State of Charge (SoC) estimation of a lithium battery with polynomials

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Estimating the state of charge of a lithium based on voltage measurements from the battery is rather challenging. This is due to not only the state of chacrge but also the condition of the battery, current drawn, ambient temperature, etc all having a significant impact on the voltage measured. The best way for SoC estimation would be a columb counter which wasn’t available for my project. For my project the current drawn is rather constant around 200ma and the temperature is relatively stable around 20-25C. Thus a much better estimate should be possible with polynomials than the simple linear SoC estimations. For the polynomial regeressions and to find the polynomial coefficients r was used.

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Sending HTML Lotus Notes Email including a HTML Signature from Excel with VBA

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This is a VBA script that allows you to send a Lotus Notes email with VBA from excel. What is new here is that you can write the email in HTML and also attach your standard HTML signature. This seems to have been a major issue with VBA generated Lotus notes emails, as the signature is usually missing. The script also takes the email addresses from an excel spreadsheet.

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Animals and scenes of the Daintree Rainforest

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This footage was shot during our camping trip to the daintree rain forest and surroundings. We spotted Cassowaries , Kookaburras, Forest dragons, Kangaroos and many others. What a beautiful rain forest Australia has. The aim was to test the movie capabilities of the D7000. Thus everything was filmed with the Nikon D7000, a Sigma 18-200mm and a Nikon 50mm F2.

Make sure to watch it in HD!

Sort eBay Search by Bids

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Not too long ago eBay discovered that the removal of the sort by bids feature forces customers to spend much more time on their site. What an absolute nightmare.

I have thus written a free program with AutoIt called Sesbyb to fix this situation. With this program the items of your eBay “BuyItNow” search will be sorted according to their sales rank, meaning items with most bids will appear first in the list.

Supported options include:
– Number of results to sort
– Local or global search
– Min and max price

Planned are the options to enter your own search url as well processing search results of more than 200 items if there is demand for thos features. Furthermore the whole string seperation process will be overhauled.

Sesbyb - Sorting search result by bids

Sesbyb – Sorting search result by bids

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Wind Energy in China (2012)

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Global warming and carbon emissions have strongly shaped policies around the world during the past decade. Today most governments around the world see it as their goal to reduce greenhouse gas emissions. When China surpassed the US in carbon emission in 2006 the country came into the spotlight of carbon and renewable energy discussions with the country’s energy consumption relying greatly on fossil fuels. Currently, China’s energy supply is dominated by coal consumption, while natural gas and oil are in relative short supply. In 2007 fossil fuels accounted for more than 90 percent of China’s energy consumption, of which roughly 75 percent came from coal. [1] This is largely the result of coal being China’s most abundant fossil energy resource with an estimated 5,570 billion tonnes in coal deposits located within the country, making up roughly 12.6 percent of the world’s total coal reserves. [2] Despite its abundant reserves China became a net importer of coal in 2009.

China also overtook the United States in 2009 to become the world’s largest energy user and as a by-product also became the leader in greenhouse gas emissions. In 2011 China was estimated to emit more CO2 than the US and Canada together, an increase of 171 percent since the year 2000.[3]

Carbon dioxide emissions per country

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Mosquito attractants for an effective trap

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Clearly various species of female mosquitoes and myself seem to have a slight communication issue. Having been forced into this rather parasitic polygamous relationship my patience has, after over two decades of torture, finally run out. Furthermore considering that various mosquitoes act as vectors for diseases such as yellow fewer and malaria I do not wish to push my luck any further during my future trips into the rainforests of this world. Hoping to build an effective, affordable and portable trap it is as a first step necessary to understand what exactly mosquitoes are attracted to.

Female Anopheles albimanus mosquito

Female Anopheles albimanus mosquito while she is feeding on a human host, thereby, becoming engorged with blood. (Source: Center for Disease Control and Prevention, ID 7861)

“Using their highly sensitive olfactory organs, these mosquitoes can select more attractive persons over less attractive ones by identifying chemicals present in breath, sweat and other skin emanations originating from the persons. Though not adequately understood, these evolutionary host preferences may benefit the mosquitoes in a number of ways including the identification of hosts with more nutritive blood, or those who are less defensive against mosquito bites.” (Okumu et al. 2010) In the following paragraphs various possible attractants will be investigated as a potential suitable lure for the trap.

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Logitech C910 and C920 IR (Infrared) conversion for nightvision

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This is a tutorial on how to convert your Logitech C910 or C920 webcam into an HD nightvision camera by removing the Hot Mirror Filter. For the C920 please read the comments. Once you have completed the conversion, your camera will be very sensitive to infrared light. However, it should be noted that one of the main reasons for the IR filter’s existence is to get a sharper image. The quality of the image is thus affected and furthermore your webcam image will have a very strong red tint. (Of course if you would use a lightsource without infrared, such as an LCD, that would not be the case.) Furthermore, in my case the autofocus does not seem to work very well after the conversion. The manual focus on the other hand works just fine, This is all I need for my purpose.

Please note that you are converting the camera at your own risk.

Below you find an image taken with my converted C910. The picture was taken through a 850nm IR filter. The LED’s are 950nm. Looking through the filter the room appears absolutely pitch black to the naked eye.

Photo of two 950nm IR LED's taken through an 850nm IR Filter with the converted Logitech C910.

Photo of two 950nm IR LED

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Ultrasonic Dimmer (without humming or buzzing noise)

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Arduino based Ultrasonic Dimmer

I have been working on this project for a while and whilst it is still under development here’s a short guide after several requests to do so. The dimmer uses an interrupt driven XL-Maxsonar EZ1 ultrasound range finder to measure the distance between the sensor and your hand. By moving your hand up and down over the sensor you can increase or decrease the amount of light emitted by the connected halogen lamp.

In this post I will explain how one can make the basic dimmer based on a simplified circuit. This dimmer later evolved to include an LCD, SHT15 temperature and humidity sensor, DS1307 realtime clock and a mosfet driver to drive the mosfet above 30Khz so the unpleasant dimmer humming noise would disappear. I will talk more about this later.

First things first, here’s a movie of the latest version of the dimmer in action, it includes an LCD, a temperature and humidity sensor, a realtime clock and an alarm function that simulates a sunrise:

[youtube width=”590″ height=”420″]http://www.youtube.com/watch?v=NGR54NZKIrM[/youtube]

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