The most common shielding gases used for these main arc welding processes include argon (Ar), helium (He), carbon dioxide (CO2) and oxygen (O2). While Ar, He and CO2 may be used by themselves (i.e. 100%) for certain applications, in other cases the four gases are mixed together in different combinations to form shielding gas blends.
Cluster reduction in speech is when a consonant cluster, that is two or three consonants occurring in sequence in a word (like ândâ in friend), is reduced by a child into a single consonant through omission.
Cluster simplification. In cases of consonant cluster simplification, one or more consonants present in the underlying representation (UR) of a form are deleted. Some phonologists view simplication as a result of constraints on the ways that a language allows consonants to combine into syllable structures, while others attribute it to articulatory causes.