Cosmic Collisions in the Experimental Chamber

2015 ◽  
Vol 37 (1) ◽  
pp. 30-37
Author(s):  
Thomas Kenkmann ◽  
Michael Poelchau ◽  
Alex Deutsch ◽  
Klaus Thoma
Keyword(s):  
Experimental Chamber

scholarly journals In-Situ Synchrotron X-ray Diffraction Investigation of Microstructural Evolutions During Low-Pressure Carburizing

2021 ◽  
Author(s):  
Ogün Baris Tapar ◽  
Jérémy Epp ◽  
Matthias Steinbacher ◽  
Jens Gibmeier
Keyword(s):  
Carbon Content ◽  
Carbon Diffusion ◽  
Low Pressure ◽  
Carbon Accumulation ◽  
Experimental Chamber ◽  
Carbide Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbon Supply

AbstractAn experimental heat treatment chamber and control system were developed to perform in-situ X-ray diffraction experiments during low-pressure carburizing (LPC) processes. Results from the experimental chamber and industrial furnace were compared, and it was proven that the built system is reliable for LPC experiments. In-situ X-ray diffraction investigations during LPC treatment were conducted at the German Electron Synchrotron Facility in Hamburg Germany. During the boost steps, carbon accumulation and carbide formation was observed at the surface. These accumulation and carbide formation decelerated the further carbon diffusion from atmosphere to the sample. In the early minutes of the diffusion steps, it is observed that cementite content continue to increase although there is no presence of gas. This effect is attributed to the high carbon accumulation at the surface during boost steps which acts as a carbon supply. During quenching, martensite at higher temperature had a lower c/a ratio than later formed ones. This difference is credited to the early transformation of austenite regions having lower carbon content. Also, it was noticed that the final carbon content dissolved in martensite reduced compared to carbon in austenite before quenching. This reduction was attributed to the auto-tempering effect.

CFD Simulation of Particle Transport and Dispersion in Indoor Environment by Human Walking

2012 ◽  
Author(s):  
Iman Goldasteh ◽  
Goodarz Ahmadi ◽  
Andrea Ferro
Keyword(s):  
Particulate Matter ◽  
High Speed ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Study Data ◽  
Turbulent Dispersion ◽  
Experimental Chamber ◽  
Indoor Environments ◽  
Three Dimensional Model ◽  
Particle Resuspension

Particle resuspension is an important source of particulate matter in indoor environments that significantly affects the indoor air quality and could potentially have adverse effect on human health. Earlier efforts to investigate indoor particle resuspension hypothesized that high speed airflow generated at the floor level during the gate cycle is the main cause of particle resuspension. The resuspended particles are then assumed to be dispersed by the airflow in the room, which is impacted by both the ventilation and the occupant movement, leading to increased PM concentration. In this study, a three dimensional model of a room was developed using FLUENT™ CFD package. A RANS approach with the RNG k-ε turbulence model was used for simulating the airflow field in the room for different ventilation conditions. The trajectories of resuspended particulate matter were computed with a Lagrangian method by solving the equations of particle motion. The effect of turbulent dispersion was included with the use of the eddy lifetime model. The resuspension of particles due to gait cycle was estimated and included in the computational model. The dispersion and transport of particles resuspended from flooring as well as particle re-deposition on flooring and walls were simulated. Particle concentrations in the room generated by the resuspension process were evaluated and the results were compared with experimental chamber study data as well as simplified model predictions, and good agreement was found.

Direct measurement of flow from the posterior lymph hearts of hydrated and dehydrated toads (Bufo marinus).

1997 ◽  
Vol 200 (11) ◽  
pp. 1695-1702 ◽  
Author(s):  
J M Jones ◽  
A K Gamperl ◽  
A P Farrell ◽  
D P Toews
Keyword(s):  
Heart Rate ◽  
Stroke Volume ◽  
Systolic Pressure ◽  
Lymph Flow ◽  
Bufo Marinus ◽  
Experimental Chamber ◽  
Doppler Flow ◽  
Simultaneous Measurements ◽  
Pressure Development ◽  
Lymph Heart

Flow from the posterior lymph hearts of Bufo marinus was measured using Doppler flow probes. These probes were placed on the posterior vertebral vein and recorded flow as lymph was ejected from the heart. In resting, hydrated toads, mean lymph flow from one of the paired posterior lymph hearts was 25.9 +/- 4.9 ml kg-1 h-1, stroke volume was 8.9 +/- 1.4 microL kg-1 and lymph heart rate was 47.5 +/- 3.7 beats min-1. We estimate that, together, the paired posterior lymph hearts are capable of generating flows that are approximately one-sixtieth of the resting cardiac output. Mean peak systolic pressure developed by the posterior lymph hearts was 1.62 +/- 0.08 kPa. Simultaneous measurements of lymph heart pressure development and flow revealed that the outflow pore of the heart opened at a pressure of 0.71 +/- 0.04 kPa, approximately 113 +/- 5 ms into systole. When toads were moderately disturbed, stroke volume increased by as much as fourfold with little change in lymph heart rate (< 5 beats min-1). When toads were dehydrated, lymph flow decreased by 70% at 12h and by 80% and 24h. Since there was only a modest non-significant decrease in lymph heart rate (30%), this reduction in flow was attributed to decreases in stroke volume (approximately 80%). Lymph heart flow and stroke volume returned to control values 30 min after adding water back into the experimental chamber. Stroke volume was clearly more important in regulating lymph flow than lymph heart rate under these conditions in Bufo marinus.

Development of 25N oxygen-kerosene thruster

2021 ◽  
Author(s):  
V.L. Salich
Keyword(s):  
Oxygen Supply ◽  
Rocket Engine ◽  
Experimental Chamber ◽  
Internal Cooling ◽  
Cylindrical Section

The paper introduces the scientific and technical groundwork obtained by the author and used as a basis for the development of an oxygen-kerosene rocket engine with a thrust of 25 N. This groundwork represents the results of research carried out on an experimental chamber developed by the author. The design of the chamber made it possible to study the effect of the configuration of the mixing element on its characteristics, the number of holes of oxygen supply to the internal cooling curtain, the length of the cylindrical section behind the curtain belt. The results of tests of various variants of the chamber and their analysis are presented. The results of tests of the developed engine, in which one of the camera variants is implemented, are given as well.

Analysis of Pitot Tube Static Probe Angle in the Experimental Chamber Conditions

2018 ◽  
Vol 87 (1) ◽  
pp. 369-375
Author(s):  
Pavla Hlavatá ◽  
Jiří Maxa ◽  
Petr Vyroubal
Keyword(s):  
Pitot Tube ◽  
Experimental Chamber ◽  
Probe Angle

scholarly journals Particulate Matter Dispersion Modeling in Agricultural Applications: Investigation of a Transient Open Source Solver

Agronomy ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2246
Author(s):  
David Janke ◽  
Senthilathiban Swaminathan ◽  
Sabrina Hempel ◽  
Robert Kasper ◽  
Thomas Amon
Keyword(s):  
Particulate Matter ◽  
Open Source ◽  
Turbulence Models ◽  
Continuous Phase ◽  
Experimental Chamber ◽  
Dispersion Modeling ◽  
Reynolds Stresses ◽  
Agricultural Applications ◽  
Inflow Turbulence ◽  
Turbulence Generator

Agriculture is a major emitter of particulate matter (PM), which causes health problems and can act as a carrier of the pathogen material that spreads diseases. The aim of this study was to investigate an open-source solver that simulates the transport and dispersion of PM for typical agricultural applications. We investigated a coupled Eulerian–Lagrangian solver within the open source software package OpenFOAM. The continuous phase was solved using transient large eddy simulations, where four different subgrid-scale turbulence models and an inflow turbulence generator were tested. The discrete phase was simulated using two different Lagrangian solvers. For the validation case of a turbulent flow of a street canyon, the flowfield could be recaptured very well, with errors of around 5% for the non-equilibrium turbulence models (WALE and dynamicKeq) in the main regions. The inflow turbulence generator could create a stable and accurate boundary layer for the mean vertical velocity and vertical profile of the turbulent Reynolds stresses R11. The validation of the Lagrangian solver showed mixed results, with partly good agreements (simulation results within the measurement uncertainty), and partly high deviations of up to 80% for the concentration of particles. The higher deviations were attributed to an insufficient turbulence regime of the used validation case, which was an experimental chamber. For the simulation case of PM dispersion from manure application on a field, the solver could capture the influence of features such as size and density on the dispersion. The investigated solver is especially useful for further investigations into time-dependent processes in the near-source area of PM sources.

scholarly journals Enhancing GABAergic Tone in the Rostral Nucleus of the Solitary Tract Reconfigures Sensorimotor Neural Activity

2020 ◽  
Author(s):  
Joshua D. Sammons ◽  
Caroline E. Bass ◽  
Jonathan D. Victor ◽  
Patricia M. Di Lorenzo
Keyword(s):  
Neural Activity ◽  
Inhibitory Activity ◽  
Nucleus Tractus Solitarius ◽  
Artificial Saliva ◽  
Experimental Chamber ◽  
Response Patterns ◽  
Related Activity ◽  
Electrophysiological Recordings ◽  
Rostral Nucleus ◽  
The Relationship

ABSTRACTRecent work has shown that most cells in the rostral, gustatory portion of the nucleus tractus solitarius (rNTS) in awake, freely licking rats show lick-related firing. However, the relationship between taste-related and lick-related activity in rNTS remains unclear. Here, we tested if GABA-derived inhibitory activity regulates the balance of lick- and taste-driven neuronal activity. Combinatorial viral tools were used to restrict expression of ChR2-EYFP to GAD1+ GABAergic neurons. Viral infusions were bilateral in rNTS. 2-4wks later, an optical fiber attached to 8-16 drivable microwires was implanted into the rNTS. After recovery, water-deprived rats were presented with taste stimuli in an experimental chamber. Trials were 5 consecutive taste licks [NaCl, KCl, NH4Cl, sucrose, MSG/IMP, citric acid, quinine, or artificial saliva (AS)] separated by 5 AS licks on a VR5 schedule. Each taste lick triggered a 1s train of laser light (25Hz; 473nm; 8-10mW) in a random half of the trials. In all, 113 cells were recorded in the rNTS, 50 responded to one or more taste stimuli without GABA enhancement. Selective changes in response magnitude (spike count) within cells shifted across unit patterns but preserved inter-stimulus relationships. Cells where enhanced GABAergic tone increased lick coherence conveyed more information distinguishing basic taste qualities and different salts than other cells. In addition, GABA activation significantly amplified the amount of information that discriminated palatable vs. unpalatable tastants. By dynamically regulating lick coherence and remodeling the across-unit response patterns to taste, enhancing GABAergic tone in rNTS reconfigures the neural activity reflecting sensation and movement.Significance StatementThe rostral nucleus tractus solitarius (rNTS) is the first structure in the central gustatory pathway. Electrophysiological recordings from the rNTS in awake, freely-licking animals show that cells in this area have lick- as well as taste-related activity, but the relationship between these characteristics is not well understood. Here, we showed evidence that GABA activation can dynamically regulate both of these two properties in rNTS cells to enhance the information conveyed, especially about palatable vs. unpalatable tastants. These data provide insights into the role of inhibitory activity in the rNTS.

Sign in / Sign up

Export Citation Format

Share Document