An arrival rate of 720 veh/h arrive at a single lane signalized approach that is controlled by a traffic signal that operates at a cycle length of 60 seconds and a 50:50 green split. The amber and all-red interval is 5 seconds. The unopposed saturation flow rate was measured to be 1800 veh/h/lane with a start-loss 2 seconds and end gain of 3 seconds, respectively. For the approach do the following for a single cycle length:

a. Compute the maximum queue size formed upstream the traffic signal.

b. Compute the time required to dissipate the queue.

c. Compute the average vehicle delay experienced by vehicles traveling on the approach using the macroscopic procedures that were described in the class.

d. Compute the average vehicle delay experienced by vehicles traveling on the approach by tracking the arrival and departure times of each vehicle. Assume the first vehicle arrives at the midheadway after the red interval starts.

e. Repeat part (d) considering the first vehicle arrival ranges from 0 to 5 seconds. Comment on the sensitivity of delay estimates to the arrival time of the first vehicle.

f. Compute the number of vehicles that come to a complete stop during the cycle length.

g. Compute the maximum delay experienced by a vehicle.

h. What is the delay experienced by the third vehicle in queue assuming that the first vehicle arrives at the start of the red.

The Cycle length is 60 seconds. The problem should be solved fo a single cycle length.

Infrared sensor is most used sensor in wireless technology where remote controlling functions and detection of surrounding objects/ obstacles are involved. this post will discuss about what is infrared sensor, its working principle, how it works, types, applications, advantages and disadvantages. what is infrared sensor

ir sensor is a simple electronic device which emits and detects ir radiation in order to find out certain objects/obstacles in its range. some of its features are heat and motion sensing.

ir sensors use infrared radiation of wavelength between 0.75 to 1000µm which falls between visible and microwave regions of electromagnetic spectrum. ir region is not visible to human eyes. infrared spectrum is categorized into three regions based on its wavelength i.e. near infrared, mid infrared, far infrared.

wavelength regions of infrared spectrum

near ir – 0.75µm to 3 µm
mid ir – 3 µm to 6 µm
far ir – > 6 µm
1 introduction to infrared sensor

fig. 1 – introduction to infrared sensor

working principle of infrared sensor

infrared sensors works on three fundamental physics laws:

planck’s radiation law: any object whose temperature is not equal to absolute zero (0 kelvin) emits radiation.
stephan boltzmann law: the total energy emitted at all wavelengths by a black body is related to the absolute temperature.
wein’s displacement law: objects of different temperature emit spectra that peak at different wavelengths that is inversely proportional to temperature.
key elements of infrared detection system

the key elements of infrared detection system are:

ir transmitter

ir transmitter acts as source for ir radiation. according to plank’s radiation law, every object is a source of ir radiation at temp t above 0 kelvin. in most cases black body radiators, tungsten lamps, silicon carbide, infrared lasers, leds of infrared wavelength are used as sources.

transmission medium

as the name suggests, transmission medium provides passage for the radiation to reach from ir transmitter to ir receiver. vacuum, atmosphere and optical fibers are used as medium.

ir receiver

generally ir receivers are photo diode and photo transistors. they are capable of detecting infrared radiation. hence ir receiver is also called as ir detector. variety of receivers are available based on wavelength, voltage and package.

ir transmitter and receivers are selected with matching parameters. some of deciding specifications of receivers are photosensitivity or responsivity, noise equivalent power and detectivity.

Nope
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