夯能和夯击次数在西部山区公路填方路堤中的应用

文章介绍了强夯法在国内外研究和应用的现状,结合强夯在西部山区填方路堤再压实的试验,分析了夯能和夯击次数对填方路堤沉降量的影响,提出了不同夯能条件下夯击次数的具体取值范围,为今后同类工程的设计和施工提供参考。     

上海与舟山市建立联合港区的设想

为了适应改革开放的新形势,上海港正在积极兴建新的万吨级泊位,同时对老码头进行技术改造,建立新作业区,鼓励货主自建专用码头和筹建新港区等。但作者认为,由于受长江口航道的水深限制,上海港难以成为西太平洋的枢纽大港。为了充分发挥上海市的优势,又弥补自然条件的不足,作者建议上海与拥有自然深水区域的毗邻舟山市开展横向合作,在舟山岛西南的野鸭山水域建立联合港区,建议由上海的电力企业、海运局、港务局和舟山市建立煤炭联运集团,由上海的钢铁企业、远洋运输公司、港务局、梅山钢铁公司和舟山市建立钢铁矿石联运集团。     

大骨节病和克山病共存区心电图和干骺端病变及发尿硒含量间关系的研究

通过大骨节病和克山病共存地区360名小学生手部 X 线、心电图和发、尿硒分析,结果,干骺端病变检出率为16.16%,X 线异常率为37.22%,心电图异常率为13.06%,大骨节病阳性体征和(或)X 线异常总检出率为56.11%;异常心电图与异常 X 线、阳性体征和(或)X 线征符合率分别为53.19%和72%.心电图和 X线2项检出率呈显著正相关关系;心电图、干骺端病变检出率与发、尿硒呈负相关关系.本文结果结合文献报道低硒地区有单独大骨节病、克山病存在的事实,提示病区不同人体硒水平可造成发、尿硒含量与心电图、干骺端病变检出率间有相关关系,也使心电图与 X 线2项检出率间有相关关系。不能单从两病共存地区心电图、干骺端病变、发尿硒间这种相关关系及心电图和 X 线有较高符合率,说低硒是大骨节病、克山病的共同病因,也不能说大骨节病和克山病是同病异症。     

台湾海峡冬季大风浪时的航法探讨技

台湾海峡是我国南北海运的必经之道,台湾岛是我国东南沿海各港口通往太平洋各国的重要驿站,实现两岸直接“三通”,将有力地推动海峡两岸的海运事业的发展,推进两岸经济的共同繁荣。为确保航行安全,根据实践经验,提出几条在大风浪条件下主要直航航线的航法及注意事项。     

锚泊时船舶放链长度的确定及其实用图表

本文给出了船舶锚泊时所受到的风作用力、水作用力和放出锚链长度的计算公式,以及实用数表和曲线图,可供查取。数表和曲线是根据文中确定的如下关系式编绘:L_b≈1/2Ln;L≈1.5L。(其中L_b——卧底锚链长度;L_n——悬垂锚链长度;L——放出锚链总长度)。十一例实船计算表明,根据上式计算结果,与目前国内外通用的方法确定的放链长度相符。利用这些数表和曲线图,既可合理地确定不同海况下船舶所应放出的锚链长度,也可减少起锚时的功率消耗和缩短起锚时间。     

Linking land use and transportation in a rapidly urbanizing context: A study in Delhi,India

Cities in developing countries like India are facing some of the same concerns that North American cities are: congestion and urban growth. However, there is a sense of urgency in cities like Delhi, India in that this growth is far more rapid as both urbanization and motorization are ongoing processes that have not yet peaked. In this paper, we examine land use change and its relationship with transportation infrastructure and other planning related variables in a spatial context. We estimate land use change models at two different scales from separate data. Cellular automation and Markov models were used to understand change at the regional scale and discrete choice models to predict change at the local level. The results suggest that land use in the Delhi metropolitan area is rapidly intensifying while losing variety. These changes are affected by industrial, commercial and infrastructure location and planners and policy-makers need to better understand the implications of location decisions. We also examine these results in the context of a policy framework for data-based planning that links land use and transportation models for Delhi.     

水下航行体通气超空泡的实验研究

为了研究超空泡的减阻效果,保证在较低流速下生成超空泡,在水洞中开展了水下航行体通气超空泡的实验研究.采用通气的方法在较低水速下(V=7-15 m/s)生成人工通气超空泡,通过改变通气率和弗洛德数,获得了不同条件下通气空泡的长度,给出了通气空泡长度与通气率及弗洛德数的经验公式.研究表明,来流速度不变时,空泡长度随通气率的增加而增加,空泡长度一定时,通气率随弗洛德数的增加而减少;重力场造成了空泡形态的严重不对称,通过比较相同空化数下自然空泡与通气空泡的长度,定量地给出了弗洛德数对通气空泡长度的影响.当Fr=43.74时,重力场对通气空泡长度的影响几乎可以忽略.     

Carbonate chemistry dynamics and carbon dioxide fluxes across the atmosphere–ice–water interfaces in the Arctic Ocean: Pacific sector of the Arctic

Climatic changes in the Northern Hemisphere have led to remarkable environmental changes in the Arctic Ocean, which is surrounded by permafrost. These changes include significant shrinking of sea-ice cover in summer, increased time between sea-ice break-up and freeze-up, and Arctic surface water freshening and warming associated with melting sea-ice, thawing permafrost, and increased runoff. These changes are commonly attributed to the greenhouse effect resulting from increased atmospheric carbon dioxide (CO₂) concentration and other non-CO₂ radiatively active gases (methane, nitrous oxide). The greenhouse effect should be most pronounced in the Arctic where the largest air CO₂ concentrations and winter–summer variations in the world for a clean background environment were detected. However, the air–land–shelf interaction in the Arctic has a substantial impact on the composition of the overlying atmosphere; as the permafrost thaws, a significant amount of old terrestrial carbon becomes available for biogeochemical cycling and oxidation to CO₂. The Arctic Ocean's role in determining regional CO₂ balance has been ignored, because of its small size (only  4% of the world ocean area) and because its continuous sea-ice cover is considered to impede gaseous exchange with the atmosphere so efficiently that no global climate models include CO₂ exchange over sea-ice. In this paper we show that: (1) the Arctic shelf seas (the Laptev and East-Siberian seas) may become a strong source of atmospheric CO₂ because of oxidation of bio-available eroded terrestrial carbon and river transport; (2) the Chukchi Sea shelf exhibits the strong uptake of atmospheric CO₂; (3) the sea-ice melt ponds and open brine channels form an important spring/summer air CO₂ sink that also must be included in any Arctic regional CO₂ budget. Both the direction and amount of CO₂ transfer between air and sea during open water season may be different from transfer during freezing and thawing, or during winter when CO₂ accumulates beneath Arctic sea-ice; (4) direct measurements beneath the sea ice gave two initial results. First, a drastic pCO₂ decrease from 410 μatm to 288 μatm, which was recorded in February–March beneath the fast ice near Barrow using the SAMI-CO₂ sensor, may reflect increased photosynthetic activity beneath sea-ice just after polar sunrise. Second, new measurements made in summer 2005 beneath the sea ice in the Central Basin show relatively high values of pCO₂ ranging between 425 μatm and 475 μatm, values, which are larger than the mean atmospheric value in the Arctic in summertime. The sources of those high values are supposed to be: high rates of bacterial respiration, import of the Upper Halocline Water (UHW) from the Chukchi Sea (CS) where values of pCO₂ range between 400 and 600 μatm, a contribution from the Lena river plume, or any combination of these sources.     

库水位循环作用下架空斜坡式码头力学性能研究

依托云南省富宁港一期工程,建立架空斜坡式码头三维有限元模型。基于水岩相互作用,考虑岸坡岩土体在库水位循环作用下的劣化损伤,定性分析得到架空斜坡式码头桩基及轨道梁的弯矩、剪力及轴力变化特点,为进一步研究库水位循环作用下架空斜坡式码头整体性能及力学退化特性提供基础,为实际工程中库区码头运营后的监测及防护提供建议。     

高纬度多年冻土区漠北公路路基变形特征分析

通过漠北公路沿线各试验段不同冻土条件和工程措施下各层土体沉降变形状况,分析东北高纬度岛状多年冻土区路基沉降变形主要发生土层部位及其破坏原因。分析结果表明:路基施工完成后早期路基变形较大,主要由工后不均匀沉降变形引起,变形主要由原天然地面下季节活动层的沉降压缩变形等引起,由于运营时间较短,由多年冻土融化引起的沉降变形很小。路基沉降变形主要发生在暖季,在冷季（11月~次年6月）路基基本保持稳定,变形很小。路基整体变形状况与冻土含冰量、冻土地温有一定的关系。高温多年冻土区比低温多年冻土区变形大。