CDM项目的经济性分析——太阳能发电在中国商业楼宇中的导入

运用数学模型，对在中国的商业楼字中以清洁发展机制（CDM）的方式导入太阳能发电进行了分析．该模型可以在满足电力供求平衡的前提下确定最佳的导入容量．运用该模型对投资费用和电价进行了参数分析．分析结果表明，在一定的条件下，即使没有CDM的参与，在中国的商业楼字中导入太阳能发电也是可行的．但是，通过CDM项目，可以极大地减小太阳能发电的导入壁垒，CO2的减排收益也可弥补太阳能发电的投资费用，使项目双方都获得相应的利益．     

Studies on optimization of nitrogen sources for astaxanthin production by Phaffia rhodozyma

Fermentation of Phaffia rhodozyma is a major method for producing astaxanthin, an important pigment with industrial and pharmaceutical application. To improve astaxanthin productivity, single factor and mixture design experiments were used to investigate the effects of nitrogen source on Phaffia rhodozyma cultivation and astaxanthin production. Results of single factor experiments showed nitrogen source could significantly affect P. rhodozyma cultivation with respect to carbon source utilization, yeast growth and astaxanthin accumulation. Further studies of mixture design experiments using (NH₄)₂SO₄, KNO₃ and beef extract as nitrogen sources indicated that the proportion of three nitrogen sources was very important to astaxanthin production. Validation experiments showed that the optimal nitrogen source was composed of 0.28 g/L (NH₄)₂SO₄, 0.49 g/L KNO₃ and 1.19 g/L beef extract. The kinetic characteristics of batch cultivation were investigated in a 5-L pH-stat fermentor. The maximum amount of biomass and highest astaxanthin yield in terms of volume and in terms of biomass were 7.71 mg/L and 1.00 mg/g, respectively.     

带真空和外力的可压缩Navier-Stokes方程弱解的唯一性

通过运用Gronwall不等式,在Lagrangian坐标系下,证明了带真空和外力的可压缩Navier-Stokes方程初边值问题弱解的唯一性.     

Linking leach chemistry and microbiology of low-grade copper ore bioleaching at different temperatures

The effects of temperature on chalcocite/pyrite oxidation and the microbial population in the bioleaching columns of a low-grade chalcocite ore were investigated in this study. Raffinate from the industrial bioleaching heap was used as an irrigation solution for columns operated at 20, 30, 45, and 60℃. The dissolution of copper and iron were investigated during the bioleaching processes, and the microbial community was revealed by using a high-throughput sequencing method. The genera of Ferroplasma, Acidithiobacillus, Leptospirillum, Acidiplasma, and Sulfobacillus dominated the microbial community, and the column at a higher temperature favored the growth of moderate thermophiles. Even though microbial abundance and activity were highest at 30℃, the column at a higher temperature achieved a much higher Cu leaching efficiency and recovery, which suggested that the promotion of chemical oxidation by elevated temperature dominated the dissolution of Cu. The highest pyrite oxidation percentage was detected at 45℃. Higher temperature resulted in precipitation of jarosite in columns, especially at 60℃. The results gave implications to the optimization of heap bioleaching of secondary copper sulfide in both enhanced chalcocite leaching and acid/iron balance, from the perspective of leaching temperature and affected microbial community and activity.     

湍流抑制器对中间包钢液流动的影响

采用水模拟试验研究湍流抑制器对中间包钢液流动特性的影响。结果表明,拉速变化时单层湍流抑制器对钢液流动影响程度较小,双层湍流抑制器能延长包内钢液平均停留时间;液位变化时双层湍流抑制器对钢液流动影响程度较小,相同液位下双层湍流抑制器使钢液在中间包内平均停留时间较之于单层湍抑器相应值至少增加20s;3种湍流抑制器对中间包流场的改善程度从大到小排序为:双层湍流抑制器,八角形湍流抑制器,单层湍流抑制器。     

基于理想点-未确知测度理论的区域生态安全动态评价

为研究区域生态安全的变化趋势,现将未确知测度理论引入区域生态安全评价中.以淮河生态经济带安徽区域的八座城市为研究对象,基于PSR模型构建生态安全评价指标体系,采用理想点赋权确定各指标权重,引入未确知测度理论对研究区2010—2018年生态安全状况进行动态评价,并使用地理信息系统(geographic information system,GIS)软件对评价结果进行可视化.结果表明:生态安全等级提升明显,截至2018年,安徽区域所有城市生态安全等级均达到Ⅲ级及以上水平,但区域内发展差异较明显;2010—2018年所有城市生态安全评价综合得分在波动中直线上升,城镇化快速推进对资源的消耗是制约生态安全提升的重要原因.     

基于粒子群优化算法改进的XGBoost模型制备C4烯烃工艺条件优化

C4烯烃是生产清洁友好燃料等化工产品的重要原料，提升C4烯烃收率，增大C4烯烃产量是生产过程重要的目标之一。针对乙醇偶合制备C4烯烃这一化学反应样本数量多，特征数量少等特点，本文提出一种组合模型：粒子群算法改进的XGBoost模型。首先将XGBoost模型与数据的拟合效果作为粒子群算法的目标函数，通过粒子迭代确定XGBoost模型的最优超参数; 然后通过对变量设置一定的步长构造仿真数据。最后，将优化后的XGBoost模型与仿真数据进行拟合，拟合优度由76%提升至93%。根据预测结果确定了C4烯烃的最大收率和最佳反应条件，得到C4烯烃收率的最大值为43.52%。实验结果表明，改进后的XGBoost模型在误差和精度方面都优于原始模型。