共查询到20条相似文献，搜索用时 93 毫秒
1.
公路路基施工是公路施工质量保障的基础,也是公路的主体,因此路基施工的重要性在整个施工过程中应受到施工单位的高度重视。其中保证施工质量,认真监管路基施工是施工环节中应重点考虑的问题。本文主要从施工放样、路基施工和施工程序三个方面,结合多年来的经验对其进行了较详细的阐述。 相似文献
2.
施工组织设计是施工技术和施工管理的有机结合体,是指导施工的重要技术经济文件,其本身的质量对工程建设的成败和经济效益具有决定性的影响。因此,提高施工组织设计编制工作的质量具有重大意义。现对施工阶段施工组织设计编制工作的改进提出一些粗浅的见解。1施工组织设计编 相似文献
3.
4.
指出了桥梁项目中简支拱的施工环节相对较为繁琐,并且施工起来难度较大。在简支施工的过程中要求选用高效且适当的手段。以实际工程为例,对系梁支架施工、系梁施工和拱肋施工进行了分析,提出了拱肋施工的控制措施,可保障箱梁作业的安全性与稳定性,有效地缩短施工的工期,提升作业的效益。 相似文献
5.
6.
为提高对项目施工的认识,提出林业施工企业推行项目法施工的难点及对策,改革原有施工管理体制,增强施工企业活力。 相似文献
7.
就控制施工缝的留置位置进行分析,得出按照施工规范与要求留置和处理施工缝,施工缝处的混凝土强度不会低于设计强度要求,施工缝的质量也能得到较好的控制和保证。 相似文献
8.
9.
投标书中的施工组织计划是投标报价的一个重要环节.结合南宁至北海高速公路(三岸)至南间段路基Ⅰ段K1 212,72跨TB立交桥、投标书的施工组织计划编制,从施工方案的选择、施工场地设置、施工方法及工艺流程、施工进度及资源调配计划的编制三方面,介绍了投标书的施工组织计划编制. 相似文献
10.
11.
12.
《Scandinavian Journal of Forest Research》2012,27(2):158-165
The short-term effect of thinning on cronartium rust on Scots pine ( Pinus sylvestris L.) was investigated in a stand of Scots pine (artificially seeded and in the pole-stage) severely infected by the stem-rust fungus Cronartium flaccidum (Alb. & Schwein) G. Winter. The disease rate (the number of old and fresh infections) was recorded before thinning, after which all trees with a resin-top as well as all individual branches with sporulating lesions were removed from the thinned plots, while the comparison plots remained non-thinned. The numbers of sporulating lesions were recorded on the plots annually for 2-5 yrs after thinning. Thinning had no significant short-term effect on the year-to-year relative number of sporulating lesions. The relative number of sporulating lesions, however, increased in both thinned and nonthinned trees, varying significantly from year to year. Thinning had no significant effect on the year of formation of the shoot bearing annual sporulating lesions, the duration of sporulation or the growth of the fungus along the infected shoot in perennial lesions during the first 5 yrs after the treatment. 相似文献
13.
本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献
14.
《Scandinavian Journal of Forest Research》2012,27(5):436-445
Accumulation of cadmium (Cd), lead (Pb) and mercury (Hg), as affected by organic matter content, pH of different soil compartments and the physicochemical properties of each metal, was studied in different soil types within two forested catchments of the Norway spruce (Picea abies - Vaccinium myrtillus) type. Independent of soil type, the highest metal concentrations were found in the organic layers of the soil, usually in the surface soil. The concentrations in the upper part of the mineral subsoil were about one-fifth to one-tenth, or less, of those in the organic surface soil. Concentration maxima in the B-horizon were more pronounced for Cd and Hg than for Pb. When comparing soil types, the highest concentrations of Cd were found in the less acidified fens in the discharge area, while for Hg and Pb the highest concentrations usually occurred in the mor layer of the well-drained Podzols. For all metals, the soil types with the largest accumulation had concentrations up to 2-3-fold higher in the organic layers than those with the smallest accumulation. 相似文献
15.
IntroductionDuringthepasttwodecades,studieshaverevealedthatgrowingash(Fnainusmandshurica)andlarch(LarlksPP.)togetherinaproperwaycanincreasetheproduc-tivityQfthestandsI"'}'-'].Theyieldimprovementmechanismsattributetotwoaspects,i.e.,theabovegroundandundergr… 相似文献
16.
方文彬 《中南林业科技大学学报(自然科学版)》1995,(2)
采用碘溶液和氢氧化钠两种溶液的混合液处理针叶树材管胞弦壁切片，并用干燥法脱除切片胞壁水，对碘结晶法测量木材微纤丝角的方法进行改良．结果表明，切片的木素脱除干净彻底，次生壁微纤丝之间易形成空隙，有利于碘离子进入其中形成碘结晶，可清晰地观察到微纤丝的走向，有利于有效而准确地测量微纤丝角，与改良前进行比较，具有省时省力，节约经费的优点． 相似文献
17.
Xinglian Geng Ryuichiro Kondo Kokki Sakai Zhongzheng Lee 《Journal of Wood Science》1999,45(2):143-148
A strain of the fungusCoriolus versicolor was inoculated periodically into potato dextrose agar (PDA) slants containing the effluent to enhance the natural ability to grow in the effluent. The acclimated strain grown in the 50% effluent-containing PDA slant and the original strain were employed to treat the effluent. The acclimated strain could grow in a higher concentration of the effluent than the original unacclimated one. Both the original and acclimated strains improved the dispersing ability of the effluent, especially the acclimated strain because of its higher laccase secretion. The dispersing ability of the SFP effluent was improved to a level comparable to a commercial lignosulfonate product because it was strongly polymerized by the fungus. During the fungal treatment, more than 50% of the sugars were removed from the effluent, thereby increasing the purity of the SFP lignin product.This work was presented at the 48th annual meeting of the Japan Wood Research Society, April 3–5, 1998, Shizuoka, Japa 相似文献
18.
森林冠层结构与功能及其时空变化研究进展* 总被引：16，自引：0，他引：16
林冠是森林与外界环境相互作用最直接和最活跃的界面层 ,同时 ,它本身又承载了森林生物多样性的主体部分。森林冠层研究的方法和技术在近些年取得了长足发展 ,从而促进了有关林冠结构与功能的研究。这些研究深化了人们对于林冠结构与光能截获以及群落干物质积累之间关系的认识 ,同时 ,对于森林冠层的物质循环和能量传输以及冠层内各营养级之间相互关系动态也有了更为深入的理解。考察森林冠层的结构与功能及其时空变化是深入理解整个森林生态系统的格局、过程及其运作机制的重要基础。 相似文献
19.
Pedro Ah Shenga Peter Bomark Olof Broman Dick Sandberg 《Wood material science & engineering》2017,12(4):257-262
The sawmill industry is a very important link in the Mozambique forest products value chain, but the industry is characterized by undeveloped processing technology and high-volume export of almost unrefined logs. The low volume yield of sawn timber has been identified as a critical gap in the technological development of the industry. To improve the profitability of the industry, there is thus a need to develop methods and techniques that improve the yield. In this paper, different positioning of logs prior to sawing and the possibility of increasing the volume yield of crooked logs by bucking the logs before sawing have been studied. A computer simulation was used to study the cant-sawing and through-and-through sawing of the logs to determine the volume yield of sawn timber from the jambirre (Millettia stuhlmannii Taub.) and umbila (Pterocarpus angolensis DC.) species. The optimal position, i.e. the position of the log before sawing that gives the highest volume yield of sawn timber for a given sawing pattern when the positioning parameters, offset, skew and rotation, are considered gave a considerable higher volume yield than the horns-down position. By bucking very crooked logs and using the horns-down positioning before sawing, the volume yield can be of the same magnitude as that obtained by optimal positioning on full-length (un-bucked) logs. The bucking reduces the crook of the logs and hence increases the volume yield of sawn timber. 相似文献
20.
Effect on maize growth of the interaction between increased nitrogen availability and competition with trees in alley cropping 总被引：1，自引：0，他引：1
Maize growing next toErythrina hedgerows had 44% lower biomass (p<0.01) and 35% lower N content (p<0.1) than maize growing in the middle of the alleys. Maize growing next toGliricidia hedgerows had the same biomass but 56% higher N content (p<0.1) than maize growing in the middle of the alleys. However these differences did not develop until 2 months after sowing of the maize.Spatial variability in soil nitrogen mineralization and mulch nitrogen release did not explain any of the differences in growth or N uptake of the maize with respect to distance from the trees. It is hypothesized that the slower growth of the maize next to theErythrina trees after 2 months is due to increasing light and/or nutrient competition from the trees as the trees recover from pollarding. The apparent lack of competition fromGlirigidia may be due to different rates of regrowth or different shoot and root architecture.A theoretical model is described demonstrating that if a crop is to take advantage of the higher nutrient availability under alley cropping it must complete the major part of its growth before the trees recover significantly from pollarding, and start competing strongly with the crop. 相似文献