第4题
根据气力输送的特点,降低动力消耗,节约能源是一个重要的研究课题,从经验中知,管道内径是关于能耗的重要参数。直观上看,当输送量一定时,管径过小,输送易阻滞,管径过大,虽输送畅通,但又造成能量的浪费。根据经验,把管径分成三组,各组的试验结果如下表所示,试用方差分析法比较各组的效果.
管径(mm) | 单位功耗 |
230 | 0.0308,0.0476,0.0504 |
250~260 | 0.0532,0.032,0.0218,0.028,0.028, 0.042,0.0336,0.042,0.042,0.028 |
280~320 | 0.07,0.07,0.0644,0.0312,0.0756,0.0756, 0.07,0.0588,0.0588,0.042,0.0308,0.0364, 0.0448,0.21,0.154,0.1064,0.1288,0.112, 0.1064,0.1288,0.0756,0.0644,0.0504,0.0644, 0.0504,0.0308 |
第8题
A.泡沫发脆,易破灭,不易被刮出
B.各室泡沫层变厚,气泡变小,水膜带油光
C.各室泡沫层变薄,夹有大气泡
D.泡沫坚韧,富有弹性,而且大量泡沫重叠如蜂窝状,泡沫含水多,以手接取泡沫,甩掉后不沾煤
E.泡沫发粘,稳定性高,刮入槽后不易破灭,且泡沫上多为细粒及细泥
第9题
A.连续级配比间断级配节约水泥
B.间断级配比连续级配节约水泥
C.间断级配适于配制流动性大的塑性混凝土
D.间断级配适于配制流动性小的干硬性混凝土
E.连续级配拌制的混凝土流动性好,粘聚性差
第10题
A.预拌混凝土的制备应包括原材料贮存、计量、搅拌和运输
B.预拌混凝土的制备不用符合环保的要求
C.粉料输送及称量应在密封状态下进行,并有除尘装置
D.搅拌站应对生产过程中产生的工业废水和固体废弃物进行回收处理和再生利用
第11题
我国农村正发生新的改革,推进农村改革发展具备许多有利条件,也面临不少困难和挑战,特别是()造成的深层次矛盾突出。