The Mysterious Harper Gardens, Derby

Harper Gardens is a small public space sandwiched between the A6 Pride Parkway flyover and Siddals Road. Not much larger than many suburban gardens, it’s somewhere I usually pass without a second thought on my regular walks between the office and the city centre. But today I noticed the lovely flowering cherry tree in the north-eastern corner of the plot and stopped to photograph it.

Harper GardensIt’s a curious location for a public garden. A quick search of the internet reveals that at some point in the 1940s a paint factory burned down on this spot. Quite how the site ended up in the city council’s hands and became a garden seems less clear.

If anyone can fill in the details for me, the comment box awaits below!

The Beast of Bolsover

As the weather was better than expected today, an excursion to Bolsover resulted. The castle, managed by English Heritage, is fascinating. Sir William Cavendish’s riding school, dating from the 1600s, is possibly one of the reasons why Great Britain is so good at the Olympic sport of dressage horse dancing today. The little castle is beautifully preserved, and its wall paintings are unique survivors from the pre civil war era.

The Little Castle, BolsoverI can’t recommend a visit heartily enough, especially as since the last time I went sometime in the 1990s they’ve opened a visitor centre and cafe. The cherry scone was great and the coffee will definitely put hairs on your chest. Which is perhaps just as well. For at the bottom of the Venus fountain lurks a shocking sight. The Beast of Bolsover, no less. Please look away now if you’re of a nervous disposition.

The Beast of BolsoverDon’t say that I didn’t warn you!

Two to three hours is plenty of time to walk around the castle and grounds at a reasonable pace. An excellent video guide is provided as part of the £10.20 (adult) / £6.10 (child) entrance fee. Grown-up and family friendly commentaries are available.

B5023 Duffield to Cowers Lane

While Italy were busy losing at rugby, I decided to take Gnu out for a run around the Derbyshire countryside. The day was overcast, but warm enough for me to manage with just a fleece, scarf and the heating. This was the most enjoyable stretch of the route – three and a half minutes of B road twistyness between Duffield and Cowers Lane.

I didn’t even bother to stop for the bargain bacon …

Off balance

I’m feeling a little off balance at the moment. Last Wednesday I was busy telling the ARIS and webMethods user groups that “numbers don’t speak for themselves”. I was talking about the creating business cases, but I believe the statement to be true more generally. Numbers only make sense if you can relate them to a specific context. Furthermore, the numbers used must report or measure something meaningful, otherwise there’s no point in collecting the data. (You can find my detailed explanations rants on both of theses topic here and here if you’re interested).

Anyway, this was me in action at the event. It looks a little as if I’m conducting an auction and that the chandelier is about to bring it all to a messy end.

ARIS user group meeting 1st March 2017I’d had an active week up to that point, and although I spent Thursday in the office, that day was busy too. Here’s my steps chart for the first part of the week …

Mon-Thu 27/2 - 2/3 steps… 43,611 in all. I should have been feeling great! Nicely (but not stupidly) over the 10,000 steps a day average we’re supposed to achieve, according to the NHS and others. But having wittered on about context, you should already know that I’m about to tell you what happened next.

Full week 27/2 - 5/3An average of under 1,700 steps a day for Friday to Sunday. Monday to Thursday wiped me out, so I’ve spent most of the time asleep or moping around on the sofa. I haven’t been eating (much) either.

I feel that given my opening salvo I should now provide some context to these numbers. After all, you could just assume that I’ve been really lazy for the last three days. I wish that was true!

My best case hypothesis is that I picked up a bug (or mild food poisoning) early last week. As I was rather ‘poorly’ on Thursday evening that explanation could make sense. My worst case hypothesis is that the lymphoma has started to put on a bit of a sprint. I’ve been feeling increasingly fatigued for some weeks now, with even the most sanguine of the consultants that I’ve been seeing starting to suggest that chemo might be needed ‘soon’. Having spent 2.5 years on watch and wait, I’m not sure if ‘soon’ means weeks or months or a year or more … sometimes I don’t want to know the numbers at all.

Anyway, the next few days should help me figure out which of the hypotheses is right. I’m starting to get a bit of energy back today, so I’m hopeful that the bug explanation proves to be the right context for last week’s steps chart.

Raspberry Pi – camera box

This weekend, I was finally happy that I’d managed to implement a reasonable temperature and humidity project as well as a motion detecting camera for my Raspberry Pi. I decided to invest £19 in a ModMyPi camera box to consolidate them onto my Pi 3. It arrived today, and after an evening’s fun this is the result.

Pi Camera BoxLid open for testing. The DHT22 temperature and humidity sensor is at the front, with the motion sensor and camera mounted in the lid.

Pi Camera Box - installed in the garageIn situ.

I think it looks much better than my original attempt, even if the rather fiddly assembly took a couple of hours (with testing) rather than the 10 minutes claimed by the manufacturer! It also means that as my camera is now mounted the correct way up, I no longer need to rotate the image by 180 degrees in my code …

Update: After I’d installed this in the garage, I started to get a large number of false positives. A change back to my Pi2 made little difference (although the original version I’d put together but without the DHT22 had worked well). Finally, soldering a 10k resistor between the data and ground wires of the PIR detector seems to have resolved the issue of the data pin going high without it sensing movement.

Carsington eight: a Seven driving route

Here’s an enjoyable driving route around Mid Derbyshire. Especially on a cold but sunny Saturday in February in a Caterham 7. What other way is there to travel?

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My route map is below, just in case anyone is interested in replicating the experience. I can recommend Kedleston Hall, Carsington Water’s Visitor Centre and Middleton Top as places to visit on this route if you’re not in a hurry …

Humidity and temperature monitoring with a Raspberry Pi

Continuing my quest to protect my Caterham 7 using my Raspberry Pi, I bought a bargain box of 37 assorted sensors for £21. One of the devices supplied was a DHT11, capable of monitoring temperature and humidity. A quick internet search led me to discover the very useful pigpio libraries and daemon. Wiring up the DHT11 to the Pi’s GPIO pins was simple – 3 wires, 1 to the 3V3 supply, 1 to a ground pin and the data pin of the device to GPIO pin 17. The author of the pigpio library also provides some example code for the sensor.

This was enough to demonstrate that I could get it to work, but the accuracy of the DHT11 was woeful. It’s advertised as having an accuracy of +/- 2 Celsius, but my experiments suggested that the one I had acquired for the princely sum of 57p had an accuracy of around +/- 5 Celsius. As I also wanted the sensor to work in an unheated garage, another limitation was that the DHT11 is unable to read values below freezing.

Encouraged, I decided to invest a further £6 in a plug compatible DHT22 sensor. This has an operating range of -40 Celsius to 125 Celsius, with an accuracy of +/- 0.5 degrees. Initial tests suggested that it was far more accurate than the DHT11. While the sensor produces a slightly different data stream to the DHT11, it was close enough for the example code to have been written in a way that it would still work.

As part of my experiments, I made a small modification to the example code (testDHT.c) to calculate the dew point from the temperature and relative humidity readings. I’ve also changed the way it outputs data, to write it to a file rather than the screen.

void cbf(DHTXXD_data_t r)
{
   FILE* fp;
   char buff[100];
   time_t now;
   float rdwpt,rtemp,rhum;
   extern float rdewpt_();
 
   if (r.status == 0) {
       now = time (0);
       strftime (buff, 100, "%Y%m%d-%H%M", localtime (&now));
       rtemp=r.temperature;
       rhum=r.humidity;
       rdwpt=rdewpt_(&rtemp,&rhum);
       fp=fopen("readings.txt", "a");
       fprintf(fp,"%s ",buff);
       fprintf(fp,"%.1f ", rtemp);
       fprintf(fp,"%.1f ", rhum);
       fprintf(fp,"%.1f", rdwpt);
       fprintf(fp,"\n");
       fclose(fp);
   }
}

While it would have been simple enough to write a dew point calculation in C, I decided to write it in FORTRAN instead. Hey, the more people who get to love FORTRAN the better. Here’s the function I wrote, which uses the Magnus formula. It’s declared in the C fragment above as an external function that returns a float. Parameters are passed to FORTRAN by address, rather than by value.

C
C     DEWPOINT CALCULATION FROM TEMPERATURE IN CELSIUS - RTEMP
C                               RELATIVE HUMIDITY - RHUM
C     USING THE MAGNUS FORMULA WITH CONSTANTS SUITABLE FOR A
C     TEMPERATURE RANGE OF -45 TO 60 CELSIUS
C
C     AUTHOR: TJH 28-01-2017
C
      REAL FUNCTION RDEWPT(RTEMP,RHUM)
      REAL RH
      RH = (LOG10(RHUM)-2)/0.4343+(17.62*RTEMP)/(243.12+RTEMP)
      RDEWPT = 243.12*RH/(17.62-RH)
      RETURN
      END

Compiling and linking the C and FORTRAN code using gfortran:

gfortran -Wall -pthread -o DHTXXD *.c *.f -lpigpiod_if2

produces an executable that can create a data file. This example was created using the command:

./DHTXXD -g17 -i600

which reads the data from GPIO pin 17 every 10 minutes.

20170128-2009 6.9 72.0 2.2
20170128-2019 6.9 71.7 2.1
20170128-2029 6.8 71.3 2.0
20170128-2039 6.8 71.4 2.0
20170128-2049 6.8 71.7 2.0
20170128-2059 6.8 71.4 2.0
20170128-2109 6.7 71.1 1.8

This provides data in a suitable format to use some relative simple gnuplot commands to create a charts. The first example plots the relative humidity readings over time, with the larger spikes in the relative humidity data correlating to the garage door being opened while it was raining.

set xdata time
set xlabel "Time"
set ylabel "Relative Humidity %"
set timefmt '%Y%m%d-%H%M'
set format x '%H%M'
plot 'readings.txt' using 1:3 title 'Relative Humidity' with linespoints

HumidityThe second example graphs the air temperature reading directly from the DHT22 with the dew point temperature calculated from the Magnus formula.

set xdata time
set xlabel "Time"
set ylabel "Temperature in degrees Celsius"
set timefmt '%Y%m%d-%H%M'
set format x '%H%M'
plot 'readings.txt' using 1:2 title 'Air Temperature' with linespoints, \
     'readings.txt' using 1:4 title 'Dew Point' with linespoints

Air temperature and dew pointI’m going to be keeping an eye on the data, to understand if it might be beneficial to seal the garage door more effectively than at present and invest in a dehumidifier.

Star Wars, Aliens, Zombies. Cinema firsts.

I’m not much of a film buff. I am occasionally persuaded to go to the cinema by my better half and even though I tend to gripe somewhat a lot beforehand, I usually enjoy the experience. However, I can only remember one time where I’ve visited a cinema alone – which was to see The Damned United. I even own a copy on DVD, but I don’t tend to watch it that often as it makes me cry. This is because I don’t expect to see Derby County win anything again in my lifetime, let alone The Premiership.

Anyway, the latest and 107th suggestion from Post40Bloggers is to write about your first cinema experience. As always, I’m going to bend the rules (what rules?) slightly and talk about my first three cinematic firsts instead.

My first ever trip to the cinema was with my brother to see Star Wars in 1977. My mother took us, under protest, to the long-demolished Ladbroke Film Centre in Chaddesden. Even as a mere thirteen year old I could tell that the place had seen better days. What had once been a glorious single screen Art Deco cinema had been turned into a failing bingo hall with two small upstairs screens where the balcony had once been. I remember the carpet being sticky with popcorn and something that was too orangey for crows. Star Wars seemed exciting enough at the time, but you have to remember that I didn’t have anything to compare it with. I haven’t watched Star Wars, or any of the many sequels / prequels since and I don’t feel as if I’ve missed out on life.

The second experience I’ve decided to recall is the first X certificate film I saw. I can date this precisely, to the Saturday afternoon of 24th November 1979. This was the day that the then European Cup holders lost to the mighty Rams 4-1. I know this to be the case as when I was traveling home on the 102 bus there were several people reading “the green ‘un” football special which had the glorious news splashed all over it. The joy was short-lived – Derby were relegated at the end of the season.

The film I saw? Alien. I fell in love with Sigourney Weaver, but not with the film. I’ve tried to watch it again a number of times, but I don’t think I’ve ever made it all the way through to the end.

My third cinematic first is from the summer of 1980. This was the first time I took a girl on a date to the cinema. To watch Zombies – Dawn of the dead. The one set in a shopping mall. With lots of gore and violence. Not exactly romantic. With hindsight, it perhaps wasn’t the best choice of film. Somewhere towards the end, there’s a particularly gruesome scene involving a helicopter. It certainly disturbed my companion, as she drove her very sharp nails deeply into the back of my hand. I still carry some tiny white scars from that evening today. The relationship didn’t last.

As I wrote at the start, I’m not a film buff. At all. But given my early experiences of the cinema, is it any real wonder?

Lymphoma: facing change

Last night I was on a flight from Rome to London. A couple of hours into the flight I was bored and distractedly looking at photographs on my tablet. I came across a selfie I’d taken in May 2015. I’ve no idea why I took it (I suspect that I hadn’t realised that I’d taken it), but it reminded me how much the left side of my face and neck has changed since my lymphoma diagnosis.

Here’s the photograph I found from May 2015 …

May 2015 selfie… and here’s the one I took last night somewhere over the English Channel.

January 2017 selfieI’m pleased to see that my eyebrows remain as wild and as out of control as ever. But those lumps. Crumbs. That’s some progression. It’s a good job I’ve never been vain about my astoundingly handsome looks. (I did however have to put the camera into ‘beauty face’ mode, so as not to scare the young and impressionable).

The good news is that chemotherapy will reduce the size of the lumps if it’s successful. The bad news is, well, chemotherapy. At the moment I’m happier without it given the general outcomes for MCL treatment, as the longer I can safely put treatment off the longer I’m likely to live.

I’d still got my tablet out as we were coming into land and was treated to some lovely views over London as the night was clear. I was over the wing, so my view was restricted, but here’s the most in-focus shot I managed, to distract you from gazing on my lovely countenance. Canary Wharf is in the centre, with the Millennium Dome (or whatever it’s called now) on the right. London is so much more attractive from 4,000m than at ground level.

London from the air, 14-01-2017

Inspired by the 48th post40bloggers writing prompt: Sit in front of a mirror and write about your face.

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