| 1. |
- Gupta, Alok C., et al.
(författare)
-
Multiband optical variability of the blazar OJ 287 during its outbursts in 2015-2016
- 2017
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 465:4, s. 4423-4433
-
Tidskriftsartikel (refereegranskat)abstract
- We present recent optical photometric observations of the blazar OJ 287 taken during 2015 September-2016 May. Our intense observations of the blazar started in 2015 November and continued until 2016 May and included detection of the large optical outburst in 2015 December that was predicted using the binary black hole model for OJ 287. For our observing campaign, we used a total of nine ground-based optical telescopes of which one is in Japan, one is in India, three are in Bulgaria, one is in Serbia, one is in Georgia, and two are in the USA. These observations were carried out in 102 nights with a total of similar to 1000 image frames in BVRI bands, though the majority were in the R band. We detected a second comparably strong flare in 2016 March. In addition, we investigated multiband flux variations, colour variations, and spectral changes in the blazar on diverse time-scales as they are useful in understanding the emission mechanisms. We briefly discuss the possible physical mechanisms most likely responsible for the observed flux, colour, and spectral variability.
|
|
| 2. |
- Khaware, Alok, et al.
(författare)
-
Numerical Simulation of a Radial Free Surface Liquid Jet Impinging on a Heated Surface
- 2021
-
Ingår i: Journal of Fluid Flow, Heat and Mass Transfer (JFFHMT). - : Avestia Publishing. - 2368-6111. ; 8, s. 33-41
-
Tidskriftsartikel (refereegranskat)abstract
- Impinging liquid jets have been demonstrated to be an effective means of providing high heat transfer rates, and widely used in designing cooling systems for electronic modules, plastic manufacturing, and many other applications in the industry. It is very important to study the factors which govern the heat transfer rate in the liquid impingement on a heated surface to ensure cooling efficiency. The paper presents a numerical approach to study the convective heat transfer of circular liquid jet impingement on a heated surface where influencing factors like surface tension, gravity, viscosity, surface temperature etc. are considered. Finite volume method (FVM) with pressure based coupled solver implemented in commercial ANSYS Fluent CFD is used to solve Reynolds Averaged Navier Stokes equations. Free surface flow is modelled using Volume of Fluid (VOF) Method along with the compressive scheme and sharp interface modelling which accurately captures interfaces between immiscible fluids. The liquid film formation and the heat transfer phenomenon are examined in detail. The influence of jet velocity profiles on pressure distribution and heat transfer along the heated surface is presented. The results obtained from numerical solution are validated against experiment and previously published work with a close match.
|
|
| 3. |
- Khaware, Alok, et al.
(författare)
-
Numerical Simulation of Steam Bubble Condensation Using Thermal Phase Change Model
- 2021
-
Ingår i: Journal of Fluid Flow, Heat and Mass Transfer (JFFHMT). - : Avestia Publishing. - 2368-6111. ; 8, s. 42-51
-
Tidskriftsartikel (refereegranskat)abstract
- Evaporation and condensation phenomena play a significant role in many of the nuclear, biochemical, and thermal processes in industrial applications. It is a complicated phenomenon as it undergoes both heat and mass transfer processes along with the complexities involved in the interfacial regions of vapor and liquid phases. Several experimental works have been carried out in the recent past to understand the condensation process in detail. However, understanding the phenomenon using computational technique is more advantageous as the interfacial mass transfer between gas and liquid can be modelled accurately. In the present work, condensation of a saturated vapor bubble in the sub-cooled liquid is studied, and various factors that influence the bubble shape change and the bubble lifetime, are evaluated. The analysis is carried out using the ‘Multi-Fluid Volume of Fluid’ and ‘Thermal Phase Change’ (TPC) models implemented in ANSYS Fluent commercial CFD solver. A detailed study is performed to obtain the best approach for calculating interfacial area density using a ‘user-defined function’ (UDF), and the advantage of the node-based gradient calculation method is exhibited. The numerical results obtained for the history of bubble shape and bubble lifetime are validated against the experiment and previously published works with good accuracy. The paper also elaborates on how the initial bubble diameter, the subcooling temperature, and the system pressure affects the shape and lifetime of the bubble during the condensation process.
|
|
| 4. |
- Ryan, Donna H, et al.
(författare)
-
Nonsurgical weight loss for extreme obesity in primary care settings: results of the Louisiana Obese Subjects Study.
- 2010
-
Ingår i: Archives of internal medicine. - : American Medical Association (AMA). - 1538-3679 .- 0003-9926. ; 170:2, s. 146-54
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Effective primary care practice (PCP) treatments are needed for extreme obesity. The Louisiana Obese Subjects Study (LOSS) tested whether, with brief training, PCPs could effectively implement weight loss for individuals with a body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared) of 40 to 60. METHODS: The LOSS, a 2-year (July 5, 2005, through January 30, 2008) randomized, controlled, "pragmatic clinical trial" trained 7 PCPs and 1 research clinic in obesity management. Primary outcome measure was year-2 percentage change from baseline weight. Volunteers (597) were screened and randomized to intensive medical intervention (IMI) (n = 200) or usual care condition (UCC) (n = 190). The UCC group had instruction in an Internet weight management program. The IMI group recommendations included a 900-kcal liquid diet for 12 weeks or less, group behavioral counseling, structured diet, and choice of pharmacotherapy (sibutramine hydrochloride, orlistat, or diethylpropion hydrochloride) during months 3 to 7 and continued use of medications and maintenance strategies for months 8 to 24. RESULTS: The mean age of participants was 47 years; 83% were women, and 75% were white. Retention rates were 51% for the IMI group and 46% for the UCC group (P = .30). After 2 years, the results were as follows: (1) among 390 randomized participants, 31% in the IMI group achieved a 5% or more weight loss and 7% achieved a 20% weight loss or more, compared with 9% and 1% of those in the UCC group. (2) The mean +/- SEM baseline observation carried forward analysis showed a weight loss of -4.9% +/- 0.8% in IMI and -0.2 +/- 0.3% in UCC. (3) Last observation carried forward analysis showed a weight loss of -8.3% +/- 0.79% for IMI, whereas UCC was -0.0% +/- 0.4%. (4) A total of 101 IMI completers lost -9.7% +/- 1.3% (-12.7 +/- 1.7 kg), whereas 89 UCC completers lost -0.4% +/- 0.7% (-0.5 +/- 0.9 kg); (P < .001 for all group differences). Many metabolic parameters improved. CONCLUSION: Primary care practices can initiate effective medical management for extreme obesity; future efforts must target improving retention and weight loss maintenance. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00115063.
|
|
| 5. |
- Villarroel, Beatriz, et al.
(författare)
-
Launching the VASCO Citizen Science Project
- 2022
-
Ingår i: Universe. - : MDPI AG. - 2218-1997. ; 8:11, s. 561-
-
Tidskriftsartikel (refereegranskat)abstract
- The Vanishing & Appearing Sources during a Century of Observations (VASCO) project investigates astronomical surveys spanning a time interval of 70 years, searching for unusual and exotic transients. We present herein the VASCO Citizen Science Project, which can identify unusual candidates driven by three different approaches: hypothesis, exploratory, and machine learning, which is particularly useful for SETI searches. To address the big data challenge, VASCO combines three methods: the Virtual Observatory, user-aided machine learning, and visual inspection through citizen science. Here we demonstrate the citizen science project and its improved candidate selection process, and we give a progress report. We also present the VASCO citizen science network led by amateur astronomy associations mainly located in Algeria, Cameroon, and Nigeria. At the moment of writing, the citizen science project has carefully examined 15,593 candidate image pairs in the data (ca. 10% of the candidates), and has so far identified 798 objects classified as "vanished". The most interesting candidates will be followed up with optical and infrared imaging, together with the observations by the most potent radio telescopes.
|
|
