半悬空集材索道设计系统

本文在半悬空集材索道设计的数学模型及其理论推导的基础上,用高级BASIC语言编程.该系统能对单跨半悬空集材索道的三种类型(两端固定式、松紧式、运行式)分别进行完整的设计计算.并绘制索道纵断面图。     

MECHANICAL ANALYSIS OF TREE SPARS IN CABLE YARDING SYSTEMS

Tree spars,as appropriate supports for cable yarding systems,have to beverified for the strength before any real operation.This paper gives theoretical analysisfor various cases.Tree spars without guylines are normally under heavy bending stress,which dominates the strength design.For tree spars equipped with guylines,the spardeflection follows the same way as an unguyed spar.The overload of the bending stressremains the main reason of spar failures.Several diversities of tree spars from theidealized condition are investigated for the sake of better modeling of the real situation.Analysis supports that the tree spar can generally be treated as a straight cylindricalcolumn without giving significant errors.The load can be handled as centrically applied.Design methods are provided for both guyed and unguyed tree spars,which will benefit thepractice of using tree spars as an alternative for steel spars.     

Optimum geometric layout of a single cable road

Cable-based technologies have been a backbone for harvesting on steep slopes. The layout of a single cable road is challenging because one must identify intermediate support locations and heights that guarantee structural safety and operational efficiency while minimizing set-up and dismantling costs. Our study objectives were to (1) develop an optimization approach for designing the best possible intermediate support layout for a given ground profile, (2) compare optimization procedures between linearized and nonlinear analyses of a cable structure and (3) investigate the effect of simplifying a multi-span representation. Our results demonstrate that the computational effort is 30–60 times greater for an optimization approach based on nonlinear cable mechanical assumptions than when considering linear assumptions. Those nonlinear assumptions also stipulate lower heights for intermediate supports and a larger span length. Finally, compared with the unloaded case, tensile force in the skyline is increased by as much as 80% under load for a single-span skyline configuration. Our approach provides additional value for cable operations because it ensures greater structural safety at a lower cost for installation. Improvements are still needed in developing a stand-alone application that can be easily distributed. Moreover, our rather simple assumptions regarding set-up and dismantling costs must be refined.     

The ability of a carriages developed for a mobile tower yarder: A comparison of the hauling force and walking time in a line pulling out process

The ability of a newly developed carriage equipped with a remote control lock and self line extraction system manufactured by Oikawa motors Co., Ltd. was analyzed. The study investigated the reduction of the work load of the choker setter in the haul line-pulling out process of a cable logging system by a mobile tower yarder. The main objective was to compare the walking time, pulling out time, and the tension force using the three types of cable setting method, a running skyline with a simple carriage, a fixed skyline with a simple carriage and a fixed skyline with a newly developed carriage. The measuring of haul line pulling out was conducted on different slope gradients at different distances from the tower spar by four choker setters. The study showed that choker setters could reduce the force exerted by about 33%, and a decrease in the heart beat rate of 12%, when using the fixed skyline with the newly developed carriage as opposed to the running skyline with the simple carriage. The fixed skyline with the newly developed carriage resulted in more pulling speed than the running skyline with the simple carriage on the slope gradient of over 2° and the fixed skyline with simple carriage on the slope gradient of over 7°. With the newly developed carriage the pulling tension, time and heart rate are lower, when the haul line is pulled out. Thus it can be concluded that the new carriage is more productive than the simple carriage in the line pulling out process.     

Tree row spacing affected agronomic and economic performance of Eucalyptus-based agroforestry in Andhra Pradesh, Southern India

The 3 × 2 m spacing currently used for eucalyptus plantations in the state of Andhra Pradesh, southern India does not permit intercropping from the second year. This discourages small landholders who need regular income from taking up eucalyptus plantations and benefiting from the expanding market for pulpwood. Therefore, on-farm experiments were conducted near Bhadrachalam, Khammam district (Andhra Pradesh) for over 4 years from August 2001 to November 2005 to examine whether wide-row planting and grouping of certain tree rows will facilitate extended intercropping without sacrificing wood yield. Eucalyptus planted in five-spatial arrangements in agroforestry [3 × 2 m (farmers’ practice), 6 × 1 m, 7 × 1.5 m paired rows (7 × 1.5 PR), 11 × 1 m paired rows (11 × 1 PR) and 10 × 1.5 m triple rows (10 × 1.5 TR)] was compared with sole tree stands at a constant density of 1,666 trees ha^?1. Cowpea (Vigna unguiculata) was intercropped during the post-rainy seasons from 2001 to 2004, and fodder grasses (Panicum maximum and Brachiaria ruziziensis) were intercropped during both the seasons of 2005. At 51 months after planting, different spatial arrangements did not significantly affect height and diameter at breast height (dbh). Total dry biomass of eucalyptus in different spatial arrangements ranged between 59.5 and 52.9 Mg ha^?1, the highest being with 6 × 1 m and the lowest with 10 × 1.5 TR, but treatment differences were not significant. The widely spaced paired row (11 × 1 PR) and triple row (10 × 1.5 TR) arrangements produced 62–73% of sole cowpea yield in 2003, 59–66% of sole cowpea yield in 2004, and 79–94% of sole fodder in 2005. In contrast, the 3 × 2 m spacing allowed only 17–45% of sole crop yields in these years. The better performance of intercrops in widely spaced eucalyptus was likely because of limited competition from trees for light and water. Intercropping of eucalyptus in these wider rows gave 14% greater net returns compared with intercropping in eucalyptus spaced at 3 × 2 m, 19% greater returns compared with that from sole tree woodlot and 263% greater returns compared with that from sole crops. Therefore, in regions where annual rainfall is around 1,000 mm and soils are fairly good, eucalyptus at a density of 1,666 plants per ha can be planted in uniformly spaced wide-rows (6 m) or paired rows at an inter-pair spacing of 7–11 m for improving intercrop performance without sacrificing wood production.     

基于环境影响的公路路线方案优选

本文综合分析了公路建设中与公路选线相关的环境影响问题 ,在此基础上构建了基于环境影响的公路路线方案评价指标体系 ,并探讨了用于路线方案综合评价的数学模型。     

谈建筑施工中塔式起重机四大机构的润滑介质

建筑施工中的塔式起重机是重要的起重机械，它的四大机械有起升机构、回转机构、变幅机构、顶升机构。本论述了这四大机构润滑介质的使用选择。     

谈筑路小型液压挖掘机的发展

文中分析国外筑路小型液压挖掘机的生产、发展以及市场情况，同时探讨该产品在我国的生产现状及制约因素。     

哈尔滨松花江斜拉大桥9#主塔承台施工

大体积砼浇筑、冬季施工、水中作业是桥梁施工的难点，通过哈尔滨松花江斜拉大桥9^#主塔承台实施实践，分析总结了这三个施工工艺，从而为指导桥梁施工提供了参考。     

Forest road design with soil sediment evaluation using a high-resolution DEM

In this study, we combined a program to optimize forest road alignments with a method for prediction of surface erosion and related sediment delivered to streams. Combining the forest road design program with the high-resolution digital elevation model made it possible to estimate soil sediment based on a standard methodology, because a relatively accurate road prism could be generated. The combined program properly places and spaces drainage structures based on the Washington State Forest practice board manual. We applied the program to a part of Capitol State Forest in Washington State and optimized horizontal and vertical alignments while estimating movement of soil sediment from roads to streams. We discussed the effects of road surface materials, near-stream culvert distance to stream, and out-sloped forest road template on total road costs and soil sediment delivered to streams. Using lower quality rock surfacing reduced total costs, but the amount of soil sediment from lower quality rock surfacing was 1.5 times more than that on a higher quality rock traction surface. Therefore, lower quality rock surfacing should not be used near the stream. The placement of near-stream culverts 15 m upstream and out-sloped road template were examined using a traction surface on 15-m sections upstream and lower quality rock surfacing on other sections in order to reduce soil sediments to the stream and total costs. As a result, placing near-stream culverts 15 m upstream and using an out-sloped road template significantly reduced total road cost and soil sediment. Finally, we optimized horizontal and vertical alignments while limiting soil sediment to a specified maximum level. The model successfully optimized forest road alignments, which reduced total road cost as well as soil sediment.     

Pile movement and nutrient distribution in the soil around slash piles produced during whole-tree logging by a yarder and a processor

After mechanized whole-tree harvesting at a clear cutting site, using a cable yarding system and a processor, piles of slash remain at the landing areas near roads. This study examined the movement of slash piles and their effect on soil nutrients in the ground below the pile. The profile of one pile was measured for three years. In order to investigate nutrient concentrations, soil was sampled at two sites. The volume of the pile decreased by 6% per year. Piles placed on convex or uniform hillsides are stable, and have a low risk of sliding on a slope. Analysis of the water-soluble nutrients in the soil suggests that water carries nutrients from the pile into the soil up toca. 7 m from the pile. There is a reduction in soil acidity, and rainwater flow from the pile adds several minerals to the soil, particularly Ca. Slash in a pile on a convex or uniform hillside does not have any impact on a forest, either positively or negatively. We should try to return slash to stands or utilize it as a biomass resource. This study was supported by a Grant-in-Aid of Scientific Research (No. 09660164) from the Ministry of Education, Science, and Culture, of Japan.     

道路钢纤维混凝土性能的探讨

本文论述了掺钢纤维对混凝土抗压强度、抗折强度及磨耗性能的影响，分析了钢纤维复合材料抗压强度、抗折强度及耐磨耗。试验证明，混凝土掺钢纤维可显著减少混凝土的磨耗和提高混凝土的抗折强度，使用在路面工程中是效果最好的。     

Optimal upgrading of forest road networks: Scenario analysis vs. stochastic modelling

A two-stage stochastic model with binary choice in the first stage has been developed to optimise the upgrading of a real-world forest road network, geographically located in the middle of Sweden. We have compared the model with solutions to the same problem from deterministic scenario analysis. Upgrade policies can be achieved swiftly using both approaches, since the road network is of moderate size. However, a deterministic approach is considerably faster when larger problems are involved. The study here, furthermore, indicates that deterministic scenario analysis provides us with quick, near-optimal solutions to the stochastic model, which are of reasonable good quality. We conclude that the model used here is rather insensitive to uncertainty in critical period length, such as the length of spring thaw, at least when applied to the medium-sized problem presented here. Nevertheless, we strongly recommend the use of the stochastic model whenever possible, since the stochastic and deterministic solutions differ, due to the hedging effect in the stochastic solution.     

南方型杨树人工林最适经营密度的研究

针对湖北省南方型杨树人工林的现实特点,根据31块详细样地资料,以密度二次效应模型为基础,利用动态规划方法,对南方型杨树人工林的最适经营密度进行了探讨,同时,在兼顾单株营养面积和群众栽培习惯,以及造林可操作性的前提下,提出了适合于南方型杨树人工林在不同立地条件下的造林株行距,可为造林施工、林分抚育间伐和综合经营提供科学依据。     

土工合成材料在西部公路排水设计中的应用

本文叙述了土工合成材料在西部公路排水设计中的应用概况 ,以国内外土工合成材料在排水设计中的应用研究为基础 ,提出了应用土工合成材料进行公路排水设计的方法和发展前景。     

Assessment of cable tensile forces in active winch-assist harvesting using an anchor machine configuration

European Journal of Forest Research - The growing interest in accessing steep terrain is pushing the expansion of the operating range of ground-based machines through winch-assist technology....     

简述利用土钉治理边坡

简述土钉在公路边坡治理中的作用和特征，简介土钉施工方面的内容。     

无卷筒离合器的轻型绞盘机设计

为适应我国山地丘陵多、坡度陡和绞盘机作业强度大、维护不便等特点,提升绞盘机的操作性和转运能力,设计了一种无卷筒离合器的轻型绞盘机,阐述了绞盘机总体布置方案和工作原理,设计了采用齿轮传动的新型选筒机构,取代传统绞盘机的卷筒离合器,传动可靠,制造工艺简单,对选筒机构的花键轴和齿轮进行了强度校核,并对绞盘机传动系统的主要零部件进行了选型与设计,利用Matlab对绞盘机卷筒进行了轻量化优化设计,利用Solidworks进行了卷筒三维建模和有限元分析。结果表明,优化后的卷筒强度满足要求。该绞盘机采用新型的选筒机构,结构紧凑,安全可靠,整机轻量化程度高,便于运输,操作简便,可以有效提升绞盘机的工作效率。     

在路桥施工中应用土工布的几点做法和体会

本文论述了土工布在道桥施工中遇到护坡时以及城市道路改造工程中作为反滤层的特点,土工布在施工中的方法及注意事项。     

Evaluation of standing tree quality of Japanese cedar grown with different spacing using stress-wave and ultrasonic-wave methods

The quality of wood in 47-year-old standing trees of Japanese cedar grown in five plantation sites with different spacing (A, 1×1m; B, 2×2m; C, 3×3m; D, 4×4m; E, 5×5m) was evaluated using stress-wave and ultrasonicwave propagation methods. The magnitude of the velocities of these waves and the calculated dynamic modulus of elasticity (MOE) were used as indexes for assessing wood quality in standing trees. Results indicated that plantation spacings had moderate influence on the stress-wave and ultrasonic-wave velocities, and the degree of influence varied with the wave-propagating direction. Regardless of the testing method used, the velocities of waves propagated parallel to the grain in the standing trees with medium and poor growth conditions were significantly greater than those with superior growth conditions. The dynamic MOE of the trunk of standing trees of Japanese cedar was calculated by adjusting the effective mobility of free water and effective density in the trunk at various moisture contents. Results indicated that the dynamic MOE of wood in the standing trees of Japanese cedar was affected somewhat by the testing methods used. Furthermore, the dynamic MOE of the wood in the standing trees varied with the growth conditions imposed.Part of this report was presented at the World Conference on Timber Engineering, Montreax-Lausanne, Switzerland, August 17–20, 1998