| Last
Month….
We
had a look at a different aspect of computing which the majority
of club members will have had little or no experience of. We looked
into the world of Scuba Diving and dive computers. As some of
you will know I have a passion for scuba diving and I thought
that it might be interesting to show the members how computers
interface with the diving fraternity.
Initially
we looked at some of the risks involved with the sport and how
we may eliminate them to ensure maximum safety to the diver. All
divers suffer with the problem of increasing the nitrogen levels
in their body during a dive. If all correct procedures are adhered
to, then the risks to the body caused by nitrogen are significantly
reduced. Of the many considerations a diver must make, maximum
depth of the dive and the actual time of the dive are critical
to their safety.
At
depth the air is compressed by a 1 atmosphere for every 10 meters,
hence at 20 meters air is three times as dense as it is on the
surface. So for every breath taken at 20 meters, a diver will
take in three times the volume of air as a breath on the surface.
Air contains approximately 21% oxygen and 79% nitrogen. Oxygen
dissolves metabolically in the body but nitrogen being an inert
gas, has to be released from the body’s tissues. The nitrogen
is released from the body during the divers ascent from depth.
If however, the ascent rate is too great to release
all the nitrogen, then nitrogen bubbles can remain trapped in
air spaces in the body or the bloodstream and cause decompression
sickness or the ‘bends’.
Traditionally
there have been dive tables or Recreational Dive Planners to aid
the diver in knowing how much nitrogen is accumulating in the
body. These tables were derived from work carried out for the
Royal Navy by John Scott Haldene during the early part of the
20th century and the US Navy in the early 1950’s. The tables
give a conservative approach to recreational diving ensuring longer
surface intervals to eliminate any residual nitrogen from the
body. It is possible to misread these tables and cause additional
risk to the diver.
Enter
the dive computer. These devices first started appearing in the
1990’s and have rapidly become a standard piece of dive
equipment – so much so that dive operations in the Maldives
insist that all divers use one during a dive. Dive computers come
in all shapes and sizes and today’s offerings look very
much like oversized wristwatches. They all have a primary function
to monitor how much nitrogen the diver is absorbing. Dive computers
pretty well all work on a variation of the mathematical algorithm
ZH – L8 ADT that monitors nitrogen levels in different tissue
areas of the human body.
Dive
Computers also offer the diver ready information regarding the
current depth, maximum depth, length of dive and water temperature.
They will also calculate maximum ascent rates and any extended
stops that may be required to remove residual nitrogen from the
body. On top of all this, more advanced models can handle different
mixtures of breathing gas. The most advanced models such as the
VR3 computer, which is specifically designed for advanced technical
diving, can make calculations using multigas mixtures and advanced
rebreather systems.
Diving has come a long way with the introduction of computers
to help reduce risk and maintain individual safety. Their cost
range from around the £200 mark to well over £1100
for the VR3. One big facility of the computer is its ability to
log a dive profile. These profiles can be, with the correct software
and interface device, downloaded onto a personal computer for
further analysis of the dive.
Two
packages that I use are DataTrack, which is specific to the Uwartec
range of dive computers and a German programme called Wlog. Both
programmes give a graphical profile of the dive and the user can
add information as part of a computerized log for future reference.
Such data is extremely valuable in the event of a diving accident
and can be readily analyzed by dive medical staff.
This
presentation was a brief introduction to the world of scuba diving
and its use of modern computer technology. We have really only
scratched the surface, so if anyone wants to find out more and
even possibly get wet, let me know and I will do my best to put
you in the right direction.
Dave
Robb
Computer Security
Security
Now – a series of Podcasts by Steve Gibson and Leo Laporte
Members
who attended the February meeting of Melton Computer Club may
remember the videos that I showed from Gibson Research, a software
company based in California. Steve Gibson participates in a Canadian
TV Show called TechTV and each week they spend 30 minutes of so
talking about various computer security issues. These sessions
are available from his Web site, either as sound files, or in
various text formats. Each episode is available in 6 formats:-
High
quality mp3 file.
Lower
quality mp3 file.
Web
page with supplemental notes.
Web
page text transcript.
Simple
text transcript.
Ready
to print pdf file.
They are available from http://www.grc.com/SecurityNow.htm .
Topics
covered in recent weeks include:-
Wireless
Security
Virtual
Private Networks
Cryptography
Spyware
Password
policies
In
addition, every 4 weeks they do a question and answer session
covering a variety of security related topics.
Members
may find it interesting to browse the files, and even download
some of them.
Alan Danbury
Photographic
Competition 2006
I
know that the competition is someway off but we thought that it
would be good to have as much warning as possible as to the competition
subjects. Last month we got members to select their favourite
topics and the top six were chosen for this year’s competition.
They are as follows :-
1.
The Four Seasons (any photograph depicting one of the seasons
of the year)
2.
Landscape/Seascape
3.
Nature
4.
Industrial Landscape
5.
Image manipulation (use of any programme effects to enhance a
photograph)
6.
Close-Up
So
now you know, we will accept no excuses and happy snapping over
the next few months. The competition will take place in December
as usual.
Planned
Topics For The Rest Of 2006
The
committee try to put on a varied programme for the year and hope
to put on the following topics for the rest of the year. This
programme is by no means cast in stone and can be modified as
and when necessary.
May
10 Problem Solving/ Open Forum
June 7 Judging Photographs
Aug 2 Spreadsheets
Aug 30 SatNav
Sept 27 Vertual Storage Area Networks/ Home Networking
Oct 25 Linux
Nov 22 Custom Software
Dec
20 Photographic Competition
If
there are any further suggestions then please let the committee
know and we will do our best to accommodate.
Free
To A Good Home
One of our old members contacted me recently with news of some
surplus equipment that he has. Mick Mason has three monitors that
he no longer needs, he has 2 x 14” and a 19” which
has 4 usb ports in the base. Free to a good home. If you
are interested in any of these contact Derek who will put you
in contact with Mick.
Seagate
Technology bared the teeth of its new Barracuda 7200.10 family
of perpendicular recording-based hard drives April 26.
Currently shipping to OEMs, the devices squeeze 750GB of digital
storage space onto a single disk drive for desktop computers and
low-end servers.
The fifth perpendicular recording hard drive released by Seagate,
the 3.5-inch Barracuda 7200.10 performs about 10 percent higher
than its previous generation, the Barracuda 7200.9.
The new Barracuda family features formatted capacity points ranging
from 200GB, 250GB, 300GB, 320GB, 400GB, 500GB and 750GB on four
platters.
Additionally, interface choices include ATA/100, SATA (serial
ATA) 1.5GB per second or SATA 3GB per second with NCQ (Native
Command Queuing) capabilities.
The new Seagate hard drives offer 8MB or 16MB cache buffer options.
On the 250GB and above, 16MB cache is offered; 8MB cache on the
200GB and 250GB only; and both size cache on the 250 only.
On May 1, Seagate will launch the external hard drive counterpart
of the 750GB Barracuda 7200.10 product line.
The external version will have the same specifications and features
of the internal disk drive model, according to Joanie Clark, product
marketing manager for Scotts Valley, Calif.-based Seagate.
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