基于嵌套模型的地下水侧向径流边界刻画方法研究——以湖北碾盘山冲积平原地下水数值模拟为例

侧向径流边界的刻画方法是地下水数值模拟中的关键问题。以湖北碾盘山汉江水利水电枢纽工程为例,基于有限单元法和嵌套模型的水量转换方法,分别建立包括完整水文地质单元的区域模型和仅包含汉水Ⅰ级阶地的平原区模型;通过区域模型的分区水均衡运算,计算平原区侧向径流边界的径流量,并以区域模型水均衡为框架,分别采用二类流量边界和一类水头边界刻画侧向径流边界,建立了平原区模型;深入分析区域模型和平原区模型间参数和水量的转换关系,并对比了两类边界条件刻画方法的优缺点和适用条件。结果表明:采用嵌套模型能够得到较为准确的地下水侧向径流量;在平原区模型中采用二类流量边界刻画侧向径流边界有利于提高平原区模型的精度和稳定性;边界条件除具有双重含义外还具有双重特征,在模型建立过程中应充分认识边界条件的位置特征和数量特征,并合理概化。     

火电厂燃煤锅炉系统湿量平衡分析与计算

针对煤的有效热能降低、烟气管道和烟囱腐蚀严重,以及向环境中排放湿量过多等问题,对燃煤锅炉系统湿量来源进行分析,建立了锅炉燃烧系统湿量计算的基本模型。根据热力学基本原理和物料守恒原理,给出了燃煤锅炉系统湿量的计算方法。采用该方法对燃烧不同煤种锅炉的实际运行数据进行湿量计算分析比较。结果表明:通过理论分析计算得到的燃煤锅炉系统湿量与锅炉的实际运行时烟气湿量较吻合,所给出的燃煤锅炉系统湿量的计算方法可以用于锅炉燃烧系统的运行优化。     

浅谈水库风景区建设在生态保护与修复中的利用——以孝感市为例

在市场经济的条件下,开展水库生态风景区建设,要充分利用库区旅游资源开发带来的经济效益,结合水库风景的特点,按供需平衡关系,改变资源利用形式,按边沿景现再造模式,多层次、可持续地开发与保护水库资源,促进水利风景区的健康发展.     

碳中和目标下中国省域碳平衡能力与城镇化的关系

厘清碳平衡能力与城镇化的关系对实现碳中和目标和推动新型城镇化发展具有重要的理论价值及实践意义。采用温室气体清单法、碳吸收清查法、碳平衡指标法和多元城镇化测量法分别测算1999—2018年中国省域碳平衡能力与各类城镇化指标,利用空间自然断点分级法和Granger因果检验法分别分析中国省域碳平衡能力与城镇化的时空演变特征及互动关系。主要结论如下：（1）中国碳排放不断增多,碳吸收不断减少,碳平衡能力呈上升、下降、先减后增和先增后减四种趋势,碳排放呈“东多西少”分布,碳吸收与碳平衡能力分别呈“西多东少”和“西强东弱”分布。（2）中国人口、经济、空间、生态城镇化和城镇化综合指标不断提升,其中空间城镇化大致呈“西高东低”分布,其余则呈“东高西低”分布。（3）除空间城镇化外,中国整体碳平衡能力与各类城镇化的关系均为反馈型,而各省域增长保护型数量最多,中立型数量最少。     

污水处理过程水温变化模型构建与验证

污水处理是一个复杂的生物、物理及化学反应过程.污水水温直接影响到污染物生物处理效果,并对污水处理运行能耗产生重要影响.另一方面,污水中也蕴含着相当热能,是潜在可以回收的低品位能源,加以利用则有望实现污水处理碳中和运行.然而,现有研究很少涉及污水处理厂污水进、出水水温变化及其影响因素;工程中也只强调冬季保温,并无法从微观角度认识处理过程水温变化规律.为此,研究尝试构建污水处理过程水温变化热量衡算模型,涵盖污水生化反应、机械传热、环境热传递和水蒸发热损失等4个主要涉热过程.与此同时,收集北京某污水处理厂实际水温、气温数据,借助热量平衡图来模拟污水处理过程中水温变化,并对理论模型参数进行校验和修正.通过参数敏感性分析,可以评价不同参数对水温热量的影响程度.基于这些工作,一个污水温度变化模型被构建成功,可用于指导实际污水处理厂水温控制或余温热能回收过程,可助力污水处理厂节能降耗、甚至实现碳中和目标.     

浅析生态系统平衡及其意义

文章简要论述了生态系统的组成、影响生态系统平衡的自然因素和人为因素.生态系统平衡与失衡在自然环境中作用及其意义.生态系统是由各类生物共同组成的生物群落(bioflora)或生物系统(living things'system)与环境系统构成的具有一定结构和功能的一个不断更新和变化的开放系统.但是,生态系统这种维护自身相对平衡的能力是有条件、有一定限度的,或者说,对平衡的干扰不能超过系统本身的遭受极限,否则就会使破坏后的生态系统难于恢复到原来的平衡状态.     

Variation of soil fertility and carbon sequestration by planting Hevea brasiliensis in Hainan Island, China

The development of rubber industry depends on the sustainable management of rubber plantation. To evaluate the environmental effects of planting Hevea brasiliensis on a subsystem of tropical forest ecosystem, the variation of soil fertility and carbon sequestration under rubber plantation within 30-year life period were investigated in Hainan Island. Results showed that （1） with the increase of stand age of rubber plantation, soil fertility decreased all along. From 1954 to 1995, soil organic matter, total N, available K and available P decreased by 48.2%, 54.1%, 56.7% and 64.1%, respectively. （2） If the complete return of litters was considered without additional fertilizer application to the soil of the rubber plantations, the consumption periods for P, N, K, Mg were only 825 years, 329 years, 94 years and 65 years, respectively~ To improve soil fertility is essential for rubber plantation development. （3） The C sequestration of rubber trees per hectare accounts for 272.08 t within 30-year life period and 57.91% of them was fixed in litters. In comparison with C sequestration by rain forest （234.305 t/hm^2） and by secondary rain forest （150.203 t/hm^2）, rubber forest has more potentials for C fixation. On the base of above results, the following measures would benefit the maintenance of soil fertility and the development of rubber industry, including applying fertilizer to maintain the balance of soil nutrients, intercropping leguminous plant to improve soil fertility, reducing the collection of litters, optimizing soil properties to improve element P availability such as applying CaCO3. The information gathered from the study can be used as baseline data for the sustainable management of rubber plantation elsewhere.     

Vibrational energy loss analysis in battery tab ultrasonic welding

In ultrasonic metal welding processes, high-frequency ultrasonic energy is used to generate friction and heat at the interface between weld parts to produce solid-state bonds. It has been observed that sufficient energy is required to produce proper bonding, while excessive energy can cause such quality issues as weld fracture and perforation. Therefore, it is important to have a product/process design in ultrasonic welding to ensure efficient energy conversion from ultrasonics to welding energy, minimizing energy loss in the process. In this work, vibrational energy loss associated with the longitudinal and flexural vibrations of the Cu coupon during ultrasonic welding is studied by applying one-dimensional continuous vibration models. To facilitate our modeling, experimental results from the free response of Cu coupon were obtained to determine the damping characteristics of the Cu coupon in the welding process. Our analysis shows that substantial energy loss can occur during welding due to the flexural vibration of the Cu coupon, especially when the overhang (the upper part of the Cu coupon extended from the anvil) of the Cu coupon resonates at or close to the welding frequency (about 20 kHz), degrading the weld quality of battery tabs. This study contributes to understanding the fundamental dynamics of the Cu coupon during ultrasonic welding and its impact on weld quality.     

我国生态环境资产负债表编制框架研究

本文根据生态环境资产负债表的基本概念和理论,提出了生态环境资产负债表编制的总体框架,同时,针对环境容量资产、环境质量产品、生态产品资产的特点,分别建立了相应框架体系,提出了环境资产负债表的应用决策方向。本文研究成果对于确立统一的生态环境资产核算标准和方法、使我国生态环境资产负债核算工作逐步规范化、制度化具有重要的现实意义。     

国内首个MW级分布式能源系统烟囱合理性分析

介绍了分布式能源系统的构成、运行特点及技术发展情况,研究了国内首个MW级分布式供能系统工程的烟囱高度和形式,预测和分析了项目大气污染物对环境的影响,证明了该项目烟囱选择的合理性,为下阶段国内分布式能源系统烟囱选型奠定技术基础。