Kevin, Agreed but your arguments did make me face an issue WRT latency – which I wrongly assumed was the big difference between statistical and reliance on a very fast analog sensing loop.. every system will have the same analog latency and even your statistically driven loop will have an already closed analog feedback value that is being constantly modified by historical data or sets of algorithms derived from historical data on how the reactor responded to changes in gain previously. In theory your system SHOULD be better but my gut is telling me this isn’t the end of the story – that there are other features of PWM that will trump heated filaments as control. I will concede that statistical may be a superior method to modify a closed analog loop but hope you will in turn keep an open mind toward PWM. I kept an old 100k Varos solid state freq converter [60 to 400 hz ]alive for years beyond it’s life expectancy and was always impressed by the “statistical” waveform patterns stored as a library used to bring up and slew the output levels around as needed. Alas the wire wrap and TTL tech was pushed aside for new more efficient commercial models. Fran
From: Kevin O'Malley [mailto:kevmol...@gmail.com] Sent: Wednesday, August 20, 2014 2:13 PM To: vortex-l Subject: EXTERNAL: Re: [Vo]:No automatic control system? We're off the original subject so I think there's diminishing returns on discussing the pros & cons of controlling a reaction no one yet understands and the only guy in the neighborhood with a working box is keeping mum. On Wed, Aug 20, 2014 at 10:44 AM, Roarty, Francis X <francis.x.roa...@lmco.com<mailto:francis.x.roa...@lmco.com>> wrote: This is true, there is latency either way but IMHO PWM is safer, locks you into shutoff condition for every cycle where the most robust geometry /hotspots get a chance to diffuse and pump out energy into the immediate vicinity without melting closed. IMHO the constant drive will burn out the most robust hotspots and will need to driver a larger quanity of larger geometry regions to equal the heat generating capacity of the smaller region. There is very likely an advantage to using pwm/spark gap for the large dv/dt effect on the plasma as well. From: Kevin O'Malley [mailto:kevmol...@gmail.com<mailto:kevmol...@gmail.com>] Sent: Wednesday, August 20, 2014 11:59 AM To: vortex-l Subject: Re: EXTERNAL: Re: [Vo]:No automatic control system? You'll have latency either way. If you take a "statistical" approach you monitor far more than just temperature. You can base it on a thousand parameters if you want. And not all of them change in microseconds. On Wed, Aug 20, 2014 at 5:51 AM, Roarty, Francis X <francis.x.roa...@lmco.com<mailto:francis.x.roa...@lmco.com>> wrote: Kevin, Latency will be the issue, how to instantly sense temp beyond the geometry into the plasma itself and simultaneously couple the feedback to the plasma to control it. I think Axil is correct regarding the spark gap of DGT, it is a simple PWM scheme that relies on duty factor to provide an average time in runaway instead of actually trying to for a lesser but permanent runaway state. Fran From: Kevin O'Malley [mailto:kevmol...@gmail.com<mailto:kevmol...@gmail.com>] Sent: Wednesday, August 20, 2014 8:36 AM To: vortex-l Subject: EXTERNAL: Re: [Vo]:No automatic control system? microsecond statistical control is accomplished regularly through gigabit and wifi ethernet. It is a valid example. If you're sending a billion bits/second, you're controlling on the nanosecond level. On Wed, Aug 20, 2014 at 5:16 AM, Roarty, Francis X <francis.x.roa...@lmco.com<mailto:francis.x.roa...@lmco.com>> wrote: Kevin, Statistical is OK for loose control but in a phenomena that must be kept on the brink of destruction / half way into runaway but being thermally bled by a heat sink then fast control is required, hysteris on the scale of microseconds or less. From: Kevin O'Malley [mailto:kevmol...@gmail.com<mailto:kevmol...@gmail.com>] Sent: Wednesday, August 20, 2014 12:28 AM To: vortex-l Subject: EXTERNAL: Re: [Vo]:No automatic control system? Actually, statistical control is a reasonably strong approach. I take ethernet as an example. 10/100 Mbit ethernet was once dominated by National Semiconductor, heavily relying on their analog background to control tightly the parameters involved. They were overtaken by a disruptive technology using DSP and statistical "control". It turned out that it made the analog simpler, and the digital side of the issue meant that die shrinking took place much faster. By the time National spent $120M buying Comcore to play catchup, their die size was 60% larger than Broadcom. The next generation was gigabit ethernet, where the vast majority of the game was with DSP and Marvell entered the picture. As each generation of ethernet came out, it was more digital, more millions of transistors doing DSP where analog used to be, and eventually it was so cheap that we now buy those chips for $2 at 1Gig/s when they were originally $45 at 0.1Gig/s By using a statistical approach, Rossi puts himself on the digital scaling roadmap rather than the analog scaling roadmap. It has tremendous merits. What is the danger? If an air conditioner goes on during August when it ain't hot, what's the harm? If Rossi's device goes kaflooiee in the first generation, it will just stop working. By the time the 3rd generation rolls out, it will no longer go kaflooiee, and it will be under far tighter control than if he had taken the "analog" route. On Tue, Aug 19, 2014 at 8:45 PM, Axil Axil <janap...@gmail.com<mailto:janap...@gmail.com>> wrote: Statistical control is like saying that most of the time it is hot in august so turn on the air conditioners in august. Most of the time you are correct, but sometimes a bad thing happens.
