Energy harvesting that are able to operate in higher temperature gradients, and that can conduct electricity well without also conducting heat (something that was until recently thought impossible ), will result in increased efficiency. Future work in thermoelectrics could be to convert wasted heat, such as in automobile engine combustion, into electricity. This type of harvesting is based on the changing capacitance of vibration-dependent capacitors. Vibrations separate the plates of a charged variable capacitor, and mechanical energy is converted into electrical energy. Electrostatic energy harvesters need a polarization source to work and to convert mechanical energy from vibrations into electricity. The polarization
Biproduct If the product formula_9 and coproduct formula_10 both exist for some pair of objects "A", then there is a unique morphism formula_11 such that It follows that the biproduct formula_15 exists if and only if "f" is an isomorphism. If C is a preadditive category, then every finite product is a biproduct, and every finite coproduct is a biproduct. For example, if formula_9 exists, then there are unique morphisms formula_17 such that To see that formula_9 is now also a coproduct, and hence a biproduct, suppose we have morphisms formula_22 for some object formula_23. Define formula_24 Then formula_25 is a