卷烟厂风送系统补风计算及应用

为解决卷烟厂风力送丝系统风量不足和风机喘振问题,提出了采用变频调节及结合主管补风的方法对风送系统进行改进。通过实例计算得出,该系统风机的频率调节范围为41~50 Hz,当卷烟生产过程中有3台及以上机组停机时需要进行补风,最大补风量为3 900 m3/h。采用变频调节及结合主管补风的方法既能保证风力送丝系统有效运行,同时也提高了系统的节能效率。     

空气动力学粗糙度与植被特征关系的研究进展

由Bagnold提出的空气动力学粗糙度概念,是描述各种表面空气动力学特征的重要参数,已被广泛应用于沙面、植被覆盖表面、雪面、水面等.植被高度、密度、覆盖度、侧影盖度等特征,通过影响下垫面空气动力学粗糙度来达到抑制风蚀的效果.本文系统地总结了近年来空气动力学粗糙度与植被特征关系的研究成果,分析了各种植被特征因素与空气动力学粗糙度的关系,并对影响空气动力学粗糙度的植被因素的研究方向进行了预测.     

ATM网络中一种链路速率分配算法

针对ATM网络中不同业务的需要,提出了一种采用FIFO机制的易于实现的单队列缓存分配方案,但该方案为了获得较高的链路利用率就需要较大的缓存空间·因此进一步提出了旨在减少信息对缓存的占用的多队列链路速率分配算法,并求解了链路速率的分配规则表达式·理论分析表明,该算法能够在一定程度上克服单队列缓存分配算法对缓存空间的耗费,并保证链路速率的合理分配·     

钢框架稳定性探讨

钢框架稳定性的计算主要是柱子稳定性的计算,其中计算长度系数法避免了对结构做整体屈曲分析,因此得到广泛应用。钢框架柱的计算长度系数与多因素有关,体现在初始几何缺陷、荷载条件、节点连接刚度、支撑刚度、层间相互作用和二阶效应等方面。但钢框架的整体稳定判定准则也起着越来越重要的作用。     

草原公路直线段长度对驾驶员心率变异性的影响研究

通过草原公路实驾试验,采集了14名驾驶员在六段长度不同的相邻直线段上的心电数据,通过Kubios HRV软件分析心率变异指标SDNN值和LF/HF值,以探究草原公路直线段长度对驾驶员心率变异的影响。对SDNN值和LF/HF值进行非参数检验,结果表明个体差异对SDNN值影响大,而对LF/HF值影响小,因此可以用LF/HF值来评价直线段长度对驾驶员的影响。在一定范围内,随着草原公路直线段长度的增大,驾驶员的LF/HF值有先增大后减小的趋势,但是不同气质驾驶员的极大LF/HF值对应的直线段长度值不一样,超过该长度后,随着直线段长度的增大,驾驶员的警惕性会逐渐减小,适合草原公路驾驶员心生理情况的直线段长度应该控制在极大直线段长度左右。     

曲率效应对金属碳纳米管局域化长度的影响

基于pi轨道紧束缚模型,并考虑曲率效应的影响,解析地推导了金属（即扶手椅型）碳纳米管的局域化长度。发现,考虑曲率效应后,扶手椅型碳纳米管的局域化长度变长;还发现,曲率效应对扶手椅型碳纳米管局域化长度的影响随碳纳米管的半径的增加而迅速减小。     

Climatic significance of δ18O records from precipitation on the western Tibetan Plateau

Analysis of daily precipitation samples for stable oxygen isotopes （δ^18O） collected at the Shiquanhe and Gerze （Gaize, Gertse） stations in the Ngari （Ali） region on the western Tibetan Plateau indicates that air temperature affects the δ^18O variations in precipitation at these stations. In summer, Shiquanhe and Gerze show strongly similar trends in precipitation δ^18O, especially in simultaneous precipitation events. Moreover, both stations experienced low δ^18O values in precipitation during the active monsoon period, resulting from the southwest monsoon （the summer phase of the Indian monsoon）. However, during the break monsoon period （during the summer rainy season, when the monsoon circulation is disrupted）, δ^18O values in summer precipitation remain relatively high and local moisture recycling generally controls the moisture sources. Air temperature correlations with δ^18O strengthen during the non-monsoon period （January--June, and October--December） due to continental air masses and the westerlies. In addition, evaporation also influences the δ^18O variations in precipitation. The observed temporal and spatial variations of δ^18O in precipitation on the western Tibetan Plateau and adjacent regions show that the late May and early June-the late August and early September time frame provides an important period for the transportation of moisture from various sources on the Tibetan Plateau, and that the region of the West Kunlun-Tanggula Ranges acts as a significant climatic divide on the Plateau, perhaps for all of western China.     

Chinese kangs and building energy consumption

Chinese kangs are an integrated system for cooking, sleeping and heating in rural Northern China with more than 2000 years history. In 2004 there were 67 million Chinese kangs used by 44 million rural families or 174 million people. Chinese kangs store surplus heat from stove during cooking and releases it later for both home heating and localized bed heating. Such a widely used heating system has been rarely studied. Understanding kangs is important for developing new effective home heating systems for better energy efficiency and improving indoor air quality in Northern China. In this paper, we review and present some preliminary results from our field measurement and mathematical modeling, and discuss the development of Chinese kangs as related to future energy consumption in rural homes, and building energy consumption in China in general. We suggest that transition and new technologies for rural home heating in Northern China, i.e. the future of Chinese kangs, should be considered as the top priority in managing future building energy consumption in China. Supported by the grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant No. HKU 7154/05E) and National Natural Science Foundation of China 2007 Young Researcher Award (Grant No. 50729803) The work is also a part of the International Energy Agency Annex 44 project on Integrating Environmentally Responsive Elements in Buildings.     

On the measurement of slip length for liquid flow over super-hydrophobic surface

To design a surface with large slip or larger drag reduction is a pop issue in the fields of liquid transporting and body swimming. In this context, it is a crucial problem to measure the slip length for these surfaces. Here we propose a novel method by using rheometer for this objective. This method is implemented by designing the distribution of the super-hydrophobic area on the sample. Using this method, a slip length of 40 μm for 70 wt% glycerin flow over a super-hydrophobic surface with stripe structure （the period, width and height of ridges are 150 μm, 40 μm and 65 μm, respectively） is measured. The result shows that the slip length measured using this method is in good agreement with former results measured by other methods. This method is fit for measuring the slip length of super-hydrophobic surface whose structure ranges from microto nano-scale.     

江苏中部海岸互花米草盐沼底栖动物的组成特征

在江苏海岸,人工引种的互花米草正在成为盐沼植被的优势物种.为了了解互花米草引种对环境与生态的影响,调查了互花米草盐沼底栖动物的组成特征.在王港地区互花米草滩由西向东设置的4个站位上,进行了夏初和秋末两个时期的野外调查,采集了40个样方内可见的全部动物样本,记录了环境特征.在实验室鉴定了样本的种属,测量了动物介壳的长度.对所获数据的统计分析结果显示,本区互花米草盐沼中有7种大型底栖动物,夏初和秋末生物种类相同,但秋末生物量明显高于夏初.在代表性种属中,珠带拟蟹守螺(Cerithidea cingulata)的壳长从初夏到秋末有明显增大,而秋末粗糙滨螺(Littorna scabra)和赤豆螺(Bithynia fuchsiana)比初夏小且少.在互花米草盐沼的不同部位,腹足类物种分布有显著差异.现场观察数据显示,一些当地盐沼动物已经适应于在人工引种的互花米草盐沼中生存.