Buoyant Environment Research Articles

An Initiative to Find Better Energy Option for Growing India: Jatropha Oil

Energy is vital role input for economic growth in industries and agriculture. Fossil fuel are depleting at a faster rate due to exploitation besides increasing the environmental protection cost. Search for renewable energy source and their technology development is of paramount importance to have a balanced and buoyant environment for better quality of life. Thus this situation compels us to explore new avenues which can be used as fuel for Diesel Engines. The esters of vegetables oil and animal fats are known as Bio diesel and these are basically used as an alternative fuel for Diesel Engines. This Paper deals with the prospects of obtaining Bio diesel from Jatropha Oil. Jatropha Curcas is a renewable non- edible plant, which can be seen as a wild hardy plant grown in the arid and semi-arid regions of the country. This can easily be grown on the degraded soils having low fertility and moisture. The Jatropha seeds are very useful since they contain 50-60% oil. To conclude, this study will discuss the process of conversion of Jatropha Oil into Biodiesel by using transesterification process.

Astronaut Training using Virtual Reality in a Neutrally Buoyant Environment

<div><p>Astronauts undergo significant training in preparation for operating in space. In the past governments have been driving space exploration through ventures such as the National Aeronautics and Space Administration (NASA), however more recently new private companies have formed such as SpaceX who are designing commercially viable and reusable spacecraft. As such, the economics of space travel are more important than ever, and there is a logical need to research affordable and effective training procedures for astronauts.</p><p>Virtual Reality (VR) has been shown to be an effective technique for training people to perform high skilled physical tasks such as medical surgery. Research into VR as a platform for training astronauts has shown encouraging results with the implementation of hand tracking data gloves allowing the trainee to interact with the virtual environment. Further, there is evidence that VR can aid in the treatment of phobias with exposure therapy by better preparing the patient for real life exposure. Tactile feedback was found to enhance the treatment. Hence training with VR may help prepare an astronaut for the experience of operating in space through exposure to realistic simulations.</p><p>This paper proposes using existing underwater systems with VR to create a low cost extra vehicular activity (EVA) astronaut training simulation. Incorporation of tactile feedback and methods to track the body, hands and finger flexure, enabling user interaction with the virtual environment was explored. This allows for the creation of a varied neutrally buoyant training environment with a smaller physical space requirement compared to existing methods.</p></div>

Axial allometry in a neutrally buoyant environment: effects of the terrestrial-aquatic transition on vertebral scaling.

Ecological diversification into new environments presents new mechanical challenges for locomotion. An extreme example of this is the transition from a terrestrial to an aquatic lifestyle. Here, we examine the implications of life in a neutrally buoyant environment on adaptations of the axial skeleton to evolutionary increases in body size. On land, mammals must use their thoracolumbar vertebral column for body support against gravity and thus exhibit increasing stabilization of the trunk as body size increases. Conversely, in water, the role of the axial skeleton in body support is reduced, and, in aquatic mammals, the vertebral column functions primarily in locomotion. Therefore, we hypothesize that the allometric stabilization associated with increasing body size in terrestrial mammals will be minimized in secondarily aquatic mammals. We test this by comparing the scaling exponent (slope) of vertebral measures from 57 terrestrial species (23 felids, 34 bovids) to 23 semi-aquatic species (pinnipeds), using phylogenetically corrected regressions. Terrestrial taxa meet predictions of allometric stabilization, with posterior vertebral column (lumbar region) shortening, increased vertebral height compared to width, and shorter, more disc-shaped centra. In contrast, pinniped vertebral proportions (e.g. length, width, height) scale with isometry, and in some cases, centra even become more spool-shaped with increasing size, suggesting increased flexibility. Our results demonstrate that evolution of a secondarily aquatic lifestyle has modified the mechanical constraints associated with evolutionary increases in body size, relative to terrestrial taxa.

Investigation of density flow in dam reservoirs using a three-dimensional mathematical model including Coriolis effect

This paper aims to simulate and discuss the propagation of density current and divergence flow in a dam reservoir. The density plunging flow is modeled in three-dimensions through a dam reservoir with diverging and sloping bottom channels, and the plunging phenomenon has been reproduced in the present model. Nonlinear and unsteady continuity, momentum, energy and turbulence model equations are formulated in the Cartesian coordinates both in a sloping and in a diverging channel. For the turbulence viscosity, a k– ε turbulence model including buoyancy effects is used to reproduce the main flow characteristics. To investigate the Coriolis force effect on the density flow in a dam reservoir, Coriolis force parameter is also included in the governing equations. The equations of the model are solved based on the initial and boundary conditions of the dam reservoir flow for a range of bottom slopes and divergence angles. In this paper the main interest is the formation of separated flows, such as wall-jet and free-jet flows. The model successfully simulates the formation of attached flow, wall jets, and free jets in a negatively buoyant environment. The simulation results obtained from this study are compared with previous experimental work, and the mathematical model studies data on density current generated by the plunging of cold water in ambient warm water in a diverging channel, and is found to be of the same magnitude as the experimental measurements and followed the expected basic trend.

Psychosocial Aspects of Scuba Diving for People with Physical Disabilities: An Occupational Science Perspective

This project investigated the psychosocial benefits of scuba diving for individuals with acquired physical impairments. In-depth, semi-structured interviews were conducted with 3 volunteers recruited from a diving club specializing in training people with disabilities to dive. Qualitative methods were used to analyze the data in order to identify the themes recurring in the interviews. The respondents indicated that diving is a challenging, enjoyable activity that enhances their quality of life through enriched social experiences and improved self-concept. Furthermore, subjects stressed that carrying out the activity in a buoyant environment allowed them to feel weightless, thus free from their impairments and equal to non-disabled divers. The study highlighted the need to carry out further research in this field in order to gain better insight into the impact of scuba diving on the quality of life of people with physical impairments.

An observational study of the 7 September 2005 Barcelona tornado outbreak

Abstract. This paper presents an observational study of the tornado outbreak that took place on the 7 September 2005 in the Llobregat delta river, affecting a densely populated and urbanised area and the Barcelona International airport (NE Spain). The site survey confirmed at least five short-lived tornadoes. Four of them were weak (F0, F1) and the other one was significant (F2 on the Fujita scale). They started mostly as waterspouts and moved later inland causing extensive damage estimated in 9 million Euros, three injured people but fortunately no fatalities. Large scale forcing was provided by upper level diffluence and low level warm air advection. Satellite and weather radar images revealed the development of the cells that spawned the waterspouts along a mesoscale convergence line in a highly sheared and relatively low buoyant environment. Further analysis indicated characteristics that could be attributed indistinctively to non-supercell or to mini-supercell thunderstorms.

Self-Assembly of 3D Magnetic Tiles

Self-assembly is a term most commonly associated with biological processes, especially cellular manufacture of DNA. By utilizing a four element code, cells are able to actively reproduce the genetic framework of life. By applying a similar principle to the macro-scale, tangible 3D objects can be fashioned by a coded series of simple building blocks. The goal of this paper is to examine the fabrication needs of macro-scale 3D self-assembly. A simple way of showing 3D self-assembly is by manufacturing a chain of tiles implanted with permanent magnets. The tiles are coded by the relative orientations of two pairs of embedded NdFeB magnets. At each tile interface, the chain is bent by the simultaneous attractive and repulsive forces of the magnet pairs. Using this information, chains are coded to automatically fold into any shape without self-intersection. The principles outlined above will be shown through physical demonstrations wherein a coded chain self-assembles into a 3D object. To accomplish this, the chain is injected into a buoyant environment through a chute of comparable diameter. Beyond the scope of this project, future challenges to 3D self-assembly include applications to MEMS-scale projects and applications to practical macro-scale products.

Sudden infant death syndrome (SIDS): Microgravity and inadequate sensory stimulation

In early gestation, the human foetus develops in a buoyant environment, which is similar to the near-weightlessness of space flight. After the 26th week of gestation, the foetus gradually becomes exposed to gravitational forces. The influence of fluid immersion declines as the weight of the foetus increases. In this way, the foetus adapts and trains for the gravity environment after birth. Failure of gravitational loading in the last trimester of pregnancy delays development and maintains the pathophysiological environment of microgravity as experienced by the astronaut in space flight. The deconditioning effects of microgravity during space flight are the reverse processes of intrauterine development after the 26th week when the foetus begins training body processes for adaptation to an earthly environment. Growth requires space and movement, which suggests that a growth-retarded foetus may have been deprived of the mechanical dimension of uterine wall pressure, and, in twins, the smaller sibling may have been deprived of space. The behaviour of a study group of sudden infant death syndrome infants suggested a continuation of the effects of the foetal akinesia syndrome during the third trimester period of gestation. NASA research into the pathophysiology of microgravity was based on a simple insight: that the physiological effects of human space travel were virtually identical to the adjustments the body makes when lying down. This is the same environment as that of the human foetus in the first 22 weeks of gestation after which the uterine environment becomes a prelude to adaptations to the force of gravity.

Three-Dimensional Modeling of Negatively Buoyant Flow in Diverging Channels

Diverging channels, also known as diffusers, represent common natural and industrial outlets to lakes, reservoirs, and rivers. If the outflow in a diffuser has a larger density than the ambient water, the inflow may plunge and form a density underflow. In this paper, a three-dimensional numerical study was conducted to gain insight into the mechanism of negatively buoyant flows in diffusers with a sloping bottom. Of particular interest is the formation of separated flows such as wall-jet and free-jet flows. Various cases of plunging and the associated density current in a diffuser with different divergence angles and inflow densimetric Froude numbers are considered. The model successfully simulates the formation of attached flow, wall jets, and free jets in a negatively buoyant environment. The onset, evolution, and stabilization of a stall and the subsequent development of a wall jet in a negatively buoyant flow are investigated in detail. Computed results also show favorable agreement with some published experimental data on density current generated by the plunging of cold water in ambient warm water in a diverging channel.

A Model of Low-Speed Concurrent Flow Flame Spread Over a Thin Fuel

Abstract A numerical model is developed to examine steady, laminar flame spread and extinction over a thin solid fuel in low-speed concurrent flow. The model incorporates an elliptic treatment of the upstream flame stabilization zone near the fuel burnout point, and a parabolic treatment of the downstream flame, which has a higher flow Reynolds number. This provides a more precise fluid-mechanical description of the flame than using parabolic equations throughout, and is the first time such an approach has been used in concurrent flame spread modeling. The parabolic and elliptic regions are coupled smoothly by matching boundary conditions. The solid phase consists of an energy equation with surface radiative loss and a surface pyrolysis relation. Calculations (with the flame spread rate being an eigenvalue) are performed for forced flow without gravitational influences in a range of velocities which are lower than those induced in a normal gravity buoyant environment. Steady spread with constant flame and pyrolysis lengths is found possible for thin fuels and this facilitates the adoption of a moving coordinate system attached to the flame. Both quenching and blowoffextinction are observed. As flow velocity or oxygen percentage is reduced, the flame spread rate, the pyrolysis length, and the flame length all decrease. The flame standoff distance from the solid and the reaction zone thickness, however, first increase with decreasing flow velocity, but eventually decrease very near the quenching extinction limit. The short, weak flames observed at low flow velocities and oxygen levels are consistent with available experimental data. The maximum flame temperature decreases slowly at first as flow velocity is reduced, then falls more steeply close to the extinction limit. At low velocities, surface radiative loss becomes a significant fraction of the total combustion reactions’ heat release. In addition, the shorter flame length causes an increase in the fraction of conduction downstream (into the gas phase) compared to conduction to the fuel. These heat losses lead to lower flame temperatures, and ultimately, a quenching extinction. This extinction mechanism differs from that of blowoff, where the flame is unable to be stabilized due to the high flow velocity.

Laminar separation in buoyant channel flows

A slow moving flow in a duct emerging into a quiescent negatively buoyant environment may separate from its inner wall prior to the lip. Buoyancy accelerates the flow, curving the streamlines within the duct away from the walls. The resulting deceleration at the wall may be sufficient to provoke separation. The problem of the location of this separation point in a two-dimensional channel is studied. A potential-flow model is examined first to explore the large-Reynolds-number behaviour. The form of the potential-flow description in the vicinity of the assumed location of separation is characterized by the presence of a square-root singularity in the pressure gradient at the wall. This permits use of the ideas of viscous-inviscid interaction, proposed by Sychev (1972), to determine the separation location as a function of Froude and Reynolds numbers. Results obtained in the high-Reynoldsnumber limit show that the channel flow separates at shorter distances from the entrance as Froude number is reduced.