Experimental Investigation of 3D Velocity by Tomographic Particle Image Velocimetry (Tomo-PIV) in a Short Riser Section

AbstractThe measurement of instantaneous velocity field with high spatial resolution makes the Tomo-PIV (tomographic particle image velocimetry) technique attractive for the study of complex flows in circulating beds. The Tomo-PIV technique is employed for obtaining the velocity field of the fluid phase in three dimensions using tracer particles which follow the fluid. They are immersed in the fluid and illuminated by a source of pulsed light (laser) within a three-dimensional region. Images of the particles are recorded in the focus of several viewing directions using CCD (Charge-Coupled Device) sensors. The distribution of light intensity is discretized into a 3D array of voxels and then analyzed by interrogation of cross-correlation in three dimensions. The information field is returned in the form of instantaneous velocities of the measurement volume. This paper aims to present an experimental setup for an initial investigation of the velocity field of the particulate phase of a riser section of a circulating bed. The calibration errors were between 0.209 and 0.066 pixels and after the self-calibration errors were below 0.097 pixels. The volume investigated was 82 x 100 x 10 mm3 with a resolution of 1571 x 897 x 113 voxels. The reconstructed volumes were processed using 3D cross-correlation with a volume interrogation size of 110 voxels decreasing to a final size of 16 voxels with a 75% overlap between adjacent interrogation volumes. The velocity field produced has 224 x 393 x 28 voxels

Comparison Of Downer And Riser Flows In A Circulating Bed By Means Of Optical Fiber Probe Signals Measurements

In this work, the riser (2.42 m high) and downer (0,85 m high) sections with an ID of 82 mm in both, were analyzed to study the temporal fluid dynamics properties of a circulating bed system in terms of electrical signals of particles concentration obtained by an optical fiber probe. Experiments were conducted using ambient air as the fluid phase and FCC (fluid catalytic cracking) particles as the solid phase. The measurements with the optical fiber probe were conducted in the inlet and outlet zones of both riser and downer. Signals were evaluated in the phase space (chaos analysis), by reconstructing the attractors and calculating the Kolmogorov entropy and the correlation dimension. Results show that the downer presents a less chaotic flow, with lower values of Kolmogorov entropy and correlation dimension, compared to the riser. In the entrance of the downer, the flow is less complex and more predictable in the center due to the effect of the solid feeder. The flow develops in direction of the exit zone and at that position there is no much difference in complexity between the central and wall. In the case of the riser, at the entrance effect is caused by a question of configuration, due to a presence of a curve, making the solid concentration increase toward the wall. In the exit zone, the flow suffers the effect of the abrupt exit. © 2012 Published by Elsevier Ltd.42295302Manyelle, S.V., Zhu, J.X., Khayat, R.E., Pärssinen, J.H., Analysis of the chaotic dynamics of a high-flux CFB riser using solids concentration measurements (2006) China Particuology, 4, pp. 136-146Zhang, H., Huang, W.X., Zhu, J.X., Gas-solids flow behavior: CFB riser vs. Downer (2001) AIChE Journal, 47, pp. 2000-2011Zhu, J.X., Yu, X.Q., Jin, Y.Y., Grace, J.R., Issangya, A.S., Cocurrent downflow circulating fluidized bed reactor A state of art review (1005) Can J Chem Eng, 73, pp. 667-677Zhu, J., Yan, A., Scale-up effect of riser reactors (1): Axial and radial solids concentration distribution and flow development (2004) Ind Eng Chem Res, 43, pp. 5810-5819Broomhead, D.S., King, G.P., Extracting qualitative dynamics from experimental data (1986) Physica 20D, pp. 217-236Schouten, J.C., Takens, F., Van Den Bleek, C.M., Estimation of the dimension of a noisy attractor (1994) Phys Rev e, 50, pp. 1851-1961Schouten, J.C., Takens, F., Van Den Bleek, C.M., Maximum likelihood estimation of the entropy of an attractor (1994) Phys Rev e, 49, pp. 126-129Manyele, S.V., Zhu, J., Zhang, H., Analysis of the microscopic flow Structure of a CFB downer reactor using solids concentration signals (2003) Int J Chem React Eng, 1, pp. A55Cheng, Y., Wei, F., Lin, Q., Jin, Y., A comparison of local chaotic behaviors in a riser and a downer (1998) Fluidization IX, pp. 613-620. , L.-S. Fan and T.M. Knowlton, editors, New York: Engineering Foundatio

The factor structure of the Forms of Self-Criticising/Attacking & Self-Reassuring Scale in thirteen distinct populations

There is considerable evidence that self-criticism plays a major role in the vulnerability to and recovery from psychopathology. Methods to measure this process, and its change over time, are therefore important for research in psychopathology and well-being. This study examined the factor structure of a widely used measure, the Forms of Self-Criticising/Attacking & Self-Reassuring Scale in thirteen nonclinical samples (N = 7510) from twelve different countries: Australia (N = 319), Canada (N = 383), Switzerland (N = 230), Israel (N = 476), Italy (N = 389), Japan (N = 264), the Netherlands (N = 360), Portugal (N = 764), Slovakia (N = 1326), Taiwan (N = 417), the United Kingdom 1 (N = 1570), the United Kingdom 2 (N = 883), and USA (N = 331). This study used more advanced analyses than prior reports: a bifactor item-response theory model, a two-tier item-response theory model, and a non-parametric item-response theory (Mokken) scale analysis. Although the original three-factor solution for the FSCRS (distinguishing between Inadequate-Self, Hated-Self, and Reassured-Self) had an acceptable fit, two-tier models, with two general factors (Self-criticism and Self-reassurance) demonstrated the best fit across all samples. This study provides preliminary evidence suggesting that this two-factor structure can be used in a range of nonclinical contexts across countries and cultures. Inadequate-Self and Hated-Self might not by distinct factors in nonclinical samples. Future work may benefit from distinguishing between self-correction versus shame-based self-criticism.Peer reviewe

Comparative outcomes for mature T-cell and NK/T-cell lymphomas in people with and without HIV and to AIDS-defining lymphomas

There are no studies comparing the prognosis for mature T-cell lymphoma (TCL) in people with HIV (PWH) to people without HIV (PWoH) and to AIDS-defining B-cell lymphomas (A-BCLs) in the modern antiretroviral therapy era. North American AIDS Cohort Collaboration on Research and Design and Comprehensive Oncology Measures for Peripheral T-cell Lymphoma Treatment are cohorts that enroll patients diagnosed with HIV and TCL, respectively. In our study, 52, 64, 101, 500, and 246 PWH with histologic confirmation of TCL, primary central nervous system lymphoma, Burkitt’s lymphoma, diffuse large B-cell lymphoma (DLBCL), and Hodgkin’s lymphoma (HL), respectively, and 450 TCLs without HIV were eligible for analysis. At the time of TCL diagnosis, anaplastic large-cell lymphoma (ALCL) was the most common TCL subtype within PWH. Although PWH with TCL diagnosed between 1996 and 2009 experienced a low 5-year survival probability at 0.23 (95% confidence interval [CI]: 0.13, 0.41), we observed a marked improvement in their survival when diagnosed between 2010 and 2016 (0.69; 95% CI: 0.48, 1; P = .04) in contrast to TCLs among PWoH (0.45; 95% CI: 0.41, 0.51; P = .53). Similarly, PWH with ALCLs diagnosed between 1996 and 2009 were associated with a conspicuously inferior 5-year survival probability (0.17; 95% CI: 0.07, 0.42) and consistently lagged behind A-BCL subtypes such as Burkitt’s (0.43; 95% CI:0.33, 0.57; P = .09) and DLBCL (0.17; 95% CI: 0.06, 0.46; P = .11) and behind HL (0.57; 95% CI: 0.50, 0.65; P < .0001). Despite a small number, those diagnosed between 2010 and 2016 experienced a remarkable improvement in survival (0.67; 95% CI: 0.3, 1) in comparison with PWoH (0.76; 95% CI: 0.66, 0.87; P = .58). Thus, our analysis confirms improved overall survival for aggressive B- and T-cell malignancies among PWH in the last decade

CD4/CD8 Ratio and Cancer Risk among Adults with HIV

Background: Independent of CD4 cell count, a low CD4/CD8 ratio in people with HIV (PWH) is associated with deleterious immune senescence, activation, and inflammation, which may contribute to carcinogenesis and excess cancer risk. We examined whether low CD4/CD8 ratios predicted cancer among PWH in the United States and Canada. Methods: We examined all cancer-free PWH with 1 or more CD4/CD8 values from North American AIDS Cohort Collaboration on Research and Design observational cohorts with validated cancer diagnoses between 1998 and 2016. We evaluated the association between time-lagged CD4/CD8 ratio and risk of specific cancers in multivariable, time-updated Cox proportional hazard models using restricted cubic spines. Models were adjusted for age, sex, race and ethnicity, hepatitis C virus, and time-updated CD4 cell count, HIV RNA, and history of AIDS-defining illness. Results: Among 83 893 PWH, there were 5628 incident cancers, including lung cancer (n = 755), Kaposi sarcoma (n = 501), non-Hodgkin lymphoma (n = 497), and anal cancer (n = 439). The median age at cohort entry was 43 years. The overall median 6-month lagged CD4/CD8 ratio was 0.52 (interquartile range = 0.30-0.82). Compared with a 6-month lagged CD4/CD8 of 0.80, a CD4/CD8 of 0.30 was associated with increased risk of any incident cancer (adjusted hazard ratio = 1.24 [95% confidence interval = 1.14 to 1.35]). The CD4/CD8 ratio was also inversely associated with non-Hodgkin lymphoma, Kaposi sarcoma, lung cancer, anal cancer, and colorectal cancer in adjusted analyses (all 2-sided P <. 05). Results were similar using 12-, 18-, and 24-month lagged CD4/CD8 values. Conclusions: A low CD4/CD8 ratio up to 24 months before cancer diagnosis was independently associated with increased cancer risk in PWH and may serve as a clinical biomarker