sethoflagos

In my experience (albeit limited to ANI), the reality is merely a shift in boundaries. If anything, the coastline - the boundary where human inspiration is necessary - grows larger as established knowledge expands and new operations come within paddling distance of the beach. On a philosophical level, the universe is driven by a hugely diverse array of PDEs, most of which are non-analytic in their practical realisation, and each of which is subject to a (literally!) infinite variety of boundary conditions and consequent infinity of plausible solutions. Gathering the experimental data necessary to confirm each advance is not a trivial exercise. I think we're safe for a few millennia on that count alone. This afternoon while doing a bit of background study on another thread, I asked one of Google's demonic offspring to back calculate the 1D wave equation from the general solution as a check. It proceeded to use the shorthand symbol f'' for the second partial derivative of f(r,t) irrespective of whether it was with respect to the spatial or time variable, and thus convinced itself that the two quantities must be equal. (They don't even have the same dimensions). Wouldn't accept that it was wrong. And if one lacks the capability to question one's results, then how can one possibly advance?

Tom R. A. Marmot hears more about his restaurant problems: Unembraced is loop nosh, Tom: and tarsier to sip, a koala, okapi. So tries rat DNA, moths on poolside carb menu.

During my chem eng degree course in the '70s, I had a similar exposure to computers as @MigL , (mainframe Fortran mk IV, leading to in-house development of mini and microcomputer applications in later years). The combined understanding of the strengths and weaknesses of software applications and 'old-fashioned' hand calculation of standard chem eng problems earned me a lot of work in the '90s with major engineering design companies helping develop and evaluate engineering software applications that on the face of it, were intended to put chemical engineers out of a job. I doubt if anybody has routinely done the long-winded iterative stuff like distillation column tray calculations manually for a quarter of a century now, but software whether AI or conventional remains ill-equipped to deal with novelty or unpredictability, the areas where experienced chemical engineers really earn their paychecks, and I don't see the scope of those reducing in the foreseeable future. Academia, particularly that of the developing nations, has become highly proficient at churning out low cost CAD monkeys (pray forgive me!) over the last few decades, and perhaps that's no bad thing. But there are much more rewarding jobs available for those who are prepared to knuckle down and gain a thorough understanding of the fundamentals. In essence, that division between steady Eddies and bright sparks has always existed. And both are necessary, they have a symbiotic relationship.

the 1300 section seems too easy (in order to ''prove' a point I suspect). Compare with this page of the Kelmscott Chaucer, with language dating from nearly a century later (and without the ''runes'').

There's a significant difference between failing to recognise social cues and dismissing them with contempt. I'm not a psychologist, but I might wager a modest sum on entitlement mentality and narcissistic personality disorder. A lot going around just now it seems. Sim-post with @exchemist Sim-post with @exchemist

Fair comment. However, it is 'simply' a matter of being absolutely clear about the substitution choices that are being made - ensuring that all other things remain equal and that the comparison is not being compromised. If the electricity produced is used to substitute for currently consumed electricity produced by fossil fuel combustion, there are potential reductions in both greenhouse gas emissions and total heat exhausted to the troposphere (because of reduced waste heat). If it is used to meet an increase in global power consumption, that energy ends up as increased tropospheric heating with no savings to mitigate. Indistinguishable. The installation costs of the solar panels could alternatively be used to cover the same land area in mirrors negating most albedo considerations. Subject to cloud cover, most of this energy would be reflected back into space reducing thermal input to the troposphere. Convince me that the 1:1 conversion of tropospheric kinetic energy into tropospheric thermal energy does not lead to a pro rata nett reduction in tropospheric kinetic energy. Is the new thermal energy reconverted back to new wind with no consequent increase in global temperatures? You may be right, at least in part. But this one is not so simple. The big models would have to be consulted I think.

That is an additional 13.7 GW of solar irradiance converted to thermal energy thus increasing the planet's surface temperature. 13.7 GW that could have been better reflected back into space by a mirror rather than absorbed by photovoltaic cells. Increasing civilisation's energy consumption simply and proportionally impacts the rate of global warming.

I meant to add to my posting that those modes of vibration that are a) consistent with the general solution and b) are self-reinforcing due to system harmonic resonance tend to appropriate most of the energy available to the system into a dynamic equilibrium of standing waves that dominate system behaviour. I've really only gone deeply into this in acoustics, where for instance musical instruments driven by a 'white noise' excitation produce clear notes with harmonic wavelengths based on integer fractions of a characteristic dimension of the instrument. Non-harmonic waves and other possible modes simply can''t compete.

Emily advises South African to let sleeping goblins lie Dale, I pray ye no help pass orc asleep no lemon roll or no melon peels across apple honey, yarpie lad!

Deleted. Cathartic post ran off-topic.

Perhaps the concept of a ''gentle giant' is one of yours. I am however embedded in a culture where dowries are payable, and this does put a particular slant on things, providing as it does a financial imperative for families to protect their daughters from ''spoilage'' prior to marriage. Perhaps that's a more convincing origin of these social conventions than the forces of industrialisation I mentioned above,

In who's universe? In my modest experience, most women would seem to prefer a mate who doesn't slap them around all the time.

An analogous case occurs in fluid mechanics only featuring sonic velocity instead of c. My kneejerk simplification would be to convert to spherical spatial coordinates and look at a spherically symmetrical system such as an oscillating bubble (all the phis and thetas drop out) 1/r2 d/dr(r2dY/dr) - 1/c2 d2Y/dt2 = 0 The standard substitution Y(r,t) = u(r,t)/r yields the 1D wave equation: d2u/dr2 - 1/c2d2u/dt2 = 0 which has the general solution: Y(r,t) = f(r - ct)/r + g(r + ct)/r (outgoing wave + incoming wave) The general solution just happens to support standing waves, so we can insert one or two as boundary conditions yielding forms such as:: Y(r,t) = A/r ei(kr-wt) + B/r e-i(kr+wt) (k = w/c as per usual) If we relax the spherical symmetry, terms in phi and theta appear as interference patterns. Apologies if I've missed something much deeper, but its where my mental pictures come from. Oscillating bubbles.

... which are all abstract constructions specific to a particular culture (ie yours) at a particular time in its development (ie now). Case in point is my mother-in-law, Catherine, a charming and intelligent woman now in her late seventies who believes that she may have been twelve when she was married to a man more than double her age. In conversation, it is clear that she remembers her husband with great affection and that her sole regret is that he died before his time leaving her with eight children to raise on her own... ... or rather, with the help of relatives and neighbours in the community - a support structure that most members of this site do not have access to. She is happy that her five daughters all had better educational opportunities and the chance to experience more of life before settling down into marriage. But she herself does not feel hard done by. It was simply the way things were done back then. And Igbo culture has a far longer history of stable continuity than that of those outsiders who may criticise some of its traditions. Cultural relativism is a tricky subject with all sorts of pitfalls to trap the unwary into being unable to condemn any behaviour as intrinsically 'bad'. But we must ask ourselves what might be intrinsically 'good' about enforcing a mandatory, possibly unnatural, extended period of sexual abstinence between the onset of puberty and an arbitrary 'age of consent'. The Marxist inside me suggests a socioeconomic force to produce a well-schooled pool of skilled labour to drive the ever-increasing technological demands of the military-industrial complex. The Anarchist just says I'm fortunate my preferences in the day ran to strong, full-figured women in their prime. No one ever really objected to that.

I don't frequent international fast-food franchises myself, but Domino's has built a reputation for good hygiene standards so it could be a reasonable option for you. My local Domino's (in Nigeria) is fully halal certified as it happens, but don't expect that to be the case in India. >95% of what I consume is prepared by myself. That way, I get to eat exactly what I like to eat (mainly Indian style cuisine), with lots of diet diversity, and have complete control over the hygiene aspects. This probably isn't of much help to you, but it's how I've adapted to cope over the 25+ years I've lived here. Just a matter of adopting a few sensible routine habits and not being stupid.

This pdf from microbiologysociety.org covers the basics. This may provide less protection than you imagine, especially if you are not in a predominantly Moslem region. Two reasons: they are in fact very serious about personal hygiene, only their habits and practices are unfamiliar to tourists and largely unpublished; and they will likely have increased resistance to local infectious agents. Based on personal experience, I would strongly recommend that you familiarise yourself with the what toilet facilities are standard for the area you are visiting in advance, and equip yourself accordingly. And avoid touching stuff like doorknobs and handrails in busy public areas.

Since xA+xB = 1 for a binary mixture, your equation simplifies to xA = xA which is true but of no use to anyone. Your terminology is nowhere explained, so again, that is no use to anyone. Perhaps you should start with the fundamental definition of xA and xB in terms of molar quantities nA and nB in the liquid phase. That might help get us all on the same page. Since xA+xB = 1 for a binary mixture, your equation simplifies to xA = xA which is true but of no use to anyone. Your terminology is nowhere explained, so again, that is no use to anyone. Perhaps you should start with the fundamental definition of xA and xB in terms of molar quantities nA and nB in the liquid phase. That might help get us all on the same page.

For those who just can't get enough of this thread, tune into BBC Brit - Channel 120 on African Dstv - and watch endless repeats of 'Pointless'

The main practical discriminator is scale. Given an amenable geography, hydro comfortably works with GW. Flywheels work with MW. Ditto weight-lifting. The efficiency figures for pumped hydro are clear enough. Large water pumps have a hydraulic efficiency ~85%, and Francis turbines (typical design for large units) can reach ~95% efficiency. Pipe and distribution losses add a couple of per cent each giving the overall round trip efficiency of ~75% I quoted earlier. I don't believe solar evaporation losses are a thing in Wales. But bear in mind that the context is trading up low cost wind energy on a stormy night in November to high value peak load GW at very short notice on Christmas Eve with perhaps a ten-fold increase in billable revenue - and the efficiency only needs to be reasonable. Availability at required scale is the ultimate measure.

Don't forget that winching systems rely on belt friction for cables to grip pulleys etc. (capstan equation and all that good stuff), and high ratio gearboxes can have significant losses. I wouldn't contradict your expectation as such, but I'd prefer to check the data first. It may not be quite so clear cut. Again... no free lunches. Not to mention the capital costs involved... (Apologies for delayed response - network went awol for 24 hrs) Does anyone actually understand this? Is that 30MW for a millisecond or a millennium? Surely the unit of interest is Joules.

Not quite the same thing, Ken. Granted, much of the physical hardware is the same, but syncons are specifically designed for power factor correction, and therefore have excitation circuitry designed for the production of reactive power, either lead or lag, as an alternative to (typically) thyristor switched static VAR compensators (SVCs). What they don't do is generate torque to any large degree and are thus unable (in standard form) to replace active power generation shortfalls beyond a few cycles. The flywheel version provides the necessary large energy storage capacity to fulfill that role. It's interesting to consider whether these various functionalities could be combined in a single machine, though I suspect that idea would run into significant degrees of freedom issues.

Swings and roundabouts. Flywheels lose ~4% a day, pumped hydro has a round trip efficiency of about 75%. No free lunches.

... Not an issue apparently, see Flywheel Storage Power System Reading between the lines, the limited current scale of such installations seems due to a lack of perceived urgency rather than any significant technological limit. And the UK always has Dinorwig - it would take one monster of a flywheel to compete with that.

I've had similar thoughts. However, the units couldn't be 'unpowered' otherwise there would be no electrical coupling. What I'm not clear on is whether rotational KE on the demand side (power consuming units) is as useful as that of power generating units. Both tend to flatten the rate of frequency change, but act in opposite directions which might be an issue.

Absolutely no offence taken 🙂 Though I will continue to discriminate between those artists who sacrificed the full 10,000 hours of childhood to their vocation, and those who chose an easier path 😜