvious lithium segregation at grain boundaries was observed in the transition zone via time-of-flight secondary ion mass spectroscopy analysis, but not in the shoulder-affected zone or the pin-affected zone. The combined actions of both the two factors resulted in the appearance of preferential intergranular fracture in the transition zone and eventually caused the failure in the SZ. The lithium segregation at grain boundaries in the transition zone was closely associated with both the segregation in the base material and the partially dynamically recrystallized microstructure resulting from the inhomogeneous plastic deformation in the SZ.

  4. Origin of unusual fracture in stirred zone for friction stir welded 2198-T8 Al-Li alloy joints

    International Nuclear Information System (INIS)

    Tao, Y.; Ni, D.R.; Xiao, B.L.; Ma, Z.Y.; Wu, W.; Zhang, R.X.; Zeng, Y.S.

    2017-01-01

    Friction stir welded (FSW) joints of conventional precipitation-hardened aluminum alloys usually fracture in the lowest hardness zone (LHZ) during tension testing. However, all of the FSW joints of a 2198-T8 Al-Li alloy fractured in the stirred zone (SZ) instead of the LHZ with the welding parameters of 800 rpm-200 mm/min and 1600 rpm-200 mm/min under the condition that no welding defects existed in the SZ. The experiment results revealed that lazy S was not the dominant factor resulting in the unusual fracture. The SZ consisted of three subzones, i.e., the shoulder-affected zone, the pin-affected zone, and the transition zone between them. While the former two zones were characterized by fine and equiaxed recrystallized grains, incompletely dynamically recrystallized microstructure containing coarse elongated non-recrystallized grains was observed in the transition zone. The transition zone exhibited the lowest average Taylor factor in the SZ, resulting in a region that was crystallographically weak. Furthermore, obvious lithium segregation at grain boundaries was observed in the transition zone via time-of-flight secondary ion mass spectroscopy analysis, but not in the shoulder-affected zone or the pin-affected zone. The combined actions of both the two factors resulted in the appearance of preferential intergranular fracture in the transition zone and eventually caused the failure in the SZ. The lithium segregation at grain boundaries in the transition zone was closely associated with both the segregation in the base material and the partially dynamically recrystallized microstructure resulting from the inhomogeneous plastic deformation in the SZ.

  5. Optimization of Friction Stir Welding Tool Advance Speed via Monte-Carlo Simulation of the Friction Stir Welding Process.

    Science.gov (United States)

    Fraser, Kirk A; St-Georges, Lyne; Kiss, Laszlo I

    2014-04-30

    Recognition of the friction stir welding process is growing in the aeronautical and aero-space industries. To make the process more available to the structural fabrication industry (buildings and bridges), being able to model the process to determine the highest speed of advance possible that will not cause unwanted welding defects is desirable. A numerical solution to the transient two-dimensional heat diffusion equation for the friction stir welding process is presented. A non-linear heat generation term based on an arbitrary piecewise linear model of friction as a function of temperature is used. The solution is used to solve for the temperature distribution in the Al 6061-T6 work pieces. The finite difference solution of the non-linear problem is used to perform a Monte-Carlo simulation (MCS). A polynomial response surface (maximum welding temperature as a function of advancing and rotational speed) is constructed from the MCS results. The response surface is used to determine the optimum tool speed of advance and rotational speed. The exterior penalty method is used to find the highest speed of advance and the associated rotational speed of the tool for the FSW process considered. We show that good agreement with experimental optimization work is possible with this simplified model. Using our approach an optimal weld pitch of 0.52 mm/rev is obtained for 3.18 mm thick AA6061-T6 plate. Our method provides an estimate of the optimal welding parameters in less than 30 min of calculation time.

  6. Theoretical modeling for optimizing horizontal production well placement in thermal recovery environments to maximize recovery

    Energy Technology Data Exchange (ETDEWEB)

    Bourgeois, D.J. [Schlumberger Canada Ltd., Calgary, AB (Canada)

    2008-07-01

    Heavy oil has a high viscosity and a low API gravity rating. Since it is difficult to get a fluid of this nature to flow, enhanced oil recovery techniques are required to extract the oil from the reservoir. Thermal recovery strategies such as steam assisted gravity drainage (SAGD) and cyclic steam injection stimulation (CSS) can be used. These techniques involve injecting steam into a formation which heats up the fluid in place decreasing its viscosity and allowing it to flow into the producing well bore. In order to maximize hydrocarbon recovery from this type of geological environment, the placement of the horizontal production well bore relative to the base of the reservoir is important. In conventional oil and gas plays, well placement methods involving directional deep resistivity logging while drilling (DDR-LWD) measurements to map formation contacts while drilling have enabled wells to be placed relative to formation boundaries. This paper discussed a study that presented some theoretical resistivity inversion and forward modeling results generated from a three-dimensional geocellular model to confirm that this evolving DDR-LWD technology may be applicable to western Canada's Athabasca heavy oil drilling environments. The paper discussed the effect of well bore position, thermal recovery, and pro-active well placement. Resistivity modeling work flow was also presented. It was concluded that being able to drill a horizontal production well relative to the base of the formation could help minimize abandoned oil ultimately leading to better recovery. 4 refs., 8 figs.

  7. Experimental and kinetic modeling study of 3-methylheptane in a jet-stirred reactor

    KAUST Repository

    Karsenty, Florent

    2012-08-16

    Improving the combustion of conventional and alternative fuels in practical applications requires the fundamental understanding of large hydrocarbon combustion chemistry. The focus of the present study is on a high-molecular-weight branched alkane, namely, 3-methylheptane, oxidized in a jet-stirred reactor. This fuel, along with 2-methylheptane, 2,5-dimethylhexane, and n-octane, are candidate surrogate components for conventional diesel fuels derived from petroleum, synthetic Fischer-Tropsch diesel and jet fuels derived from coal, natural gas, and/or biomass, and renewable diesel and jet fuels derived from the thermochemical treatment of bioderived fats and oils. This study presents new experimental results along with a low- and high-temperature chemical kinetic model for the oxidation of 3-methylheptane. The proposed model is validated against these new experimental data from a jet-stirred reactor operated at 10 atm, over the temperature range of 530-1220 K, and for equivalence ratios of 0.5, 1, and 2. Significant effort is placed on the understanding of the effects of methyl substitution on important combustion properties, such as fuel reactivity and species formation. It was found that 3-methylheptane reacts more slowly than 2-methylheptane at both low and high temperatures in the jet-stirred reactor. © 2012 American Chemical Society.

  8. Effect of process parameters on microstructure and mechanical properties of friction stir welded joints: A review

    Science.gov (United States)

    Wanare, S. P.; Kalyankar, V. D.

    2018-04-01

    Friction stir welding is emerging as a promising technique for joining of lighter metal alloys due to its several advantages over conventional fusion welding processes such as low thermal distortion, good mechanical properties, fine weld joint microstructure, etc. This review article mainly focuses on analysis of microstructure and mechanical properties of friction stir welded joints. Various microstructure characterization techniques used by previous researchers such as optical microscopes, x-ray diffraction, electron probe microscope, transmission electron microscope, scanning electron microscopes with electron back scattered diffraction, electron dispersive microscopy, etc. are thoroughly overviewed and their results are discussed. The effects of friction stir welding process parameters such as tool rotational speed, welding speed, tool plunge depth, axial force, tool shoulder diameter to tool pin diameter ratio, tool geometry etc. on microstructure and mechanical properties of welded joints are studied and critical observations are noted down. The microstructure examination carried out by previous researchers on various zones of welded joints such as weld zone, heat affected zone and base metal are studied and critical remarks have been presented. Mechanical performances of friction stir welded joints based on tensile test, micro-hardness test, etc. are discussed. This article includes exhaustive literature review of standard research articles which may become ready information for subsequent researchers to establish their line of action.

  9. Effect of density step on stirring properties of a strain flow

    International Nuclear Information System (INIS)

    Gonzalez, M; Paranthoen, P

    2009-01-01

    The influence of steep density gradient on stirring properties of a strain flow is addressed by considering the problem in which an interface separating two regions with different constant densities is stabilized within a stagnation-point flow. The existence of an analytic solution for the two-dimensional incompressible flow field allows the exact derivation of the velocity gradient tensor and of parameters describing the local flow topology. Stirring properties are affected not only by vorticity production and jump of strain intensity at the interface, but also by rotation of strain principal axes resulting from anisotropy of pressure Hessian. The strain persistence parameter, which measures the respective effects of strain and effective rotation (vorticity plus rotation rate of strain basis), reveals a complex structure. In particular, for large values of the density ratio, it indicates dominating effective rotation in a restricted area past the interface. Information on flow structure derived from the Okubo-Weiss parameter, by contrast, is less detailed. The influence of the density step on stirring properties is assessed by the Lagrangian evolution of the gradient of a passive scalar. Even for a moderate density ratio, alignment of the scalar gradient and growth rate of its norm are deeply altered. Past the interface effective rotation indeed drives the scalar gradient to align with a direction determined by the local strain persistence parameter, away from the compressional strain direction. The jump of strain intensity at the interface, however, opposes the lessening effect of the latter mechanism on the growth rate of the scalar gradient norm and promotes the rise of the gradient.

  10. Prediction of mechanical properties in friction stir welds of pure copper

    International Nuclear Information System (INIS)

    Heidarzadeh, A.; Saeid, T.

    2013-01-01

    Highlights: • Range of parameters for defect-free friction stir welded pure copper was reached. • Models were developed for predicting UTS, TE and hardness of pure copper joints. • Analysis of variance was used to validate the developed models. • Effect of welding parameters on mechanical behavior of welded joints was explored. • The microstructure and fracture surface of welded joints were investigated. - Abstract: This research was carried out to predict the mechanical properties of friction stir welded pure copper joints. Response surface methodology based on a central composite rotatable design with three parameters, five levels, and 20 runs, was used to conduct the experiments and to develop the mathematical regression model by using of Design-Expert software. The three welding parameters considered were rotational speed, welding speed, and axial force. Analysis of variance was applied to validate the predicted models. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters on mechanical properties of friction stir welded joints were analyzed in detail. The results showed that the developed models were reasonably accurate. The increase in welding parameters resulted in increasing of tensile strength of the joints up to a maximum value. Elongation percent of the joints increased with increase of rotational speed and axial force, but decreased by increasing of welding speed, continuously. In addition, hardness of the joints decreased with increase of rotational speed and axial force, but increased by increasing of welding speed. The joints welded at higher heat input conditions revealed more ductility fracture mode

  11. Efficacy of double inversion recovery magnetic resonance imaging for the evaluation of the synovium in the femoro-patellar joint without contrast enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Son, Ye Na; Jin, Wook; Jahng, Geon-Ho; Park, Yong Sung; Park, So Young [Kyung Hee University School of Medicine, Department of Radiology, Kyung Hee University Hospital at Gangdong, Seoul (Korea, Republic of); Cha, Jang Gyu [Soonchunhyang University Bucheon Hospital, Department of Radiology, Bucheon-si, Gyeonggi-do (Korea, Republic of); Yun, Seong Jong [Kyung Hee University School of Medicine, Department of Radiology, Kyung Hee University Hospital at Gangdong, Seoul (Korea, Republic of); Department of Radiology, Aerospace Medical Center, Republic of Korea Air Force, Cheongwon-gun, Chungcheongbuk-do (Korea, Republic of); Park, Ji Seon; Ryu, Kyung Nam [Kyung Hee University Hospital, Department of Radiology, Seoul (Korea, Republic of)

    2018-02-15

    To investigate the efficacy of double inversion recovery (DIR) sequence for evaluating the synovium of the femoro-patellar joint without contrast enhancement (CE). Two radiologists independently evaluated the axial DIR and CE T1-weighted fat-saturated (CET1FS) images of 33 knees for agreement; the visualisation and distribution of the synovium were evaluated using a four-point visual scaling system at each of the five levels of the femoro-patellar joint and the location of the thickest synovium. The maximal synovial thickness at each sequence was measured by consensus. The interobserver agreement was good (κ = 0.736) for the four-point scale, and was excellent for the location of the thickest synovium on DIR and CET1FS (κ = 0.955 and 0.954). The intersequential agreement for the area with the thickest synovium was also excellent (κ = 0.845 and κ = 0.828). The synovial thickness on each sequence showed excellent correlation (r = 0.872). The DIR showed as good a correlation as CET1FS for the evaluation of the synovium at the femoro-patellar joint. DIR may be a useful MR technique for evaluating the synovium without CE. (orig.)

  12. Clinical value of periventricular low-intensity areas detected by fluid attenuated inversion recovery (FLAIR). Relationships between perinatal vital parameter and neonatal MRI

    Energy Technology Data Exchange (ETDEWEB)

    Kadowaki, Sachiko; Iwata, Osuke; Tamura, Masanori [Nagano Children' s Hospital, Toyoshina (Japan)] (and others)

    2002-01-01

    A follow-up study was performed to assess the correlation among the incidence of periventricular low intensities (PVLI) on MRI (magnetic resonance imaging) FLAIR (fluid attenuated inversion recovery) imaging, clinical evidence of perinatal insults that may cause white matter damage, and the outcome of the infants. We evaluated periventricular white matter lesions of 329 neonates whose MRI were obtained before two months corrected age. The detective rate of periventricular abnormalities on FLAIR imaging was significantly higher than that of T1-T2 weighted imaging. The most typical lesion detected on FLAIR imaging was periventricular low intensities (PVLI), frequently observed in the neonates with a history of preterm labour, very low birth weight, birth asphyxia and severe respiratory failure. Although we could not characterize the risk factors of PVLI, the incidence of PVLI had a strong correlation with the scores of motor and developmental tests at 12 and 36-months corrected age. In conclusion, FLAIR imaging, detecting the border zone damage of white matter, would be a strong tool to pick out neonates at high risk of neurological disturbances from those without clinical evidence of neurological insults in the neonatal period. (author)

  13. Adaptive Controller Design for Continuous Stirred Tank Reactor

    OpenAIRE

    K. Prabhu; V. Murali Bhaskaran

    2014-01-01

    Continues Stirred Tank Reactor (CSTR) is an important issue in chemical process and a wide range of research in the area of chemical engineering. Temperature Control of CSTR has been an issue in the chemical control engineering since it has highly non-linear complex equations. This study presents problem of temperature control of CSTR with the adaptive Controller. The Simulation is done in MATLAB and result shows that adaptive controller is an efficient controller for temperature control of C...

  14. Friction stir weld-bonding defect inspection using phased array ultrasonic testing

    NARCIS (Netherlands)

    Fortunato, J.; Anand, C.; Braga, Daniel F.O.; Groves, R.M.; Moreira, P. M.G.P.; Infante, V

    2017-01-01

    Weight reduction is an important driver of the aerospace industry, which encourages the development of lightweight joining techniques to substitute rivet joints. Friction stir welding (FSW) is a solid-state process that enables the production of lighter joints with a small performance reduction

  15. Effect of Welding Speed on Microstructure and Mechanical Properties due to The Deposition of Reinforcements on Friction Stir Welded Dissimilar Aluminium Alloys

    Directory of Open Access Journals (Sweden)

    Baridula Ravinder Reddy

    2017-01-01

    Full Text Available The strength of the welded joint obtained by solid state stir welding process was found to be improved as compared to fusion welding process. The deposition of reinforcements during friction stir welding process can further enhance the strength of the welded joint by locking the movement of grain boundaries. In the present study, the aluminium alloys AA2024 and AA7075 were welded effectively by depositing the multi-walled carbon nanotubes in to the stir zone. The mechanical properties and microstructures were studied by varying the traverse speed at constant rotational speed. The results show that rotating tool pin stirring action and heat input play an important role in controlling the grain size. The carbon nanotubes were found to be distributed uniformly at a welding speed (traverse speed of 80mm/min. This enhanced the mechanical properties of the welded joint. The microstructure and Electron dispersive X-ray analysis (EDX studies indicate that the deposition of carbon nanotubes in the stir zone was influenced by the traverse speed.

  16. Thermal analysis of friction stir welding process and investigation into affective parameters using simulation

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Mahmoud [University of Kashan, Kashan (Iran, Islamic Republic of); Bagheri, Behrouz [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Keivani, Rasoul [Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2015-02-15

    Friction stir welding (FSW) as an efficient solid state joining process has numerous applications in industries. Temperature distribution analysis through simulation not only brings the possibility to characterize the microstructure of different zones, but also enables one to save cost and energy as optimum welding variables are obtained with less concern. In the present study, the temperature distribution during the friction stir welding (FSW) process of AA6061-T6 was evaluated using finite element method (FEM). Since experimental measurements cannot be readily made in the weld region, it is difficult to understand physics in the stir zone of the welds without simulation. Abaqus software was applied to model the parts and simulate the process of welding, while Johnson-Cook law utilized to evaluate the effect of strain rate and generated heat. FE-results were verified by experimental results. The comparisons revealed a good compatibility between the results. The effect of probe shape on temperature distribution was also studied. It was found that spherical pins result in the highest temperatures at workpieces with respect to cylindrical and tapered pins. Additionally, it was concluded that more heat is generated in workpieces as pin angle increases.

  17. Effect of Heat Exposure on the Fatigue Properties of AA7050 Friction Stir Welds

    Science.gov (United States)

    White, B. C.; Rodriguez, R. I.; Cisko, A.; Jordon, J. B.; Allison, P. G.; Rushing, T.; Garcia, L.

    2018-05-01

    This work examines the effect of heat exposure on the subsequent monotonic and fatigue properties of friction stir-welded AA7050. Mechanical characterization tests were conducted on friction stir-welded specimens as-welded (AW) and specimens heated to 315 °C in air for 20 min. Monotonic testing revealed high joint efficiencies of 98% (UTS) in the AW specimens and 60% in the heat-damaged (HD) specimens. Experimental results of strain-controlled fatigue testing revealed shorter fatigue lives for the HD coupons by nearly a factor of four, except for the highest strain amplitude tested. Postmortem fractography analysis found similar crack initiation or propagation behavior between the AW and HD specimens; however, the failure locations for the AW were predominantly in the heat-affected zone, while the HD specimens also failed in the stir zone. Microhardness measurements revealed a relatively uniform strength profile in the HD group, accounting for the variety of failure locations observed. The differences in both monotonic and cyclic properties observed between the AW and HD specimens support the conclusion that the heat damage (315 °C at 20 min) acts as an over-aging and a quasi-annealing treatment.

  18. Thermal analysis of friction stir welding process and investigation into affective parameters using simulation

    International Nuclear Information System (INIS)

    Abbasi, Mahmoud; Bagheri, Behrouz; Keivani, Rasoul

    2015-01-01

    Friction stir welding (FSW) as an efficient solid state joining process has numerous applications in industries. Temperature distribution analysis through simulation not only brings the possibility to characterize the microstructure of different zones, but also enables one to save cost and energy as optimum welding variables are obtained with less concern. In the present study, the temperature distribution during the friction stir welding (FSW) process of AA6061-T6 was evaluated using finite element method (FEM). Since experimental measurements cannot be readily made in the weld region, it is difficult to understand physics in the stir zone of the welds without simulation. Abaqus software was applied to model the parts and simulate the process of welding, while Johnson-Cook law utilized to evaluate the effect of strain rate and generated heat. FE-results were verified by experimental results. The comparisons revealed a good compatibility between the results. The effect of probe shape on temperature distribution was also studied. It was found that spherical pins result in the highest temperatures at workpieces with respect to cylindrical and tapered pins. Additionally, it was concluded that more heat is generated in workpieces as pin angle increases.

  19. Development, optimisation and application of polyurethane foams as new polymeric phases for stir bar sorptive extraction.

    Science.gov (United States)

    Neng, N R; Pinto, M L; Pires, J; Marcos, P M; Nogueira, J M F

    2007-11-09

    In this contribution, polyurethane foams are proposed as new polymeric phases for stir bar sorptive extraction (SBSE). Assays performed for polyurethane synthesis demonstrated that four series of formulations (P(1), P(2), P(3) and P(4)) present remarkable stability and excellent mechanical resistance to organic solvents. For polymer clean-up treatment, acetonitrile proved to be the best solvent under sonification, ensuring the reduction of the contamination and interferences. SBSE assays performed on these polyurethane polymers followed by liquid desorption and high-performance liquid chromatography-diode array detection (LD-HPLC-DAD) or large volume injection-capillary gas chromatography-mass spectrometry (LD-LVI-GC-MS), showed that P(2) presents the best recovery yields for atrazine, 2,3,4,5-tetrachlorophenol and fluorene, used as model compounds in water samples at a trace level. SBSE(P(2)) assays performed on this polymer mixed up with several adsorbent materials, i.e. activated carbon, a mesoporous material and a calixarene, did not bring any advantages in relation with the polymeric matrix alone. The comparison between assays performed by SBSE(P(2)) and by the conventional SBSE(PDMS) showed much better performance for the former phase on aqueous samples spiked with atrazine, 2,3,4,5-tetrachlorophenol and fluorene, in which the foremost two analytes present recovery values 3- and 10-fold higher, respectively. The polyurethanes proposed as new polymeric phases for SBSE provided powerful capabilities for the enrichment of organic compounds from aqueous matrices, showing to be indicated mainly in the case of the more polar analytes.

  20. Effect of Water Cooling on the Performances of Friction Stir Welding Heat-Affected Zone

    Science.gov (United States)

    Zhang, H. J.; Liu, H. J.; Yu, L.

    2012-07-01

    The heat-affected zone (HAZ) is generally the intrinsic weakest location of the normal friction stir welded precipitate hardened aluminum alloys. In order to improve the mechanical properties of the HAZ by controlling the temperature level, underwater friction stir welding (FSW) of an Al-Cu aluminum alloy was conducted in the present study. The results indicate that the hardness of the HAZ can be improved through underwater FSW. Microstructural analysis reveals that the hardness improvement is attributed to the lowering of precipitate coarsening level and the narrowing of precipitate free zone, which are essentially induced by the variations of welding thermal cycles under the cooling effect of water.