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There are 27 user-controllable LEDs on the DE2-70 board. Eighteen red LEDs are situated above the 18 toggle switches, and eight green LEDs are found above the pushbutton switches (the 9th green LED is in the middle of the 7-segment displays). Each LED is driven directly by a pin on the Cyclone II FPGA; driving its associated pin to a high logic level turns the LED on, and driving the pin low t
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通過采用非線性彈簧模擬鋼球-溝道接觸,在螺栓與構(gòu)件接觸區(qū)域施加等效均勻壓力模擬螺栓預緊力,對轉(zhuǎn)盤軸承的有限元模型進行了簡化,通過理論和經(jīng)驗公式驗證了該簡化模型的正確性,并利用此模型分析了螺栓預緊力對軸承載荷分布的影響,結(jié)果表明:鋼球-溝道最大接觸載荷與螺栓預緊力成反比;內(nèi)、外圈螺栓預緊力差異引起上、下排鋼球-溝道接觸載荷差異增大;非均布螺栓預緊力使鋼球-溝道接觸載荷波動加劇,使最大接觸載荷及其出現(xiàn)的位置發(fā)生變化。