基于模糊相似优先比的黄土路堑高边坡稳定性评价

充分挖掘大量已知其稳定性状况的公路黄土路堑高边坡,根据模糊相似优先比的概念,构造了一个基于模糊变权相似优先的边坡范例推理模型。对每一个黄土边坡稳定性的影响因素,分别建立边坡的目标范例与源范例之间的模糊相似优先关系。经过影响因素之间的两两比较,获得了不同的影响因素下边坡的目标范例与源范例之间的相似性序列,在确定影响因素各自的权重之后,经计算可获得边坡的目标范例与源范例之间的综合相似性序列,从而最终找出与边坡的目标范例最相似的源范例,进而实现了黄土边坡目标范例的稳定性评价。实例分析表明:边坡稳定性评价结果与其实际状态吻合较好。     

浅谈城市房价与地价

地价与房价作为房地产市场的两个重要指标，其水平高低对房地产市场的正常、有序发展起者重要作用。房价与地价在一定范围内、一定条件下相互作用，相互影响。正确分析和处理房价与地价的关系，促进房地产业健康发展，可采取以下措施：土地交易信息公开、透明；土地及时开发，及时入市；加强对土地市场供需结构的宏观调控和经济适用房、廉租房体系的建设等。     

中国安全经济贡献率的计量分析

安全经济贡献率的准确计算对于指导国家安全投入力度和宏观安全决策起着重要作用。为了准确计算中国安全生产对经济的贡献率,以弥补以往经验取值方法的局限,笔者通过建立计量经济学模型,获得了精确的安全产出与安全投入的函数关系,并得出我国安全生产规模报酬递增的结论。在此基础上又建立时间序列模型,预测出我国2005年的安全经济贡献率为3.01%,安全投入产出比为1.00∶1.81。从预测结果来看,计量模型收到了满意的结果,对国家宏观安全决策具有一定的指导意义。     

添加剂对CaCO_3固硫效果的影响

鉴于钙基固硫剂普遍存在固硫率低的情况,用CaCO3为主固硫剂,分别添加Na2CO3,MgO,Al2O3三种助剂,在ZCL型自动测硫仪上进行了不同温度、不同钙硫比(Ca/S)条件下的固硫试验。结果表明:Na2CO3对改善CaCO3的固硫效果最好,可以使固硫率提高42%;其次是Al2O3,MgO反而使固硫率下降。在此基础上,通过分析和研究,解释了添加剂的作用机理:Na2CO3能增加固硫反应活性,并能提高扩散控制阶段的固硫反应率;Al2O3可以降低固硫产物的分解率;MgO使反应控制阶段固硫反应的有效接触面积下降。     

Effect of diet manipulation in dairy cow N balance and nitrogen oxides emissions from grasslands in northern Spain

Dietary modifications in dairy cattle have been reported as a useful strategy to alter the composition of manure. Many reports have been published on how changes in dietary crude protein content and forage-to-concentrate ratio reduces animal nitrogen (N) excretion, but little information exists about the effect of diet modification on nitrous oxide (N₂O) and nitric oxide (NO) emission when the subsequent slurry is applied on grassland. Two diets differing in forage:concentrate ratio (high forage or HF diet, 75:25; low forage or LF diet, 55:45) were tested to detect the improvement of N use efficiency in milk and the reduction of urinary and fecal N excretion. Triticale silage and barley grain were used as the main forage and concentrate sources in the diets. The subsequent slurries were characterized for N and ammonium-N content (NH₄⁺-N) and applied on grassland in order to study total and pattern of emission of N₂O and NO.The HF diet reduced the voluntary dry matter intake of the cows, N intake and urinary and fecal N excretion. However, the reduction of N intake did not improve the N use efficiency in milk (NUE) (21.0%) and did not reduce N excretion per unit of milk produced (15 g N l⁻¹) due to the lower milk yield. Slurries were similar in N content but differed in NH₄⁺ content, being lower in HF. Therefore, different slurry amounts were needed to be applied on grassland to reach the correct fertilisation rate (120 kg NH₄⁺-N ha⁻¹). Total emissions of N₂O (5.8 and 5.0 kg N₂O-N ha⁻¹) and NO (507.2 and 568.6 g NO-N ha⁻¹), and the pattern of emissions were not affected by dietary treatments. When fertilisation management depends on the collected volume to empty the slurry pit, higher N₂O and NO emissions per kg of slurry could be expected from LF slurry. Nevertheless, if slurry is applied following recommendation rates, N₂O and NO emission per unit of milk produced might be slightly lower from LF slurry. Grass yield (1.5 t dry matter ha⁻¹) and N uptake (50 kg N ha⁻¹) did not vary due to the applications of different slurries, and was attributed to low rainfalls. The correct management of the slurries on grasslands may justify an adequate nutritional strategy of dairy herds from an environmental and productive point of view.     

区域资源禀赋对资源利用效率影响研究

论文将研究的视点从关注资源禀赋与经济发展的关系,转向资源禀赋对资源利用效率的影响上,选取了中国大陆31个省(自治区、直辖市,未计算香港、澳门地区)2008年能源和水资源的面板数据,力图用统计模型来验证资源禀赋对资源利用效率存在负相关作用的假说,即资源越丰富的地区,对该种资源使用效率往往越低。研究发现:资源禀赋对资源利用效率存在显著的逆向影响,资源的"诅咒"效应不仅作用于区域经济发展上,也同样作用于资源利用效率上;然而,不同于经济诅咒,资源禀赋与资源利用效率之间的这种负相关关系在分散型资源上体现更加明显。对区域资源禀赋与资源利用效率之间影响关系与作用机制更深入的研究将为科学、高效的资源管理政策提供理论支持。     

回流比对投料A~2/O工艺脱氮除磷影响的中试研究

试验采用了投料A2/O脱氮除磷工艺在广州市某污水处理厂进行中试,考察了不同混合液回流比及污泥回流比对投料A2/O工艺脱氮除磷的影响。结果表明,混合液回流比对COD、TP和NH3-N影响较小,对TN的去除率影响较大,系统混合液回流比为200%时,系统处理效果最佳;污泥回流比对系统整体功能的影响较大,随污泥回流比的增大,各指标的去去除率随之增大,结合处理效果和能耗情况,污泥回流比为75%时系统效果最佳。     

海洋环境下7A52铝合金电偶腐蚀行为研究

通过电偶序测试,对3.5%（质量分数）NaCl水溶液中7A52的腐蚀倾向进行了预测;通过对不同金属耦合的电偶电流与电偶电压的测试,验证了阳极电偶腐蚀效应,得到了电偶腐蚀过程受阴极控制的结论;通过对7A52与5A06在不同面积比情况下偶合电偶电流的测试,发现电偶电流与面积比呈线性关系。     

某城市污水处理厂A—A^2／O工艺运行影响分析

以江南地区某城市污水处理厂A—A^2／O工艺实际运行资料为背景,对污水处理厂的工艺流程、设计参数和工艺特点进行了介绍;分别从进水水量、容积负荷、进水浓度、C／N比与C／P比、同化作用的影响等5个方面对污水厂运行影响因素进行了分析。分析结果对此污水处理厂的提标改造具有重要的参考意义。     

Effect of substrate COD/N ratio on performance and microbial community structure of a membrane aerated biofilm reactor

Two parallel carbon-membrane aerated biofilm reactors were operated at well-defined conditions to investigate the e ect of substrate COD/N ratios on the performance and microbial community structure of the bioreactor. Results showed that at substrate COD/N of 5, organic and nitrogen could be eliminated simultaneously, and COD removal degree, nitrification and denitrification e ciency reached 85%, 93% and 92%, respectively. With increasing substrate COD/N ratios, the specific oxygen utilization rates of nitrifying bacteria in biofilm were found to decrease, indicating that nitrifying population became less dominant. At substrate COD/N ratio of 6, excessive heterotrophs inhibited the activity of nitrifying bacteria greatly and thus led to poor nitrification process. With the help of fluorescence in situ hybridization (FISH), Nitrosomonas and Nitrosospira were identified as dominant ammonia-oxidizing bacteria in the biofilm at substrate COD/N of 0, whereas only Nitrosospira were detected in the biofilm at COD/N ratio of 5. Nitrospira were present as dominant nitrite-oxidizing bacteria in our study. Confocal laser scanning microscopy images revealed that at substrate COD/N ratio of 0 nitrifying bacteria existed throughout the biofilm and that at COD/N ratio of 5 they were mainly distributed in the inner layer of biofilm.