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  • Fluidics
    the pressure to drop in the zones between the stream and the walls creating an unstable situation Any disturbance or change in the shape of the container right will cause the equalizing return flow of air to push the stream toward one wall where it will remain locked as long as the stream keeps flowing Two different techniques of fluid control are being investigated one quite simple the other more complex and more versatile Let us begin with the elementary system Consider a solid block of steel plastic or any other suitable material in which shallow channels have been cut for passage of the fluid see illustration FLUID AMPLIFIER above A high energy stream of fluid called the power stream is pumped in through the inlet at one end The stream passes across a widened chamber designed for reasons we shall consider later to prevent the stream from clinging to one of the channel walls and arrives at a fork consisting of two outgoing channels separated by a pointed structure called the splitter If the power stream has not been disturbed and hits the splitter head on the stream will be divided in two half of the fluid passing into one outlet channel and half into the other As the power stream enters the system however it runs the gamut of two control jets one on each side Let us say that one of the jets is turned on and this control stream hits the main stream with a certain momentum It will deflect the power stream by a certain amount and the stream will then have a net momentum that is the sum of the original momenta of the power stream and the control stream taking direction into account as the geometric diagram below shows Given just the right amount of nudge by the control stream the entire main stream will be bent in the direction of one of the outlet channels and will pass out through that output Obviously the output represents an amplification of the energy applied by the control jet and the gain is equal to the ratio between the power stream s momentum and the momentum of the control jet The degree of the deflection of the power jet is proportional to the momentum of the control jet The system is therefore called proportional control The control jet s signal can be measured in terms of either momentum or pressure depending on the way the apparatus is set up if the control nozzle is placed close to the power stream the main factor deflecting the stream will be pressure rather than momentum The elementary setup I have described is of course only a single stage affair It is easy to see that it can be expanded into a multistage system simply by using the output stream of one stage as the control stream for the next see illustration TWO STAGE FLUID AMPLIFIER above By making each successive power injection larger than the one before one can build up almost any degree of gain or amplification one wishes That is to say the small nudge or signal applied by a control jet in the first stage can be amplified by successive steps to control a very large power stream indeed in the final stage This then is the basic outline of the first of the two fluid control techniques under study As an instrument of proportional control it performs amplification in the usual sense of the word and it promises a number of interesting applications including its use as an element in an analogue computer The other technique of fluid control does not produce proportional amplification rather it corresponds to a triode that turns a flow of electrons on or off It is essentially like an element in a digital computer In this system the fluid power stream left to itself locks onto one wall of the channel in which it is flowing and as a result the stream exits through the outlet on that side An injection of fluid from the control jet on the same side will cause the stream to swing over to the other side and lock onto the wall there so that it then flows out of the other outlet In either case the stream maintains a stable position flowing only to a particular outlet unless it is switched by a control jet The reasons for this are inherent in the mechanics of the situation Consider a high speed stream of air injected through a nozzle into a wide container of air I call the fluid air to make the example specific the results to be described would apply to any gas or liquid As the stream moves along it will entrain air from both sides and become broader carrying more air toward the open end of the container see bottom illustration COANDA EFFECT above The stream s pickup of air along its sides however causes the pressure to drop in the zones between the stream and the walls of the container The resulting pressure difference creates an unstable situation the higher pressure of the surroundings ambient pressure will push air back into the low pressure zones on both sides of the stream to equalize the pressure Suppose now there is some disturbance or asymmetry say in the shape of the container that causes the equalizing return flow to push the stream toward one wall As the zone between the stream and that wall narrows there is less room for the admittance of counterflow to replace the air being entrained by the stream on that side and therefore the comparative pressure in the zone drops further Very quickly the stream moves over against the wall It stays locked onto that wall as long as the stream keeps flowing because on the wall side a region of low pressure persists near the nozzle whereas on the opposite side of the stream the ambient pressure pushes the stream toward that region The phenomenon is known as the Coanda effect so designated because it was first studied by a Romanian engineer named Henri Coanda in the 1930 s PROPORTIONAL CONTROL the principle on which the fluid amplifiers at the top and middle of the opposite page are based is illustrated geometrically The vector representing the momentum of the control jet light colored arrows is added to the vector of the power stream s momentum solid colored arrows to obtain the momentum of the output stream black arrows Thus the gain or amplification produced by the fluid system is equal to the ratio between the power stream s momentum and the momentum of the control jet The degree of deflection of the power jet is proportional to the momentum of the control jet SCHLIEREN PHOTOGRAPH made by an optical technique that detects density gradients in a gas flow demonstrates Coanda effect A high energy stream of air is locked onto the chamber wall at right after being subjected to a short blast of air from control jet at left Obviously the stream can be moved away from the wall in either of two ways by increasing the pressure on the stream from the wall side or by reducing the pressure on the opposite side This can easily be done by means of control jets on the sides If the stream is locked onto the right wall injection of air from the right jet or removal of air through the left jet will cause the stream to swing away from the right wall as soon as the pressure on the right side becomes higher than that on the left Once the stream has crossed the center line of the channel it will go on to attach itself to the left wall for the same reasons that it originally locked onto the right one The control jet can then be shut off the stream will stay locked onto the left side without help In the two outlet type of device the locking of the stream onto the right wall means of course that the entire stream exits through the right outlet and when it is switched to the left wall it goes to the left outlet The Coanda effect explains by the way why the proportional contro1 amplifier must have the channel widened into a heart shape near the power stream nozzle this configuration prevents the stream from locking onto a wall It has turned out that the behavior of the stream depends a great deal on the distance of the splitter from the power stream nozzle Warren of the Harry Diamond Laboratories has investigated this matter in detail see illustration DISTANCE OF SPLITTER below DISTANCE OF SPLITTER from power stream nozzle in the standard two outlet type of fluid switching device has an important effect on the behavior of the stream When the splitter is very close to the nozzle top row the stream does not lock spontaneously onto either wall The stream can be directed into one outlet or tl1e other by a pulse injection from a control jet but as soon as the control injection stops the stream resumes its normal behavior of dividing at the splitter and flowing into both outlets lf the splitter is located at a distance amounting to three to five nozzle widths from the nozzle second row from top most of the stream will begin to flow spontaneously to one outlet When the splitter is six nozzle widths or more away from the nozzle bottom two rows the stream will lock onto one wall and flow only to the outlet it has chosen spontaneously or the one to which it is switched By blocking one of the outlets second column from right one can divert the stream from the outlet it naturally prefers to the opposite one but when the block is removed column at extreme right stream will return spontaneously to preferred outlet When the splitter is very close to the nozzle within a distance not more than about twice the nozzle s width the stream does not lock onto either wall because the distance is not sufficient for a significant pressure difference to develop The stream can be directed into one outlet or the other by a pulse injection from a control jet but as soon as the control injection stops the stream resumes its normal behavior of dividing at the splitter and flowing to both outlets If the splitter is located at a distance amounting to three to five nozzle widths from the nozzle the stream begins to be influenced by the Coanda effect in the presence of an asymmetry most of it will flow spontaneously to one outlet When the splitter is six nozzle widths or more away from the nozzle the Coanda effect takes full charge The stream will lock onto one wall and flow only to the outlet it has chosen spontaneously or the one to which it is switched Some very interesting effects can be produced by blocking one of the outlets as the illustration on page 85 shows In one arrangement such a block will divert the stream from the outlet it naturally prefers to the opposite one but when the block is removed the stream will return spontaneously to the preferred outlet Thus the device exhibits a property that amounts to memory and it can be put to use for that purpose Of the various possible uses of fluid control devices the most intriguing is their application as the basis of a digital computer The type of device in which the stream locks onto one wall or the other is precisely suited for functioning as an all around element for such a computer It gives a binary digital response the stream can be directed to either of two exit ports one representing 0 the other representing 1 It can be shifted back and forth from one port to another like a flip flop switch Indeed it can even serve as an oscillator This can be accomplished by connecting the control jets on the opposite sides of the main stream by a tube that will transmit sound VV hen the main stream flops from one side to the other it generates sound waves a compression wave on one side of the stream and a rarefaction wave on the other If the sonic path through the tube connecting the two sides has a length that is about half the wavelength of the full sound wave the compression and rarefaction waves traveling through the tube in opposite directions will cross to the opposite sides in the same time This change in pressure at the respective sides from compression to rarefaction on one side and from rarefaction to compression on the other is sufficient to switch the main stream from one wall to the other The stream will oscillate back and forth as the sound waves travel back and forth The fluid device can also be designed to act as a logical gate expressing the concept and or or For the and gate the jets are so arranged that jet A alone will go to one output jet B alone will go to a different output and the two jets combined will go to a third output that signifies A and B see top illustration LOGICAL AND GATE below For the or gate there are two jets A and B on one side of the main stream either jet A or jet B on being activated will cause the main stream to go to a certain exit port see middle illustration LOGICAL OR GATE below The fluid control concept lends itself to a great variety of arrangements The device can be designed for example to reset itself with the main stream always returning to a given exit port in the absence of a deflecting pulse this can be achieved simply by placing the main stream nozzle closer to the right wall say than to the left wall By building a network of channels of varying cross section and with varying conntrols it is possible to create a system that will carry out a series of different operations And the characteristics of the system can be varied by using various fluids In most of the computational elements constructed so far the working fluid is air because it is so readily available and easy to handle Let us look now at a couple of specific applications of fluid control on which considerable research has been done One is the steering of rockets in flight This is managed at present by the use of devices such as jet vanes and swiveled nozzles through which pulses of exhaust are discharged to apply small thrusts correcting the trajectory of the rocket These devices are far from ideal because it takes a great deal of force to operate them their response to commands is fairly slow andf they involve moving parts that are subject to being put out of action by the hot exhaust streams A fluid control system now under study would avoid those difficulties The control would be applied to the main exhaust stream itself that is the thrust that drives the rocket A small power stream would be bled from the main exhaust and this small stream would be used to deflect the main stream when necessary to change the direction of the rocket see bottom illustration ROCKET CAN BE STEERED below The small stream would be controlled by a pair of jets when the right jet was turned on it would turn the stream so that it struck the main exhaust from the side thereby changing the direction of the driving thrust slightly with a resulting change in the trajectory of the rocket s flight The idea has been tested in a small land vehicle powered by a turbine engine By means of a five stage proportional amplifier weighing less than 10 pounds an extremely small fluid signal amounting to a flow of less than five thousandths of a pound per minute controlled a jet of 33 pounds per minute that was used to deflect the power stream driving the vehicle LOGICAL AND GATE can be built using fluid control components Jets are so arranged that jet A alone will go to one output left jet B will go to a different output middle and two jets combined will go to a third output right that signifies A and B LOGICAL OR GATE contains two control jets A and B on one side of the main power stream With neither jet on the stream will go to one output left Either jet A or jet B on being activated will cause the stream to go to other output middle and right ROCKET CAN BE STEERED by the fluid control device depicted here A small power stream is bled from the main rocket exhaust and used to deflect the main stream when necessary to change the direction of the rocket The power stream is controlled by a pair of jets When one jet is on left the stream simply adds to the main driving thrust of the rocket When the other jet is on right it switches the stream so that it strikes the main exhaust from the side thereby changing the direction of the driving thrust and hence the trajectory of the rocket s flight Fluid system appears to be more efficient and reliable than other systems currently in use The other application I want to describe is an artificial heart pump developed jointly by workers at the Harry Diamond Laboratories and the Walter Reed Army Institute of Research This device uses a fluid amplifier of the wall locking type with air as the working fluid The stream of high velocity air emerging from the power nozzle locks onto one wall and then flows on to a chamber containing an artificial ventricle that is made of a flexible plastic and is filled with blood see illustration

    Original URL path: http://miriam-english.org/files/fluidics/FluidControlDevices.html (2016-04-25)
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  • Index of /files/fluidics/images
    png SA Fluidics 03 1 png SA Fluidics 03 2 png SA Fluidics 03 3 png SA Fluidics 04 png SA Fluidics 05 jpg SA Fluidics 06 png SA Fluidics 07 1 png SA Fluidics 07 2 png SA Fluidics

    Original URL path: http://miriam-english.org/files/fluidics/images/ (2016-04-25)
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  • Index of /files/fluidics/science-mechanics_fluid-transistor-circuits
    Index of files fluidics science mechanics fluid transistor circuits Parent Directory fluid transistor circuits html images

    Original URL path: http://miriam-english.org/files/fluidics/science-mechanics_fluid-transistor-circuits/ (2016-04-25)
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  • Four Nuclear Myths
    annual electricity than all U S nuclear plants do now for 7 kWh busbar including the cost of new transmission lines and the 0 5 kWh cost of grid integration That s one third higher than the actual price of windpower sold from U S windfarms installed in 2007 87 or about one half to one third of the industry reported cost for power from a new U S nuclear plant Another misleading and tendentious reference is offered on p 103 to support the claim that nuclear power in the United States is under subsidized and renewables are over subsidized The opposite is true as shown in many analyses by the most knowledgeable independent student of this subject Doug Koplow at www earthtrack net 88 Of course on this as on many other controversial topics one can easily shop for references to support a desired conclusion Any scholar should know and any author should ascertain whether those references are far from the analytically defensible end of a large distribution of diverse findings In perhaps the most egregious speculation Brand avers on p 96 that the standard no threshold theory the linear hypothesis that the biological harmfulness of ionizing radiation is proportional to dose down to even the smallest doses is wrong as most scientists suspect it is He even lends credence to the claim that a little ionizing radiation is good for you radiation hormesis He does not mention that neither theory is accepted by any radiation protection authority including the International Commission on Radiological Protection and the U S National Council on Radiation Protection and Measurements despite many years of strenuous lobbying by the nuclear industry which would find acceptance of these notions economically helpful As Brand says on p 96 At stake are hundreds of billions of dollars a tipoff that careful scholarship is especially important The balanced Controversy discussion of this issue in the Wikipedia 89 correctly says their rejection of radiation hormesis is partly for the sake of caution and partly for the lack of contrary evidence The notion that hormesis is a widespread of important phenomenon in biological systems is not widely accepted The claim that most scientists suspect the linear hypothesis to be wrong is unsupported and unsupportable Sloppy scholarship Other poor scholarship is evident throughout the nuclear chapter For example p 80 describes California and U S energy use when it means electricity use per capita It also says the abandonment of the Shoreham nuclear plant in or around 1980 helped frighten the American nuclear industry to a standstill actually the plant was completed in 1984 and abandoned in 1988 89 but the industry s last order was in 1978 the year before Three Mile Island and all orders after 1973 were cancelled Page 84 says the world and the U S increased their energy intensity it means decreased Pages 88 89 misrepresents as nuclear proponents several people whose views they tell me are the opposite Pages 91 and elsewhere list nuclear power s 2008 share of world electricity production as 16 it was actually 14 and still falling Page 91 lists 443 civilian power reactors as operating in 2008 the IAEA listed 436 of which five have been in long term shutdown since the mid 1990s and at least 17 generated no power in 2008 At 13 October 2009 the IAEA listed 436 operating reactors eight fewer than in 2002 Pages 92 and 95 misspell the name of John Gofman Page 98 erroneously includes end use efficiency as part of micropower Page 107 repeats all the standard fallacies debunked by National Academy and many other independent studies about reprocessing s alleged ability to make nuclear waste more compact easy and cheap to manage in fact it does the opposite The troubled La Hague plant is also said to have an impeccable safety record Thankfully Brand acknowledges reprocessing s bad economics but then praises breeders which require it Page 111 uses the nonsensical unit 2 gigawatts per year as a rate of electricity flow Page 116 assumes people without electricity can get it only from the grid actually when offered it from decentralized solar power as in Kenya most prefer and adopt that instead Brand s external summaries of his nuclear thesis rely upon these and other obvious errors 90 Some topics are so thoroughly garbled that one must simply start over from scratch For example the discussion of proliferation in most experts view including mine nuclear power s biggest noneconomic issue on pp 108 111 misses all the basic points e g that the problem is not just fissionable materials but also equipment technology skills knowledge and cadres of nuclear experts all wrapped in innocent civilian disguise that nonproliferation requires unmasking proliferators by removing that ambiguity that supposedly safe materials like low enriched LWR fuel do have significant military potential that recognizing nuclear power s economic failure offers a unique opportunity to disambiguate it and that the civil and military sides of nuclear energy have always been and today remain closely intertwined 91 I concur with Socolow and Glaser who judge the hazard of aggressively pursuing an expansion of nuclear power today to be worse than the hazard of slowing the attack on climate change by whatever increment such caution entails 92 Of course the simplest way to avoid this disagreeable choice is to take economics seriously and choose the best buys first thus gaining the most climate protection per dollar and per year through inherently nonviolent technologies Brand also claims that nuclear power is a major method of reducing nuclear weaponry He s referring to the downblending of Russian weapons highly enriched uranium into reactor fuel at low or natural 235U concentration That s an excellent idea but it doesn t require that the resulting low enriched uranium be used optionally fissioning it in reactors simply helps repay its exorbitant sunk cost and is not a disarmament benefit of nuclear power On the contrary nuclear power creates demand and cover for ambiguous dual purpose enrichment plants as in Iran The safety and waste issues are similarly too complex to cover here Suffice it to say that Brand oversimplifies both into engineering issues then sweeps them away with breathtaking insouciance These issues have vexed skilled nuclear engineers and scientists for decades because they re hard not because they re easy yet Brand mentions none of them specifically Rather he breezily proclaims at p 91 Reactor safety is a problem already solved nuclear waste probably isn t so dangerous major accidents weren t really so bad operators presumably better than those at Three Mile Island will keep reactors safe to prevent huge financial losses we need to let go of our irrational fears the engineers assure him they ve figured it all out he s comfortable with their unmentioned solutions and if anything goes wrong our descendents can figure out better solutions later As Hugh Nash said how can we better pay tribute to our descendents boundless technological ingenuity than to make damned sure they ll need it Of course these are not purely engineering issues either they have a long and disturbing history of human fallibility 93 institutional laxity regulatory capture and sometimes outright mendacity which has apparently concealed from him among other things the geological unsuitability of Yucca Mountain and the many basic reactor safety problems still unsolved since the 1960s Nuclear vs competitors market status and prospects Perhaps the clearest example of why we differ on nuclear power s status and prospects is his emphasis on pp 98 100 on my supposedly being flat wrong about nuclear power s failure in the marketplace As contrary evidence he adduces a long list of countries that he claims are planning or building nuclear power plants 94 In fact most of those are mere gleams in vendors eyes or have merely asked the IAEA for information about nuclear power or have made a political announcement of intended nuclear plants but without the money skills political acceptance or infrastructure to build and run them and often without even a power grid big enough to put one into The IAEA says a nuclear plant can t be bigger than 10 of the grid s total capacity and the smallest power reactors on the market are at least 0 4 0 5 GW yet Brand lists as now building nukes for the first time such nations as Albania with a mere 1 7 GW grid Bangladesh with 4 7 GW and Burma which uses less electricity than one modern reactor makes He can only be referring to a 10 MWt research reactor now proposed by Myanmar s generals probably for military use or threat it s 0 2 the size of a modern power reactor France hopes Vietnam and Thailand will buy reactors but neither has adequate funds infrastructure or grid In short many countries nuclear prospects as thoroughly documented elsewhere 95 are far dimmer than a mere wish list implies The IAEA says it typically takes 15 years for a country with little developed technical base to implement its first nuclear power plant 96 Some discrepancies are particularly glaring For example Brand says Ireland Norway and Poland were planning their first reactors in 2007 97 yet according to the IAEA and the OECD Nuclear Energy Agency Ireland and Norway were and are doing nothing of the sort Ireland s supposed nuclear customer confirmed to me in May 2009 its intent to go all renewable Poland s state power company did announce a wish to build two reactors by 2020 but has no money to buy them no site selection is 3 5 years away no political consensus and no legal framework or institutional infrastructure 98 And while it s true that more countries are valuing carbon they all face fierce nuclear capital cost escalation from bottlenecked suppliers short of capacity and skills Any countries that pay attention will see too that their options aren t just nuclear vs coal To be sure some centrally planned power systems do continue to order and build nuclear plants regardless almost always drawing directly or indirectly on the public purse Brand notes that in 2007 the IAEA listed 31 reactors as under construction I ll spot him 21 more as of 1 August 2009 there were 52 compared with 120 at the end of 1987 or with 233 at the ordering peak in 1979 To be sure 52 is more than the 24 observed at the ordering nadir in 2004 but it s also below the annual ordering level of each year during 1967 93 and is just 22 of the peak thirty years ago Viewed graphically the past few years small uptick of construction starts looks like what stockmarket watchers call a dead cat bounce especially when one looks more closely at those 52 plants under construction 99 13 have been under construction for over 20 years 24 have no officially planned start date half are late often substantially 36 over two thirds are in just four countries China India Russia and South Korea none of which use competitive markets to choose whether or which power plants are built and none of which is very transparent about construction status or decision process In Europe where Brand presents a distorted picture of supposed nuclear revival there s just one nuclear project that might look at first glance like a private sector purchase a TVA like nonprofit Finnish consortium of utilities municipalities and major industries bought the Olkiluoto 3 plant As its manager recently explained during my site visit the deal was backed by their balance sheets under a unique take or pay capital charge contract of indefinite duration with a fixed price turnkey construction contract from the now foundered Areva Siemens joint venture But the full story is more interesting The plant was largely financed at far below market rates through regional parastatal banks in France and Germany the builders home countries That s still under legal challenge as an illegal subsidy After three and a half years construction the project is at least three years late and 77 100 over budget with probably worse to come the Finnish regulator is publicly very unhappy In France the 91 state owned vendor Areva has been given an order and an announcement of a second order by the 85 state owned national utility Électricité de France despite its manifest nuclear overcapacity The ordered plant Flamanville 3 bid 20 higher than the identical Finnish unit and not at a fixed price has been under construction for a year and a half and is likely a year late and at least 20 over budget All this may reflect an atrophy of world leading vendor Areva s capabilities not surprisingly since its last order before the Finnish plant was in 1992 The only other European units under construction are mid 1980s projects in Bulgaria and Slovakia Politically weak Prime Ministers in Italy and Britain declaim about building more reactors but they lack financing are barred by EU rules from offering subsidies and will face serious domestic obstacles as they try to adopt French political structures and decisionmaking practices to support their proposed outsourcing of nuclear construction financing and to some degree regulation to organs of the French state My 2008 conclusion which Brand correctly quotes but disputes was Nuclear power is continuing its decades long collapse in the global marketplace because it s grossly uncompetitive unneeded and obsolete Since he acknowledged and discussed none of the evidence presented for this view in refs 1 6 let me repeat here an illustrative summary of the past three years nuclear vs competing orders and installations worldwide Observed global market behavior tells the story with striking clarity By 2006 micropower was producing one sixth of the world s total electricity slightly more than nuclear power one third of the world s new electricity and from one sixth to more than half of all electricity in a dozen industrial countries not including the badly lagging U K or U S at 7 whose rules favor incumbents and their large plants In 2006 nuclear power worldwide added 1 44 billion watts about one big reactor s worth of net capacity more than all of it from uprating old units since retirements exceeded additions But photovoltaics added more capacity than that in 2006 wind power ten times more micropower 30 41 times more depending on whether you include standby and peaking units Micropower plus negawatts probably provided over half the world s new electrical services In China the world s most ambitious nuclear program ended 2006 with one seventh the installed capacity of China s distributed renewables and was growing only one seventh as fast In 2007 the U S Spain and China each added more wind capacity than the world added nuclear capacity and the U S added more wind capacity than it added coal fired capacity during 2003 07 inclusive China beat its 2010 windpower target In 2008 China doubled its windpower installations for the fourth year in a row and looked set to beat its 2020 windpower target in 2010 101 Windpower pulled ahead of gas fired capacity additions for the first year in the U S and the second year in the EU For the first time in the nuclear era no new nuclear plants came online worldwide nuclear net capacity and output fell At 12 October 2009 no new nuclear unit had reportedly come online since August 2007 in Romania after 24 years construction Nuclear orders trickled in from centrally planned systems but not from markets garnering only a few percent market share and 4 4 of all global capacity under construction In the U S from August 2005 to August 2008 with the most robust capital markets and nuclear politics in history and despite new nuclear subsidies on top of the old ones rivaling or exceeding new nuclear plants total construction cost not a penny of private equity was offered for any of the 9 planned or 24 proposed new units their developers were happy to risk taxpayers money but not their own Meanwhile distributed renewables worldwide in 2008 added 40 GW from 100 billion of investment That plus 40 billion for big hydro dams brought renewable power production for the first time in about a century more investment than the 110 billion put into fossil fueled power stations The billions of watts GW of new wind photovoltaic and nuclear generating capacity added to the grid worldwide in each year during 1990 2008 are as follows Fig 2 The latest data on micropower s worldwide electricity production are as follows renewables actual through 2008 cogeneration actual through 2006 and about to be updated to mid 2009 nuclear projections assuming that all announced completions occur on time and very implausibly that no retirements occur in 2010 12 hence the jump shown in apparent output in those years Fig 3 102 This rout of nuclear power in the global marketplace and its inability to persuade private investors anywhere to risk their money on its equity marks the biggest collapse of any industrial enterprise in the history of the world Brand can ignore it only by reading World Nuclear Association press releases instead of actual market order and installation data and by pretending that the decentralized technologies that actually add tens of times more global capacity each year than nuclear power adds somehow cannot be important or effective competitors He describes solar as a bit player yet even PVs the costliest renewable have added more new unit capacity and output than nuclear has in each of the past three years and nuclear may never catch up with its explosive growth As ref 10 describes new reactor types pp 113 114 aren t materially different No wonder German Environment Minister Sigmar Gabriel whose country Brand inaccurately says has reneged on its nuclear shutdown law stated on 27 August 2009 in releasing his Ministry s publication the World Nuclear Industry Status Report 2009 ref 95 103 The renaissance of nuclear energy much trumpeted by its supporters is not taking place The only thing frequently revived is the announcement The study shows the number of old nuclear power plants which are decommissioned worldwide is greater than the number of new ones taking up operation Available resources engineering performance and funds are not even enough to stop the downward trend let alone increase the number of reactors All the facts are in favour of phasing out this technology while at the same time expanding the use of renewable energies and energy efficiency as this is a promising option for the future Conspicuously absent from Brand s assessment of new nuclear plants is their offset by larger nuclear retirements as ref 95 trenchantly analyzes The average nuclear plant in 2009 is 25 years old vs 22 for the 123 units already closed To offset the plants reaching age 40 their typical now expected operating life or 32 by law for the 17 German units would require completion of all 52 units under construction at 1 August 2009 planning construction and startup of 42 more plants one every six weeks to 2015 plus 192 more one every 19 days over the following decade The 2015 target is unachievable due to constraints on capacity to manufacture key components so the number of reactors operating will decline over the years to come even if the installed capacity could be maintained unless lifetime extension beyond 40 years becomes standard raising difficult safety maintenance cost and other issues 104 U S regulators uniquely have approved 54 license extensions from 40 to 60 years other countries have not and the only two reactors in the world that have run for more than 40 years are slated for shutdown within two years so operating experience to justify 60 year licenses is extremely sparse The U S extensions only slightly postpone the inevitable global decline in operating nuclear units Perhaps Brand s disagreement with my assessment is not really about nuclear power s failure in as I said the global marketplace rather he s emphasizing its pursuit in countries that don t have a marketplace for power plants A few countries that centrally plan their power systems and socialize their costs do buy nuclear plants some still in substantial numbers What s in dispute is whether that s the exception or the new rule for the future world I think nuclear power can t get far without having a business case in market economies too because I doubt that most of the world s economy will adopt a command and control energy economy Brand apparently thinks they will and should because p 105 Market forces cannot limit greenhouse gases Governments have to take the lead What they deem the atmosphere requires will be the prime driver of the economics of energy Of course carbon pricing whether by carbon taxes or cap and trade is a market mechanism instituted by governments to limit CO 2 by correcting the market failure of this unpriced major externality From there he leaps boldly to the supposition that the nuclear imperative he perceives should must and will override all economic security and other considerations and cause governments to mandate and finance nuclear construction Even if this logic held the biggest centrally planned energy systems have their own fiscal and logistical limits that are coming into view China has nearly one third of all reactors under construction worldwide with a 2020 nuclear target that was 30 40 GW in 2006 but was recently raised to 70 GW Brand states and then to 80 GW Clearly if anyone can build enough reactors quickly enough to matter it s China Yet if the extraordinarily ambitious target of 80 GW in 2020 were achieved it would offset only about one fifth of the expected global retirements of nuclear plants meanwhile This looks unlikely Many analysts doubt that even China can build or finance 80 GW so quickly Even if construction time shrank to 5 0 years from the first ten units 6 3 years they d all need to be under construction by 2015 i e in the next five years In 2008 China had 8 4 GW of nuclear plants installed making about 2 of her electricity and 0 8 of her primary energy Only 16 units have started construction in the past four years leaving another 57 to start in the next five years one a month Even for China that s a big challenge Precedent is no proof but China s 1985 nuclear target of 20 GW in 2000 was missed by tenfold the 2009 capacity is still under 10 GW less than windpower though characteristically official press releases still describe nuclear s share numerically and all other non big hydro renewables larger share as trivial or negligible By autumn 2009 China s acceleration to 16 nuclear units 15 GW officially under construction was raising questions about logistical and safety performance Zhang Guobao head of the National Energy Administration warned of signs of improper and too fast nuclear development in some regions and added We d rather move slower and achieve less than incur potential safety concerns in terms of nuclear energy 105 Meanwhile China is moving toward more transparent decisionmaking and more competitive capital allocation Global experience suggests that neither trend bodes well for prolonged nuclear expansion China s electricity demand dominated by energy intensive and export oriented basic materials industries dipped in 2008 and is still recovering to 2007 levels Power plant construction has slackened Tough efficiency standards and policies are also gaining momentum throughout the economy So are many competitors A modern natural gas sector is emerging and China believes it has at least half as much gas as coal while some foreign experts think it has far more it doesn t matter since the supergiant east Siberian fields will ultimately flow eastward Chinese analysts are further starting to realize that new coal power is much costlier than meets the eye especially due to its huge opportunity cost of bottlenecking the winter rail network In striking contrast to central stations China s aggressively entrepreneurial largely private sector vendors of distributed generation seem much better able to meet their newly raised 2020 targets including 150 GW of windpower and 20 GW of PVs than nuclear power can China is 1 in 5 6 renewable technologies and aims to be in all it became 1 in PV making in 2008 and should become 1 in wind installing in 2009 Though windpower s rapid scaling up is subject to many mishaps it s lately outpaced both grid expansion and quality control such glitches can be fixed much more easily in modular renewables than in unforgiving monolithic nuclear construction projects All the fast and cheap skills that China brings to thermal power plants apply in spades to windpower too because its tractable unit size quick manufacturing and modularity can rapidly capture volume economies and learning effects And a new Harvard Tsinghua analysis confirms that available suitable windy Chinese sites can meet all China s electrical needs the total not just the growth cost effectively through at least 2030 106 Brand thinks renewables can t be important because wind and PVs aren t baseload and dismisses or ignores the equally large dispatchable renewables cogeneration fuel switching or efficiency so he thinks the only relevant comparison is nuclear vs coal The nuclear industry shares and spreads this view that its most potent actual competitors aren t legitimate and scarcely matter But the global power industry knows better It is shifting massively even in China from coal to efficiency cogeneration and renewables Its top officials tell me so Reforms like decoupling and shared savings already adopted in 8 of the United States and pending in 11 for electricity adopted in 18 and pending in 5 for natural gas will greatly accelerate this shift by rewarding utilities for cutting your bill not for selling you more energy So will financial innovations like PACE bonds for retrofitting efficiency and renewables into buildings 107 So will climate and national security pressures Brand believes p 105 these pressures can work only through national policy so governments will set prices and subsidies that will reverse or bypass the market s trend toward micropower But carbon pricing though helpful especially in the electricity sector because it will speed the shift away from coal 108 seems to me likely to exert less leverage on big energy investments than the underlying competition between efficiency and supply or between central stations and micropower A 20 tCO 2 carbon tax makes nuclear look 2 kWh better vs coal or 1 kWh against gas but it doesn t help any of those three prevail against the zero carbon efficiency wind and solar competitors that are rapidly grabbing the power market from all kinds of central thermal stations The only key sense in which governments matter to the nuclear choice is whether market economies will force taxpayers to buy lots of the nuclear plants that private investors refuse to finance The U S has tried this since 2005 but no equity has been offered so now the industry is trying to eliminate the legal requirement for it If this succeeded on an extremely large scale hard to imagine for both budgetary and political reasons even if competitive logic were utterly abandoned this might perhaps raise nuclear power s market share from a few percent to nearer micropower s tens of times larger level But I think the expenditures needed are so large that they would quickly exhaust both fiscal capacity and political tolerance and vendors recent track record makes it doubtful that they could deliver Therefore I keep returning to nuclear power s lack of a tenable business case and its grave opportunity cost of reducing and retarding climate protection These issues demand answers Myths are not a responsible substitute Physicist Amory Lovins is cofounder Chairman and Chief Scientist of Rocky Mountain Institute http www rmi org and Chairman Emeritus of one of its five for profit spinoffs http www fiberforge com and has written 29 books and hundreds of papers His wide ranging innovations in energy security environment and development have been recognized by the Blue Planet Volvo Onassis Nissan Shingo and Mitchell Prizes MacArthur and Ashoka Fellowships the Benjamin Franklin and Happold Medals 11 honorary doctorates honorary membership of the American Institute of Architects Fellowship of the Royal Society of Arts Foreign Membership of the Royal Swedish Academy of Engineering Sciences and the Heinz Lindbergh Right Livelihood National Design and World Technology Awards He has taught such topics as design economics and business in eight universities most recently as a 2007 visiting professor in Stanford University s School of Engineering He has briefed 20 heads of state advised governments and major firms worldwide on advanced energy and resource efficiency and led the technical redesign of more than 30 billion worth of industrial facilities in 29 sectors and in scores of buildings to achieve very large energy savings at typically lower capital cost He has been an independent student of nuclear power for over 40 years and has consulted for over 100 utilities many of them nuclear operators In 2009 Time named him one of the 100 most influential people in the world Mr Lovins gratefully acknowledges valuable comments and counsel by 20 peer reviewers especially Ralph Cavanagh Tom Dinwoodie Michael Eckhart Jim Harding Paul Hawken Hutch Hutchinson Prof Dan Kammen Dr Jonathan Koomey Walt Patterson Mycle Schneider and Prof Robert Socolow Sole responsibility for the result rests with the author RMI staff members Aris Yi and Bennett Cohen and former staff member Imran Sheikh kindly helped with graphics and research References 1 A B Lovins Mighty Mice Nuclear Engineering International pp 44 48 Dec 2005 http www rmi org images PDFs Energy E05 15 MightyMice pdf summarizing ref 2 A World Nuclear Association critique and my response are at http www neimagazine com comments asp sc 2033302 2 Nuclear Power Economics and Climate Protection Potential RMI Publ E05 14 6 Jan 2006 http www rmi org images PDFs Energy E05 14 NukePwrEcon pdf 3 A B Lovins I Sheikh A M Markevich Forget Nuclear RMI Newsletter Apr 2008 http www rmi org sitepages pid467 php summarizing refs 4 and 5 4 Nuclear Power Climate Fix or Folly RMI Publ E09 01 Dec 2008 http www rmi org images PDFs Energy E09 01 NuclPwrClimFixFolly1i09 pdf updating and expanding ref 3 5 A B Lovins I Sheikh The Nuclear Illusion draft 18 preprint posted by permission May 2008 at http www rmi org images PDFs Energy E08 01 AmbioNucIllusion pdf draft 20 revision to be published in early 2010 in Ambio Royal Swedish Academy of Sciences 6 Particularly in refs 2 4 and 5 ref 4 is the best starting point for most readers with ref 5 as its detailed backup A more recent short article assesses new Gen 4 reactor types which look broadly comparable to today s Gen 2 3 reactors in waste production might in some respects be safer are generally as or more proliferative and lack the economic and other advantages often claimed for them e g by Brand at pp 113 114 A B Lovins New Nuclear Reactors Same Old Story RMI Solutions J Spring 2009 http www rmi org sitepages pid601 php 7 A simple introduction is at http en wikipedia org wiki Concentrating solar power In spring 2008 J Romm s assessment found a practical potential to scale up and mass produce 50 100 GW y of concentrating solar power indefinitely http www salon com news feature 2008 04 14 solar electric thermal print html at a busbar cost Sandia National Laboratory estimated in 2008 at 8 10 kWh once 3 GW has been made The current order pipeline with scores of projects by some counts 180 contemplated in just Spain and the U S is a substantial multiple of 3 GW and may exceed 40 GW Some innovators also believe costs around or below 6 kWh are coming into view CSP capacity coming online in 2009 appears competitive with new nuclear capacity Of course large scale deployment in deserts would require dry cooling due to water scarcity as is similarly or more true for nuclear or coal plants 8 All these and other micropower data documented to standard industry sources are posted at RMI s longstanding database see http www rmi org sitepages pid256 php Publ E05 04 The 2008 renewable data will be posted shortly and the latest cogeneration data in late 2009 The 2008 capacity factor of the global installed base is 66 for all micropower 83 for non biomass cogeneration 60 collectively for geothermal small hydro biomass waste 40 and rising for all distributed renewables 0 26 for wind 0 17 for PV and 80 for nuclear power 9 For example untapped U S industrial cogeneration potential is at least comparable to U S nuclear capacity and output O Bailey and E Worrell Clean Energy Technologies A Preliminary Inventory of the Potential for Electricity Generation LBNL 57451 Apr 2005 http repositories cdlib org lbnl LBNL 57451 See also P Lemar Jr The potential impact of policies to promote combined heat and power in U S industry En Pol 29 14 1243 1254 Nov 2001 Cogeneration potential in buildings is unmeasured but very large and is not confined to large buildings e g Honda has sold over 100 000 home cogeneration systems and VW has just entered the market with LichtBlick which plans a German 2 GW virtual decentralized power plant to firm renewable power Old but still useful estimates of European industrial and building CHP potential are in F Krause et al Fossil Generation The Cost and Potential of Low Carbon Resources Options in Western Europe IPSEP 1994 http files me com jgkoomey c49xzn 10 Noted gas expert R A Hefner s The Grand Energy Transition Sept 2009 rev edn Wiley Sept 2009 notes that simply dispatching existing U S combined cycle gas fired plants before coal fired plants would displace about one third of all U S coal fired electricity lowering CO 2 emissions by several hundred million tonnes a year without building any new capacity This would increase operating costs by 2 kWh many times less than substituting new nuclear plants refs 4 5 11 I assume that readers interested in the economic arguments are acquainted with both the long term and the recent economic history of nuclear power Basic readings are I C Bupp J C Derian The Failed Promise of Nuclear Power Basic Books NY 1981 J G Koomey N E Hultman A reactor level analysis of busbar costs for U S nuclear plants 1970 2005 En Pol 35 11 5630 5642 Nov 2007 http dx coi org 10 1016 j enpol 2007 06 005 F Krause et al Nuclear Power The Cost and Potential of Low Carbon Resource Options in Western Europe IPSEP 1994 http files me com jgkoomey b7fi62 MIT The Future of Nuclear Power An Interdisciplinary MIT Study 2003 http web mit edu nuclearpower Keystone Center Nuclear Power Joint Fact Finding June 2007 http www keystone org spp documents FinalReport NJFF6 12 2007 1 pdf and for France ref 83 12 Nobody claims that efficiency can generate power but rather that it displaces the need to generate part of the power currently needed to do a given task Negawatts are functionally equivalent not identical to megawatts 13 S Doig et al Assessing the Electric Productivity Gap and the U S Efficiency Opportunity RMI 2009 http ert rmi org research cgu html the 62 is an equivalent TWh y figure and doesn t reflect hourly dispatch 14 McKinsey Global Energy and Materials Unlocking Energy Efficiency in the U S Economy July 2009 http www mckinsey com clientservices ccsl An authoritative U S government study also shows encouraging potential M Brown et al Scenarios for a

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  • how to resize pictures for email
    purposes Cubic works best It does a very good job of averaging groups of pixels when shrinking them down to a lesser number of pixels a surprisingly tricky problem So just click the Scale button at the bottom right after you ve entered the new width or height and you are done Save the picture Don t forget to save the final image File Save As Making sure you save it somewhere you will find it later of course Some notes on file format Most photographs should probably be saved using JPEG jpg file format It is a system developed by the Joint Photographic Experts Group hence the name This is a very efficient format that saves even quite large pictures as suprisingly small filesize It does in a very tricky fashion taking advantage of the fact that we re not good at seeing slight variations in very light or very dark parts of images So it throws a lot of that data away you ll probably not notice If you choose a low number for the quality of the compression then it will save your big picture as a very small file by discarding lots of information perhaps even from parts of the image that you will notice If you choose a very high number then it will lose very little data but your filesize will be accordingly larger A good choice for most situations seems to be between 80 and 95 I usually use 85 The reason why it is important to know how JPEG works becomes apparent if you want to enhance a file by perhaps bringing out detail on a person s face who is deep in shadow If you are working from a JPEG picture to start with then you ll find that all the detail in the shadows have already been thrown away by JPEG compression If you want to play with a picture then it is best to use one of the non lossy formats like PNG or TIFF then when you are satisfied with the final result save that as JPEG Needless to say it is no use re saving a JPEG file as PNG in order to work on it because the damage was already done when it was first compressed as JPEG I should point out that the formats are determined by how the picture is stored the extension jpg or png or tif or gif is just an indicator for the human to let them know what format the file is stored as If you change the jpg at the end of a file to png it will still be a JPEG file The computer will know this but renaming the file this way will simply confuse the human by making them think it isn t JPEG files are stored by breaking the image down into ever smaller squares until pixels in that square differ by less than a certain amount then storing that square as a single value

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  • Amateur Scientist 1975 March - The ultimate in sailing is a rig without a hull.
    This takes the trickiness out of the proa Moreover the live ballast can be dispensed with because the keel can be shaped to generate a force that opposes the part of the wind force that tends to tip the boat and lift the keel from the water It turns out that the required keel has the shape of a curiously curved symmetrical dagger for which I have coined the name hapa primarily because it sounds Polynesian The hapa is supported by two outrigger arms that pivot on vertical axes at both ends so that the orientation of the hapa with respect to the hull can be varied by changing the length of the lines connected to both ends of the boat see illustration at right This linkage system enables the crew to alter the hapa s angle of attack as required by the strength of the wind As in the proa the hull and the sail are symmetrical fore and aft The hapa is similarly symmetrical The craft can sail equally well in either direction with outrigger always to windward The Mariana Islands where the proa was developed lie roughly at right angles to the prevailing westerly wind Inter island traffic moves essentially north and south To return from a voyage native crews simply reverse their sitting positions instead of turning the proa around Details of the hapa Although natives of the Marianas were content with a boat designed to sail north and south most of the rest of us insist on sailing in any direction we please Changing course with a boat employing a hapa as an outrigger might be exciting in a strong wind The outrigger assembly is a restraining device but the actual villain is the boat It cannot move sideways easily Instead of going through the wind in tacking to windward it would doubtless be best to pull the hapa to its new position and simultaneously let the sheet go at the mast so that the triangular sail would turn broadside and stop the boat The other sheet would then be tightened near the foot of the mast after which the sheet that is now aft would be pulled to set the new course It is quite probable that the first time this maneuver was attempted in a strong wind the whole thing would capsize at the precise moment the hapa reversed direction As I have mentioned the connection between the hapa and the boat through the pair of rigid arms constitutes an unsatisfactory restraint Why not replace the outrigger by a flexible system of lines One problem is that to make the hapa behave as one wished would require so many guy ropes that their induced drag would be prohibitive The idea of a hapa on a flexible leash was so attractive however that I could not resist the temptation to redesign it The new hapa would have to resemble a paravane which is the underwater kite employed in minesweeping It turned out to be frustratingly difficult to design a hydrodynamically efficient hapa that can be pulled on a line The contraption must follow a stable course just below the surface of the water a problem that is more difficult than stabilizing a kite because the hapa must operate within the zone of radical transition from water to air My first experimental models either jumped out of the water or dived to the bottom even at walking velocities It became obvious that a solution might lie in the elimination of cramping restraints Recognition of this principle made practical machines of helicopters Pursuit of this concept eventually resulted in a well behaved hapa at least through the anticipated range of running speeds It includes a dishlike hydrofoil resembling a shallow meniscus lens supported by a rigid shaft on which the lens is free to turn see illustrations at left The hapa can never exert a couple even if it strikes an obstruction Although this arrangement is attractive it imposes drastic limits on the shape of the hapa which must function effectively as a hydrofoil For example the aspect ratio of a disk cannot exceed unity whereas the hapa developed for hulls and rigs of the proa type may have an aspect ratio of 4 1 or even 5 1 The complete hapa includes the lenslike hydrofoil and the haft or shaft attached to a torpedo shaped float fitted with a tail fin The assembly is towed by a bridle The principal parts are made of epoxy reinforced by fiberglass The hollow lens fills with water Its buoyancy is essentially neutral in both fresh water and salt water The haft is mounted in a double race ball bearing and can turn freely around the axis of symmetry of the lens The fulcrum point at the other end of the haft in the float was placed about 5 percent forward of the axis of the lens for maximum pull to drag ratio The haft takes the place of the three lines that customarily serve to maintain a hydrofoil in the water at the correct angle of attack for the optimum lift to drag ratio It would be possible to support the disklike member by a bridle of three lines to achieve an essentially unrestrained system but the scheme would be vulnerable to submerged obstacles The apparatus would also be somewhat less free to turn A sailboat with a hapa The chief difficulty of the central haft stems from its required thickness It must be rigid and strong The haft of one experimental model measured 1 5 by five centimeters Its streamlined cross section introduces negligible drag but it achieves this performance at the cost of symmetry The haft has the same pernicious preference for traveling broadside to the direction of motion as the Papuan s dugout A compromise must be made between the unacceptable high resistance of a symmetrical cylindrical haft and the instability that is introduced by the hydrodynamically ideal cross section The unavoidable instability is counteracted

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  • Fluid Transistor Circuits - Science and Mechanics magazine
    M Horton is a physicist and electrical engineer and is chief of the Systems Research Laboratory of DOFL Dr R E Bowles started as a mechanical engineer later specialized in aeronautical engineering and is chief of DOFL s Non Radio System Branch Raymond W Warren is a mechanical engineer and research supervisor in the Non Radio System Branch This actual working PFA was first made as a large aluminum template with a circuit carved into it A planograph was then used to reduce it in size Heavy glass is used over the critical area of action so that the PFA s operation can be demonstrated with colored gas or smoke Boundary Layer Gives Memory The boundary layer effect in large part responsible for aircraft flight also has been applied to fluid amplifiers To use this effect the inventors enclosed the PFA systems by cutting circuit diagrams into the surface of metal plastic and ceramic blocks When face plates were bolted over the channels and grooves the result was a solid block containing tunnels Figs 4 and 5 This is the circuit of the PFA shown in Fig 4 Note the offset to the left of the power stream opening which results in boundary layer effect so that low pressure between side wall and the power stream is used to help deflect the power stream This permits the use of very low control pressure In Fig 5 the power jet is at the bottom two control jets on either side Passageways are split as a V to carry the deflected power stream either to the right or to the left outlets at the top Note that one passageway is wide and the other is narrow to create an imbalance When the power stream comes from its jet it sucks fluid molecules from the region on each side of the jet and lowers the pressure on each side If there is a higher pressure on the right than on the left for example an unbalanced force pushes the stream to the left This can be achieved by proper chamber design If the chamber walls are close enough together one side will develop a lower pressure the power stream will be more efficient in sucking molecules from that area and it will deflect toward that wall This is a boundary layer If the outlet for the power stream deflected by the boundary layer is plugged the power stream spills over to the other chamber However it continues to push against the plugged outlet This is a type of memory This lets specific conditions deflect a power stream in a desired direction and guarantees that the energy flow will continue in that direction until it is changed by a signal control stream By combining memory units and oscillating units in sophisticated circuits pure fluid amplification can do practical work They can replace electrical components in electronic systems and they can replace mechanical parts and moving part fluid amplifiers in fluid systems Diagram shows PFA

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