ROCKVILLE, Md. (AP) ¿ Argan Inc., which designs and builds energy plants, said Tuesday its fiscal second-quarter net income more than tripled as falling costs offset a decline in revenue. The company said it earned $2.7 million, or 19 cents per share, during the three months ended July 31. It earned $806,000, or 7 cents per share, in the same quarter last year. Revenue fell 12.8 percent to $65.5 million from $75.1 million. The company attributed the falling revenue to the construction of two biofuel facilities in Texas. It also took a $1.9 million impairment charge in the year-ago quarter. Its selling, general and administrative expenses fell to $3.1 million from $4 million. Shares of Argan rose a 15 cents to $14.15 in afternoon trading.