Numerical simulation and energy flux vector visualization of radiative-convection heat transfer in a porous triangular enclosure

A detailed theoretical examination laminar natural convection heat flow in a triangular porous cavity with significant radiative heat transfer and porosity variation is presented. Twodimensional laminar incompressible flow is considered with the left slant and right walls are low and high temperature respectively, and the remaining (top) wall prescribed as adiabatic. The Darcy-Brinkman isotropic model is utilized, and the coupled governing equations are solved by a numerical method utilizing finite differences. Visualization of isotherms and streamlines is achieved with the method of Energy Flux Vectors (EFVs). The impacts of the different model parameters (Rayleigh number Ra, Darcy number-Da, porosity-E and radiation parameter-Rd) on the thermo fluid characteristics are studied in detail. The computations show that convective heat transfer is enhanced with greater Darcy parameter (permeability) which also leads to intensification in the density of energy flux vector patterns. The flow is accelerated with increasing buoyancy effect (Rayleigh number) and temperatures are also increased with greater radiative flux. Average Nusselt number is decreased with higher porosity. The simulations are relevant to hybrid porous media solar collectors

Numerical simulation and energy flux vector visualization of radiative-convection heat transfer in a porous triangular enclosure

A detailed theoretical examination laminar natural convection heat flow in a triangular porous cavity with significant radiative heat transfer and porosity variation is presented. Twodimensional laminar incompressible flow is considered with the left slant and right walls are low and high temperature respectively, and the remaining (top) wall prescribed as adiabatic. The Darcy-Brinkman isotropic model is utilized, and the coupled governing equations are solved by a numerical method utilizing finite differences. Visualization of isotherms and streamlines is achieved with the method of Energy Flux Vectors (EFVs). The impacts of the different model parameters (Rayleigh number Ra, Darcy number-Da, porosity-E and radiation parameter-Rd) on the thermo fluid characteristics are studied in detail. The computations show that convective heat transfer is enhanced with greater Darcy parameter (permeability) which also leads to intensification in the density of energy flux vector patterns. The flow is accelerated with increasing buoyancy effect (Rayleigh number) and temperatures are also increased with greater radiative flux. Average Nusselt number is decreased with higher porosity. The simulations are relevant to hybrid porous media solar collectors

Diabetes mortality and trends before 25 years of age: an analysis of the Global Burden of Disease Study 2019

Background Diabetes, particularly type 1 diabetes, at younger ages can be a largely preventable cause of death with the correct health care and services. We aimed to evaluate diabetes mortality and trends at ages younger than 25 years globally using data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019. Methods We used estimates of GBD 2019 to calculate international diabetes mortality at ages younger than 25 years in 1990 and 2019. Data sources for causes of death were obtained from vital registration systems, verbal autopsies, and other surveillance systems for 1990–2019. We estimated death rates for each location using the GBD Cause of Death Ensemble model. We analysed the association of age-standardised death rates per 100 000 population with the Socio-demographic Index (SDI) and a measure of universal health coverage (UHC) and described the variability within SDI quintiles. We present estimates with their 95% uncertainty intervals. Findings In 2019, 16 300 (95% uncertainty interval 14 200 to 18 900) global deaths due to diabetes (type 1 and 2 combined) occurred in people younger than 25 years and 73·7% (68·3 to 77·4) were classified as due to type 1 diabetes. The age-standardised death rate was 0·50 (0·44 to 0·58) per 100 000 population, and 15 900 (97·5%) of these deaths occurred in low to high-middle SDI countries. The rate was 0·13 (0·12 to 0·14) per 100 000 population in the high SDI quintile, 0·60 (0·51 to 0·70) per 100 000 population in the low-middle SDI quintile, and 0·71 (0·60 to 0·86) per 100 000 population in the low SDI quintile. Within SDI quintiles, we observed large variability in rates across countries, in part explained by the extent of UHC (r2=0·62). From 1990 to 2019, age-standardised death rates decreased globally by 17·0% (−28·4 to −2·9) for all diabetes, and by 21·0% (–33·0 to −5·9) when considering only type 1 diabetes. However, the low SDI quintile had the lowest decline for both all diabetes (−13·6% [–28·4 to 3·4]) and for type 1 diabetes (−13·6% [–29·3 to 8·9]). Interpretation Decreasing diabetes mortality at ages younger than 25 years remains an important challenge, especially in low and low-middle SDI countries. Inadequate diagnosis and treatment of diabetes is likely to be major contributor to these early deaths, highlighting the urgent need to provide better access to insulin and basic diabetes education and care. This mortality metric, derived from readily available and frequently updated GBD data, can help to monitor preventable diabetes-related deaths over time globally, aligned with the UN's Sustainable Development Targets, and serve as an indicator of the adequacy of basic diabetes care for type 1 and type 2 diabetes across nations.publishedVersio

Hall and ionslip effects on nanofluid transport from a vertical surface : Buongiorno’s model

The non-linear, non-isothermal, magnetohydrodynamic (MHD) laminar convection flows of Buongiorno’s nanofluid past a vertical surface with Darcy-Forchheimer model is mathematically investigated in the present article. Keller’s Box implicit finite difference technique is utilized to solve the dimensionless conservation equations. Graphical and tabulated results are analyzed to study the behavior of primary and secondary velocity, temperature, nanoparticle volume fraction, shear stress rate, heat transfer rate and mass transfer rate for various emerging thermos-physical parameters. The Hall current and ion slip current effects are also considered. Validations of earlier solutions in the literature is also included. The study finds applications in nanomaterial fabrication processing, biomedical, polymer processing, chemical engineering, crude oil purifying, etc

Ein Experiment zur Erzeugung ultrakurzer Roentgenpulse an der Speicherringanlage DELTA

Available from TIB Hannover: RO 8093(216) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Simulation of the Touschek effect for BESSY II - a Monte Carlo approach

The Touschek effect is one of the dominant loss mechanisms for electrons in a low emittance storage ring. For the case of the BESSY II optics, a detailed Monte Carlo simulation of this effect is presented and the validity of simplifications usually made in analytical calculations (e.g. the non-relativistic approximation) is discussed. The Touschek lifetime is calculated as function of momentum acceptance and aperture with typical currents and bunch lengths for single- and multi-bunch operation. Results are presented for beam energies ranging from 900 MeV to 1900 MeV. Furthermore, the influence of beam polarization on the lifetime is demonstrated. (orig.)SIGLEAvailable from TIB Hannover: RO 8093(177) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Eine HOM-gedaempfte Cavity als longitudinaler Feedback-Kicker

Available from TIB Hannover: RO 8093(217) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Einfluss von anthropogenen Schadstoffen (PAK und PCB) auf terrestrische Invertebraten urbaner Oekosysteme Abschlussbericht

Das Projekt wurde von August 1993 bis Mai 1997 durchgefuehrt. Ziele waren die Erarbeitung (a) von Wirkschwellen fuer organische Schadstoffgruppen (PAK, PCB) und Schwermetalle im Boden fuer Destruenten urbaner Oekosysteme, (b) von Biotestsystemen zur Bewertung der Lebensraumfunktion belasteter Boeden und (c) von Hinweisen zur kontrollierten Nutzung belasteter Flaechen. Diese Fragestellungen wurden bearbeitet durch Freilanduntersuchungen auf stillgelegten Rieselfeldern der Stadt Berlin zur Abundanz, Artendiversitaet und Dominanzstruktur terrestrischer Anneliden (Lumbriciden, Enchytraeiden), durch Biotests unter Verwendung kontaminierter Rieselfeldboeden und aufdotierter Boeden (BaP, Fla, PCB 52, Cd, Cu) und durch Untersuchung zur Akkumulation, Elimination und Biotransformation bei Anneliden. Auf 12 der 17 untersuchten Rieselfeldstandorten wurden keine Regenwuermer gefunden, auf zwei keine Enchytraeiden. Die Enchytraeidenabundanz lag zwischen 500 und 12.500/m"2 und damit weit unter der von Kontrollflaechen (25.000 bis 280.000/m"2). Die Annelidenfeindlichkeit der Rieselfeldboeden wurde durch den Koederstreifen-Test und durch Biotests mit Enchytraeus crypticus, E. albidus, E. buchholzi und Eisenia f. fetida bestaetigt. Die Oekotoxizitaet der rieselfeldtypischen Schadstoffkombinationen wurde durch den sauren Boden-pH und Bodenumlagerungen verstaerkt. Die Toxizitaet der organischen und anorganischen Schadstoffe fuer Anneliden wurde durch Kurz- und Langzeituntersuchungen im Agar-Testsystem bestaetigt. Die Untersuchungsmethoden koennen zur Bewertung komtaminierter Boeden herangezogen werden. (orig.)The project was conducted from August 1993 until May 1997. The objectives were (a) an elaboration of effect concentrations and index values for organic contaminants (PAH, PCB) and heavy metals in soil of conurbations for the community of decomposers, (b) the improvement of a biotest system for the evaluation of the habitat function of contaminated soils and (c) to obtain informations concerning a controlled utilization of contaminated areas. For that purpose field investigations in former sewage water irrigation areas of Berlin, Germany, concerning the abundance, species composition and dominance structure of terrestrial annelids (Enchytraeids, Lumbricids) were performed, as well as bioassays using contaminated soils of these sites and soils spiked with bezo(a)pyrene, fluoranthene, PCB 52, Cd and Cu and experiments on accumulation, elimination and biotransformation in annelids. 12 of the 17 sites investigated lacked earthworms, while only 2 sites lacked enchytraeids. The abundance of enchytraeids was in the range of 500 to 12.500/m"2, compared to 25.000 to 280.000/m"2 on reference sites. The hostility of the soils of former irrigation fields to annelids was confirmed by lamina bait tests and by bioassays with Enchytraeus crypticus, E. albidus, E. buchholzi and Eisenia f. fetida. The ecotoxicity of the combined contaminants was enforced by the acidity and the degradation of the soils. The toxicity of organic and inorganic contaminants to terrestrial annelids was definitely proved by reproduction tests in the agar test system. The applied methods of investigation can be used for evaluation of contaminated soils. (orig.)Available from TIB Hannover: F98B1125+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman