关于CASS工艺在设计过程中值得优化问题的探讨

循环式活性污泥法CASS工艺在设计过程中的经验参数较多,而规范中仅对部分参数的取值范围进行了限定,故不同设计人员的计算结果可能会有很大出入。该文结合该工艺目前在国内的使用情况,对该工艺的适用条件、部分关键参数的取值及设计过程中值得优化的问题进行了总结,以期在类似工程中可结合各工程自身特点予以应用。     

变频器在供热锅炉节能技术上的应用与研究

根据风机与泵类轴功率与转速的立方成正比的特点，分析供热锅炉辅机泵与风机的流量、扬程（压头）、功率与转速间的关系，阐述变频调速节能原理，并举例比较了水泵采用变频调速控制与阀门控制所产生的效益情况。提出变流量运行时，泵与风机应采用变频技术，以降低成本，延长设备使用寿命，提高经济效益。     

船舶受非均匀风力的计算方法

在船舶航海性能及航泊机动的定量分析中,通常以均匀风取代实际的非均匀风,从而影响了定量分析的精度及分析的可靠性。现提出一种新的计算作用在船舶非均匀风力的方法。仿真表明,该方法是可行的。     

大跨度连续刚构桥最大双悬臂施工状态的风致内力分析

以主跨为200m的预应力混凝土三跨连续刚构桥为工程背景,通过数值分析,讨论了其动力特性;给出了设计风速范围内、两种不同工况作用下,最大双悬臂施工状态主梁各控制截面的风致内力。     

翼型风帆的气动力学分析研究

在NACA0006翼型和圆弧型风帆的基础上,针对船用助航风帆的特点设计出一种新型翼型风帆,并采用标准κ-ε模型,利用FLUENT软件对翼型在8个不同风向角下的空气动力特性进行了数值模拟计算,获得翼型风帆在8种不同风向角下的升力系数和阻力系数,并对计算风帆模型进行风洞试验,风洞试验得到的升力系数和阻力系数结果与模拟计算结果有较好的吻合,通过试验结果对比证明其升力系数比常规的矩形圆弧风帆有很大提高.     

H型钢接触网支柱在风荷载作用下的疲劳性能分析

H型钢接触网支柱在高速铁路中得到广泛使用,直接影响铁路接触网系统安全。长期处于风荷载作用下,H型钢接触网支柱存在疲劳问题。通过建立数值计算模型,应用热点应力的表面外推法,对H型钢接触网支柱柱脚焊缝在风荷载作用下的疲劳性能进行分析。以兰新高铁H型钢接触网支柱为例,依据热点应力-寿命曲线,计算支柱焊缝的疲劳寿命。分析结果表明:其他条件不变的情况下,改变型钢规格和柱高,热点位置不发生变化;随着支柱高度增加,疲劳寿命降低21%左右;随着型钢截面的增大,疲劳寿命增加23%左右。     

Gas transfer velocities of CO2 and CH4 in a tropical reservoir and its river downstream

We have measured simultaneously the methane (CH₄) and carbon dioxide (CO₂) surface concentrations and water–air fluxes by floating chambers (FC) in the Petit-Saut Reservoir (French Guiana) and its tidal river (Sinnamary River) downstream of the dam, during the two field experiments in wet (May 2003) and dry season (December 2003). The eddy covariance (EC) technique was also used for CO₂ fluxes on the lake. The comparison of fluxes obtained by FC and EC showed little discrepancies mainly due to differences in measurements durations which resulted in different average wind speeds. When comparing the gas transfer velocity (k₆₀₀) for a given wind speed, both methods gave similar results. On the lake and excluding rainy events, we obtained an exponential relationship between k₆₀₀ and U₁₀, with a significant intercept at 1.7 cm h^− 1, probably due to thermal effects. Gas transfer velocity was also positively related to rainfall rates reaching 26.5 cm h⁻¹ for a rainfall rate of 36 mm h^− 1. During a 24-h experiment in dry season, rainfall accounted for as much as 25% of the k₆₀₀. In the river downstream of the dam, k₆₀₀ values were 3 to 4 times higher than on the lake, and followed a linear relationship with U₁₀.     

Sail–sail and sail–hull interaction effects of hybrid-sail assisted bulk carrier

In a previously reported study, wind tunnel experiments were undertaken to investigate the aerodynamic characteristics of hybrid-sails in isolation. Such sails are seen as providing a worthwhile reduction in the delivered power to the propeller and hence the engine generated thrust, with a corresponding reduction in the CO₂ production of diesel engine exhaust. In this paper, wind tunnel testing is used to investigate sail–sail interaction effects for two sets of four identical hybrid-sails, and the sail–hull interaction effects for the same two sets of four identical sails in the presence of a bulk carrier hullform. The analysis presented suggests that to build a sail-assisted ship requires an appreciation of the sail–sail and sail–hull interaction effects.     

连续刚构桥动力特性和抗风分析

黑沟特大桥为主跨150m的预应力混凝土高桥墩连续刚构桥,位于峡谷出口处,风速较大。文章利用有限元方法建立其模型,模拟桥梁的施工过程,探讨其结构动力学特性和风荷载作用下的应力和变形,为桥梁施工和控制提供参考。     

r Huaihe River Basin and neighbor regions,

porting water vapor. The second one is from South China Sea. It is the weakest one. The third is from the tropical Pacific Ocean to the east