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Everything posted by studiot

  1. Does anyone have a solvent recipe for cleaning the works of an Epson or Brother inkjet ? I found this website that has some interesting suggestions, but more are welcome. http://www.northlight-images.co.uk/inkjet-printer-cleaning/
  2. Every degree above the optimal represents wasted heat and possibly dangerous conditions. Do you like being suddenly scalded in the shower ?
  3. I think it is rather more complicated than that. The lower the input temperature the more heat you need to raise the water to the fixed output temperature. It also need to be considered whether the boiler is running in DHW or CH mode. But it is good to discuss these things to gain understanding.
  4. Thank you for your reply, and the graph which does not display the quantity you asked for and I said was meaningless. You asked for You also wanted to be 'scientific' and cast various nastertiums about this forum. Your graph does show temperature (but not condensing temperature) but it does not show heat gained (which is the meaningless term) it shows efficiency. I was going to offer you some real world discussions, including practical facts and figures, from a 'plumber's' site - actually a very valuable resource, But it is important to actually be scientific and understand what you are talking about. It would be more profitable to discuss the science of condensing boilers, particularly in relatation to your excellent graph (+1 for that), rather than continued sniping. In particular your graph show boiler 'efficiency' falling dramatically with rising water inlet temperature, which begs the question of what is meant by efficiency?
  5. Well I hope you got something out of it for you did not ask a silly question at all. It was a perfectly reasonable question for someone starting to study these matters. You didn't say whether you read my first post, at least you didn't answer it. Do you still want answers to your questions ? The short answer to your headline question is Yes it is one dimensional in that it acts along a specific line. But there is a lot more to the subject which your other questions suggest you haven't yet understood.
  6. swansont was (correctly) quoting actual thermodynamic theory. unfortunately boilers such as condensing boilers can appear to havve efficiencies greater than 100% (according to advertisers and politicians) due to the way they measure it. The correct name for this term is COP (for Coefficient of Performance.)
  7. I don't know much about gauge conditions, but having 'one' EM field assumes homegenity does it not. Otherwise epsilon and mu become tensors in their own right. I hope this discussion has not frightened off the OP as the level is way above his presentation as I have already pointed out.
  8. So it is difficult to know how or even if to answer. So it good that your second post has improved my understanding over your first one. Have you considered looking at history and the development of Maths teaching in schools ? Much of what you describe already happens so is there to be studied. Also you should review your conception of 'first principles'. Maths has advanced to the point where many of the most basic principles are also the most difficult.
  9. When I used to service/repair instrumentation as part of my business I could put up with inadequate initial fault reports since I was being paid to fix things. Here at SF we are not paid. Another member here tried to be helpful (+1) as the user manual contains troubleshooting advice and does indeed list and offer advice on similar circumstances. So how about a proper fault report, starting with Hs this machine ever worked ? If so when and how did it go wrong ? What have you tried apart from battery replacement? Have you for instance tried any of the troubleshooting proceedures listed in the manual ?
  10. You don't seem very interested in answers to your question(s) , despite the effort you put into your opening post. Let us start again. I think your difficultly is mixing up an electric field and an electric force. This is very common at the beginning of study. Are you studying this ? Swanson mentioned vectors, do you understand what he meant ? Would you like an explanation of vectors and vector fields (of which electric forces and fields are an example ?
  11. studiot

    math test

    Yes it is copy and pastable, but sadly I now note that it did not produce my intended effect. Yes I copy.pasted from your post and it reproduced the listing of your code as you have shown it, But MathJax the Mangler later intervened and now my copy comes out showing the action (ie the fraction) not the code.
  12. studiot

    electric car

    If you really want to improve battery life, reduce the weight. So look at a car and ask yourself what can I remove to reduce the weight. Look around at vehicle occupancy. How many are full and how many have only one person ? So would a car to seat only one person need the same size battery as a car to seat four ? Alternatively which car would the same capacity battery take further? So you could own several cars say a big one and a little one ? Why is an electic bike or scooter battery smaller than an electric car battery ? Note that the wiring in a bike is shorter than the wiring in a car (why?) So resistive power losses in the wiring will be greater in a car unless the wiring is of greater gauge and so much heavier. Another thing to consider is that a fully charged battery will take you further than a partially exhausted one as their internal resistance rises with discharge. Good use of this fact used to be made in the days when we had daily home milk deliveries. Dairies used to maintain a fleet of electric powered milk 'floats' and charge them every night. In the morning the float started with a full milk payload and a full battery, but as the round proceeded the battery became discharged but the payload became less as the milk was delivered. This partly compensatd for the lowering of the batterie's efficientcy as it discharged. The floats could be seen to whiz out in the early morning, but crawl back slowly to the depot as their batteries discharged. This of course brings me to the last major variable affecting performance. Speed. Over a few mph, the slower you go the longer your battery will last. Air resistance due to speed is the most important factor in vehicle dynamics as it increases with a power somewhere between a quadratic and a cubic of the speed. You should also investgate driving style in relation to acceleration/braking.
  13. Well I can't agree with that statement. but I can (almost) agree with this one As always it is instructive to consider the behaviour of a simpler system than the universe. So I propose a football match between teams A and B. Now at kick-off there are no goals, and no football. Sometime into the match team A scores a goal. Later team A scores another goal. Later team B scores a goal. Now we could set up coordinate axes, including time, which extend beyond the game and pitch. But from the point of view of the match (which B won) there are 3 'events' of importance, since the object is to score more goals than the other side. So 'nothing' happened before kick off (ie there were no events) all time before kickoff is the same and effectively does not exist. 'Nothing' happened between kickoff and the first goal so nothing happened in measurable time before the first goal, but after kickoff. There were two further events before full time but again nothing happened between the third goal and full time, after which all time is the same. Hwever the entire match could be described in terms of those three goals and the (time) distance between them is fixed. Nothing else matters. Thus there is a simple system which has all the essential characteristics of a relativistic universe viz a fixed chain of events and a coordinate system which could extend empty to infinity.
  14. I am going to take you are your words here for your interest and say +1 for this part of your post. The thing is that the reference you alluded to is a biography (of a man). Biographies are not always the best places to study the history and philosophy of a subject. Obviously they provide the equivalent for the people. Fields and Relativity and the so called 'action at a distance question' all have a history, separate from, but connected to many people and their biographies. Here is a bibliography of the history and philosophy of these subjects (as well as the connnections to their author's bographies) you might find on interest. Brfore the list a further note is in order. Some of these authors are Mathematicians, setting the subjects in the context of pure mathematics and applying more general principles to the specific applications of Relativity and Fields. Others work are Physicists and Philosophers and work in the other direction using the physical observation and reasoning from it to develop the appropriate Mathematics to describe it and predict new phenomena. Yet others are the actual originators themselves. (I would beware of Whittaker - he was a Mathematician, but he was rather biased in his treatments of the work of others.) So The Physicists first. James Clerk Maxwell Matter and Motion, with appendices by Sir Joseph Larmour James Clerk Maxwell A Dynamical Theory of the Electromagnetic Field Einstein The Principle of Relativity This book is a collection of original papers by Einstein, Weyl, Minkowski and Lorentz with notes by Sommerfield Pedro G Ferreirra The Perfect Theory - A century of geniuses and the battle over General Relativity. Ferreira is currently Professor of Astrophysics at Oxford. Wilczek The Lightness of Being - Nobel Physicist brings in his modern version of the aether, via Feynman and others. Now the Mathematicians Erwin Schrodinger Space-Time Structure Shlomo Sternberg Dynamical Systems A mathematical companion to Relativity, setting it in modern mathematical terms. Finally the Philosopher in the chapter onRelativity. Sir Harold Jeffreys Scientific Inference. A good account of who new what, when they new it, and what that meant in the chaptern on relativity. William Berkson Fields of Force - the development of a World view from Faraday to Einstein.
  15. I see that a company near me is offering products that 'protect against harmful radiation' via Amazon amongst other outlets. These are called smart dots, pet dots and slep dots. https://www.bbc.co.uk/news/technology-55613452 They appear to be just stickers for the rich and gullible.
  16. studiot

    math test

    \[ \frac{a}{b} \] \[ \frac{a}{b} \] Yes it seems to be copy and pastable. I say that as I try to provide something that does not generate an error code here but can be copy/pasted rather than typed in.
  17. studiot

    math test

    \[CaC{O_3}\xrightarrow[{heat}]{}CaO + C{O_2}\] Displaying the command text in AMS Latex works if you omit the first backslash or put it between < > [CaC{O_3}\xrightarrow[{heat}]{}CaO + C{O_2}\] <\>[CaC{O_3}\xrightarrow[{heat}]{}CaO + C{O_2}\]
  18. Not all all sure about either the question or the answer. Iron particles are not soluble in water. They may be suspended which is a different thing. Since there is no solvation, there is no heat of solution to replace when you de-suspend them. In fact the particles move to a lower energy state because of the introduced magnetic field. But the jar containing the supension is definitely a closed system.
  19. Thank you, I like it. There is a twist in that it is instructive to compare the economics of such a scheme in India and say, Arizona. How much would you have to pay an American to clean the panels compared to an Indian ?
  20. I too would like further explanation of this statement. At the moment I am not at all sure what you mean. Note the English appears very very old fashioned (by at least a century) to me. This is not a criticism but an offer to help recast your words into modern English so that nobody misunderstands them.
  21. studiot

    Delay lines

    What indeed ? Perhaps if you explained the context in which you are asking this and what your thoughts are on the subject, since this is homework, then someone might help further.
  22. Thank you for your reply. I am really wondering if big business should be allowe to overturn the long held maxim "There are no unsafe roads only unsafe drivers" The idea that no matter how difficult the conditions and configuration of a particular section of road, there is a safe precedure set down in the driving regulations for negotiating it. The responsibility lies fairly and squarely with the driver (and other road users of course) to follow that procedure. Automated vehicles take away (some of) the drivers ability to follow that maxim.
  23. Should car manufacturers blame road design and construction or themselves if their technology fails to account for all road types ? https://www.bbc.co.uk/news/uk-england-somerset-55571080
  24. swansont said much of what I was going to say, but I think the question was a good one and deserves encouragement so +1. Firstly no nuclear reaction produces or generates electricity. So by themselves nuclear reactors (ie plant and equipment where controlled nuclear reactions take place) need further plant and machinery to generate the electricity. Nuclear reactions generate heat (and fission products of course) - lots of it. So much of it that much is wasted. However this released heat is used to heat coolants by a series of heat exchangers to drive turbines that drive the generators. But the reactor is designed to run 'up slowly'. In theory it may be run down very quickly for emergency purposes by moderators. The issue then becomes how to use the spare heat to meet a sudden increase in demand. One way is to have standby generators that can be brought online very quickly. These would be needed in any case for maintenance purposes. Another way would be to divert more steam to driving turbines, but that would mean they were working at less than full capacity before. Another way would be electricity or heat storage, neither being very practical in marine environments, though a buffer of either could help overcome a short term increase in demand. Electricity storage would be better for this. In any event the whole power plant comprises more than just the nuclear reactor.
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