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31/8/2021 - 'nuther gem

Dark - rather metallic blue spinel in my Apostate-A cut with 8 frosted crown facets. Worked out rather well in a dark and slightly ominous manner. I do like this cut.

video works best in HD btw


29/8/2021 - Infrasound Code Upgrade

Over the past week I have completed a radical rewrite of the Infrasound Monitor code. The structure has been tidied, simplified and variable names conformed to pep-8 standards.

Added is the plotting and storing of the current week's acoustic power readings. This caused problems, taking more than 20 hrs of work to resolve. It appears that the excellent matplotlib plotting library (the finest computer data-plotting system available i.m.h.o.), called by ObsPy persisted in memory between calls by the different plotting functions.

Now finally sorted. Infrasound Monitor code in 'Downloads' section (above) has been updated to this version.

infrasound acoustic power monitor


27/7/2021 - Infrasound Thunderstorm

Brief at ~17:45 U.T.C

gpu openacc gfortran gpu openacc gfortran


3/7/2021 - Spinel Elune's Tears

I believe that it has something to do with World of Warcraft

Tears of Elune, design by Arya Akhavan. Cut in vivid blue lab spinel. Nice: shard like narrow pear shape. Somewhat time consuming and fiddly to cut taking me about twice as long as similar pear designs.


1/7/2021 - Invited to Prague

Myself and my two eldest have been invited to Prague to display our school geophysics projects at the 2022 European STEM Education Show. We'll take the Infrasound Monitor doi, the Solar Magnetometer doi, and likely a couple of others.

Great for the boys - not many pre-university students get their names on peer-reviewed papers or invited from the UK to this. V.expensive but worth it.


4/5/2021 - OpenAcc and fortran - success

Following on from yesterday's post. Now midnight and I have successfully compiled and run openacc fortran code on an nvidia gpu. This using the nvidia fortran compiler rather than my preferred gcc/gfortran.

Will continue plugging away at gfortran.

gpu openacc gfortran


3/5/2021 - OpenAcc, gcc and gfortran

Been investigating using video card GPUs to accelerate processing of my virtual diffraction software. Originally I looked at using NVidia's Cuda but that is a) too complex and b) too proprietary.

OpenAcc is much simpler - at the cost of slower processing. I have spent the weekend playing around with gfortran/gcc - and pgi/nvfortran - though would prefer to write vanilla fortran under gfortran.

interestingly a study of one supercomputer rig in the U.S. 2014-15 showed that gfortran/gcc/g++ made up 71% of 105,000 instances (jobs?), followed by Intel at 22% and Cray compilers at 6% -- doi

Positives - I can now compile code under gfortran/gcc with OpenAcc directives which offloads processing to the graphics card.

Negatives - it does not complete a run. A simple Jacobi matrix relaxation program - which completes in ~10s on the cpu starts but never seems to end on the graphics card. Definitely doing something judging by the GPU maxing out 100% and the video card fan emulating a phasor on overload (if you get that reference you are dead old)!

Larger brain required. Will try something dead simple such as a Monte Carlo determination of Pi.

gpu openacc gfortran
Will it ever end?

If anyone is interested I am using gfortran-11.1, gcc-11.1, gcc-11-offload-nvptx with a compiler directive of gfortran -cpp -fopenacc -foffload=nvptx-none -foffload="-O3" -O3 xyz.f90 on an Elementary 5.1 intel pc.


28/4/2021 - Young Scientists - an early start

The boys appear to have been cited in an academic paper [doi] for their infrasound article [doi] - not bad going for a 15 and 17 yr old :-) They are keen to do more and should look stunning on a university application. For years I have been pushing for British pre-university science students to contribute to research. On the odd occasion that it happens here, generally at a private school, this is thought newsworthy. In the US and Europe this is a more routine component of education - a chance for the keen to shine. Almost all the queries I get come from Europe and the US.


25/4/2021 - Aurora Monitor - Standard Dev plots now working

Took a bit longer than I thought but the RPi Aurora Monitor project now produces daily and weekly plots of the hourly standard deviations in the local magnetic field. This seems a good starting point to automatically alert the likely appearance of aurora. Now that we are moving into a more active phase in the solar cycle (link) this may generate data of interest.

See Aurora Monitor for current plots. The RPi monitoring program may be grabbed from the downloads page.


18/4/2021 - Aurora Monitor - new Visualisation

I am coding the RPi's monitor program to plot 'hourly standard deviations' a plot every 60 seconds of the standard deviations of the preceeding hour's data. HSD plots are used by organisations such as B.G.S. to indicate when solar storms may be occuring - see B.G.S.


8/4/2021 - Aurora Monitor Sound Converter Working

I think I have sorted rendering the aurora monitor's magnetic field strengths as an audio file. Previously there was clicking between samples due to not aligning the start phase of a new tone with the end phase of the previous. Still the occasional click which I need to look into. Rather chuffed though.

see Downloads page (above)

earth field magnetometer
24 hours of magnetometer data rendered as 86 sec of audio


27/3/2021 - Natural Citrine - partly cut gemstone

This is old stock citrine from 1974 - absolutely gorgeous golden colour. I'm having a go at Marco Voltolini's 'Asahi' cut based on the Japanese Rising Sun motif.


27/3/2021 - Easter Hols - 2 weeks of coding n' stuff

Aiming to finalise a couple of projects over the break. Some electronics and rather more coding in Python, C, VHDL and for the computationally intensive physics stuff - Fortran. Specifically using NVIDIA's CUDA Fortran compiler.

The Simpson - Fortran
“Fortran, the greatest of the programming languages.” The Simpsons s26e10

I do like so Fortran - the elegant simplicity when mathematical modelling, the speed of code generate by its' excellent compilers and the abhorrence it seems to generate in some Computer Scientists.

I have never understood the vehemence one can find in discussions of the merits of differing computer languages. I have seen a number of such discussions rise to a level of hatred normally only reached by political or religious nuts - most odd. Saying this I never understood the whole Emacs thing either.

LaTeX however is a different matter - all uncritically Hail the prophet Knuth - peace to every keyboarder though death, or at least inconsistent formatting, to the WYSIWYGy unbelievers :-)


20/3/2021 - Aurora Monitor Progress

I have been working on converting the Aurora monitor output to an audio file. Getting there aside from some annoying pulsing.

earth field magnetometer
24 hours of magnetometer data rendered as 86 sec of audio


15/3/2021 - Faceting Article Published

On building a precision rotary encoder (see downloads page) published in UK Facet Cutters Guild Newsletter #121.


8/3/2021 - Leuco Sapphire

Pure white sapphire - first design in my 'Apostate' series. Brilliant cut pavilion. A high crown with 8 narrow frosted parallel-sided facets.


7/3/2021 - Comp Phys Course #5: Cyclotron Sim

Also developing a cyclotron simulation. Will have to write an exercise where students become familier with vector operations such as cross and dot product.


7/3/2021 - Set a Topaz

Blue Topaz "Chrysanthemum Flower" in sterling silver crown setting with rabbit ear bail. Setting entirely handformed from sheet silver.


6/3/2021 - Comp Phys Course #5: Linac Simulation

Back working on our pre-university computational physics course... 'Learning Higher School Physics through Coding'. Now into motion of charged particles in E & B fields. Shown is v.early skeleton of a simulation of a linear accelerator with three drift tubes.

Aiming for release summer 2021, other project work permitting.


27/2/2021 :: Green sapphire - No4 Iconoclast

Precision faceted green sapphire
Iconoclast - Green sapphire!

Lab green sapphire in my Iconoclast cut. Green sapphire is rather uncommon - and expensive. Nice colour though.


28/1/2021 :: Partially cut natural blue topaz

Precision faceted natural blue topaz gemstone
Blue Topaz - partially cut

Halfway through cutting a large natural blue topaz in Jeff Graham's 'Brilliant Pear' cut. The pavilion (bottom) of the stone has been cut. It will now be transferred to another 'dop-stick' to cut and polish the table (top). The faint marks are not on the surface rather the result of veils - imperfections within the body of the stone.

If you want a perfect crystal then one needs to cut lab-grown rather than natural stones.


28/1/2021 :: Silversmithing Tools Fetish

Just got some tasty new pliers - the two at the bottom. These are British made Maun parallel pliers with flat jaws. Used in silversmithing to bend metal without damaging the surface.

Silversmithing Pliers
You can never have too many pliers.


24/1/2021 - Infrasound - max sampling rate hit

Looks like we've hit a maximum sample rate of ~142Hz giving a maximum signal detection of ~70Hz. Rather impressive for such a low-cost device (Amphenol DLVR-F50D mems differential pressure sensor). Very quiet at the mo so little to see at the higher frequencies - hopefully a chopper or storm will come soon.


22/1/2021 - Infrasound - increasing fmax #2

We have successfully raised the infrasound sampling rate to 100Hz without problems. Now testing at 150Hz.


19/1/2021 - Infrasound - increasing fmax

As per post 17/1 this evening we started testing pushing up the sample rate on infrasound monitor gamma - this uses a 20m porous hose filter with signals processed by a new RPi 4. We aim to reach 200Hz sampling rate - fingers crossed.


17/1/2021 - Infrasound Musings

Thinking more around helicopters. Infrasound is defined as that below the frequency limit of human hearing i.e. <~20Hz. Many infrasound systems have this as their upper cut-off. This seems odd, after all an event may generate frequencies both below and above 20Hz - helicopters certainly do.

In the 1990's Rafael developed 'Helispot' an acoustic helicopter detector. Apparently no longer in production this used a microphone array to detect, characteurise and track helicopters out some 'some tens of km'. Israel has for obvious reasons a track record in infrasound research under the CNTBTO. Given such factors as size, topology, educational system, and regional politics, Israel is one country where a national infrasound network may be of benefit.

Helicopter Power band
Sound intensity as a function of frequency and time, for a UH-1helicopter flying past the acoustic detector. Horizontal red power bands will be harmonics of the blade pass frequency. From S. Tenney, ARL.
Scud Missile Launch
Scud missile launch from 27km at ~ 150s. From S. Tenney, ARL.

Both the above from 'Tactical Infrasound - 2005 - Mitre Corp - JSR-03-520'

We'll investigate pushing the sampling rate of our mems/RPi system up. Presently it samples at 40Hz giving a 20Hz maximum signal frequency. The sensor has a sample rate of less than 4ms so we should be able to sample at up to 250Hz giving an upper signal frequency of 125Hz. A problem is that the Pi may not be able to keep up or may stutter. Given that this is an educational project we don't want to use a more electronically complex system.

Will keep posting here if we get anywhere...


14/1/2021 - Infrasound Trace - Helicopter

The excitement of real investigation. Whilst in the bath this evening I heard a helicopter overhead. Infrasound monitor Gamma, fitted with a porous hose filter picked up a strong signal (link). Monitor Alpha in my loftspace also registered this though with greater attenuation.

Helicopter Infrasound Trace
Civilian helicopter trace (at ~9min) 0.5-10Hz - click for zoomed image.


22/1/2021 - Aurora Ahoy

BBC news report Aurora visible in Northern Scotland last night (11/1/21). The Aurora monitor (link) clearly showed an unusually active plot that evening. For comparison the bottom plot is typical of that during quiescence .

Magnetic Field Variation Aurora
Unusual earth field variation in the evening when aurora reported 200km North (spike at ~9am car moving)
Magnetic Field Variation Aurora
Typical earth field variation in the evening during quiescence.
From BBC News report (21/1/21 - photo Simmer Dim/BBC Weather Watchers).


9/1/2021 - 3 Crosses

3 gemstones cut in my 'Iron Cross' design. Blue is lab-grown spinel, black is natural black spinel, clear is lab-grown 'white' sapphire.

The Iron Cross has been a German military award from 1877 to the present and its design may be traced back to the cross pattée of the 11th century Teutonic Knights of Jerusalem and earlier.