Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Frank Krygowski <frkrygow@sbcglobal.net>
Newsgroups: rec.bicycles.tech
Subject: Re: Suspension losses
Date: Fri, 17 Jan 2025 12:06:29 -0500
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On 1/17/2025 12:33 AM, Jeff Liebermann wrote:
> On Mon, 13 Jan 2025 14:33:13 -0500, Catrike Ryder
> <Soloman@old.bikers.org> wrote:
> 
>> On Mon, 13 Jan 2025 11:28:12 -0800, Jeff Liebermann <jeffl@cruzio.com>
>> wrote:
>>
>>> On Mon, 13 Jan 2025 08:57:18 -0500, zen cycle
>>> <funkmasterxx@hotmail.com> wrote:
>>>
>>>> On 1/13/2025 2:01 AM, Jeff Liebermann wrote:
>>>>> On Mon, 13 Jan 2025 13:20:04 +0700, John B. <slocombjb@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> But long before the days of transistors and "circuit boards" my folks
>>>>>> had an electric blanket... used it all the rest of their lives. Is the
>>>>>> modern one better?
>>>>>
>>>>> Not really better, but certainly safer.  Electric heaters are all 100%
>>>>> efficient.  Every watt you shove into the heating wires is turned into
>>>>> heat.  There's no way to improve on 100% efficiency.
>>>>
>>>> Nothing is 100% efficient
>>>
>>> Well, the heater wires might radiate some EM radiation, which then is
>>> absorbed by nearby objects and is converted to IR which adds to the
>>> heat produced by the heater wires.  There might be some radiation at
>>> other frequencies (RFI, EMI, microwaves, visible light, UV, etc) but
>>> most of the radiation is ends up somewhere in the IR bands.
>>>
>>> Incidentally, I'm usually amused at the advertising for electric
>>> heaters all claiming that their more "efficient" than the competition.
>>> Of course, no numbers and certainly no calculations are ever provided.
> 
>> They could always do a study where they ask people which heater made
>> them feel warmer.
> 
> I've seen that in advertisements and ad agency generated "scientific"
> studies.  Usually, the winner is the electric heater with a parabolic
> reflector to concentrate the heat in a small area.  The dish is not a
> true parabola.  If it were, such a heater could probably burn a hole
> in whatever it's pointed at. 

A mathematical quibble: You may be thinking of an ellipsoidal reflector. 
An ellipsoid would take the radiation emanating from its focal point and 
concentrate it at its other focal point. And at other locations, there 
wouldn't be much concentration anyway.

A parabolic (or parabaloid) reflector would take the radiation emanating 
from its focal point and send it out in parallel lines. Again, no great 
concentration.

See 
https://sciencetech-inc.com/web/content/?model=product.template.website_pdf&id=1297&filename_field=name&field=doc&filename=doc.pdf


-- 
- Frank Krygowski