SBR法处理高盐肝素废水运行参数优化研究

采用SBR法处理高盐肝素钠生产废水,探讨了曝气时间、进水p H、温度等参数对COD和氨氮降解效果及污泥生长的影响。结果表明,控制曝气时间为10 h、进水p H为7.5、反应温度在26~29℃时,COD和氨氮去除率均能稳定在85%以上;对氨氮去除效果较差的反应器,适当添加K+、Ca2+、Mg2+可以取得一定的改善作用,其中K+对Na+和NH4+双重毒性抑制的拮抗效应最明显;经参数优化后的SBR反应器对不同污泥负荷和盐度负荷具有较好的适应能力,受到冲击后COD和氨氮去除率均能在2~3个运行周期内恢复至90%以上。     

杉木人工林生态系统可燃物空间分布规律研究

在国家野外科学观测研究站-会同生态站的集水区中设置固定标准地,利用标准地和生物量调查数据,对杉木人工林的可燃物负荷量空间分布规律进行了研究,结果表明:杉木人工林生态系统的自然整枝能力较差,细小可燃物的空间分布均匀,易燃可燃物连续性好;含水率以近地面的最小;11年生的杉木人工林生态系统的枯死枝叶的总负荷量高达0.198 t.hm-2,分布于0～1.5 m的空间层中,这种均匀的空间分布规律为树冠火的发生创造了条件,从而加大了杉木人工林生态系统的火险性.建议在杉木人工林生态系统的经营过程中,要加强人工整枝,改变可燃物的空间分布;减少易燃可燃物的数量,降低森林的燃烧性;对于枯死枝叶可采取人工和计划烧除的措施进行清理.     

Variations in booster seat use by child characteristics

IntroductionChild weight and height are the basis of manufacturer and best practice guidelines for child restraint system use. However, these guides do not address behavioral differences among children of similar age, weight, and height, which may result in child-induced restraint use errors. The objective of this study was to characterize child behaviors across age in relation to appropriate restraint system use during simulated drives. Methods: Fifty mother–child (4–8 years) dyads completed an installation into a driving simulator, followed by a simulated drive that was video-recorded and coded for child-induced errors. Time inappropriately restrained was measured as the total amount of the simulated drive spent in an improper or unsafe position for the restraint to be effective divided by the total drive time. Kruskal-Wallis tests were used to determine differences across age in the frequency of error events and overall time inappropriately restrained. Results: Children in harnessed seats had no observed errors during trips. Within children sitting in booster seats there were differences in time inappropriately restrained across age (p = 0.01), with 4 year-olds spending on average 67% (Median = 76%) of the drive inappropriately restrained, compared to the rest of the age categories spending less than 28% (Medians ranged from 3% to 23%). Conclusion: Some children may be physically compatible with booster seats, but not behaviorally mature enough to safely use them. More research is needed that examines how child behavior influences child passenger safety. Practical Applications: Not all children physically big enough are behaviorally ready to use belt positioning booster seats. Primary sources of information should provide caregivers with individualized guidance about when it is appropriate to transition children out of harnessed seats. Additionally, best practice guidelines should be updated to reflect what behaviors are needed from children to safely use specific types of child restraint systems.     

Frontal crash simulations using parametric human models representing a diverse population

Abstract

Objective: Analyses of crash data have shown that older, obese, and/or female occupants have a higher risk of injury in frontal crashes compared to the rest of the population. The objective of this study was to use parametric finite element (FE) human models to assess the increased injury risks and identify safety concerns for these vulnerable populations.

Methods: We sampled 100 occupants based on age, sex, stature, and body mass index (BMI) to span a wide range of the U.S. adult population. The target anatomical geometry for each of the 100 models was predicted by the statistical geometry models for the rib cage, pelvis, femur, tibia, and external body surface developed previously. A regional landmark-based mesh morphing method was used to morph the Global Human Body Models Consortium (GHBMC) M50-OS model into the target geometries. The morphed human models were then positioned in a validated generic vehicle driver compartment model using a statistical driving posture model. Frontal crash simulations based on U.S. New Car Assessment Program (U.S. NCAP) were conducted. Body region injury risks were calculated based on the risk curves used in the US NCAP, except that scaling was used for the neck, chest, and knee–thigh–hip injury risk curves based on the sizes of the bony structures in the corresponding body regions. Age effects were also considered for predicting chest injury risk.

Results: The simulations demonstrated that driver stature and body shape affect occupant interactions with the restraints and consequently affect occupant kinematics and injury risks in severe frontal crashes. U-shaped relations between occupant stature/weight and head injury risk were observed. Chest injury risk was strongly affected by age and sex, with older female occupants having the highest risk. A strong correlation was also observed between BMI and knee–thigh–hip injury risk, whereas none of the occupant parameters meaningfully affected neck injury risks.

Conclusions: This study is the first to use a large set of diverse FE human models to investigate the combined effects of age, sex, stature, and BMI on injury risks in frontal crashes. The study demonstrated that parametric human models can effectively predict the injury trends for the population and may now be used to optimize restraint systems for people who are not similar in size and shape to the available anthropomorphic test devices (ATDs). New restraints that adapt to occupant age, sex, stature, and body shape may improve crash safety for all occupants.     

海南省畜禽粪便分布特征及耕地负荷研究

通过利用国内较通用的经验系数计算以及利用耕地负荷分级方法,了解海南省畜禽粪便分布特征及耕地负荷情况。海南省畜禽粪便产生量最多的市县是海口市和儋州市、文昌市,分别达到244.45万t/a和214.89万t/a、211.26万t/a;畜禽粪便耕地负荷量最大的是文昌市、琼海市,分别为61.29 t/(hm.2a)、61.19 t/(hm.2a),属于对环境威胁严重;有3个市县畜禽粪便耕地负荷量属于对环境威胁较严重,7个市县属于对环境有威胁,4个市县对环境稍有威胁,2个市县对环境无威胁。     

GWLF模型的原理、结构及应用

GWLF(Generalized Watershed Loading Function)模型是一个半分布式、半经验式的流域负荷模型。它能够利用GIS及RS提供的空间数据,在中型尺度流域的范围内进行非点源污染负荷估算,模型比较适合于数据量少,参数相对缺乏的地区。重点介绍了GWLF模型的污染物负荷估算的原理,同时将GWLF模型应用于天津市于桥水库流域,利用沙河流域1999年水量、水质数据进行校准,初步估算出于桥水库上游流域的非点源负荷。     

混凝土单轴动态强度理论的探讨

在分析相关试验结果的基础上,系统地对混凝土在单轴动态加载下的强度特征进行了研究分析。结果表明,不仅加载速率对动态强度有着重要的影响,加载速率对材料弹性参数的影响也很大。结果显示:①混凝土在加载初始阶段,应力—应变表现为线性关系,可认为混凝土处于弹性阶段;随着压力的增加,混凝土产生非线性变形,并出现峰后应力下降;②混凝土的抗压极限强度随着加载速率的增加而增加;③混凝土的弹性模量随着加载速率的增加而提高,而泊松比保持不变。最终提出了一种改进的弹性损伤动态强度的本构理论。     

化学物添加控制湖泊内源磷负荷的有效性研究

利用太湖五里湖湖水和未受破坏原柱状沉积物样组成的系统进行投加生石灰、铁盐和铝盐的湖水脱磷效果的实验室研究。分别一次性向各柱状样上覆水体中投加6种不同质量浓度的铝盐、钙盐和铁盐溶液,经过一段时间的观察和测定。结果表明,3种化学物的添加均能使实验上覆水体中总磷质量浓度大幅度降低,并且随着投加的生石灰、铁盐和铝盐的量的增加,上覆水体中总磷的质量浓度下降幅度越大,水体中总磷的去除率越高,同时这3种化学物的添加对湖泊沉积物内源磷的释放有一定的抑制作用。     

污泥林地处理氮素负荷的研究

通过污泥要地小区试验及示范工程,以树木生长所需的营养元素“氮素”为设计参数,计算污泥负荷量。探讨污泥作为商品肥料补充的可行性方案。既为污泥找到了最佳出路,达到了处理污泥的目的,又可以废物利用,并同时做到保护环境不造成二次污染,为污泥的处理提供了有利的技术保障。     

含硫酸盐高有机物浓度酵母生产废水两相厌氧处理

采用“铁床＋产酸相＋空气吹脱＋产甲烷相”相串联工艺处理富含硫酸盐的高浓度酵母生产废水，实现了硫酸盐及有机物有效去除的双重目标。