Flow characteristics of Newtonian and non-Newtonian fluids in a vessel stirred by a 60° pitched blade impeller

Mean and rms velocity characteristics of two Newtonian flows at Reynolds numbers of 12,800 (glycerin solution) and 48,000 (water) and of a non-Newtonian flow (0.2% CMC solution, at a power number similar to the Newtonian glycerin flow) in a mixing vessel stirred by a 60° pitched blade impeller have been measured by laser Doppler velocimetry (LDV). The velocity measurements, resolved over 360° and 1.08° of impeller rotation, showed that the mean flow of the two power number matched glycerin and CMC flows were similar to within 3% of the impeller tip velocity and the turbulence intensities generally lower in the CMC flow by up to 5% of the tip velocity. The calculated mean flow quantities showed similar discharge coefficient and pumping efficiency in all three flows and similar strain rate between the two power number matched glycerin and CMC flows; the strain rate of the higher Reynolds number Newtonian flow was found to be slightly higher. The energy balance around the impeller indicated that the CMC flow dissipated up to 9% more of the total input power and converted 7% less into the turbulence compared to the glycerin flow with the same power input which could lead to less effective mixing processes where the micro-mixing is important

Single and two-phase flows in ducts and stirred reactors

Imperial Users onl

Association between sleep duration and metabolic syndrome in a population-based study: Isfahan Healthy Heart Program

Abstract BACKGROUND: Recent epidemiologic studies have found that self-reported sleep duration is associated with components of metabolic syndrome (MS) such as obesity, diabetes and hypertension. This relation may be under influence of regional factors in different regions of the world. The association of sleep duration and MS in a sample of Iranian people in the central region of Iran was investigated in this study

Predictions of Vortex Flow in a Diesel Multi-Hole Injector Using the RANS Modelling Approach

The occurrence of vortices in the sac volume of automotive multi-hole fuel injectors plays an important role in the development of vortex cavitation, which directly influences the flow structure and emerging sprays that, in turn, influence the engine performance and emissions. In this study, the RANS-based turbulence modelling approach was used to predict the internal flow in a vertical axis-symmetrical multi-hole (6) diesel fuel injector under non-cavitating conditions. The project aimed to predict the aforementioned vortical structures accurately at two different needle lifts in order to form a correct opinion about their occurrence. The accuracy of the simulations was assessed by comparing the predicted mean axial velocity and RMS velocity of LDV measurements, which showed good agreement. The flow field analysis predicted a complex, 3D, vortical flow structure with the presence of different types of vortices in the sac volume and the nozzle hole. Two main types of vortex were detected: the “hole-to-hole” connecting vortex, and double “counter-rotating” vortices emerging from the needle wall and entering the injector hole facing it. Different flow patterns in the rotational direction of the “hole-to-hole” vortices have been observed at the low needle lift (anticlockwise) and full needle lift (clockwise), due to their different flow passages in the sac, causing a much higher momentum inflow at the lower lift with its much narrower flow passage

Association between sleep duration and metabolic syndrome in a population-based study: Isfahan Healthy Heart Program

Background: Recent epidemiologic studies have found that self-reported sleep duration is associated with components of metabolic syndrome (MS) such as obesity, diabetes and hypertension. This relation may be under influence of regional factors in different regions of the world. The association of sleep duration and MS in a sample of Iranian people in the central region of Iran was investigated in this study. Methods: This cross-sectional study was conducted as a part of the Isfahan Healthy Heart Program (IHHP). A total of 12492 individuals aged over 19 years, 6110 men and 6382 women entered the study. Definition of National Cholesterol Education Program was used to define MS. Sleep duration was reported by participants. Relation between sleep duration with MS was examined using categorical logistic regression in two models; unadjusted and adjusted for age and sex. Results: In our study, 23.5 % of participants had MS. Compared with sleep duration of 7-8 hours per night; sleep duration of less than 5 hours was associated with a higher odds ratio for MS. This association remained significant even after adjustment for age and sex (OR: 1.52; 95%CI: 1.33-1.74). However, sleep duration of 9 hours or more showed a protective association with MS (OR: 0.79; 95%CI: 0.68-0.94). Conclusions: There was a positive relation between sleep deprivation and MS and its components. This relation was slightly affected by sex and age

Improved minimum volume simplex analysis algorithm for unmixing of hyperspectral data

Some of the robust and high-ability processing methods like the improved Minimum Simplex Volume Analysis (MVSA) algorithm are generally time-consuming in hyperspectral data dealing especially the ground resolution is higher. In this research, MVSA was conducted for spectral analysis of HyMap and Hyperion data after a proposed data reduction to overcome the mentioned problem. The data cloud was therefore clustered based on the spectral angle mapper and Multi-Attribute Decision Making (MADM) based methods were used to determine the best threshold angle. Consequently, four indicators were applied as evaluation attributes for selecting the appropriate alternative, and “Technique for Order Preference by Similarity to Ideal Solution (TOPSIS)” and “ELimination Et Choice Translating REality (ELECTRE)” were employed to finalize the decision. The methods resulted in 0.8 and 1.3 degrees as optimal spectral angles for HyMap and Hyperion, respectively. In this case, the image processing computational burden and the noise effect were considerably alleviated and the procedure led to accurate endmember identification

Relation between usual daily walking time and metabolic syndrome

Background: There are several studies about the positive relation between physical inactivity or low cardio respiratory fitness with development of metabolic syndrome (MS). In contrast, physical activity had favourable effects on all components of MS but the quantity and the frequency of physical activity necessary to produce this beneficial effect has not been defined as yet. The aim of this survey was to study the association of regular physical activity, measured by patient′s estimation of walking time per day, with MS. Materials and Methods: This cross-sectional study was conducted as a part of Isfahan Healthy Heart Program (IHHP). Persons who had no component of MS were considered as reference group. Demographic data were collected by questionnaire. Relation between walking time and MS was evaluated by using logistic regression adjusted by age, sex, socioeconomic status (SES), life style and food item. Results: The study populations consisted of 4151 persons. Lower physical activity was associated with higher prevalence of MS (P < 0.001). There was a negative relation between the usual daily walking time and MS. Adjusted odds ratio for age groups, sex, SES, life style and food items (fat and oil, sweet and sweet drink, rice and bread, fried food) revealed that MS decreases with increasing walking time (P < 0.05) [OR = 0.70 (0.52-0.94)]. Conclusion: Total daily walking time is negatively associated with MS and increasing daily walking time is an effective way for preventing MS

Investigation of antimicrobial susceptibility, class I and II integrons among Pseudomonas aeruginosa isolates from hospitalized patients in Isfahan, Iran

Abstract Objectives The role of integrons in the transfer of antibiotic resistance is one of the important issues, therefore, this study is aimed to investigate antibiotic resistance pattern and prevalence of class 1 and 2 integrons in P. aeruginosa isolated. Results Out of 72 confirmed P. aeruginosa isolates, 50% were from ICU patients. Antibacterial susceptibility pattern showed that isolates were most resistant to ceftazidime (76.4%) and colistin was the most effective antibiotic (100%) and molecular analysis of class I and II integrons showed 55.5% and 29.1% of isolates were positive, respectively and the proportions of MDR isolates were significantly higher among integron-positive isolates with 73.6% compared to negative isolates with 22.9%. Our results showed that there was a correlation among class 1 and 2 integrons with MDR P. aeruginosa isolates. According to the importance of integrons in acquisition and dissemination of antibiotics resistance genes, the performance of antibiotic surveillance programs and investigating the role of integrons is recommended to control the spreading of antibiotics resistance genes

Correction to: Investigation of antimicrobial susceptibility, class I and II integrons among Pseudomonas aeruginosa isolates from hospitalized patients in Isfahan, Iran

Following publication of the original article [1], an error was reported in the tables due to a typesetting mistake. Table 3 is presented as a duplicate of Table 2. In this Correction, the correct presentation of Table 3 is shown