The problem is that, once you get above a certain photon energy (in other words, a short enough wavelength), it becomes much more difficult to efficiently generate light.
Liquid desiccant cooling allows to generate remotely and efficiently a moisture absorbing liquid.
The immune system does not efficiently generate antibodies against them and infections often persist at extremely low levels, making other forms of detection technically challenging.
The Fast Walsh transform can be used to efficiently generate samples using this model.
The household microwave oven uses a magnetron tube to efficiently generate hundreds of watts of microwave power.
Cuckoo search can also be used to efficiently generate independent test paths for structural software testing and test data generation.
The ziggurat algorithm, a more advanced example, is used to efficiently generate normally-distributed pseudorandom numbers.
The dihedral angle between two planes relies on being able to efficiently generate a normal vector to each of the planes.
In computational number theory, a variety of algorithms make it possible to generate prime numbers efficiently.
Shinohara (1) invented the method to efficiently generate nitrate from in water.