<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Norbert et al</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>Thanks for bringing up this (low cost testing) topic - which has certainly been a major problem area for everybody trying to improve stoves.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>I found this subsequent article by many of the same authors you found: <a href="https://cleancookstoves.org/binary-data/RESOURCE/file/000/000/130-1.pdf" class="">https://cleancookstoves.org/binary-data/RESOURCE/file/000/000/130-1.pdf</a></div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>and <a href="http://cleancookstoves.org/resources_files/real-time-assessment-of-black.pdf" class="">http://cleancookstoves.org/resources_files/real-time-assessment-of-black.pdf</a></div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>I'm very unlikely to ever put together by myself a system based on LEDs. But talking to others recently, I know there is a big need for list members to be able to do repeatable testing to know they are making progress - even if they can't equate directly until they are able to work with a hood, etc. LEDs sound promising. CO sensors are cheap enough - but not designed for stove testing</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>Kirk Harris has reported recently that he can run with zero soot appearing on the cookpot. That is great but not as quantitative as he or anyone would like.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>So this is to hope that anyone working on Tier-type measurements of CO and particulates can pipe in to help all - with LEDs or anything.</div><div class=""><br class=""></div><div class="">Ron</div><div class=""><br class=""></div><div class=""><br class=""></div><br class=""><div><blockquote type="cite" class=""><div class="">On Sep 6, 2018, at 3:39 PM, Norbert Senf <<a href="mailto:norbert.senf@gmail.com" class="">norbert.senf@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="">Thanks, Nikhil. You are well versed in this, and have an interesting take on it. It is an education for me.</div><div class=""><br class=""></div><div class="">I have recently re-read a paper by Tami Bond (attached), coincidentally with re-discovering Forrest Mims III, an amateur scientist who has done some interesting stuff with low cost and accurate atmospheric measurement. In fact, he annually calibrates some of the instruments at Mauna Loa observatory in Hawaii. Anyway, I have a sudden interest in atmospheric science.</div><div class=""><br class=""></div><div class="">Tami Bond's paper gives a pretty convincing demo of being able to measure PM in the field and getting a correspondence between gravimetric methods (filters) and optical methods (3 bands). The optical method is able to distinguish between EC and OC, whereas the filter method gives only the sum. I had missed the significance of a table of results she presents, where EC + OC, obtained optically, = PM(gravimetric) within 10%.</div><div class=""><br class=""></div><div class="">Forrest Mims discovered in the early 70's that LEDs can also be used as photoreceptors and give you the same results as high end optical narrow bandpass filters. LEDs these days are available basically for free, and in pairs form narrow band emitters/receptors and span the range from ultraviolet to far infrared. It ties in conveniently with work we will be doing this winter.<br class=""></div><div class=""><br class=""></div><div class="">Best .......... Norbert<br class=""></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Thu, Sep 6, 2018 at 4:03 PM, Nikhil Desai <span dir="ltr" class=""><<a href="mailto:pienergy2008@gmail.com" target="_blank" class="">pienergy2008@gmail.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="">Norbert: <br class=""></div></blockquote></div></div></div></div></blockquote></div><br class=""><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span><snip; not on measurement approaches></div></body></html>