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Flow Rate Measurement (flow + rate_measurement)
Selected AbstractsTemperature effects on the mass flow rate in the SBI and similar heat-release rate test equipmentFIRE AND MATERIALS, Issue 1 2007Bart J. G. Sette Abstract In various medium-to-large-scale fire test equipments like the ISO room corner test (RC), and more recently, the single burning item test (SBI) the mass flow rate measurement of the combustion gases plays a key role in the determination of the heat-release rate and smoke-production rate. With the knowledge of the velocity profile and the temperature of the flow, the mass flow rate is obtained by measuring the velocity on the axis of the duct. This is done by means of a bi-directional probe based on the pitot principle. However, due to the variation of the mean temperature and the temperature gradient in any cross section of the duct, introduced by ever changing combustion gas temperatures, the velocity nor the density profile are constant in time. This paper examines the resulting uncertainty on the mass flow rate. Copyright © 2006 John Wiley & Sons, Ltd. [source] Prediction method of critical power by film flow rate measurement and subchannel analysisHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 5 2005Miyuki Akiba Abstract This paper presents a method that can estimate the critical power of boiling water reactors, BWRs, with regard to spacer geometry. The current experimental method for estimating the critical power for BWR design requires many trained experts and expensive facilities to conduct the experiments. In the present method, the liquid film flow rate of adiabatic gas-liquid two-phase flow and a subchannel analysis of the actual BWR flow condition are measured experimentally and analyzed. In the experiment, deposition enhancement coefficients of three spacer geometries,a ferrule, an egg-crate, and a ferrule spacer with twisted tape (CYCLONE spacer),were estimated by measuring the liquid film flow rate of air-water two-phase flow flowing up in a vertical square (4 × 4) rod bundle that simulated the rod bundle of a BWR. Using these coefficients, the critical powers for bundles using each type of spacer geometry were calculated in the subchannel analysis. This method was validated using previous critical power data in the actual BWR flow condition. The critical powers predicted by this method agreed well with those of the experimental data. The result confirmed the effectiveness of this experiment-simulation combined method, as well as the advantage over current experimental methods in terms of human and facility costs. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(5): 309,323, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20069 [source] Color inhibition of phenolic antioxidants in Ziegler-Natta polyethylene.JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 1 2009Although the level of transition-metal catalyst residues in polyethylene (PE) has been drastically reduced over the years, they can still give rise to discoloration, particularly when associated with other additives such as antioxidants. This first of this series of papers screens a variety of candidate color suppressants featuring a range of functional groups, including alcohols, amine/sulfur compounds, and acid-containing species. These candidate color suppressants were melt-blended into a Ziegler-Natta linear low-density PE in combination with 2,2,-isobutylidenebis(4,6-dimethylphenol) (a highly discoloring hindered bisphenol antioxidant) and zinc stearate antacid. Yellowness index measurements made after multiple extruder passes indicated that dipentaerythritol (DPE) and triisopropylamine (TIPA) gave good color inhibition and, in some cases, outperformed established phosphites. The DPE and TIPA were found (via melt flow rate measurement) not to affect melt stability, and hydroperoxide determination revealed that DPE had no peroxide decomposition activity. The latter results indicate that the color-suppression mechanism of DPE and TIPA is different from that associated with phosphites. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers [source] Preoperative urodynamic and symptom evaluation of patients undergoing transurethral prostatectomy: analysis of variables relevant for outcomeBJU INTERNATIONAL, Issue 4 2003O.W. Hakenberg OBJECTIVE To assess the value of preoperative symptom score assessment and pressure-flow measurement in men undergoing transurethral prostatectomy (TURP). PATIENTS AND METHODS In a prospective study, 95 men (mean age 74.3 years) scheduled for TURP because of their lower urinary tract symptoms, flow rates and urinary residual volumes were assessed using the self-administered International Prostate Symptom Score (IPSS) and urodynamic pressure-flow studies. At 3 months after TURP the patients were reassessed with a flow rate measurement and the IPSS. The baseline IPSS and urodynamic values were analysed with respect to the endpoints of the study, flow rate and IPSS after TURP, and the improvements thereof, respectively. RESULTS There were significant improvements in mean IPSS (, 10.87 points) and peak flow rate (+ 7.06 mL/s) 3 months after TURP. Classifying the patients into subgroups with distinctly different initial values for IPSS, flow rate, residual urine volume and degree of obstruction (as expressed by Abrams-Griffiths number) showed that the flow rate and degree of obstruction influenced the improvement in flow rate but not in symptoms after TURP. Symptom improvement was only related to the initial level of symptoms. In a multivariate analysis, only age was an independent predictor of the outcome variables of flow rate and symptoms. CONCLUSIONS Clinical decision-making remains a valid instrument for selecting patients for TURP. Both the IPSS and pressure-flow assessment are useful to exclude patients who are unlikely to benefit from TURP. Age is an important predictor of the improvement in symptoms and flow rates after TURP for the lower urinary tract symptom complex associated with benign prostatic enlargement. [source] A prospective study of conservatively managed acute urinary retention: prostate size mattersBJU INTERNATIONAL, Issue 7 2000V. Kumar Objective To evaluate in a prospective study the medium- to long-term outcome of a policy of conservatively managing acute urinary retention (AUR), arising solely by bladder outlet obstruction caused by benign prostatic enlargement (BPE), and to identify the factors favouring a positive outcome of a trial without catheter (TWOC). Patients and methods All men admitted as an emergency with primary AUR caused by BPE (from August 1997 to March 2000) underwent a TWOC. The following variables were recorded; the nature and duration of any preceding lower urinary tract symptoms, previous episodes of retention, concomitant anticholinergic medication, coexisting constipation, alcohol as a precipitating cause of AUR, previous prostatectomy, confirmed urinary tract infection, residual urine drained on catheterization and prostate size, as determined by a digital rectal examination (DRE) carried out by one consultant urologist in all patients. Those voiding successfully were followed up prospectively using the International Prostate Symptom Score (IPSS), quality-of-life score, urinary flow rate measurement and ultrasonographic measurement of the postvoid residual (PVR). Results Of the 40 men with AUR, 22 (55%) voided spontaneously after removing the catheter and continued to do so with mean peak flow rates of 12.2 mL/s and mean PVRs of 69.6 mL over a follow-up of 8,24 months. These patients remained asymptomatic, with a mean IPSS of 5.2 and quality-of-life score of 0.9. These men had a mean prostatic size of 15.9 g and a mean catheterized residual volume of 814 mL, while in those who had an unsuccessful TWOC the mean prostate size was 27.5 g (P = 0.006) and a mean catheterized residual volume of 1062 mL (P = 0.09). Prostate size as assessed by the DRE was the most significant factor in predicting the outcome of a TWOC. Conclusion A TWOC is justified in the long-term for men presenting with AUR caused by BPE. Prostate size is the most important factor for predicting the outcome of such a trial. [source] Monolithic poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for simultaneous separation of low- and high-molecular-weight compoundsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15-16 2009Andreas Greiderer Abstract Monolithic poly(1,2-bis(p -vinylphenyl)ethane (BVPE)) capillary columns were prepared by thermally initiated free radical polymerisation of 1,2-bis(p -vinylphenyl)ethane in the presence of inert diluents (porogens) and ,,,,-azoisobutyronitrile (AIBN) as initiator. Polymerisations were accomplished in 200 ,m ID fused silica capillaries at 65°C and for 60 min. Mercury intrusion porosimetry measurements of the polymeric RP support showed a broad bimodal pore-size-distribution of mesopores and small macropores in the range of 5,400 nm and flow-channels in the ,m range. N2 -adsorption (BET) analysis resulted in a tremendous enhancement of surface area (101 m2/g) of BVPE stationary phases compared to typical organic monoliths (,20 m2/g), indicating the presence of a considerable amount of mesopores. Consequently, the adequate proportion of both meso- and (small) macropores allowed the rapid and high-resolution separation of low-molecular-weight compounds as well as biomolecules on the same monolithic support. At the same time, the high fraction of flow-channels provided enhanced column permeability. The chromatographic performance of poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for the separation of biomolecules (proteins, oligonucleotides) and small molecules (alkyl benzenes, phenols, phenons) are demonstrated in this article. Additionally, pressure drop versus flow rate measurements of novel poly(1,2-bis(p -vinylphenyl)ethane) capillary columns confirmed high mechanical robustness, low swelling in organic solvents and high permeability. Due to the simplicity of monolith fabrication, comprehensive studies of the retention and separation behaviour of monolithic BVPE columns resulted in high run-to-run and batch-to-batch reproducibilities. All these attributes prove the excellent applicability of monolithic poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for ,-HPLC towards a huge range of analytes of different chemistries and molecular sizes. [source] Assessment of Salivary Flow Rate: Biologic Variation and Measure Error,THE LARYNGOSCOPE, Issue 10 2004Peter H. Jongerius MD Abstract Objective: To investigate the applicability of the swab method in the measurement of salivary flow rate in multiple-handicap drooling children. To quantify the measurement error of the procedure and the biologic variation in the population. Study Design: Cohort study. Methods: In a repeated measurements design, a baseline series of salivary flow rates were obtained from 45 children. The within-subject SD (SW) was calculated to express the measurements error according to a procedure introduced by Bland and Altman. Results: Two hundred twenty-four samples (mean 0.40 mL/min, SD 0.19 mL/min) were obtained and analyzed. The results of this study indicate that consistent scores were obtained at subsequent measurements, and good parity existed between the two measurements of salivary flow rate at each session. The SW could be estimated (0.11 mL/min), which was applied to quantify the specific variation of the salivary flow rate in our population. Conclusion: According to Bland and Altman, the SW, which is a quantification of the measurement error and biologic variation, was found to be a useful tool to evaluate the obtained baseline salivary flow rate measurements. The swab method can be used to evaluate salivary flow rates in drooling children with cerebral palsy during interventional studies that aim to reduce saliva production. [source] Blood flow rate measurements with indicator techniques revisitedCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 6 2009Per Sejrsen Summary In view of the emerging role, disturbances in regional blood flow rate seem to play in the pathogenesis of the metabolic syndrome; we review the concepts of the classical indicator dilution and washout techniques used for determinations of regional blood flow rate. Prerequisites, assumptions, necessary precautions for the application of these experimental techniques are emphasized. Special attention has been carried out to elucidate the consequence of a choice of indicators having a large distribution volume in the tissues. [source] Causative or precipitating aspects of burning mouth syndrome: a case,control studyJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 8 2006Andrea Sardella Background:, On causative or precipitating causes of burning mouth syndrome (BMS), there is a lack of consensus. In this prospective case,control study, we compared clinical features and laboratory aspects to evaluate the association of the proposed causative/precipitating factors of BMS. Methods:, A total of 61 BMS patients and 54 control subjects underwent several evaluations: rest and stimulated salivary flow rates measurements, laboratory tests, isolation of Candida species, assessment of parafunctional activities, detection of anxiety and depression by means of the Hospital Anxiety and Depression Scale. Odds ratio and 95% confidence interval were calculated to compare the variables. Results:, No statistically significant differences were found with regard to the tested variables except for anxiety and depression. Conclusions:, The results of this study seem not to support a role for the usually reported causative or precipitating factors of BMS and efforts should be addressed towards different aetiologies including possible neuropathic mechanisms of BMS. [source] | |||||||||||||