The draining of capillary liquids from containers with interior corners aboard the ISS

In this work, we analyze liquid drains from containers in effective zero-g conditions aboard the International Space Station (ISS). The efficient draining of capillary fluids from conduits, containers, and media is critical in particular to high-value liquid samples such as minuscule biofluidics processing on earth and enormous cryogenic fuels management aboard spacecraft. The amount and rate of liquid drained can be of key concern. In the absence of strong gravitational effects, system geometry, and liquid wetting dominate capillary fluidic behavior. During the years 2010–2015, NASA conducted a series of handheld experiments aboard the ISS to observe “large” length scale capillary fluidic phenomena in a variety of irregular containers with interior corners. In this work, we focus on particular single exit port draining flows from such containers and digitize hours of archived NASA video records to quantify transient interface profiles and volumetric flow rates. These data are immediately useful for theoretical and numerical model benchmarks. We demonstrate this by making comparisons to lubrication models for slender flows in simplified geometries which show variable agreement with the data, in part validating certain geometry-dependent dynamical interface curvature boundary conditions while invalidating others. We further compare the data for the draining of complex vane networks and identify the limits of the current theory. All analyzed data is made available to the public as MATLAB files, as detailed within.

Parallel Wiring Using a Single Intravascular Ultrasound Catheter with Double Rapid Exchange Lumens Technique for Chronic Total Occlusions in Peripheral Artery Disease

Purpose: To describe a parallel wiring using a single intravascular ultrasound catheter with double rapid exchange lumens (PASSABLE) technique for peripheral CTOs. Technique: The technique is demonstrated in a 73-year-old patient with CTOs of the superficial femoral and popliteal artery. Intravascular ultrasound (IVUS) examination revealed the first guidewire was advanced to the intramedial space of the popliteal artery. Following insertion of the first guidewire into only the distal rapid exchange lumen of the IVUS catheter and a second guidewire into the proximal rapid exchange lumen, a guidewire torquer was passed over it and tightened close to an exit port of the proximal rapid exchange lumen to prevent it from exiting an entry port while advancing the IVUS catheter. The IVUS catheter was advanced to the intraplaque region using only the distal rapid exchange lumen and the second guidewire was then advanced to the intraplaque region under IVUS guidance. The IVUS-guided wiring using the second guidewire on both the distal and proximal rapid exchange lumen was continued and resulted in a successful guidewire crossing into the distal true lumen. Conclusion: This novel technique may prove beneficial in enabling operators to perform IVUS-guided parallel wiring more easily and efficiently.

Dynamic Path Optimization with Real-Time Information for Emergency Evacuation

In order to find the optimal path for emergency evacuation, this paper proposes a dynamic path optimization algorithm based on real-time information to search the optimal path and it takes fire accident as an example to introduce the algorithm principle. Before the accidents, it uses the Dijkstra algorithm to get the prior evacuation network which includes evacuation paths from each node to the exit port. When the accidents occur, the evacuees are unable to pass through the passage where the accident point and the blocking point are located, then the proposed method uses the breadth-first search strategy to solve the path optimization problem based on the prior evacuation network, and it dynamically updates the evacuation path according to the real-time information. Because the prior evacuation network includes global optimal evacuation paths from each node to the exit port, the breadth-first search algorithm only searches local optimal paths to avoid the blockage node or dangerous area. Because the online optimization solves a local pathfinding problem and the entire topology optimization is an offline calculation, the proposed method can find the optimal path in a short time when the accident situation changes. The simulation tests the performances of the proposed algorithm with different situations based on the topology of a building, and the results show that the proposed algorithm is effective to get the optimal path in a short time when it faces changes caused by the factors such as evacuee size, people distribution, blockage location, and accident points.

Auroral all-sky camera calibration

A two-step procedure to calibrate the spectral sensitivity to visible light of auroral all-sky cameras is outlined. Center pixel response is obtained by the use of a Lambertian surface and a standard 45 W tungsten lamp. Screen brightness is regulated by the distance between the lamp and the screen. All-sky flat-field correction is carried out with a 1 m diameter integrating sphere. A transparent Lexan dome at the exit port of the sphere is used to simulate observing conditions at the Kjell Henriksen Observatory (KHO). A certified portable low brightness source from Keo Scientific Ltd was used to test the procedure. Transfer lamp certificates in units of Rayleigh per Ångstrøm (R/Å) are found to be within a relative error of 2%. An all-sky camera flat-field correction method is presented with only 6 required coefficients per channel.

Auroral all-sky camera calibration

A two-step procedure to calibrate the spectral sensitivity to visible light of auroral all-sky cameras is outlined. Center pixel response is obtained by the use of a Lambertian surface and a standard 45W tungsten lamp. Screen brightness is regulated by the distance between the lamp and the screen. All-sky flat-field correction is carried out with a 1 m diameter integrating sphere. A transparent Lexan dome at the exit port of the sphere is used to simulate observing conditions at the Kjell Henriksen Observatory (KHO). A certified portable low brightness source from Keo Scientific Ltd. was used to test the procedure. Transfer lamp certificates in units of Rayleigh per Ångstrøm (R Å−1) are found to be within a relative error of 2%. An all-sky camera flat-field correction method is presented with only 6 required coefficients per channel.

Studies on Optimization of a Liquid Fuel Based Low Emission Combustor

This paper presents experimental and numerical results on a single stage burner configuration with flameless/MILD combustion with liquid fuel. The proposed burner configuration is designed for 20 kW thermal input with heat intensity of ∼ 5 MW/m3 using kerosene as fuel and air at ambient conditions as the oxidizer. Air is injected through four tangential injection holes near the bottom of the combustor results high swirl flow in the combustor helps to enhance the internal recirculation of the combustion products. Computational and experimental analysis is carried out simultaneously for optimization of combustor configuration. In swirl combustor configurations the reactants dilution ration (recirculation) is function of combustor geometry, exit diameter and inlet velocity of air. In the first step of study four different combustor configurations are considered, one cylindrical and three conical combustors with diverging angles of 30°, 45° and 60°. In the second step the effect of exit port diameter on the recirculation and quality of flameless combustion is studied. The exit port diameter varied from 80 mm to 25 mm. In the third step the inlet velocities of air varied by inserting different inlet diameters of 2 to 7 mm in a step of 1mm. Based on combustion completeness and emission analysis, the 60° diverging angle combustor with air inlet diameter of 4 or 5 mm and 25 mm exit diameter is considered as optimistic configuration to obtain flameless combustion mode with liquid fuels. The acoustic emissions and the emissions of CO and NOX are measured for different configurations.

A Zero-Dimensional Model to Predict the Performance of the Claw Type Vacuum Pump

A new type of mechanical vacuum pump is introduced in this paper. It is composed of two conjugated rotors spinning in opposite directions. The shape of rotor looks like a claw, and it is called a claw vacuum pump. A zero dimensional model was used in this paper to analyze the performance of this vacuum pump. The whole system was decomposed into five subsystems. Each subsystem has its own values in temperature, pressure and mass. The pressure variations and the temperature variations as well as the work required to complete the whole cycle were calculated with this model. It was found that the major leakage route is from exit port to chamber. The averaged outlet temperature may reach 483K. However, inner leakage may ease the problem of high temperature flow.