Scour on Alluvial Bed Downstream of Grade-Control Structures

This paper describes an approach for predicting local scour downstream of grade control structures. The developed analysis applies the incomplete self-similarity (ISS) theory for deducing some physically based dimensionless groups controlling the geometrical pattern of the scour profile. The scour measurements available in the literature in conjunction with numerous unpublished data allow a multiregressive calibration of the ISS relationships. The experimental sample includes different bed grain-size distributions and scales of the erosive phenomenon. The results prove that the ratio between the upstream water head and the weir height is able to explain the measurements of scour depth carried out in both small- and large-scale installations. This estimation of maximum scour depth was improved, introducing variables representative of both the jet contraction and the bed particle grain-size distribution. Variables related to the longitudinal sizes of the scour profile tend to be predicted with more accuracy than those related to the scour depth and appear more influenced by the coarsest component of the alluvial bed.     

Canadian university students in wireless classrooms: What do they do on their laptops and does it really matter?

Two studies were conducted to examine what undergraduate students do on their laptops during class time and the extent to which laptop usage behaviors are associated with academic success. In Study 1, a sample of 1129 students from a Canadian university completed a survey measuring prototypical behaviors emitted on laptops during class time. Results of factor analyses indicated that laptop behaviors can be regrouped in two dimensions: School related and school unrelated laptop utilization. School unrelated laptop behaviors were significantly associated with lower levels of self-reported academic achievement and satisfaction. School related laptop behaviors were positively associated with academic satisfaction. These results were invariant across different faculties on campus. In Study 2, another sample of 88 students was recruited to examine the longitudinal association between laptop behaviors and semester grade point average obtained at the end of the semester. Results of Study 2 showed that school unrelated laptop behaviors were prospectively associated with lower semester grade point average, even after controlling for a series of potentially confounding influences (i.e., self-regulation failure, motivational deficit, disorganized learning, internet addiction, and school disenchantment). Overall, these results provide theoretically important support to suggest that in-class laptop utilization is a unique and contemporary mode of learning that should not be treated as an epiphenomenon merely accountable and reducible to other sources of psychological influences.     

矿石品位指标优化方法在二峰山铁矿的应用

阐述在实用磁滑轮预选工艺条件下对入选品位，截止出矿品位，边界品位进行优化的方法和依据，介绍二峰山铁矿选矿厂进行矿石品位优化的实际情况，实践证明优化矿石品位不但可以提高经济效益，而且可以充分利用矿资源。     

基于三维地质统计学的矿床建模实践研究

结合一个实际的铜铁共生矿床，对应用三维地质统计学方法研究矿床建模工作涉及的若干技术与方法。首先进行了合理而有效的样品组合计算，同时研究了该矿铜，铁样品品位的分布规律，通过交叉验证工作，得出了相应铁原样品位及铜的对数转换品位进行矿床建模的结论，并分析建立了这2种元素的品位模型，然后对建模结果与实际矿床进行了比较，其结果表明了建模的准确性，最后得出了应用地质统计学方法进行矿床建模工作的一些有意义的结论和建议。     

脉冲与直流供电下旋风静电除尘器的性能对比研究

研究了供电方式对旋风静电除尘器除尘性能影响，在同一入口风速、工作电压、入口粉尘浓度下，测试了脉冲供电与直流供电方式下旋风静电除尘器的总除尘效率及分级除尘效率。实验结果表明：脉冲供电有效地提高了旋风静电除尘器的除尘效率，特别是对于粒径小于2μm的粉尘，旋风脉冲静电除尘器的分级除尘效率比旋风静电除尘器的提高20％以上。     

工业低品位余热应用于城市集中供热的技术途径与潜力研究

本文以国内某钢铁厂为例,探讨了工业余热梯级综合利用方式问题,并研究了将钢铁厂低品位余热进行回收并用于城镇集中供热的技术途径及经济性,对国内钢铁行业内低品位余热资源的种类与规模进行了初步评估,指出钢铁厂等高耗能企业通过低品位余热供热可为大规模解决我国北方地区城镇集中供热提供一种具有循环经济属性的新型供热方式,并具有重要的节能减排、降耗增效的意义.     

低配棉36．4tex转杯纺产品的工艺研究

在对转杯纺工艺理论和试验研究基础上,探讨了低配棉36．4tex转杯纺产品的工艺流程设计和各工序的主要技术措施。在生产中,各工序通过优化配置工艺参数,保证了纺纱的顺利进行,提高了成纱质量。     

等级粕生产技术在油脂工业中的运用研究

本文对油料加工过程中影响粕质量的因素进行了分析,提出生产等级粕的概念,设计不同油料生产出不同等级粕的工艺和设备选型,建议在新建油脂加工企业增加生产等级粕工艺,同时建议尽快出台等级粕质量标准.     

棉花品级检测中HVI与人工检测法相关度分析

HVI是一种综合性的棉花质量检测仪器,现阶段国内对HVI的应用主要集中在测试强度和马克隆值方面,在确定棉花外观等级方面应用较少。通过分析HVI在品级检测中的应用得出,在多数情况下,HVI检测结果可以作为品级检测的最终结果。相对于人工检测,HVI测试是一种简单实用的新检测方法。     

二等标准铂电阻温度计校准结果不确定度评定

在二等标准铂电阻温度计固定点的校准中,使用的标准器具、固定点容器及测温电桥等都会对测量产生影响。文中分析了各因素对校准结果扩展不确定度的影响,并根据JJF 1059—1999《测量不确定度评定与表示》技术规范,对二等标准铂电阻温度计水三相点、锌凝固点及锡凝固点的校准结果进行不确定度评定。