转炉二次烟气除尘变工况及风机调速

根据转炉二次烟气除尘风量随冶炼周期变化的特征,利用工艺设备工况特征信号控制各除尘阀门的开闭,并根据各个除尘分支管道工况的变化,确定系统在不同工作点的总阻力、风量和风机转速,达到自动控制风机调速,节约电能的目的。     

A population comparison of the strength and persistence of innate colour preference and learning speed in the bumblebee <Emphasis Type="Italic">Bombus terrestris</Emphasis>

Studies of innate colour preference and learning ability have focused on differences at the species level, rather than variation among populations of a single species. Initial strength and persistence of colour preferences are likely to affect colour choices of naïve flower visitors. We therefore study the influence of both the strength and persistence of innate colour preference (for blue) on an operant learning task (associating food reward with yellow flowers) in two populations of the bumblebee Bombus terrestris. We found that both strength and persistence of blue preference differed significantly between populations: B. terrestris dalmatinus had a weaker and less persistent blue preference than B. terrestris audax. These differences in preference also influenced learning performance. Considering only landing behaviours, one-trial learning occurred in the majority (73%) of bees, and was achieved sooner in B. terrestris dalmatinus because of its weaker blue preference. However, compared to landing behaviours the relative frequency of approach flights to rewarding and unrewarding flower types changed more slowly with task experience in both populations. When considering both approaches and landings, the rate of learning, following the first rewarded learning trial, was faster in B. terrestris audax than B. terrestris dalmatinus. However, the net effects of population differences in blue preference and learning dynamics result in similar final levels of task performance. Our results provide new evidence of behavioural differences among isolated populations within a single species, and raise intriguing questions about the ecological significance and adaptive nature of colour preference.     

Heavier birds react faster to predators: individual differences in the detection of stalking and ambush predators

The relationship between body mass and reactions speed in response to a predatory threat is poorly understood. Theory predicts that different vigilance patterns are optimal for the detection of different predator types. We suggest that birds of different individual state might also differ in their speed of response dependent upon predator type. We used laboratory trials of wild caught chaffinches (Fringilla coelebs) to determine how between individual differences in chaffinch behaviour and state correlate with latency to react to a ground predator model (domestic cat), thus providing a comparison with previous work in the same model system using aerial predator models. In experiment 1, we observed chaffinch responses to a moving cat model, simulating a stalking predator. In experiment 2, we used a camouflaged cat model simulating an ambush predator. Both experiments show evidence suggesting heavier individuals (which previous literature has linked to impaired flight performance) responded more quickly to the model cat. Heavier individuals also had shorter interscan intervals. In contrast to a previous study, both experiments found individuals with a higher intake rate were not faster at responding to the cat model. In addition, individuals in experiment 1 that head turned more while scanning were slower to respond to the stalking cat model. Our work suggests that although heavier individuals may have impaired escape performance they appear to show behavioural compensation by allocating more attention to anti-predator behaviour and by modifying their interscan intervals, resulting in faster response times to a ground predator. We suggest more experiments investigating response time to different predatory types and explicitly manipulating state to elucidate cause and effect.     

梯形巷道平均风速分布特征的数值与实验研究

为实现矿井巷道内风量的准确监测,基于3D数值模型,对梯形截面巷道内平均风速的分布规律进行了数值分析,并通过实验研究对模拟结果进行对比验证,同时在不同断面尺寸及不同通风风速条件下,数值分析了梯形巷道内紊流充分发展截面上平均风速点的分布特征。结果表明:平均风速分布呈现环状连续分布,数值结果与实验结果符合良好;梯形截面上平均风速点的分布与通风风速无关,仅与巷道截面特征和参数有关;得到了梯形截面平均风速分布曲线在巷道顶部的特征方程。     

Modeling quenching distance and flame propagation speed through an iron dust cloud with spatially random distribution of particles

In this research combustion of iron dust particles in a medium with spatially discrete sources distributed in a random way has been studied using a numerical approach. A new thermal model is generated to estimate flame propagation speed and quenching distance in a quiescent reaction medium. The flame propagation speed is studied as a function of iron dust concentration and particle diameter. The predicted propagation speeds as a function of these parameters are shown to agree well with experimental measurements. In addition, the minimum ignition energy has also been investigated as a function of equivalence ratio and particle diameter. The quenching distance has been studied as a function of particle diameter and validated by the experiment. Considering random distribution of particles, the obtained results provide more realistic and reasonable predictions of the combustion physics compared to the results of the uniform distribution of particles.     

长三角高速铁路网建设对江苏省煤炭铁路运输能力的影响

铁路运输是我国煤炭运输的重要方式。我国高速铁路的建设不仅对经济社会发展产生重大影响,也释放出一定的运能,促进铁路煤炭运输能力的提升。文章以江苏省为实证区域,针对江苏省铁路运煤特点,构建计算方法,估算了长三角高速铁路建设之前,京沪、沪宁等高速铁路通车后,以及长三角高速铁路网初步形成后江苏省主要铁路运煤线路的运输能力。结果表明：在长三角高速铁路建设之前,江苏铁路运煤线路受制于大量开行高等级旅客列车、线路技术等级低、施工维护等因素,煤炭运输压力巨大;随着长三角高铁建设的不断推进,一些铁路运煤线路运能得到释放;今后随着高速铁路网络的形成,“客货分线”得以实现,加上规划新建的铁路,铁路运煤能力将有较大提升。     

自动扶梯曳引机由静态元件供电的拖动线路及PLC控制

文章分析了GBI6899—2011《自动扶梯和自动人行道的制造与安装安全规范》中曳引电机由静态元件供电的要求,讨论了使用两个和一个电源接触器切断曳引机供电的线路。并优先使用一种两个电源接触器切断供电的线路,设计了该线路的一种PLC控制电路,讨论了其起动和停止的控制过程。并给出了PLC控制梯形图程序的结构图。     

纵向风速对隧道内烟气发展影响的实验研究

通过在鹰嘴岩隧道内的现场模拟火灾试验,对不同纵向通风速率下隧道内烟气发展过程进行了研究。结果表明,纵向风速和火源大小均对烟气层沉降有重要影响。相比之下,纵向风速对烟气层沉降的影响更大;火源位置较高时,烟气层热膨胀力较大,在距离火源一定距离外仍可产生上游方向的烟气逆流;一定坡度的隧道在某种条件下可以产生"弱烟囱效应",导致烟气向下游方向的流速增加。在隧道设计中可以考虑利用这一点来增加排烟效率。     

拉萨和合肥环境下不同厚度保温材料EPS火蔓延特性研究

为了揭示保温材料EPS在不同厚度以及不同压力和氧气浓度等条件下火蔓延特性规律,分别在高原地区的拉萨和平原地区的合肥对其进行了火蔓延实验。实验是在小尺寸火蔓延实验台中进行的。通过分析在水平放置时,不同厚度保温材料在两地火蔓延过程中火蔓延速度、平均池火长度、平均最大火焰高度等特性参数的变化规律,定量地揭示了高原和平原环境对不同厚度保温材料EPS火蔓延特性参数的影响。结果表明,保温材料EPS火蔓延速度、平均池火长度、平均最大火焰高度在拉萨和合肥环境条件下,均随着保温材料厚度的增加而增加。同种厚度EPS在两地火蔓延过程中,火蔓延速度、平均池火长度、平均最大火焰高度在合肥地区都高于拉萨地区的特点。     

隧道火灾的全尺寸试验研究

在3条公路隧道上进行了10次全尺寸试验,研究不通火灾条件和风速下烟气的运动情况。主要测量了各隧道1000m范围内的拱顶下方烟气温度、烟气层高度分布以及烟气前锋的运动情况等,并分析了纵向风速对火灾羽流形态、烟气前锋运动速度、隧道内线型缆式感温探测系统响应等的影响。此处所列的所有全尺寸试验数据可以进行进一步的分析,以便研究各种已知火灾模型在计算长隧道火灾时所得的结果是否有效。