D墨铸铁玻璃模具的组织与性能研究

研究对玻璃模具用D型石墨铸铁的化学成分进行了合理设计和优选。结果表明,显微组织、抗氧化、抗生长和热疲劳抗力等性能,均有显著的改善和提高。经工业性试验,模具的寿命成倍提高。     

水质远程监控通讯安全性问题的探讨——利用现有网络条件确保远程监控通讯安全性的解决方案

针对我国总体水质情况不容乐观的现实 ,提出解决办法之一是对排污口实施大规模远程监控 ,而远程通讯的安全性又是最直接、最核心的问题。文章着重阐述了如何解决在现有网络条件下实时运行的网络运行速度和数据的加解密等具体问题。     

P204f(D2EHPA)萃取分离回收催化剂母液中钴、锰

石油化工和化纤工业中大量使用钴,锰催化剂,应及时从各种废液中回收、再生,本文在25±1℃下研究了D_2EHPA-煤油从硫酸盐介质中萃取分离钴(Ⅱ)、锰(Ⅱ)的工艺,考察了萃取剂浓度、平衡pH值、相比对萃取的影响,求取了较适宜的工艺条件,利用五级逆流萃取模拟试验将钴、锰浓度比从1:1.5提高到1000:1,加入洗涤段后,又可获得金属含量比为1000的纯锰溶液,初步探索了用先进的液膜萃取新技术从溶液中分别富集、分离钴(Ⅱ)、锰(Ⅱ)的方法,找出了体系pH值对液膜萃取的影响,提出了从PTA氧化母液中回收废催化剂,萃取分离钴、锰,再生制备醋酸钴、醋酸锰和其他含钴、锰精细化工产品的工艺。     

Driver glare exposure with different vehicle frontlighting systems

Introduction: Highway safety performance at night has received less attention in research than daytime, despite the higher accident rates occurring under night-time conditions. This study presents a procedure to assess the potential hazard for drivers created by headlight glare and its interaction with the geometric design of highways. Method: The proposed procedure consists of a line-of-sight analysis performed by a geoprocessing model in geographic information systems to determine whether the rays of light that connect headlights and oncoming drivers are obstructed by either the roadway or its roadsides. Then, the procedure checks whether the non-obstructed rays of light are enclosed by a given headlight beam. Different hypotheses were set concerning the headlight beam features, including the horizontal spread angle and whether the headlights are fixed or swiveling. A highway section was selected to test and validate the procedure proposed. A 3D recreation of the highway and its environment derived from a LiDAR point cloud was used for this purpose. Results: The findings disclose how glare is produced on tangents, horizontal curves, transitions between them and sequences of curves. The effect of visual obstructions conveniently placed is also discussed. Conclusions: A greater glare incidence is produced as the horizontal headlights spread angle increases. Swiveling headlights increase glare on highways left curves and reduce it on right curves. Practical Applications: The procedure and conclusions of this study can contribute to develop more effective glare avoidance technologies as well as identify and assess glare-prone sections. The glare evaluation assists in evaluating glare countermeasures such as deciding whether to place a vegetation barrier and where.     

HYDRUS-1D模型对河套灌区不同灌施情景下氮素迁移的模拟

选取河套灌区五原建丰的典型土壤,应用HYDBUS-1D 模型对不同灌溉强度、不同表施浓度以及将表施改为灌施3类情景下土壤氮元素的迁移进行了动态模拟,研究了灌溉和施肥对河套灌区典型区域土壤氮元素迁移的影响.结果表明,灌水强度小于0.10 cm·h-1时,铵态氮与硝态氨累积流出通量变化极为缓慢;强度大于 0.14 cm·h-1时,累积流出通量急剧攀升,表明氮元素大量向土层深层流失.铵态氮表施浓度的变化对氮素的迁移几乎没有影响.保持相同的施肥量,灌施情景对铵态氮迁移几乎无影响,但表施换为灌施后硝态氮下渗浓度增加47%,更易于向深层渗漏.     

基于三维“O”型圈的采空区多场分布特征数值模拟

为进一步研究综放采空区的多场分布特征,以大兴矿N2-706工作面为例,构建"双三"模型,即优化三维"O"型圈采空区冒落非均质多孔介质数学模型及"U"型通风方式下的三维综放采空区物理模型,重点考虑了采空区垂直方向上的孔隙率变化,并实现了孔隙率的三维可视化。运用Fluent软件加载自定义UDF对采空区气体压力分布、漏风场及氧气、瓦斯分布情况进行了数值模拟,得出与实际情况相吻合的采空区气体压力分布、合理漏风量范围内的风流场分布,其中重点分析瓦斯体积分数分布规律。结果表明:考虑三维孔隙率的数值模拟结果收敛性更好,采空区瓦斯的积聚现象不仅出现在采空区顶部,在距底板20~25 m高度的位置就大量上浮,且呈现高体积分数瓦斯积聚分布的特征规律。     

HIPS阻燃复合材料三元潜在火灾危险性评价

将高抗冲聚苯乙烯树脂颗粒(纳米/微米级)、十溴二苯乙烷颗粒、三氧化二锑、弹性体、分散剂和偶联剂通过一步熔融共混工艺先行制备UL94 V-0级阻燃母粒,再将其与HIPS本体树脂按不同比例混合制得阻燃复合材料,并利用极限氧指数(LOI)、垂直燃烧(UL94)及ISO 5660锥形量热计三项测试表征制得样品的燃烧和火灾性能,从中提炼和分析LOI、垂直燃烧等级和最大热释放速率(Pk HRR)等三元关键指标相关性,给出了定性定量相结合的潜在火灾危险性分级范围。结果表明:UL94燃烧等级和Pk HRR相关性体现为当Pk HRR≤330.0 k W/m~2时,试样UL94等级均为V-0级;UL94燃烧等级和LOI相关性体现为随UL94燃烧等级从V-0降到HB时,试样LOI从27.0降到17.0;Pk HRR与LOI相关性体现为Pk HRR与LOI呈粗略反向线性相关性;UL94燃烧等级、Pk HRR和LOI三元相关性体现为当LOI22.0、Pk HRR为399.0~665.0 k W/m~2时,材料UL94燃烧等级介于HB~V-2。     

贡湖生态修复区水质净化模拟与净化能力

利用三维水质模型,对藻类生长以及沉水植物（穗花狐尾藻、菹草、苦草）的生长和分布进行模拟,探讨春、夏不同季节情况下,贡湖生态修复区对流域内流入的氮、磷污染负荷的净化效果,旨在进一步定量地揭示沉水植物对富营养化水体净化的重要作用.结果表明贡湖生态修复区夏季（7~9月）出水口IV类水水质达标率略优于春季（3~5月）,主要体现在春季氮、磷污染负荷流入,刺激藻类生长,叶绿素a浓度较高;夏季沉水植物生长旺盛,能够与藻类竞争营养盐,从而抑制藻类生长.考虑氮磷污染物流入湖体的后续效应,180d内春季贡湖生态修复区总氮、总磷平均稀释净化效率分别为74.76%和71.00%,180d内夏季贡湖生态修复区总氮、总磷平均稀释净化效率分别为73.20%和64.65%.修复区最大净化能力估算结果为加强生态修复区的管理,保障清水还湖水质提供了参考依据.     

Scarcity, growth and R&D

The limits to economic growth due to resource scarcity can be alleviated only by the development of backstop substitutes. This paper combines resource-based economic growth with R&D to reduce the cost of backstop technologies. Characterizing the entire dynamics of optimal growth and R&D processes, we find that an economy's growth prospects depend on its type, as determined by its production technology and learning ability, and by its knowledge–capital endowment. A wide variety of growth patterns emerges, ranging from cases in which an economy that without R&D eventually stagnates (converges to a steady state) is diverted by R&D onto a path of sustained growth, to cases in which R&D is not warranted. Resource scarcity is shown to encourage R&D due to the increased reliance on the backstop technology.     

基于3D-σ数值模拟的锚喷支护机理解析

根据联拱隧道动态设计施工的实质,结合某在建隧道工程,采用3D-σ对隧道中导洞锚喷支护设计进行了力学响应动态模拟研究,并分析了锚喷支护机理以及围岩体应力场和位移变形状况,并由此提出了联拱隧道合理的施工工序,用以指导隧道施工,取得了较好的经济效益。