Response of a liquid bridge to an acceleration varying sinusoidally with time

The response of a long cylindrical liquid column subjected to an axial microgravity field has been experimentally studied on a TEXUS sounding rocket flight to check with theoretical predictions. The expected response of the liquid bridge was a quasi-static amphora-type deformation of the cylindrical shape. However, the experimental results showed a more complex behaviour. Nevertheless it has been possible to find out the reasons of this discrepancy except for a mysterious 0.5% uncertainty in the stimuli

Stability of Long Liquid Columns

The aim is to measure the outer shape deformation of long liquid bridges under microgravity when subjected to mechanical disturbances, namely change of geometry, rotation and vibration. This configuration has, aside of its own relevance in fluid mechanics and interface science, a well-known application in materials processing, particularly in Ore floating zone technique of crystal growth in the semiconductor industry. As a spin-off of this research, this configuration has proved to be a unique accelerometer at very low frequencies

Stability of Long Liquid Columns

A description at this experiment, the data analysis performed and tlie results obtained are presented. Three successful runs v/ere executed: the first one included a detailed oscillation test around a low eigenlrequency of the liquid column, the second was a stretching at constant volume until breakage, and the third one included an unexplained instability of an unequal-discs liquid column. The main diagnostic is the image analysis of the recorded videotape, and the most important result is that a residual axial acceleration of less than 5 ]±g is deduced from this SL-D-2 experiment, in contrast to the 70 ,ug deduced from the SL-D1 experiment in 19S5

Spacecraft thermal control design data

This paper shows the actual state of a compilation work on Thermal Control Design Data being done at Madrid (Lamf-ETSIA) under several ESTEC contracts, introducing a Handbook already issued, its additions and updatings

Freezing of a Long Liquid Column on the Texus-18 Sounding Rocket Flight

A free-surface cylindrical column of water (86 mm long by 30 mm diameter) was established during the first minute of microgravity on a sounding-rocket flight. Cooling was applied at one of the supporting discs to permit the advance of the solidification front and free-surface deformation to be observed during the ensuing 5 min of microgravity. The solidification front remained planar and the free surface remained cylindrical throughout, until affected by re-entry deceleration

Digital Optical Ballistocardiographic System for Activity, Heart Rate, and Breath Rate Determination during Sleep

In this work, we present a ballistocardiographic (BCG) system for the determination of heart and breath rates and activity of a user lying in bed. Our primary goal was to simplify the analog and digital processing usually required in these kinds of systems while retaining high performance. A novel sensing approach is proposed consisting of a white LED facing a digital light detector. This detector provides precise measurements of the variations of the light intensity of the incident light due to the vibrations of the bed produced by the subject’s breathing, heartbeat, or activity. Four small springs, acting as a bandpass filter, connect the boards where the LED and the detector are mounted. Owing to the mechanical bandpass filtering caused by the compressed springs, the proposed system generates a BCG signal that reflects the main frequencies of the heartbeat, breathing, and movement of the lying subject. Without requiring any analog signal processing, this device continuously transmits the measurements to a microcontroller through a twowire communication protocol, where they are processed to provide an estimation of the parameters of interest in configurable time intervals. The final information of interest is wirelessly sent to the user’s smartphone by means of a Bluetooth connection. For evaluation purposes, the proposed system has been compared with typical BCG systems showing excellent performance for different subject positions. Moreover, applied postprocessing methods have shown good behavior for information separation from a single-channel signal. Therefore, the determination of the heart rate, breathing rate, and activity of the patient is achieved through a highly simplified signal processing without any need for analog signal conditioning.Junta de Andalucia European Commission PYC20-RE-040 UGR MCIN/AEI/10.13039/501100011033/with PID2019-103938RB-I00European Commissio

The variable geometry central receiver system concept. First results and comparison with conventional central receiver systems

In line with the global trend for improving efficiency of existing solar power plants, the CTAER has developed and built a variable geometry central receiver facility, in which the solar field rotates around the tower axis following the sun's position during the day. The goal of this new approach is to increase the optical efficiency of the field by significantly reducing the angle of incidence of the Sun on the heliostats. This paper presents the advantages of this new variable geometry design and describes the main features of the experimental facility based on this approach as built by CTAER in Almeria. It also compares a conventional solar central receiver plant (i.e., with stationary heliostats and receiver) and an equivalent variable geometry power plant. For this study we employed published data from a real solar central receiver plant with known production (Abengoa’s PS10). The results of the study show an increase in annual energy collection and distribution by the variable geometry plant, leading to a potential reduction in the number of heliostats required compared to a conventional central receiver plant for the same annual energy collection