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Thermodynamic Model Of Decompression
The thermodynamic model was one of the first decompression models in which decompression is controlled by the volume of gas bubbles coming out of solution. In this model, pain only DCS is modelled by a single tissue which is diffusion-limited for gas uptake and bubble-formation during decompression causes "phase equilibration" of partial pressures between dissolved and free gases. The driving mechanism for gas elimination in this tissue is inherent unsaturation, also called partial pressure vacancy or the oxygen window, where oxygen metabolised is replaced by more soluble carbon dioxide. This model was used to explain the effectiveness of the Torres Straits Island pearl divers empirically developed decompression schedules, which used deeper decompression stops and less overall decompression time than the current naval decompression schedules. This trend to deeper decompression stops has become a feature of more recent decompression models. Concept Brian A. Hills analysed the exi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermodynamic Vs US Navy Decomnpression Profiles 1
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of thermodynamics which convey a quantitative description using measurable macroscopic physical quantities, but may be explained in terms of microscopic constituents by statistical mechanics. Thermodynamics applies to a wide variety of topics in science and engineering, especially physical chemistry, biochemistry, chemical engineering and mechanical engineering, but also in other complex fields such as meteorology. Historically, thermodynamics developed out of a desire to increase the efficiency of early steam engines, particularly through the work of French physicist Sadi Carnot (1824) who believed that engine efficiency was the key that could help France win the Napoleonic Wars. Scots-Irish physicist Lord Kelvin was the first to formulate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Suunto
Suunto Oy is a Finnish company that manufactures and markets sports watches, dive computers, compasses and precision instruments. Headquartered in Vantaa, Finland, Suunto employs more than 300 people worldwide, and its products are sold in over 100 countries. Although globally active, the headquarters is placed next to the factory, in which most of the work stages are still handcrafted. Suunto is a subsidiary of Amer Sports, owned since 2019 by the Chinese group Anta Sports, with sister brands Wilson, Atomic, Sports Tracker, Salomon, Precor, Arc'teryx. The company's name comes from the Finnish word , meaning "direction" or "path", or in navigation, "bearing" or "heading". History In 1932 the company's founder, Tuomas Vohlonen, a surveyor by profession, applied for a patent for a unique method of filling and sealing a lightweight compass housing made entirely of celluloid and filled with liquid to dampen the needle and to protect it from shock and wear due to excessive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half Time (physics)
In several team sports, matches are played in two halves. Half-time (also written halftime or half time) is the name given to the interval between the two halves of the match. Typically, after half-time, teams swap ends of the field of play in order to reduce any advantage that may be gained from wind or a slope to the playing surface, for example. While it exists mainly to allow competitors to rest briefly and recover from the play of the first half, half-time also serves a number of other purposes. It also serves as an intermission for spectators, and it often features entertainment, such as cheerleading performances, tifos, performances by school marching bands (particularly in high school and collegiate sports in North America), or concerts featuring popular music acts (particularly in major events such as the Super Bowl). On games that are broadcast on television and radio, it also provides broadcasters with an opportunity to give a recap of the first half of the game, air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bühlmann Decompression Algorithm
The Bühlmann decompression algorithm is a mathematical model (algorithm) of the way in which inert gases enter and leave the human body as the ambient pressure changes. Versions are used to create Bühlmann decompression tables and in personal dive computers to compute no-decompression limits and decompression schedules for dives in real-time. These decompression tables allow divers to plan the depth and duration for dives and the required decompression stops. The algorithm was developed by Swiss physician Dr. Albert A. Bühlmann, who did research into decompression theory at the Laboratory of Hyperbaric Physiology at the University Hospital in Zürich, Switzerland. The results of Bühlmann's research that began in 1959 were published in a 1983 German book whose English translation was entitled ''Decompression-Decompression Sickness''. The book was regarded as the most complete public reference on decompression calculations and was used soon after in dive computer algorithms. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Scott Haldane
John Scott Haldane (; 2 May 1860 – 14/15 March 1936) was a British physician and physiologist famous for intrepid self-experimentation which led to many important discoveries about the human body and the nature of gases. He also experimented on his son, the celebrated and polymathic biologist J. B. S. Haldane, even when he was quite young. Haldane locked himself in sealed chambers breathing potentially lethal cocktails of gases while recording their effect on his mind and body. Haldane visited the scenes of many mining disasters and investigated their causes. When the Germans used poison gas in World War I, Haldane went to the front at the request of Lord Kitchener and attempted to identify the gases being used. One outcome of this was his invention of the first respirator. Haldane's investigations into decompression sickness resulted in the first reasonably reliable decompression tables, and his mathematical model is still used in highly modified forms for computing d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exponential Distribution
In probability theory and statistics, the exponential distribution is the probability distribution of the time between events in a Poisson point process, i.e., a process in which events occur continuously and independently at a constant average rate. It is a particular case of the gamma distribution. It is the continuous analogue of the geometric distribution, and it has the key property of being memoryless. In addition to being used for the analysis of Poisson point processes it is found in various other contexts. The exponential distribution is not the same as the class of exponential families of distributions. This is a large class of probability distributions that includes the exponential distribution as one of its members, but also includes many other distributions, like the normal, binomial, gamma, and Poisson distributions. Definitions Probability density function The probability density function (pdf) of an exponential distribution is : f(x;\lambda) = \begin \lam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffusion
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical potential. It is possible to diffuse "uphill" from a region of lower concentration to a region of higher concentration, like in spinodal decomposition. The concept of diffusion is widely used in many fields, including physics ( particle diffusion), chemistry, biology, sociology, economics, and finance (diffusion of people, ideas, and price values). The central idea of diffusion, however, is common to all of these: a substance or collection undergoing diffusion spreads out from a point or location at which there is a higher concentration of that substance or collection. A gradient is the change in the value of a quantity, for example, concentration, pressure, or temperature with the change in another variable, usually distance. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perfusion
Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion is measured as the rate at which blood is delivered to tissue, or volume of blood per unit time (blood flow) per unit tissue mass. The SI unit is m3/(s·kg), although for human organs perfusion is typically reported in ml/min/g. The word is derived from the French verb "perfuser" meaning to "pour over or through". All animal tissues require an adequate blood supply for health and life. Poor perfusion (malperfusion), that is, ischemia, causes health problems, as seen in cardiovascular disease, including coronary artery disease, cerebrovascular disease, peripheral artery disease, and many other conditions. Tests verifying that adequate perfusion exists are a part of a patient's assessment process that are performed by medical or emergency personnel. The most common methods include eva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mares (scuba Gear Company)
Mares is a manufacturer of scuba equipment. Founded in 1949 by Ludovico Mares in Rapallo, Italy, the company initially made diving masks and spearguns. It has since expanded to become one of the largest scuba manufacturers, having merged with US manufacturer Dacor. Products The Mares product range includes the following products: * Diving Regulators - Both first stage and second stage regulators * Dive computers * Instruments - compasses, pressure gauges, Personal computer interfaces for their dive computers and watches * B.C.D.s * Diving Wear – including Wetsuits, Drysuits and Rash guards * Fins * Diving masks and Snorkels * Accessories - Their accessories line includes dive torches, knives, Surface marker buoys, diving sportswear, bags, weight belts, hangers, dry boxes, etc. In 2019 Mares entered the rebreather A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's breathing, exhaled breath to permit the rebreathing (recycling) of the su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dive Computer
A dive computer, personal decompression computer or decompression meter is a device used by an underwater diver to measure the elapsed time and depth during a dive and use this data to calculate and display an ascent profile which according to the programmed decompression algorithm, will give a low risk of decompression sickness. Most dive computers use real-time ambient pressure input to a decompression algorithm to indicate the remaining time to the no-stop limit, and after that has passed, the minimum decompression required to surface with an acceptable risk of decompression sickness. Several algorithms have been used, and various personal conservatism factors may be available. Some dive computers allow for gas switching during the dive. Audible alarms may be available to warn the diver when exceeding the no-stop limit, the maximum operating depth for the gas mixture, the recommended ascent rate or other limit beyond which risk increases significantly. The display provides da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brian Andrew Hills
Brian Andrew Hills, born 19 March 1934 in Cardiff, Wales, died 13 January 2006 in Brisbane, Queensland, was a physiologist who worked on decompression theory. Early decompression work was done with Hugh LeMessurier's aeromedicine group at the department of Physiology, University of Adelaide. His "thermodynamic decompression model" was one of the first models in which decompression is controlled by the volume of gas bubbles coming out of solution. In this model, pain only DCS is modelled by a single tissue which is diffusion-limited for gas uptake, and bubble-formation during decompression causes "phase equilibration" of partial pressures between dissolved and free gases. The driving mechanism for gas elimination in this tissue is inherent unsaturation, also called partial pressure vacancy or the oxygen window, where oxygen metabolised is replaced by more soluble carbon dioxide. This model was used to explain the effectiveness of the Torres Strait Islands pearl divers' empiricall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
