Two-machine flow-shop scheduling to minimize total late work: revisited

This article revisits the scheduling problem in a two-machine flow-shop system with the total late work criterion, which penalizes parts of jobs executed after their due dates. Firstly, it is shown that a lower bound presented previously in the literature, in the context of a branch-and-bound algorithm proposed for the same problem, is invalid. Then a novel proposal of the branch-and-bound method is given equipped with a new lower-bound technique, as well as an upper-bound and dominance rules. Numerical experiments show that the newly proposed lower-bound technique works well in cutting unpromising branches.     

Lowering the outdoor temperature in high-rise high-density residential developments of coastal Hong Kong: The vegetation influence

This paper investigates the impact of on-site variables on the influence of vegetation in lowering outdoor temperature. The study uses six critical on-site variables such as surface albedo, sky view factor, altitude, shrub cover, tree cover and average height to floor area ratio to carry out analysis in five data sets. The climatic parameters and physical characteristics were measured and surveyed, respectively in 216 stations in high-rise high-density residential developments of coastal Hong Kong. The data set is mainly categorised into peak summer clear sky days (PSCS-days), peak summer partially cloudy days (PSPC-days) and late summer days to address the issues related to cloudy sky conditions in Hong Kong. The trend analysis shows that at a lower sky view factor, ranging from 0.1 to 0.25, shrub cover as low as 10–15% in a 1000 m² open area is more effective in reducing outdoor temperature than the same level of tree cover in a location with a higher sky view factor (0.4 or above). The regression models used in this study were able to explain the influence of on-site variables on vegetation in lowering the outdoor temperature within the respective urban settings. In high-rise high-density environments, on-site variables such as sky view factor and altitude have a substantial impact on the influence of vegetation in lowering outdoor temperature. However, off-site variables such as high urban density and anthropogenic heat could negate the behaviour of sky view factor and altitude. The study suggests that increasing the tree cover from 25% to 40% in the pocket parks in coastal area residential developments of Hong Kong could reduce daytime urban heat island intensity (UHI) by further 0.5 °C.     

初探南宋后期以重庆为中心的山地城池防御体系

在长达40多年南宋后期的抗蒙战争中,以重庆为中枢、合川钓鱼城为支柱建立的山地城池防御体系,依山为点,以江为线,点线结合,网状分布,层次分明,改变了单个城池布防的策略,最大限度地发挥出多重城池防守的作用,创造了一个军事战争史上的奇迹。文中通过对山地城池防御体系的初步研究,旨在探索因地制宜、据险设防的山地城池构筑原则;以及依山建城、环江为池,独具山地特色的南宋军事建筑艺术魅力。     

元坝气田须三段气藏层序沉积与储层特征

四川盆地川东北元坝气田的多口井于上三叠统须家河组三段获得中—高产工业气流,表明该层段具有良好的天然气勘探开发潜力。为进一步做好该气田须三段气藏的开发前期评价工作,综合利用岩心观察、岩心样品薄片及岩心物性分析等资料,结合测井解释与地震储层预测成果,对该气藏的地层层序、沉积相、储层特征等进行了研究,分析了控制储层发育的主要因素。结果表明:(1)元坝地区须三段地层可划分为一个三级层序和五个四级层序,并进一步细分为五个砂组;(2)平行于物源方向的须三段地层厚度变化较大,呈"西北厚、东南薄"展布,前积特征明显,属于进积式辫状河三角洲沉积;(3)须三段气藏储集岩以钙屑砂岩为主,主要储集空间是溶孔—微溶孔,物性表现为特低孔—特低渗且非均质性强;(4)储层发育的最有利岩相为辫状河三角洲平原—前缘(即三角洲平原与三角洲前缘过渡位置)的分流河道钙屑砂岩,该沉积环境在一定程度上控制了该区须三段气藏储层溶蚀成岩作用的发育。     

元坝气田长兴组生物礁气藏特征及开发对策

四川盆地元坝气田是世界上已发现埋藏最深的高含硫碳酸盐岩气田,上二叠统长兴组生物礁气藏具有埋藏超深,礁体小、散、多期,储层薄、物性差、非均质性强,流体分布复杂,直井产量低等特点;气藏开发面临礁相白云岩储层时空展布规律研究需不断深化,小礁体精细刻画与薄储层定量预测困难,水平井部署与优化设计影响因素众多,长水平段水平井长穿优质薄储层难度大等诸多难题。为实现对该气田的高效开发,开展了生物礁储层分布规律与发育模式研究、小礁体精细刻画与薄储层定量预测、条带状小礁体气藏水平井优化设计、超深薄储层水平井轨迹实时优化调整等技术攻关。相关系列攻关成果有力地支撑了元坝气田的开发建设,建成了我国首个超深高含硫生物礁大气田,混合气产能可达40×10~8m~3/a。该气田的成功投产,一方面奠定了我国在高含硫气田开发领域的领先地位;另一方面,对保障"川气东送"沿线六省两市70多个城市的长期稳定供气,对促进中西部产业结构调整和沿江区域经济发展也具有重大意义。     

元坝气田超深酸性气藏石油工程技术实践与展望

位于四川盆地的元坝气田是我国目前已开发的埋藏最深的大型海相碳酸盐岩酸性气田,其上二叠统长兴组生物礁气藏具有超深、高含硫化氢、中低孔渗、储层厚度较薄等特征,气藏经济评价结果认为只有水平井才能降低总体开发投资进而有效开发该气藏。目前,全球开发该类超深高酸性气藏的石油工程技术实践较少,面临着超深水平井安全优快钻完井、测录井、井下作业、安全环保等一系列石油工程技术难题。为此,中石化西南石油工程有限公司以工程地质一体化为手段,基于成功开发普光气田的经验,通过针对性技术攻关和7年潜心实践,形成了超深高酸性气藏水平井钻井提速提效关键技术、超深水平井测录井关键技术、超深高酸性气藏井下作业核心技术和超深高酸性气藏安全环保技术等18项核心技术成果,在元坝气田一、二期产能建设中应用近40口井,全部建成商业气井,实现了34×108 m3净化气产能建设目标。所形成的超深酸性气藏石油工程系列技术对于国内外类似气藏的勘探开发具有借鉴作用。     

利用地球化学标志识别沉积环境：以中扬子台地北缘上震旦统为例

晚震旦世 ,中扬子台地北缘碳酸盐岩沉积发育 ,可分为浅水台地和深水台盆 2个相区和 7种不同相带。地球化学分析表明 ,该区地球化学特征与沉积环境有密切的关系 :常量元素Mn在局限海湾相中明显偏高 ,而在其它相带中均较低 ;微量元素B在台缘滩相中含量最低 ,仅 0 .82× 1 0 -6 ,而在其它相带中均大于1× 1 0 -6 ,最高可达 6.56× 1 0 -6 ;微量元素Sr和Sr/Ca× 1 0 3 比值与沉积环境密切相关 ,以浅滩相为中心 ,向局限海湾和深水盆地方向明显增加 ,呈双峰分布。因此 ,利用地球化学标志可以判别沉积相。图 4表 1参 7(邹冬平摘 )     

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川西地区新场气田生产层位是上株罗统蓬莱镇组。以往观点认为“侏罗红层”不具生烃能力。新场气田的气源来自上三叠以须家河组陆相含煤碎屑岩系。通过对新场气田蓬莱镇组沥青地球化学特征及成因的初步研究,探讨了川西地区侏罗系是否具备生烃能力,是有过液态石油烃生成和运移过程等问题。沥青饱和烃生源构成表明,沥青变异前的的油田两部分构成,即上伏上三叠统须家河组和侏罗系暗色泥岩供给的原油。色谱特征和族组成碳同位素资料表     

塔东北地区上震旦统—下古生界沉积演化

塔里木盆地东北部上震旦统—下古生界经历了漫长的沉积演化过程,是一套巨厚的以碎屑岩为主的沉积。根据该区露头、地震资料,结合钻井信息,应用层序地层学理论,对该套地层的沉积演化史进行了分析,认为该区上震旦统—下古生界存在四个不整合面和二个可能的不整合界面,据此可将这套地层划分出5个三级层序,4套完整的生、储、盖组合。     

聚丙烯催化剂研究进展

综述了Ziegler-Natta聚丙烯催化剂技术的发展历史与研究动态,介绍了茂金属催化剂和后过渡金属催化剂的研究进展,展望了未来聚丙烯催化科技术的发展前景．提出了我国发展聚丙烯催化剂的建议。