Incidence of spinal injuries in migratory Yellowstone cutthroat trout captured at electric and waterfall‐velocity weirs

The South Fork Snake River (Idaho, USA) supports a native Yellowstone cutthroat trout (YCT) population Oncorhynchus clarkii bouvieri (Richardson) threatened by non‐native rainbow trout O. mykiss (Walbaum). Electric weirs prevent rainbow trout passage into YCT spawning tributaries but may cause spinal injuries. YCT captured at electric weirs on Palisades and Pine Creeks and a control waterfall‐velocity weir on Burns Creek were X‐rayed in 2012 and 2013 to estimate spinal injury rates. Electrical pulse frequency was increased from 2012 to 2013 at the Palisades (from 11.5 to 20 Hz) and Pine weirs (13–20 Hz), and spinal injury rates were found to increase from 11.3 to 21.3% at Palisades and from 6.5 to 14.7% at Pine, while Burns injury rates remained constant (4.5% in 2012 and 6.0% in 2013), suggesting the electric weirs caused spinal injuries in YCT. Lower pulse frequencies may minimise YCT spinal injury but still prevent rainbow trout from accessing YCT spawning tributaries.     

A radial basis function neural network based self adapting predictive decoupling control system for gas collector pressure in coke ovens

Pressure is measured at different levels in the loop layer because self adapting predictive decoupling control systems are strongly coupled, disturbed, and non linear and there is a long time delay for gas collector pressure systems in coke ovens. By combing the traditional neural network control and proportional integral differential(PID) controllers based on radial basis function(RBF) neural network identification, the gas collector pressure is ensured to reach the desired technology range. The prediction model of an RBF neural network is used for advanced prediction of the actual output pressure to overcome delays in general gas collection. The simulation results and application indicate that the method can obtain ideal control results.     

小麦降温保水通风试验

选取两栋条件相同的高大平房仓,分别采用离心风机和轴流风机在冬季对库存小麦进行降温通风试验,并对通风前后的粮食温度、水分变化情况进行比较,同时分析两种通风方式的经济效益。通过试验研究得出,冬季在我国北方地区,可适时利用轴流风机对储存粮食进行降温保水通风,既可减少因通风所产生的粮食水分损耗,提高经济效益,又可以达到较理想的降温目的。     

离心风机叶片三维反问题优化设计

基于三维反问题设计方法和CFD技术,结合试验设计方法、响应面方法和模拟退火优化算法,建立了离心风机叶片三维形状的优化设计方法。以叶轮效率为优化目标,以环量分布参数为优化设计变量,进行了离心风机叶片的优化设计,优化设计结果叶轮效率提高了2.2%。根据建立的优化设计变量和叶轮效率之间的响应面函数关系式,分析了不同环量分布参数及参数间交互效应对叶轮效率的影响,结果显示轮毂进口段环量分布对叶轮效率有较大影响;轮缘处的环量分布形式对叶轮效率影响更为显著。     

离心风机叶轮三维反问题气动优化设计

基于三维反问题设计方法和CFD技术,结合试验设计方法和模拟退火优化算法,以轴面流道形状参数和叶片形状参数为设计变量,以叶轮效率为优化目标,建立了离心风机叶轮三维反问题气动优化设计方法。叶片形状通过三维反问题设计方法由叶轮的环量分布参数表达。运用该方法进行了离心风机叶轮的优化设计,叶轮效率提高了3.3%。根据建立的优化设计变量和叶轮效率之间的响应面函数关系式,分析了不同轴面流道形状参数和环量分布参数及参数间交互效应对叶轮效率的影响。结果表明:相对于轮盘处轴面流道轮盖处型线和环量分布形式,轴面流道叶片进口边倾斜角对叶轮效率影响更为显著。     

密集烤房装烟密度和变黄期风机转速对烟叶淀粉降解及经济性状的影响

以云烟87中部叶为试验材料,研究了密集烤房装烟密度和变黄期风机转速对烟叶淀粉降解和经济性状的影响。结果表明,装烟密度55～65 kg/m3配合变黄期风机转速960 r/min有利于淀粉的降解和烤后烟叶质量的形成。淀粉含量随着烘烤过程的进行逐渐降低,还原糖含量随着烘烤过程的进行逐渐升高。互作效应对烟叶淀粉和还原糖含量的影响在42℃末、47℃末、54℃末及烤后达到极显著水平。装烟密度和变黄期风机转速对烟叶总氮和烟碱含量的影响分别达到极显著水平。装烟密度55～65 kg/m3配合变黄期风机转速960 r/min烤后烟叶均价最高。     

密集烘烤干筋期风机转速对上部烟叶香气物质和评吸质量的影响

为了进一步提高上部烟叶的可用性和优化密集烘烤工艺,通过变频器控制密集烤房循环风机转速,研究密集烘烤干筋期风机转速对烤后上部烟叶香气物质和感官评吸质量的影响.结果表明,适当降低干筋期风机转速能明显改善烟叶的香气质量,且干筋前期降低风机转速对香气物质含量的影响相对于后期更大,其中T3处理(54～60℃风机转速为720 r·...     

新型端风机型炉气间接加热木材干燥窑

介绍了一种新型炉气间接加热木材干燥窑,适用于没有锅炉供热的中、小型木材加工企业使用.     

斋堂盆地的河谷地貌结构及近万年以来的水土流失概况

根据斋堂盆地的河谷地貌结构,估算出10000aB.P.～8500aB.P.的河流年平均侵蚀量为158.0×10³t/a,8500aB.P.～4000aB.P.的河流年平均堆积量为3.31×10³t/a,4000aB.P.以来的河流年平均侵蚀量为96.3×10³t/a。经比较得出,该区近万年以来的水土流失,受自然条件影响大。但随着人类活动作用的加强,人为因素逐渐成为水土流失的主导因素,现今的土地受人为破坏严重。     

新疆奎屯河流域山前河流地貌特征及演化

结合野外实地调查,对新疆奎屯河流域山前河流阶地和山前冲积扇的形态、结构以及时代进行了研究,并对奎屯河流域山前河流阶地和山前冲积扇的发育过程进行了演化。奎屯河山前的阶地可以划分出四级连续的河流阶地。在阶地形成和发育的过程中,由于受到构造运动的影响四级阶地都发生了明显、复杂的变形。奎屯河山前四期冲积扇由南向北呈串珠状发育。北天山的构造活动对奎屯河山前地貌发育起到了至关重要的作用。