Wednesday, February 27, 2008

HDTV blur

HDTV blur is a common term used to describe a number of different artifacts on consumer modern high definition television sets:

The following factors are generally the primary or secondary causes of HDTV blur; in some cases more than one of these factors may be in play at the studio or receiver end of the transmission chain.

• Pixel response time on LCD displays (blur in the color response of the active pixel)
• Slower camera Shutter speeds common in hollywood production films (blur in the HDV content of the film)
• Blur from eye tracking fast moving objects on sample-and-hold LCD, Plasma, or Microdisplay.
• Resolution resampling (blur due to resizing image to fit the native resolution of the HDTV)
• Blur due to 3:2 pulldown and/or motion-speed irregularities in framerate conversions from film to video
• Computer generated motion blur introduced by video games

Friday, February 22, 2008

Acoustic Intelligence

Sensors relatively close to a nuclear event, or a high-explosive test simulating a nuclear event, can detect, using acoustic methods, the pressure produced by the blast. These include infrasound microbarographs (acoustic pressure sensors) that detect very low-frequency sound waves in the atmosphere produced by natural and man-made events.

Closely related to the microbarographs, but detecting pressure waves in water, are hydro-acoustic sensors, both underwater microphones and specialized seismic sensors that detect the motion of islands.

Sunday, February 17, 2008

Derivative action

The derivative part is concerned with the rate-of-change of the error with time: If the measured variable approaches the setpoint rapidly, then the actuator is backed off early to allow it to coast to the required level; conversely if the measured value begins to move rapidly away from the setpoint, extra effort is applied — in proportion to that rapidity — to try to maintain it.

Derivative action makes a control system behave much more intelligently. On systems like the temperature of a furnace, or perhaps the motion-control of a heavy item like a gun or camera on a moving vehicle, the derivative action of a well-tuned PID controller can allow it to reach and maintain a setpoint better than most skilled human operators could.

Friday, February 08, 2008

System dynamics

System Dynamics was founded in the late 1950s by Jay W. Forrester of the MIT Sloan School of Management with the establishment of the MIT System Dynamics Group. At that time, he began applying what he had learned about systems during his work in electrical engineering to everyday kinds of systems. Determining the exact date of the founding of the field of system dynamics is difficult and involves a certain degree of arbitrariness.

Jay W. Forrester joined the faculty of the Sloan School at MIT in 1956, where he then developed what is now System Dynamics. The first published article by Jay W. Forrester in the Harvard Business Review on "Industrial Dynamics", was published in 1958. The members of System Dynamics Society have chosen 1957 to mark the occasion as it is the year in which the work leading to that article, which described the dynamics of a manufacturing supply chain, was done.