سوال ۱۸ کنکور ارشد مهندسی مکانیک ۱۴۰۴

PART C: Reading Comprehension — Read the following passage and answer the question by choosing the best choice (1), (2), (3), or (4).

PASSAGE 2 (paragraph 2):

There is a group of properties which usually is considered to be very important in mechanical constructions: strength, stiffness, operating temperature and ductility. In addition to strictly technical parameters, two other requirements must be considered: the density of materials and materials cost, in some aspects these attributes being interconnected. Weight reduction is important in mechanical design for many reasons. The benefits from weight savings are changing considerably with the field of industry: they are very important for the aerospace industry, and for the automobile industry and are not to be disregarded in mechanisms, for which the operating mode is associated with reciprocating or rotating mass. Weight savings are obviously crucial for energy (fuel) economy. Weight reduction could be achieved by the density decrease of structural alloys; the alloys of aluminium, magnesium or titanium, for instance, are important in this respect.

Which of the following techniques is used in paragraph 2?