energy
Tracing Power Lines with the Pylon Appreciation Society
Pylons
Not all the towers along a transmission line are identical. Look closely at a tower where the line makes a sharp turn and you will likely find it is wider and beefier than other towers along the route. The added strength and weight are needed to resist the unbalanced pull of the conductors, which might overturn an ordinary tower. These special towers are called deviation or angle towers.
The transmission-line tower everybody knows is an Erector Set latticework of steel girders and diagonal braces. The techniques for designing and building these towers are the same ones used in constructing steel bridge trusses or crane booms. The individual pieces can be made cheaply from rolled steel and then bolted together on the site. This last point is more important than it might seem: transporting a fully assembled tower 100 feet tall is an awkward and expensive business.
A haunting, syncopated music
"Rappers" on the roof of the electrostatic precipitator knock the accumulated dust free, letting it fall into the storage hopper. Each rapper is the size and shape of a baseball bat. Inside is an electromagnet that pulls a steel plunger upward, then allows it to fall again, producing a sharp knock. The rappers are energized at seemingly random intervals, producing a haunting, syncopated music. (The rhythm seemed more modern jazz than rap.)
Safety cut rope axe man
In the first nuclear reactor, constructed by Enrico Fermi in 1942 under the bleachers of the University of Chicago football stadium, the control rods were held up by a manila rope. A man with an axe was told to cut the rope if the reactor got out of hand. This "safety cut rope axe man" is supposedly the origin of the term SCRAM for an emergency shutdown procedure.
Color coding
Telephone wires erupt in a multicolor cascade in a ground-level, pedestal-type splice case on a city street.
Dividing the set of 10 colors into two contrasting groups of 5 allows for exactly 25 combinations with one color from each group; thus, each pair in a bundle can be uniquely colored. A similar color code is applied to the ribbons that bind together all the pairs in a bundle, and to those of the superbundles. The result is highly festive! A specific wire might be identified as the blue-red conductor within the orange-black bundle within the brown-yellow superbundle.
Manifesto for Agile Software Development
We are uncovering better ways of developing software by doing it and helping others do it. Through this work we have come to value:
- Individuals and interactions over processes and tools
- Working software over comprehensive documentation
- Customer collaboration over contract negotiation
- Responding to change over following a plan
That is, while there is value in the items on the right, we value the items on the left more.
Deliver early and continuously
Our highest priority is to satisfy the customer through early and continuous delivery of valuable software.
Welcome changing requirements
Welcome changing requirements, even late in development. Agile processes harness change for the customer's competitive advantage.
Self-organizing teams
The best architectures, requirements, and designs emerge from self-organizing teams.
Technical excellence and good design
Continuous attention to technical excellence and good design enhances agility.
Agility and sustainability
Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.
The amount of work not done
Simplicity—the art of maximizing the amount of work not done—is essential.
The primary measure of progress
Working software is the primary measure of progress.
Build projects around motivated individuals
Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done.
Deliver working software frequently
Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale.
Business people and developers
Business people and developers must work together daily throughout the project.
Face-to-face conversations
The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.
Reflect, tune, adjust
At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.